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*Furnace Type (spray roaster, fluidised bed or combined furnace)
*Physical Properties of Iron Oxide By-Product (ferric oxide powder or pellets)
*Purity and commercial value of Iron Oxide By-Product
**Cl content
**SiO content (typically 40 to 1000 ppm)
**other impurities
**specific weight (typically 0.3 to 4 kg per litre)
**specific surface (typically 0.01 to 8 m2/g)
*Energy Consumption (between 600 and 1200 kcal/L)
*Fuel type
*Concentration of regenerated acid (typically approx. 18% wt/wt)
*Purity of regenerated acid (remaining Fe content, Cl content)
*Recovery efficiency (typically 99%)
*Rinse water utilization
*Stack emissions (HCl, Cl, Dust, CO, NOx)
*Liquid effluents (composition, amount) | 1 | Inorganic Reactions + Inorganic Compounds |
Trioxidane readily decomposes into water and singlet oxygen, with a half-life of about 16 minutes in organic solvents at room temperature, but only milliseconds in water. It reacts with organic sulfides to form sulfoxides, but little else is known of its reactivity.
Recent research found that trioxidane is the active ingredient responsible for the antimicrobial properties of the well known ozone/hydrogen peroxide mix. Because these two compounds are present in biological systems as well it is argued that an antibody in the human body can generate trioxidane as a powerful oxidant against invading bacteria. The source of the compound in biological systems is the reaction between singlet oxygen and water (which proceeds in either direction, of course, according to concentrations), with the singlet oxygen being produced by immune cells.
Computational chemistry predicts that more oxygen chain molecules or hydrogen polyoxides exist and that even indefinitely long oxygen chains can exist in a low-temperature gas. With this spectroscopic evidence a search for these type of molecules can start in interstellar space. A 2022 publication suggested the possibility of the presence of detectable concentrations of polyoxides in the atmosphere. | 1 | Inorganic Reactions + Inorganic Compounds |
Reaction of diborane with ammonia mainly gives the diammoniate salt (diammoniodihydroboronium tetrahydroborate). Ammonia borane is the main product when an adduct of borane is employed in place of diborane:
It can also be synthesized from sodium borohydride. | 1 | Inorganic Reactions + Inorganic Compounds |
Hexachlorophosphazene has a core with six equivalent P–N bonds, for which the adjacent P–N distances are 157 pm. This is characteristically shorter than the ca. 177 pm P–N bonds in the valence saturated phosphazane analogues.
The molecule possesses D symmetry, and each phosphorus center is tetrahedral with a Cl–P–Cl angle of 101°.
The ring in hexachlorophosphazene deviates from planarity and is slightly ruffled (see chair conformation). By contrast, the ring in the related hexafluorophosphazene species is completely planar. | 1 | Inorganic Reactions + Inorganic Compounds |
Xenon trioxide is an unstable compound of xenon in its +6 oxidation state. It is a very powerful oxidizing agent, and liberates oxygen from water slowly, accelerated by exposure to sunlight. It is dangerously explosive upon contact with organic materials. When it detonates, it releases xenon and oxygen gas. | 1 | Inorganic Reactions + Inorganic Compounds |
Because the stereoselectivity of carbocupration is extremely high, the reaction has been applied to the synthesis of pheromones in which the geometric purity of double bonds is critical. One example is the insect pheromone of Cossus cossus, which is synthesized by syn-selective carbocupration of acetylene and alkylation of the resulting organocuprate in the presence of added phosphite. | 0 | Organic Reactions |
Trioxidane can be obtained in small, but detectable, amounts in reactions of ozone and hydrogen peroxide, or by the electrolysis of water. Larger quantities have been prepared by the reaction of ozone with organic reducing agents at low temperatures in a variety of organic solvents, such as the anthraquinone process. It is also formed during the decomposition of organic hydrotrioxides (ROOOH). Alternatively, trioxidane can be prepared by reduction of ozone with 1,2-diphenylhydrazine at low temperature. Using a resin-bound version of the latter, relatively pure trioxidane can be isolated as a solution in organic solvent. Preparation of high purity solutions is possible using the methyltrioxorhenium(VII) catalyst. In acetone-d at −20 °C, the characteristic H NMR signal of trioxidane could be observed at a chemical shift of 13.1 ppm. Solutions of hydrogen trioxide in diethyl ether can be safely stored at −20 °C for as long as a week.
The reaction of ozone with hydrogen peroxide is known as the "peroxone process". This mixture has been used for some time for treating groundwater contaminated with organic compounds. The reaction produces HO and HO. | 1 | Inorganic Reactions + Inorganic Compounds |
An antichlor is a substance used to decompose residual hypochlorite or chlorine after chlorine-based bleaching, in order to prevent ongoing reactions with, and therefore damage to, the material that has been bleached. Antichlors include sodium bisulfite, potassium bisulfite, sodium metabisulfite, sodium thiosulfate, and hydrogen peroxide.
In the textile industry, the antichlor is usually added right before the end of the bleaching process. Antichlors are used mainly on fiber, textiles, and paper pulp. Rinsing with water should follow the antichlor treatment in order to flush out by-products of the procedure. For household use, rinsing both before and after use is recommended.
Hydrogen peroxide is by itself a strong bleaching agent and should be used only in diluted form, such as a 3% solution in water. Hypochlorite plus peroxide releases triplet oxygen, which is itself a bleaching agent, but is short-lived in water solution. Reacting large amounts of peroxide can release enough oxygen to create a fire or explosion hazard.
Antichlors are sometimes added to shampoos for treating hair after swimming in chlorinated water. | 1 | Inorganic Reactions + Inorganic Compounds |
Ammonium metavanadate is the inorganic compound with the formula NHVO. It is a white salt, although samples are often yellow owing to impurities of VO. It is an important intermediate in the purification of vanadium. | 1 | Inorganic Reactions + Inorganic Compounds |
Alkoxyaluminium and closely related hydride reagents reduce a wide variety of functional groups, often with good selectivity. This section, organized by functional group, covers the most common or synthetically useful methods for alkoxyaluminium hydride reduction of organic compounds.
Many selective reductions of carbonyl compounds can be effected by taking advantage of the unique reactivity profiles of metal alkoxylaluminium hydrides. For instance, lithium tri-tert-butoxy)aluminium hydride (LTBA) reduces aldehydes and ketones selectively in the presence of esters, with which it reacts extremely slowly.
α,β-Unsaturated ketones may be reduced selectively in a 1,2 or 1,4 sense by a judicious choice of reducing agent. Use of relatively unhindered lithium trimethoxyaluminium hydride results in nearly quantitative direct addition to the carbonyl group (Eq. ()). On the other hand, use of the bulky reagent LTBA leads to a high yield of the conjugate addition product (Eq. ()).
Ether cleavage is difficult to accomplish with most hydride reagents. However, debenzylation of benzyl aryl ethers may be accomplished with SMEAH. This protocol is a useful alternative to methods requiring acid or hydrogenolysis (e.g., Pd/C and hydrogen gas).
Epoxides are generally attacked by alkoxyaluminium hydrides at the less substituted position. A nearby hydroxyl group may facilitate intramolecular delivery of the hydride reagent, allowing for selective opening of 1,2-disubstituted epoxides at the position closer to the hydroxyl group. The configuration at the untouched epoxide carbon is preserved.
Unsaturated carbonyl compounds may be reduced either to saturated or unsaturated alcohols by alkoxyaluminium hydride reagents. Addition of an unsaturated aldehyde to a solution of Red-Al afforded the saturated alcohol; inverse addition yielded the unsaturated alcohol product.
Alkenes undergo hydroalumination in the presence of some alkoxyaluminium hydrides. In a related application, NaAlH(OCHCHOCH) (sodium bis(methoxyethoxy) aluminium dihydride, SMEAH or Red-Al) reacts with zirconocene dichloride to afford zirconocene chloride hydride (Schwartz's reagent). Alkenes undergo hydrozirconation in the presence of this reagent, affording functionalized products after quenching with an electrophile.
Functional groups containing heteroatoms other than oxygen may also be reduced to the corresponding hydrocarbons in the presence of an alkoxyaluminium hydride reagent. Primary alkyl halides undergo reduction to the corresponding alkanes in the presence of NaAlH(OH)(OCHCHOCH). Secondary halides are less reactive, but afford alkanes in reasonable yield.
Sulfoxides are reduced to the corresponding sulfides in good yield in the presence of SMEAH.
Imines are reduced by metal alkoxyaluminium hydrides to the corresponding amines. In the example below, use of the exo amine forms with high diastereoselectivity. The selectivity of hydride reduction in this case is higher than that of catalytic hydrogenation. | 0 | Organic Reactions |
The reaction was initially demonstrated using a ketone as the directing group, but other functional groups have been reported, including esters, imines, nitriles, and imidates. Murai reactions have also been reported with disubstituted alkynes. Bidentate directing groups allow ortho alkylation of aromatic rings with α,β-unsaturated ketones, which typically are unreactive in Murai reactions.
Early examples of the reaction suffered from side products of alkylation at both ortho positions. This problem can be partially solved using an ortho methyl blocking group. Unfortunately, with ortho methyl groups both the rate and generality of the reaction are reduced. Substituents at the meta position influence regioselectivity. The reaction preferentially adds at the least sterically hindered ortho position, except when there is a meta group capable of coordinating with the Ru catalyst. Methoxyacetophenones show preferential reaction at the more hindered position. | 0 | Organic Reactions |
It is important to note that the list given above is qualitative and describes trends. The ability of a group to leave is contextual. For example, in SAr reactions, the rate is generally increased when the leaving group is fluoride relative to the other halogens. This effect is due to the fact that the highest energy transition state for this two step addition-elimination process occurs in the first step, where fluoride's greater electron withdrawing capability relative to the other halides stabilizes the developing negative charge on the aromatic ring. The departure of the leaving group takes place quickly from this high energy Meisenheimer complex, and since the departure is not involved in the rate limiting step, it does not affect the overall rate of the reaction. This effect is general to conjugate base eliminations.
Even when the departure of the leaving group is involved in the rate limiting step of a reaction there can still exist contextual differences that can change the order of leaving group ability. In Friedel-Crafts alkylations, the normal halogen leaving group order is reversed so that the rate of the reaction follows RF > RCl > RBr > RI. This effect is due to their greater ability to complex the Lewis acid catalyst, and the actual group that leaves is an "ate" complex between the Lewis acid and the departing leaving group. This situation is broadly defined as leaving group activation.
There can still exist contextual differences in leaving group ability in the purest form, that is when the actual group that leaves is not affected by the reaction conditions (by protonation or Lewis acid complexation) and the departure of the leaving group occurs in the rate determining step. In the situation where other variables are held constant (nature of the alkyl electrophile, solvent, etc.), a change in nucleophile can lead to a change in the order of reactivity for leaving groups. In the case below, tosylate is the best leaving group when ethoxide is the nucleophile, but iodide and even bromide become better leaving groups in the case of the thiolate nucleophile. | 0 | Organic Reactions |
Hydroboration is typically anti-Markovnikov, i.e. the hydrogen adds to the most substituted carbon of the double bond. That the regiochemistry is reverse of a typical HX addition reflects the polarity of the B-H bonds. Hydroboration proceeds via a four-membered transition state: the hydrogen and the boron atoms added on the same face of the double bond. Granted that the mechanism is concerted, the formation of the C-B bond proceeds slightly faster than the formation of the C-H bond. As a result, in the transition state, boron develops a partially negative charge while the more substituted carbon bears a partially positive charge. This partial positive charge is better supported by the more substituted carbon. Formally, the reaction is an example of a group transfer reaction. However, an analysis of the orbitals involved reveals that the reaction is pseudopericyclic and not subject to the Woodward–Hoffmann rules for pericyclic reactivity.
If BH is used as the hydroborating reagent, reactions typically proceed beyond the monoalkyl borane compounds, especially for less sterically hindered small olefins. Trisubstituted olefins can rapidly produce dialkyl boranes, but further alkylation of the organoboranes is slowed because of steric hindrance. This significant rate difference in producing di- and tri-alkyl boranes is useful in the synthesis of bulky boranes that can enhance regioselectivity. | 0 | Organic Reactions |
Steric approach control is common in conjugate addition reactions. Thus, in cyclic substrates, a trans relationship between substituents on the α- and β-carbons is common. The configuration at the α-position is less predictable, especially in cases when epimerization can occur. On the basis of steric approach control, the new α-substituent is predicted to be trans to the new β-substituent, and this is observed in a number of cases. | 0 | Organic Reactions |
Radical reactions must be carried out under inert atmosphere as dioxygen is a triplet radical which will intercept radical intermediates. Because the relative rates of a number of processes are important to the reaction, concentrations must be carefully adjusted to optimize reaction conditions. Reactions are generally carried out in solvents whose bonds have high bond dissociation energies (BDEs), including benzene, methanol or benzotrifluoride. Even aqueous conditions are tolerated, since water has a strong O-H bond with a BDE of 494 kJ/mol. This is in contrast to many polar processes, where hydroxylic solvents (or polar X-H bonds in the substrate itself) may not be tolerated due to the nucleophilicity or acidity of the functional group. | 0 | Organic Reactions |
A two-stage approach proved to be the key to successful synthesis of pure digallane. Firstly the dimeric monochlorogallane, (containing bridging chlorine atoms and thus formulated as () was prepared via the hydrogenation of gallium trichloride, , with trimethylsilane, . This step was followed by a further reduction with (lithium tetrahydrogallate), solvent free, at −23 °C, to produce digallane, in low yield.
Digallane is volatile and condenses at −50 °C into a white solid. | 1 | Inorganic Reactions + Inorganic Compounds |
Aza enolates (also known as imine anions, enamides, metallated Schiff bases, and metalloenamines) are nitrogen analogous to enolates. When imines get treated with strong bases such as LDA, highly nucleophilic aza enolates are generated.
The major benefit of using aza enolates is that they don't undergo self-condensation (i.e. aldol reaction for aldehydes) in a basic or neutral solution, but rather they favor alkylation on the alpha-carbon. This is mainly because imines contain carbon-nitrogen double bonds unlike aldehydes, which contain oxygen-carbon double bonds. Since oxygen is more electronegative than nitrogen, it withdraws more electron density from the carbonyl carbon, inducing a greater partially positive charge on the carbon. Therefore, with more electrophilic carbon, aldehydes allow for better nucleophilic addition to the carbon on the carbon-oxygen double bond.
On the other hand, imine has less electronegative nitrogen which induces a weaker partially positive charge on the carbonyl-carbon. As a result, while imines can still react with organolithiums, they don't react with other nucleophiles (including aza enolates) to undergo nucleophilic additions.
Instead, aza enolates react similarly to enolates, forming SN2 alkylated products. Through nitrogen lone pair conjugation, β-carbon becomes a nucleophilic site, permitting aza enolates to undergo alkylation reactions. Thus, aza enolates can react with numerous electrophiles like epoxides and alkyl halides to form a new carbon-carbon bond on β-carbon.
Two potential reaction mechanisms are shown below:
Since epoxide is a three-membered ring molecule, it has a high degree of ring strain. Although the carbons in the ring system are tetrahedral, preferring 109.5 degrees between each atom, epoxide strains the ring angles into 60 degrees. To counter this effect, the nucleophilic aza enolates easily react with epoxides to reduce their ring strains.
Besides reacting with epoxides, aza enolates can also react with alkyl halides (or allyl halides as depicted above) to form a new carbon-carbon sigma bond. This reaction is one of the key steps in the synthesis of the male aggression pheromone, Oulema melanopus. Aza enolate is generated by LDA reacting with pivaldehyde, which then reacts with an alkyl halide to form an Oulema melanopus intermediate.
Aza enolates can also be formed with Grignard reagents and react with other soft electrophiles, including Michael receptors. | 0 | Organic Reactions |
The asymmetric hydrogenation of aromatic (especially heteroaromatic), substrates is a very active field of ongoing research. Catalysts in this field must contend with a number of complicating factors, including the tendency of highly stable aromatic compounds to resist hydrogenation, the potential coordinating (and therefore catalyst-poisoning) abilities of both substrate and product, and the great diversity in substitution patterns that may be present on any one aromatic ring. Of these substrates the most consistent success has been seen with nitrogen-containing heterocycles, where the aromatic ring is often activated either by protonation or by further functionalization of the nitrogen (generally with an electron-withdrawing protecting group). Such strategies are less applicable to oxygen- and sulfur-containing heterocycles, since they are both less basic and less nucleophilic; this additional difficulty may help to explain why few effective methods exist for their asymmetric hydrogenation. | 0 | Organic Reactions |
Many acetylations are achieved using these three reagents:
*Acetic anhydride. This reagent is common in the laboratory; its use cogenerates acetic acid.
*Acetyl chloride. This reagent is also common in the laboratory, but its use cogenerates hydrogen chloride, which can be undesirable.
*Ketene. At one time acetic anhydride was prepared by the reaction of ketene with acetic acid: | 0 | Organic Reactions |
The acidity of boric acid solutions is greatly increased in the presence of cis-vicinal diols (organic compounds containing similarly oriented hydroxyl groups in adjacent carbon atoms, ) such as glycerol and mannitol.
The tetrahydroxyborate anion formed in the dissolution spontaneously reacts with these diols to form relatively stable anion esters containing one or two five-member rings. For example, the reaction with mannitol , whose two middle hydroxyls are in cis orientation, can be written as
Giving the overall reaction
The stability of these mannitoborate ester anions shifts the equilibrium of the right and thus increases the acidity of the solution by 5 orders of magnitude compared to that of pure boric oxide, lowering the pK from 9 to below 4 for sufficient concentration of mannitol. The resulting solution has been called mannitoboric acid.
The addition of mannitol to an initially neutral solution containing boric acid or simple borates lowers its pH enough for it to be titrated by a strong base as NaOH, including with an automated a potentiometric titrator. This property is used in analytical chemistry to determine the borate content of aqueous solutions, for example to monitor the depletion of boric acid by neutrons in the water of the primary circuit of light-water reactor when the compound is added as a neutron poison during refueling operations. | 1 | Inorganic Reactions + Inorganic Compounds |
The Danheiser benzannulation is a regiocontrolled phenol annulation. This annulation provides an efficient route to form an aromatic ring in one step. It is a thermal combination of a substituted cyclobutenones with heterosubstituted acetylenes to produce highly substituted aromatic compounds, specifically phenols or resorcinols (Scheme 1). This benzannulation reaction creates previously unaccessed aromatic substitution patterns. A variety of substituted aromatic rings can be prepared using this method including: phenols, naphthalenes, benzofurans, benzothiophenes, indoles, and carbazoles.
The modified Danheiser benzannulation allows the synthesis of polycyclic aromatic and heteroaromatic systems. This also includes napthalenes, benzofurans and indoles. This second generation aromatic annulation is achieved by irradiation of a solution of acetylene and a vinyl or aryl α-diazo ketone in dichloroethane. This reaction utilizes the photochemical Wolff rearrangement of a diazoketone to generate an aryl or vinylketene. These ketene intermediates cannot be isolated due to their high reactivity to form diketenes. These rearrangements are performed in the presence of unsaturated compounds which undergo [2+2] cycloadditions with the in situ generated ketenes. When ketenes are formed in the presence of alkynes they proceed through pericyclic reactions to generate a substituted aromatic ring (Scheme 2). Avoiding the use of the high energy cyclobutenone starting materials provides access to a wider variety of substituted aromatic compounds.
This reaction is quite complementary to the Wulff–Dötz reaction. This is a [2+1] cycloaddition of a carbene to an alkyne or alkene (more specifically in the Dӧtz reaction a carbene coordinated to a metal carbonyl group) to produce substituted aromatic phenols. | 0 | Organic Reactions |
has an extended (chain or network) structure in which xenon and oxygen have coordination numbers of four and two respectively. The geometry at xenon is square planar, consistent with VSEPR theory for four ligands and two lone pairs (or AXE in the notation of VSEPR theory).
In addition, the existence of an XeO molecule was predicted by an ab initio quantum chemistry method several years earlier by Pyykkö and Tamm, but these authors did not consider an extended structure. | 1 | Inorganic Reactions + Inorganic Compounds |
Reductions of carbon-carbon double and triple bonds are most commonly accomplished through catalytic hydrogenation:
However, diimide reduction offers the advantages that the handling of gaseous hydrogen is unnecessary and removal of catalysts and byproducts (one of which is gaseous dinitrogen) is straightforward. Hydrogenolysis side reactions do not occur during diimide reductions, and N–O and O–O bonds are not affected by the reaction conditions. On the other hand, diimide reductions often require long reaction times, and reductions of highly substituted or polarized double bonds are sluggish.
In addition, an excess of the reagent used to generate diimide (e.g. dipotassium azodicarboxylate) is required for hydrogenation because of the two competing processes of disproportionation (to and ) and decomposition (to and ) that the liberated diimide can also undergo. Unfortunately, this means that in the case of alkyne reduction, over-reduction to the alkane can occur resulting in diminished yields where the cis alkene is the desired product. | 0 | Organic Reactions |
Cobalt chloride can be prepared in aqueous solution from cobalt(II) hydroxide or cobalt(II) carbonate and hydrochloric acid:
: + 2 HCl → + +
: + 2 HCl → + 2
The solid dihydrate and hexahydrate can be obtained by evaporation. Cooling saturated aqueous solutions yields the dihydrate between 120.2 °C and 51.25 °C, and the hexahydrate below 51.25 °C. Water ice, rather than cobalt chloride, will crystallize from solutions with concentration below 29%. The monohydrate and the anhydrous forms can be obtained by cooling solutions only under high pressure, above 206 °C and 335 °C, respectively.
The anhydrous compound can be prepared by heating the hydrates.
On rapid heating or in a closed container, each of the 6-, 2-, and 1- hydrates partially melts into a mixture of the next lower hydrate and a saturated solution—at 51.25 °C, 206 °C, and 335 °C, respectively. On slow heating in an open container, so that the water vapor pressure over the solid is practically zero, water evaporates out of each of the solid 6-, 2-, and 1- hydrates, leaving the next lower hydrate, at about 40°C, 89°C, and 125°C, respectively. If the partial pressure of the water vapor is in equilibrium with the solid, as in a confined but not pressurized contained, the decomposition occurs at about 115°C, 145°C, and 195°C, respectively.
Dehydration can also be effected with trimethylsilyl chloride:
:•6 + 12 → + 6 + 12 HCl
The anhydrous compound can be purified by sublimation in vacuum. | 1 | Inorganic Reactions + Inorganic Compounds |
Glucuronidation consists of transfer of the glucuronic acid component of uridine diphosphate glucuronic acid to a substrate by any of several types of UDP-glucuronosyltransferase.
UDP-glucuronic acid (glucuronic acid linked via a glycosidic bond to uridine diphosphate) is an intermediate in the process and is formed in the liver. One example is the N-glucuronidation of an aromatic amine, 4-aminobiphenyl, by UGT1A4 or UGT1A9 from human, rat, or mouse liver.
The substances resulting from glucuronidation are known as glucuronides (or glucuronosides) and are typically much more water-soluble than the non-glucuronic acid-containing substances from which they were originally synthesised. The human body uses glucuronidation to make a large variety of substances more water-soluble, and, in this way, allow for their subsequent elimination from the body through urine or feces (via bile from the liver). Hormones are glucuronidated to allow for easier transport around the body. Pharmacologists have linked drugs to glucuronic acid to allow for more effective delivery of a broad range of potential therapeutics. Sometimes toxic substances are also less toxic after glucuronidation.
The conjugation of xenobiotic molecules with hydrophilic molecular species such as glucuronic acid is known as phase II metabolism. | 0 | Organic Reactions |
Toluene derivatives with heteroatom-containing substituents in the ortho position undergo site-selective benzylic lithiation in the presence of organolithium compounds (either alkyllithiums or lithium dialkylamides). Coordination of the Lewis acidic lithium atom to the Lewis basic heteroatom, as well as inductive effects derived from the electronegativity of the heteroatom, encourage selective deprotonation at the benzylic position. Competitive ring metalation (directed ortho-metalation) is an important side reaction, but a judicious choice of base often allows for selective benzylic metalation. Useful heteroatom-containing directing groups include dialkylamines, amides (secondary or tertiary), ketone enolates, carbamates, and sulfonates. Lateral lithiation of alkyl-substituted heterocycles incorporating heteroatom-containing substituents is also possible, although ring lithiation α to the ring heteroatom may compete with lateral lithiation. The products of lateral lithiation react with a variety of electrophiles, including reactive alkyl halides (allylic, benzylic, and primary), carbonyl compounds, silyl and stannyl chlorides, disulfides and diselenides, and others. A general, highly selective method for benzylic metalation using a mixed lithium and potassium metal amide (LiNK chemistry) has been developed which permits metalation regardless of the relative position (ortho, meta or para) of the methyl group to the heteroatom containing substituent | 0 | Organic Reactions |
Pyrohydrolysis of hydrochloric spent pickle liquor from carbon steel pickling lines is a hydrometallurgical reaction which takes place according to the following chemical formulae:
4 FeCl + 4 HO + O = 8 HCl + 2 FeO
2 FeCl + 3 HO = 6 HCl + FeO
The process is an inversion of the chemical descaling (pickling) process. | 1 | Inorganic Reactions + Inorganic Compounds |
In biological systems, oxocarbenium ions are mostly seen during reactions of carbohydrates. Since sugars are present in the structure of nucleic acids, with a ribose sugar present in RNA and a deoxyribose present in the structure of DNA, their chemistry plays an important role in wide range of cellular functions of nucleic acids. In addition to their functions in nucleotides, sugars are also used for structural components of organisms, as energy storage molecules, cell signaling molecules, protein modification and play key roles in the immune system, fertilization, preventing pathogenesis, blood clotting, and development. The abundance of sugar chemistry in biological processes leads many reaction mechanisms to proceed through oxocarbenium ions. Several important biological reactions that utilize oxocarbenium ions are outlined in this section. | 0 | Organic Reactions |
In heterocyclic chemistry, organic reactions are classified by the type of heterocycle formed with respect to ring-size and type of heteroatom. See for instance the chemistry of indoles. Reactions are also categorized by the change in the carbon framework. Examples are ring expansion and ring contraction, homologation reactions, polymerization reactions, insertion reactions, ring-opening reactions and ring-closing reactions.
Organic reactions can also be classified by the type of bond to carbon with respect to the element involved. More reactions are found in organosilicon chemistry, organosulfur chemistry, organophosphorus chemistry and organofluorine chemistry. With the introduction of carbon-metal bonds the field crosses over to organometallic chemistry. | 0 | Organic Reactions |
In coupling reactions between aromatic compounds and metal-trifluoromethyl complexes the metal is usually copper, Pd and Ni are less prominent. The reactions are stoichiometric or catalytic. In the McLoughlin-Thrower reaction (1962) iodobenzene reacts with trifluoroiodomethane (CFI) and copper powder in dimethylformamide at 150 °C to trifluoromethylbenzene. The intermediate in this reaction type is a perfluoromethyl-metal complex.
A palladium acetate catalysed reaction described in 1982 used zinc powder with the main intermediate believed to be CFZnI with Pd(0) is the active catalyst. The first copper catalysed coupling was reported in 2009 and based on an iodoarene, a trifluoromethylsilane, copper iodide and 1,10-phenanthroline. Variations include another CF donor potassium (trifluoromethyl)trimethoxyborate, the use of aryl boronic acids or the use of a trifluoromethyl sulfonium salt or the use of a trifluoromethylcopper(I) phenanthroline complex. A catalytic palladium catalysed reaction was reported in 2010 using aryl halides, (trifluoromethyl)triethylsilane and allylpalladium chloride dimer | 0 | Organic Reactions |
*Alkylation
*Methoxy
*Titanium–zinc methylenation
*Petasis reagent
*Nysted reagent
*Wittig reaction
*Tebbe's reagent | 0 | Organic Reactions |
Protein acylation is the post-translational modification of proteins via the attachment of functional groups through acyl linkages. Protein acylation has been observed as a mechanism controlling biological signaling. One prominent type is fatty acylation, the addition of fatty acids to particular amino acids (e.g. myristoylation, palmitoylation or palmitoleoylation). Different types of fatty acids engage in global protein acylation. Palmitoleoylation is an acylation type where the monounsaturated fatty acid palmitoleic acid is covalently attached to serine or threonine residues of proteins. Palmitoleoylation appears to play a significant role in the trafficking, targeting, and function of Wnt proteins. | 0 | Organic Reactions |
C-S-H is a nano sized material with some degree of crystallinity as observed by X-ray diffraction techniques. The underlying atomic structure of C-S-H is similar to the naturally occurring mineral tobermorite. It has a layered geometry with calcium silicate sheet structure separated by an interlayer space. The silicates in C-S-H exist as dimers, pentamers and 3n-1 chain units (where n is an integer greater than 0) and calcium ions are found to connect these chains making the three dimensional nano structure as observed by dynamic nuclear polarisation surface-enhanced nuclear magnetic resonance. The exact nature of the interlayer remains unknown. One of the greatest difficulties in characterising C-S-H is due to its variable stoichiometry.
The scanning electron microscope micrographs of C-S-H does not show any specific crystalline form. They usually manifest as foils or needle/oriented foils.
Synthetic C-S-H can be divided in two categories separated at the Ca/Si ratio of about 1.1. There are several indications that the chemical, physical and mechanical characteristics of C-S-H varies noticeably between these two categories. | 1 | Inorganic Reactions + Inorganic Compounds |
In chemistry, acylation is a broad class of chemical reactions in which an acyl group () is added to a substrate. The compound providing the acyl group is called the acylating agent. The substrate to be acylated and the product include the following:
*alcohols, esters
*amines, amides
*arenes, ketones
A particularly common type of acylation is acetylation, the addition of the acetyl group. Closely related to acylation is formylation, which employ sources of "HCO in place of "RCO". | 0 | Organic Reactions |
Definitive mechanistic studies of rhodium-catalyzed cyclopropanation are lacking. However, the mechanism has been rationalized based on product distribution and stereoselectivity. Attack of the diazo compound on the metal center generates a zwitterionic metal alkyl complex, which expels nitrogen gas to afford a metal carbene intermediate. Concerted addition of the metal carbene to the olefin (without direct coordination of the olefin to the metal) generates the observed cyclopropane product. The configuration of the olefin is retained throughout the process; however, metal carbenes with heterotopic faces may generate a mixture of diastereomers, as shown at the right of Eq. (2).
The configuration of the product is determined by the trajectory of approach of the olefin to the metal carbene. In reactions of monosubstituted metal carbenes with terminal olefins, the olefin likely approaches "end-on" (with the carbon-carbon double bond of the olefin nearly parallel to the metal-carbon double bond of the carbene) with the olefin R group pointed away from the substituent of the carbene. A second transition state model has been proposed for reactions of vinyl-substituted carbenes. In this model, the olefin approaches "side-on" (with the carbon-carbon double bond of the olefin perpendicular to the metal-carbon double bond of the carbene) with the olefin R group far from the vinyl group. | 0 | Organic Reactions |
In combination with its use as an insecticide, boric acid also prevents and destroys existing wet and dry rot in timbers. It can be used in combination with an ethylene glycol carrier to treat external wood against fungal and insect attack. It is possible to buy borate-impregnated rods for insertion into wood via drill holes where dampness and moisture is known to collect and sit. It is available in a gel form and injectable paste form for treating rot affected wood without the need to replace the timber. Concentrates of borate-based treatments can be used to prevent slime, mycelium, and algae growth, even in marine environments.
Boric acid is added to salt in the curing of cattle hides, calfskins, and sheepskins. This helps to control bacterial development, and helps to control insects. | 1 | Inorganic Reactions + Inorganic Compounds |
Fischer glycosidation (or Fischer glycosylation) refers to the formation of a glycoside by the reaction of an aldose or ketose with an alcohol in the presence of an acid catalyst. The reaction is named after the German chemist, Emil Fischer, winner of the Nobel Prize in chemistry, 1902, who developed this method between 1893 and 1895.
Commonly, the reaction is performed using a solution or suspension of the carbohydrate in the alcohol as the solvent. The carbohydrate is usually completely unprotected. The Fischer glycosidation reaction is an equilibrium process and can lead to a mixture of ring size isomers, and anomers, plus in some cases, small amounts of acyclic forms. With hexoses, short reactions times usually lead to furanose ring forms, and longer reaction times lead to pyranose forms. With long reaction times the most thermodynamically stable product will result which, owing to the anomeric effect, is usually the alpha anomer. | 0 | Organic Reactions |
*The reaction has been attempted in the microwave, improving yields with the α-glucopyranoside to 88% and reducing the reaction time significantly to 14 minutes.
*The original paper by Tipson and Cohen also used acyclic sugars to illustrate the utility of the reaction. Thus the reaction is not limited to cyclic carbohydrate derivatives.
*Sulphonoxy groups such as methanesulfonyl and toluenesulfonyl were both used, however it was found that substrates with toluenesulfonyl groups gave higher yields and lower reaction times. | 0 | Organic Reactions |
Ammonium perrhenate may be prepared from virtually all common sources of rhenium. The metal, oxides, and sulfides can be oxidized with nitric acid and the resulting solution treated with aqueous ammonia. Alternatively an aqueous solution of ReO can be treated with ammonia followed by crystallisation. | 1 | Inorganic Reactions + Inorganic Compounds |
Benzylic activation and stereocontrol in tricarbonyl(arene)chromium complexes refers to the enhanced rates and stereoselectivities of reactions at the benzylic position of aromatic rings complexed to chromium(0) relative to uncomplexed arenes. Complexation of an aromatic ring to chromium stabilizes both anions and cations at the benzylic position and provides a steric blocking element for diastereoselective functionalization of the benzylic position. A large number of stereoselective methods for benzylic and homobenzylic functionalization have been developed based on this property. | 0 | Organic Reactions |
Mercury(II) oxide, also called mercuric oxide or simply mercury oxide, is the inorganic compound with the formula HgO. It has a red or orange color. Mercury(II) oxide is a solid at room temperature and pressure. The mineral form montroydite is very rarely found. | 1 | Inorganic Reactions + Inorganic Compounds |
Praseodymium(III) fluoride is an inorganic compound with the formula PrF, being the most stable fluoride of praseodymium. | 1 | Inorganic Reactions + Inorganic Compounds |
In radical trifluoromethylation the active species is the trifluoromethyl free radical. Reagents such as bromotrifluoromethane and haloform have been used for this purpose but in response to the Montreal Protocol alternatives such as trifluoroiodomethane have been developed as replacement. One particular combination is CFI / triethylborane
Other reagents that generate the CF radical are sodium trifluoromethanesulfinate and bis(trifluoroacetyl) peroxide.
In the CF radical the fluorine atom is an electron-withdrawing group via the inductive effect but also a weak pi donor through interaction of the fluorine lone pair with the radical center's SOMO. Compared to the methyl radical the CF radical is pyramidal (angle 107.8 °C ) with a large inversion barrier, electrophilic and also more reactive. In reaction with styrene it is 440 times more reactive. An early report (1949) describes the photochemical reaction of iodotrifluoromethane with ethylene to 3-iodo-1,1,1-trifluoropropane. Reagents that have been reported for the direct trifluoromethylation of arenes are CFI, CFBr (thermal or photochemical), silver trifluoroacetate/TiO (photochemical) and sodium trifluoromethanesulfinate/Cu(OSOCF)/tBuOOH. | 0 | Organic Reactions |
Methylations are commonly performed using electrophilic methyl sources such as iodomethane, dimethyl sulfate, dimethyl carbonate, or tetramethylammonium chloride. Less common but more powerful (and more dangerous) methylating reagents include methyl triflate, diazomethane, and methyl fluorosulfonate (magic methyl). These reagents all react via S2 nucleophilic substitutions. For example, a carboxylate may be methylated on oxygen to give a methyl ester; an alkoxide salt may be likewise methylated to give an ether, ; or a ketone enolate may be methylated on carbon to produce a new ketone.
The Purdie methylation is a specific for the methylation at oxygen of carbohydrates using iodomethane and silver oxide. | 0 | Organic Reactions |
The HTL process differs from pyrolysis as it can process wet biomass and produce a bio-oil that contains approximately twice the energy density of pyrolysis oil. Pyrolysis is a related process to HTL, but biomass must be processed and dried in order to increase the yield. The presence of water in pyrolysis drastically increases the heat of vaporization of the organic material, increasing the energy required to decompose the biomass. Typical pyrolysis processes require a water content of less than 40% to suitably convert the biomass to bio-oil. This requires considerable pretreatment of wet biomass such as tropical grasses, which contain a water content as high as 80-85%, and even further treatment for aquatic species, which can contain higher than 90% water content.
The HTL oil can contain up to 80% of the feedstock carbon content (single pass). HTL oil has good potential to yield bio-oil with "drop-in" properties that can be directly distributed in existing petroleum infrastructure.
The energy returned on energy invested (EROEI) of these processes is uncertain and/or has not been measured. Furthermore, products of hydrous pyrolysis might not meet current fuel standards. Further processing may be required to produce fuels. | 0 | Organic Reactions |
The favored azaenolate is the dominant starting molecule for the subsequent alkylation reaction. There are two possible faces of accessing for any electrophile to react with. The steric interaction between the pyrrolidine ring and the electrophilic reagent hinders the attack of the electrophile from the top face. On the contrary, when the electrophile attacks from the bottom face, such unfavorable interaction does not exist. Therefore, the electrophilic attack proceeds from the sterically more accessible face. | 0 | Organic Reactions |
Sulfur isotopes of sediments are often measured for studying environments in the Earth's past (Paleoenvironment). Disproportionation of sulfur intermediates, being one of the processes affecting sulfur isotopes of sediments, has drawn attention from geoscientists for studying the redox conditions in the oceans in the past.
Sulfate-reducing bacteria fractionate sulfur isotopes as they take in sulfate and produce sulfide. Prior to 2010s, it was thought that sulfate reduction could fractionate sulfur isotopes up to 46 permil and fractionation larger than 46 permil recorded in sediments must be due to disproportionation of sulfur intermediates in the sediment. This view has changed since the 2010s. As substrates for disproportionation are limited by the product of sulfate reduction, the isotopic effect of disproportionation should be less than 16 permil in most sedimentary settings.
Disproportionation can be carried out by microorganisms obligated to disproportionation or microorganisms that can carry out sulfate reduction as well. Common substrates for disproportionation include elemental sulfur, thiosulfate and sulfite. | 0 | Organic Reactions |
Silver being in the same group as copper, Pd–Ag(I) bimetallic systems are inherently similar to Pd–Cu catalytic systems. However, silver salts are better suited for protodecarboxylation of carboxylic acids than their copper equivalents, allowing milder reaction conditions in Pd–Ag cycles relative to Pd–Cu cycles.
Ag(I) catalyzed monometallic systems have also been reported. Their proficiency (relative to copper) is likely attributed to lower electronegativity and greater expansion of d-orbitals, which promote decarboxylation of the substrate.
One limitation of this catalyst combination is that the silver salts will form insoluble silver halides, forcing the reaction to require a stoichiometric amount of Ag if halides are present. This obstacle was overcome by Goossen et al. in 2010 by using aryl triflates, and catalytic reaction with aryl sulfonates has also been reported. | 0 | Organic Reactions |
The three oxygen atoms form a trigonal planar geometry around the boron. The B-O bond length is 136 pm and the O-H is 97 pm. The molecular point group is C.
Two crystalline forms of orthoboric acid are known: triclinic and hexagonal. The former is the most common; the second, which is a bit more stable thermodynamically, can be obtained with a special preparation method. | 1 | Inorganic Reactions + Inorganic Compounds |
Ziegler and coworkers reacted an allyl iodide with the azaenolate to generate a chiral hydrocarbon chain. To avoid loss of the enantiomeric purity of the product, the authors used cupric acetate to regenerate the carbonyl group, obtaining only moderate yield for the cleavage of C=N bond but good enantioselectivity (ee = 89%). The ketone was transformed after several steps into denticulatin A and B - polypropionate metabolites isolated from Siphonaria Denticulata. | 0 | Organic Reactions |
Hexachlorophosphazene is an inorganic compound with the formula . The molecule has a cyclic, unsaturated backbone consisting of alternating phosphorus and nitrogen centers, and can be viewed as a trimer of the hypothetical compound . Its classification as a phosphazene highlights its relationship to benzene. There is large academic interest in the compound relating to the phosphorus-nitrogen bonding and phosphorus reactivity.
Occasionally, commercial or suggested practical applications have been reported, too, utilising hexachlorophosphazene as a precursor chemical. Derivatives of noted interest include the hexalkoxyphosphazene lubricants obtained from nucleophilic substitution of hexachlorophosphazene with alkoxides, or chemically resistant inorganic polymers with desirable thermal and mechanical properties known as polyphosphazenes produced from the polymerisation of hexachlorophosphazene. | 1 | Inorganic Reactions + Inorganic Compounds |
The reaction mechanism of 4,4-disubstituted cyclohexadienones to 3,4-disubstituted phenol is illustrated here.
The migration tendency for the two different groups (R) present at either 4,4 position or 2,2 position can be determined by comparing the relative stability of the intermediate carbocation formed during rearrangement. In case of acid-promoted conditions, some relative migration tendencies are: COOEt > phenyl (or alkyl); phenyl > methyl; vinyl > methyl; methyl > alkoxy and alkoxy > phenyl. In some cases such as allyl and benzyl group, the actual rearrangement might happen through the Cope rearrangement. Apart from acid catalysis, the dienone–phenol rearrangement is also possible in presence of base. The dienone–phenol rearrangement has been used in the synthesis of steroids, anthracenes, and phenanthrenes. | 0 | Organic Reactions |
In 1964 Hisatsune and Surez investigated the infrared spectrum of metaborate anions in dilute solid solutions of potassium salt in alkali halides such as potassium chloride KCl. | 1 | Inorganic Reactions + Inorganic Compounds |
The parent boroxine (cyclo-(HBO)) is prepared in small quantities as a low pressure gas by high temperature reaction of water and elemental boron or reaction of various boranes (BH or BH) with O. It is thermodynamically unstable with respect to disproportionation to diborane and boron oxide. Some reactivity studies and an IR spectrum are reported, but it is otherwise not well characterized.
As discovered in the 1930s, substituted boroxines (cyclo-(RBO), R = alkyl or aryl) are generally produced from their corresponding boronic acids by dehydration. This dehydration can be done either by a drying agent or by heating under a high vacuum.
Trimethylboroxine can be synthesized by reacting carbon monoxide with diborane (BH) and lithium borohydride (LiBH) as a catalyst (or reaction of borane–tetrahydrofuran or borane–(dimethyl sulfide) in the presence of sodium borohydride): | 1 | Inorganic Reactions + Inorganic Compounds |
HCN has been measured in Titans atmosphere by four instruments on the Cassini space probe, one instrument on Voyager, and one instrument on Earth. One of these measurements was in situ, where the Cassini spacecraft dipped between above Titans surface to collect atmospheric gas for mass spectrometry analysis. HCN initially forms in Titan's atmosphere through the reaction of photochemically produced methane and nitrogen radicals which proceed through the HCN intermediate, e.g., (CH + N → HCN + H → HCN + H). Ultraviolet radiation breaks HCN up into CN + H; however, CN is efficiently recycled back into HCN via the reaction CN + CH → HCN + CH. | 1 | Inorganic Reactions + Inorganic Compounds |
How stereoselectivity is achieved in asymmetric nucleophilic epoxidations depends on the method employed. Covered here are various methods for the asymmetric nucleophilic epoxidation of electron-poor olefins. See below for a survey of the substrate scope of the reaction.
When chiral, non-racemic peroxides are used, the two transition states of epoxidation leading to enantiomeric products are diastereomeric. Steric interactions between the peroxide, enone, and templating cation M influence the sense of selectivity observed.
Methods that employ metal peroxides modified by chiral, non-racemic ligands operate by a similar mechanism in which the metal cation plays a templating role. Chiral zinc alkoxides under an oxygen atmosphere have been used to epoxidize some classes of enones (see equation (8) below). The evolution of ethane gas and uptake of oxygen are evidence for ligand exchange followed by oxidation of the intermediate zinc alkoxide species. A catalytic version of this transformation has been achieved using chiral zinc alkylperoxides.
Lithium, magnesium, and calcium alkylperoxides have also been employed as asymmetric nucleophilic epoxidation reagents. Simple tartrate and pseudoephedrine ligands are effective in combination with these metals; however, little detailed information about the precise mechanisms of these systems is known.
In combination with BINOL ligands and cumene hydroperoxide, lanthanide alkoxides can be used to epoxidize both trans and cis enones with high enantioselectivity. Studies of non-linear effects with these catalyst systems suggest that the active catalyst is oligomeric.
Homopolymers of amino acids (polypeptides) can also be used to effect enantioselective epoxidations in the presence of an enone and a peroxide. Structure-reactivity relationships have not emerged, but enantioselectivities in these reactions are often high, and polypeptides can often be used when other methods fail.
Phase-transfer catalysis of nucleophilic epoxidation is also possible using cinchona-based alkaloid catalysts. Phase-transfer methods allow some variability in the oxidant used: hydroperoxides, hydrogen peroxide, and hypochlorites have all been used with some success. | 0 | Organic Reactions |
Barium azide is an inorganic azide with the formula . It is a barium salt of hydrazoic acid. Like most azides, it is explosive. It is less sensitive to mechanical shock than lead azide. | 1 | Inorganic Reactions + Inorganic Compounds |
Organic reactions can be categorized based on the type of functional group involved in the reaction as a reactant and the functional group that is formed as a result of this reaction. For example, in the Fries rearrangement the reactant is an ester and the reaction product an alcohol.
An overview of functional groups with their preparation and reactivity is presented below: | 0 | Organic Reactions |
The mechanism for the conversion of an alcohol to the N-substituted thiocarbamate is shown below. The reaction proceeds under acidic conditions. The alcohol accepts a hydrogen ion from sulfuric acid to form a water, which then leaves, creating a carbocation. The mesomeric form of the cyanogroup reacts with the carbocation. The carbocation is attacked by a water, which then loses an hydrogen to form the product. The product then undergoes hydrolysis to form the N-substituted thiocarbamate.
The reaction requires the formation of a carbocation and does not work for primary alcohols. Only secondary and tertiary alcohols undergo the Riemschneider reaction. | 0 | Organic Reactions |
Transamination is mediated by several types of aminotransferase enzymes. An aminotransferase may be specific for an individual amino acid, or it may be able to process any member of a group of similar ones, for example the branched-chain amino acids, which comprises valine, isoleucine, and leucine. The two common types of aminotransferases are alanine aminotransferase (ALT) and aspartate aminotransferase (AST). | 0 | Organic Reactions |
The sulfonyl functional group (RS(O)R') has become an important electron-withdrawing group for modern organic chemistry. α-Sulfonyl carbanions may be used as nucleophiles in alkylation reactions, Michael-type additions, and other processes. After having served their synthetic purpose, sulfonyl groups are often removed. In the presence of certain reducing agents, one of the sulfur-carbon bonds of the sulfonyl group is cleaved, leading to sulfur-free organic products. Depending on the nature of the substrate and reaction conditions, alkyl sulfones afford either the corresponding alkanes or olefins (the Julia olefination). Reductive desulfonylation is typically accomplished with active metals or salts (sodium amalgam, aluminium amalgam, magnesium, samarium(II) iodide), tin hydrides (tributyltin hydride), or transition metal complexes with reducing agents or nucleophiles (PdCl(dppp)/LiHBEt, Pd(PPh)/LiHBEt, Pd(PPh)/NaHC(COEt)). Alkyl, alkenyl, and allylic sulfones may be reduced using one or more of these methods. | 0 | Organic Reactions |
Sodium hydroxide can form several hydrates , which result in a complex solubility diagram that was described in detail by Spencer Umfreville Pickering in 1893. The known hydrates and the approximate ranges of temperature and concentration (mass percent of NaOH) of their saturated water solutions are:
* Heptahydrate, : from −28 °C (18.8%) to −24 °C (22.2%).
* Pentahydrate, : from −24 °C (22.2%) to −17.7 °C (24.8%).
* Tetrahydrate, , α form: from −17.7 °C (24.8%) to 5.4 °C (32.5%).
* Tetrahydrate, , β form: metastable.
* Trihemihydrate, : from 5.4 °C (32.5%) to 15.38 °C (38.8%) and then to 5.0 °C (45.7%).
* Trihydrate, : metastable.
* Dihydrate, : from 5.0 °C (45.7%) to 12.3 °C (51%).
* Monohydrate, : from 12.3 °C (51%) to 65.10 °C (69%) then to 62.63 °C (73.1%).
Early reports refer to hydrates with n = 0.5 or n = 2/3, but later careful investigations failed to confirm their existence.
The only hydrates with stable melting points are (65.10 °C) and (15.38 °C). The other hydrates, except the metastable ones and (β) can be crystallized from solutions of the proper composition, as listed above. However, solutions of NaOH can be easily supercooled by many degrees, which allows the formation of hydrates (including the metastable ones) from solutions with different concentrations.
For example, when a solution of NaOH and water with 1:2 mole ratio (52.6% NaOH by mass) is cooled, the monohydrate normally starts to crystallize (at about 22 °C) before the dihydrate. However, the solution can easily be supercooled down to −15 °C, at which point it may quickly crystallize as the dihydrate. When heated, the solid dihydrate might melt directly into a solution at 13.35 °C; however, once the temperature exceeds 12.58 °C it often decomposes into solid monohydrate and a liquid solution. Even the n = 3.5 hydrate is difficult to crystallize, because the solution supercools so much that other hydrates become more stable.
A hot water solution containing 73.1% (mass) of NaOH is a eutectic that solidifies at about 62.63 °C as an intimate mix of anhydrous and monohydrate crystals.
A second stable eutectic composition is 45.4% (mass) of NaOH, that solidifies at about 4.9 °C into a mixture of crystals of the dihydrate and of the 3.5-hydrate.
The third stable eutectic has 18.4% (mass) of NaOH. It solidifies at about −28.7 °C as a mixture of water ice and the heptahydrate .
When solutions with less than 18.4% NaOH are cooled, water ice crystallizes first, leaving the NaOH in solution.
The α form of the tetrahydrate has density 1.33 g/cm. It melts congruously at 7.55 °C into a liquid with 35.7% NaOH and density 1.392 g/cm, and therefore floats on it like ice on water. However, at about 4.9 °C it may instead melt incongruously into a mixture of solid and a liquid solution.
The β form of the tetrahydrate is metastable, and often transforms spontaneously to the α form when cooled below −20 °C. Once initiated, the exothermic transformation is complete in a few minutes, with a 6.5% increase in volume of the solid. The β form can be crystallized from supercooled solutions at −26 °C, and melts partially at −1.83 °C.
The "sodium hydroxide" of commerce is often the monohydrate (density 1.829 g/cm). Physical data in technical literature may refer to this form, rather than the anhydrous compound. | 1 | Inorganic Reactions + Inorganic Compounds |
The reaction steps are reversible reactions and the reaction is driven to completion by removal of water e.g. by azeotropic distillation, molecular sieves or titanium tetrachloride. Primary amines react through an unstable hemiaminal intermediate which then splits off water.
Secondary amines do not lose water easily because they do not have a proton available and instead they often react further to an aminal:
or when an α-carbonyl proton is present to an enamine:
In acidic environment the reaction product is an iminium salt by loss of water.
This reaction type is found in many Heterocycle preparations for example the Povarov reaction and the Friedländer-synthesis to quinolines. | 0 | Organic Reactions |
Barium chlorate, when burned with a fuel, produces a vibrant green light. Because it is an oxidizer, a chlorine donor, and contains a metal, this compound produces a green color that is unparalleled. However, due to the instability of all chlorates to sulfur, acids, and ammonium ions, chlorates have been banned from use in class C fireworks in the United States. Therefore, more and more firework producers have begun to use more stable compound such as barium nitrate and barium carbonate. | 1 | Inorganic Reactions + Inorganic Compounds |
Various factors affect the rate of glucuronidation, which in turn will affect these molecules' clearance from the body. Generally, an increased rate of glucuronidation results in a loss of potency for the target drugs or compounds. | 0 | Organic Reactions |
Sodium hydroxide reacts with protic acids to produce water and the corresponding salts. For example, when sodium hydroxide reacts with hydrochloric acid, sodium chloride is formed:
In general, such neutralization reactions are represented by one simple net ionic equation:
This type of reaction with a strong acid releases heat, and hence is exothermic. Such acid–base reactions can also be used for titrations. However, sodium hydroxide is not used as a primary standard because it is hygroscopic and absorbs carbon dioxide from air. | 1 | Inorganic Reactions + Inorganic Compounds |
Enzymes that catalyse this reaction are termed aminases. Amination can occur in a number of ways including reaction with ammonia or another amine such as an alkylation, reductive amination and the Mannich reaction. | 0 | Organic Reactions |
One of the earliest synthesis of gallium nitride was at the George Herbert Jones Laboratory in 1932.
An early synthesis of gallium nitride was by Robert Juza and Harry Hahn in 1938.
GaN with a high crystalline quality can be obtained by depositing a buffer layer at low temperatures. Such high-quality GaN led to the discovery of p-type GaN, p–n junction blue/UV-LEDs and room-temperature stimulated emission (essential for laser action). This has led to the commercialization of high-performance blue LEDs and long-lifetime violet laser diodes, and to the development of nitride-based devices such as UV detectors and high-speed field-effect transistors. | 1 | Inorganic Reactions + Inorganic Compounds |
Lithium amides are usually prepared in the laboratory through the addition of a titrated solution of n-butyllithium in hexanes to a solution of the amine in ether. Dry glassware and inert atmosphere are required for these reactions. Alternatively, lithium amides may be prepared by the direct action of lithium on the corresponding amine. Typical temperatures for isomerization reactions employing lithium amides are between 0 °C and reflux (ether/hexane solvent mixtures derived from the synthesis of the lithium amide are usually used directly for isomerization reactions). An excess of the base is employed to account for impurities that consume base and reaction of the base with the ether solvent. Care should be taken when HMPA is added to lithium amide reactions, as it is a known animal carcinogen.
Organolithium reagents may also be used; however, lower temperatures are required to avoid decomposition of the base. These reactions are most often run in hexanes.
Aluminum amides, which are bulkier and sometimes more selective than lithium amides, are prepared from the corresponding lithium amides and diethylaluminum chloride. Reactions are usually carried out at 0 °C in an inert atmosphere, with benzene as the solvent. | 0 | Organic Reactions |
The crystal unit of the solid hexahydrate •6 contains the neutral molecule trans- and two molecules of water of crystallization. This species dissolves readily in water and alcohol.
The anhydrous salt is hygroscopic and the hexahydrate is deliquescent. The dihydrate, CoCl(HO), is a coordination polymer. Each Co center is coordinated to four doubly bridging chloride ligands. The octahedron is completed by a pair of mutually trans aquo ligands. | 1 | Inorganic Reactions + Inorganic Compounds |
Lanthanum oxide is most useful as a precursor to other lanthanum compounds. Neither the oxide nor any of the derived materials enjoys substantial commercial value, unlike some of the other lanthanides. Many reports describe efforts toward practical applications of , as described below.
forms glasses of high density, refractive index, and hardness. Together with oxides of tungsten, tantalum, and thorium, improves the resistance of the glass to attack by alkali. is an ingredient in some piezoelectric and thermoelectric materials.
has been examined for the oxidative coupling of methane. | 1 | Inorganic Reactions + Inorganic Compounds |
Epoxidation with dioxiranes refers to the synthesis of epoxides from alkenes using three-membered cyclic peroxides, also known as dioxiranes.
Dioxiranes are three-membered cyclic peroxides containing a weak oxygen-oxygen bond. Although they are able to effect oxidations of heteroatom functionality and even carbon-hydrogen bonds, they are most widely used as epoxidizing agents of alkenes. Dioxiranes are electrophilic oxidants that react more quickly with electron-rich than electron-poor double bonds; however, both classes of substrates can be epoxidized within a reasonable time frame. Dioxiranes may be prepared and isolated or generated in situ from ketones and potassium peroxymonosulfate (Oxone). In situ preparations may be catalytic in ketone, and if the ketone is chiral, enantioselective epoxidation takes place. The functional group compatibility of dioxiranes is limited somewhat, as side oxidations of amines and sulfides are rapid. Nonetheless, protocols for dioxirane oxidations are entirely metal free. The most common dioxiranes employed for synthesis are dimethyl dioxirane (DMD) and methyl(trifluoromethyl)dioxirane (TFD). | 0 | Organic Reactions |
Glycoconjugate is the covalently bonded product of oligosaccharides to the biomolecules such as proteins and lipids. They play indispensable role in the biological activities of mammalian cells from energy generation to cell signalling. These glycoconjugates with short oligosaccharide structures are important for the characterization and purification in the course glycoconjucate vaccine developements. Therefore, research in the engineering of the glycosyl precursors that create oligosaccharides with controlled size is important in carbohydrate synthesis. | 0 | Organic Reactions |
Organostannane addition reactions comprise the nucleophilic addition of an allyl-, allenyl-, or propargylstannane to an aldehyde, imine, or, in rare cases, a ketone. The reaction is widely used for carbonyl allylation.
Organostannane addition to carbonyl groups constitutes one of the most common and efficient methods for the construction of contiguous, oxygen-containing stereocenters in organic molecules. As many molecules containing this motif—polypropionates and polyacetates, for instance—are desired by natural products chemists, the title reaction has become important synthetically and has been heavily studied over the years. Substituted allylstannanes may create one or two new stereocenters, often with a very high degree of stereocontrol.
Organostannanes are known for their stability, ease of handling, and selective reactivity. Chiral allylstannanes often react with good stereoselectivity to give single diastereomers. Models explaining the sense of selectivity are reliable. In terms of disadvantages, stoichiometric amounts of metal-containing byproducts are generated. Additions to sterically encumbered pi bonds, such as those of ketones, are uncommon. | 0 | Organic Reactions |
Cyclophosphazenes such as hexachlorophosphazene are distinguished by notable stability and equal P–N bond lengths which, in many such cyclic molecules, would imply delocalization or even aromaticity. To account for these features, early bonding models starting from the mid-1950s invoked a delocalised π system arising from the overlap of N 2p and P 3d orbitals. | 1 | Inorganic Reactions + Inorganic Compounds |
Either copper powder or copper salts can be used very generally for intramolecular reactions of diazocarbonyl compounds. This section describes the different types of diazocarbonyl compounds that may undergo intramolecular reactions in the presence of copper. Note that for intermolecular reactions of diazocarbonyl compounds, the use of rhodium catalysts is preferred.
Diazoketones containing pendant double bonds undergo cyclopropanation in the presence of copper. The key step in one synthesis of barbaralone is the selective intramolecular cyclopropanation of a cycloheptatriene.
α,β-Cyclopropyl ketones may act as masked α,β-unsaturated ketones. In one example, intramolecular participation of an aryl group leads to the formation of a polycyclic ring system with complete diastereoselectivity.
α-Diazoesters are not as efficient as diazoketones at intramolecular cyclizations in some cases because of the propensity of esters to exist in the trans conformation about the carbon–oxygen single bond. However, intramolecular reactions of diazoesters do take place—in the example in equation (5), copper(II) sulfate is used to effect the formation of the cyclopropyl ester shown.
In the presence of a catalytic amount of acid, diazomethyl ketone substrates containing a pendant double bond or aryl group undergo cyclization. The mechanism of this process most likely involves protonation of the diazocarbonyl group to form a diazonium salt, followed by displacement of nitrogen by the unsaturated functionality and deprotonation. In the example below, demethylation affords a quinone.
When no unsaturated functionality is present in the substrate, C-H insertion may occur. C-H Insertion is particularly facile in conformationally restricted substrates in which a C-H bond is held in close proximity to the diazo group.
Transannular insertions, which form fused carbocyclic products, have also been observed. Yields are often low for these reactions, however.
Insertion into carbon–carbon bonds has been observed. In the example in equation (9), the methyl group is held in close proximity to the diazo group, facilitating C-C insertion. | 0 | Organic Reactions |
At least three plausible mechanisms for the Elbs reaction have been suggested. The first mechanism, suggested by Fieser, begins with a heat-induced cyclisation of the benzophenone, followed by a [[Sigmatropic reaction#%5B1,3%5D-shifts|[1,3]-hydride shift]] to give the compound . A dehydration reaction then affords the polyaromatic.
Alternatively, in the second mechanism, due to Cook, the methylated aromatic compound instead first undergoes a tautomerization followed by an electrocyclic reaction to give the same intermediate, which then similarly undergoes a [1,3]-hydride shift and dehydration.
A third mechanism has also been proposed, involving pyrolytic radical generation. | 0 | Organic Reactions |
Starting from the late 1980s, more modern calculations and the lack of spectroscopic evidence reveal that the P 3d contribution is negligible, invalidating the earlier hypothesis. Instead, a charge separated model is generally accepted.
According to this description, the P–N bond is viewed as a very polarised one (between notional and ), with sufficient ionic character to account for most of the bond strength.
The rest (~15%) of the bond strength may be attributed to a negative hyperconjugation interaction: the N lone pairs can donate some electron density into π-accepting σ* molecular orbitals on the P. | 1 | Inorganic Reactions + Inorganic Compounds |
Secondary amines can be alkylated with cuprates. The reaction is based on the oxidative coupling of lithium alkyl copper amide which is reported to form in situ during the reaction between lithium dialkylcuprates and primary or secondary amides. | 0 | Organic Reactions |
Praseodymium(III) oxalate can be prepared from the reaction of soluble praseodymium salts with oxalic acid: | 1 | Inorganic Reactions + Inorganic Compounds |
In aqueous solution, sodium molybdate features dissociated sodium ions and tetrahedral molybdate (MoO), which adopts a sulfate-like structure. The solid dihydrate material has a complex structure typical for alkali metal salts of oxyanions. The MoO subunits are tetrahedral with Mo-O distances near 178 pm. | 1 | Inorganic Reactions + Inorganic Compounds |
Cycloisomerization is any isomerization in which the cyclic isomer of the substrate is produced in the reaction coordinate. The greatest advantage of cycloisomerization reactions is its atom economical nature, by design nothing is wasted, as every atom in the starting material is present in the product. In most cases these reactions are mediated by a transition metal catalyst, in few cases organocatalysts and rarely do they occur under thermal conditions. These cyclizations are able to be performed with excellent levels of selectivity in numerous cases and have transformed cycloisomerization into a powerful tool for unique and complex molecular construction. Cycloisomerization is a very broad topic in organic synthesis and many reactions that would be categorized as such exist. Two basic classes of these reactions are intramolecular Michael addition and Intramolecular Diels–Alder reactions. Under the umbrella of cycloisomerization, enyne and related olefin cycloisomerizations are the most widely used and studied reactions. | 0 | Organic Reactions |
Sulfones with a good leaving group in the β position may undergo reductive elimination under desulfonylation conditions to afford alkenes. This process is a key step of the Julia olefination, which yields alkenes via addition of an α-sulfonyl carbanion to an aldehyde followed by reductive elimination. Sodium amalgam or samarium(II) iodide/HMPA may be used to convert β-sulfonyloxy or β-acyloxy sulfones to the corresponding alkenes. The key mechanistic step of this process is elimination of an anionic or organometallic intermediate to generate the alkene.
The use of sodium amalgam, which promotes the formation of essentially free alkyl anions, leads to (E) alkenes with extremely high selectivity. Samarium(II) iodide also produces the (E) alkene predominantly, but with lower selectivity. | 0 | Organic Reactions |
O-linked glycosylation is a form of glycosylation that occurs in eukaryotes in the Golgi apparatus, but also occurs in archaea and bacteria. | 0 | Organic Reactions |
Electron diffraction measurements of the vapour at 255 K established that digallane is structurally similar to diborane with 2 bridging hydrogen atoms (so-called three-center two-electron bonds). The terminal Ga-H bond length is 152 pm, the Ga-H bridging is 171 pm and the Ga-H-Ga angle is 98°. The Ga-Ga distance is 258 pm. The H NMR spectrum of a solution of digallane in toluene shows two peaks attributable to terminal and bridging hydrogen atoms.
In the solid state, digallane appears to adopt a polymeric or oligomeric structure. The vibrational spectrum is consistent with tetramer (i.e. ). The vibrational data indicate the presence of terminal hydride ligands. In contrast, the hydrogen atoms are all bridging in α-alane, a high-melting, relatively stable polymeric form of aluminium hydride wherein the aluminium centers are 6-coordinated. Digallane decomposes at ambient temperatures: | 1 | Inorganic Reactions + Inorganic Compounds |
The most common composition is iron thermite. The oxidizer used is usually either iron(III) oxide or iron(II,III) oxide. The former produces more heat. The latter is easier to ignite, likely due to the crystal structure of the oxide. Addition of copper or manganese oxides can significantly improve the ease of ignition.
The density of prepared thermite is often as low as 0.7 g/cm. This, in turn, results in relatively poor energy density (about 3 kJ/cm), rapid burn times, and spray of molten iron due to the expansion of trapped air. Thermite can be pressed to densities as high as 4.9 g/cm (almost 16 kJ/cm) with slow burning speeds (about 1 cm/s). Pressed thermite has higher melting power, i.e. it can melt a steel cup where a low-density thermite would fail. Iron thermite with or without additives can be pressed into cutting devices that have heat-resistant casing and a nozzle.
Oxygen balanced iron thermite 2Al + FeO has theoretical maximum density of 4.175 g/cm an adiabatic burn temperature of 3135 K or 2862 °C or 5183 °F (with phase transitions included, limited by iron, which boils at 3135 K), the aluminium oxide is (briefly) molten and the produced iron is mostly liquid with part of it being in gaseous form - 78.4 g of iron vapor per kg of thermite are produced. The energy content is 945.4 cal/g (3 956 J/g). The energy density is 16,516 J/cm.
The original mixture, as invented, used iron oxide in the form of mill scale. The composition was very difficult to ignite. | 1 | Inorganic Reactions + Inorganic Compounds |
Carbon-based life originates from carboxylation that couples atmospheric carbon dioxide to a sugar. The process is usually catalysed by the enzyme RuBisCO. Ribulose-1,5-bisphosphate carboxylase/oxygenase, the enzyme that catalyzes this carboxylation, is possibly the single most abundant protein on Earth.
Many carboxylases, including Acetyl-CoA carboxylase, Methylcrotonyl-CoA carboxylase, Propionyl-CoA carboxylase, and Pyruvate carboxylase require biotin as a cofactor. These enzymes are involved in various biogenic pathways. In the EC scheme, such carboxylases are classed under EC 6.3.4, "Other Carbon—Nitrogen Ligases".
Another example is the posttranslational modification of glutamate residues, to γ-carboxyglutamate, in proteins. It occurs primarily in proteins involved in the blood clotting cascade, specifically factors II, VII, IX, and X, protein C, and protein S, and also in some bone proteins. This modification is required for these proteins to function. Carboxylation occurs in the liver and is performed by γ-glutamyl carboxylase (GGCX). GGCX requires vitamin K as a cofactor and performs the reaction in a processive manner. γ-carboxyglutamate binds calcium, which is essential for its activity. For example, in prothrombin, calcium binding allows the protein to associate with the plasma membrane in platelets, bringing it into close proximity with the proteins that cleave prothrombin to active thrombin after injury. | 0 | Organic Reactions |
Calcium silicate hydrates (or C-S-H) are the main products of the hydration of Portland cement and are primarily responsible for the strength of cement-based materials. They are the main binding phase ("the glue") in most concrete. Only well defined and rare natural crystalline minerals can be abbreviated as CSH while extremely variable and poorly ordered phases without well defined stoichiometry, as it is commonly observed in hardened cement paste (HCP), are denoted C-S-H. | 1 | Inorganic Reactions + Inorganic Compounds |
A variety of alternative heteroatom oxidation reagents are known, including peroxides (often employed with a transition metal catalyst) and oxaziridines. These reagents do not suffer from the over-oxidation problems and decomposition issues associated with dioxiranes; however, their substrate scope tends to be more limited. Nucleophilic decomposition of dioxiranes to singlet oxygen is a unique problem associated with dioxirane heteroatom oxidations. Although chiral dioxiranes do not provide the same levels of enantioselectivity as other protocols, such as Kagan's sulfoxidation system, complexation to a chiral transition metal complex followed by oxidation affords optically active sulfoxides with good enantioselectivity.
Oxidation of arenes and cumulenes leads initially to epoxides. These substrates are resistant to many epoxidation reagents, including oxaziridines, hydrogen peroxide, and manganese oxo compounds. Organometallic oxidants also react sluggishly with these compounds, with the exception of methyltrioxorhenium. Peracids also react with arenes and cumulenes, but cannot be employed with substrates containing acid-sensitive functionality.
The direct oxidative functionalization of C-H bonds is an ongoing problem in oxidation chemistry. Among metal-free systems, dioxiranes are the best oxidants for the conversion of C-H bonds to alcohols or carbonyls. However, some catalytic transition-metal systems, such as White's palladium-sulfoxide system, are able to oxidize C-H bonds selectively. | 0 | Organic Reactions |
Copper(II) borate can be prepared by heating a stoichiometric mixture of copper(II) oxide and diboron trioxide to 900 °C. | 1 | Inorganic Reactions + Inorganic Compounds |
In organic chemistry, dehalogenation is a set of chemical reactions that involve the cleavage of carbon-halogen bonds; as such, it is the inverse reaction of halogenation. Dehalogenations come in many varieties, including defluorination (removal of fluorine), dechlorination (removal of chlorine), debromination (removal of bromine), and deiodination (removal of iodine). Incentives to investigate dehalogenations include both constructive and destructive goals. Complicated organic compounds such as pharmaceutical drugs are occasionally generated by dehalogenation. Many organohalides are hazardous, so their dehalogenation is one route for their detoxification. | 0 | Organic Reactions |
When treated with sodium borohydride, molybdate is reduced to molybdenum(IV) oxide:
:NaMoO + NaBH + 2HO → NaBO + MoO + 2NaOH + 3H
Sodium molybdate reacts with the acids of dithiophosphates:
:NaMoO + → [MoO(SP(OR))]
which further reacts to form [MoO(SP(OR))]. | 1 | Inorganic Reactions + Inorganic Compounds |
Fluoroantimonic acid solution is so reactive that it is challenging to identify media with which it is unreactive. Materials compatible with fluoroantimonic acid as a solvent include SOClF, and sulfur dioxide; some chlorofluorocarbons have also been used. Containers for HF/SbF are made of PTFE.
Fluoroantimonic acid solutions decompose when heated, generating free hydrogen fluoride gas and liquid antimony pentafluoride at a temperature of 40 °C.
As a superacid, fluoroantimonic acid solutions protonate nearly all organic compounds, often causing dehydrogenation, or dehydration. In 1967, Bickel and Hogeveen showed that 2HF·SbF reacts with isobutane and neopentane to form carbenium ions:
:(CH)CH + H → (CH)C + H
:(CH)C + H → (CH)C + CH
It is also used in the synthesis of tetraxenonogold complexes. | 1 | Inorganic Reactions + Inorganic Compounds |
A solution of sodium hydroxide in water was traditionally used as the most common paint stripper on wooden objects. Its use has become less common, because it can damage the wood surface, raising the grain and staining the colour. | 1 | Inorganic Reactions + Inorganic Compounds |
Methanogenesis, the process that generates methane from CO, involves a series of methylation reactions. These reactions are caused by a set of enzymes harbored by a family of anaerobic microbes.
In reverse methanogenesis, methane is the methylating agent. | 0 | Organic Reactions |
As shown in Eq. 2, the neutral pathway of the Heck reaction begins with the oxidative addition of the aryl or alkenyl halide into a coordinatively unsaturated palladium(0) complex (typically bound to two phosphine ligands) to give complex I. Dissociation of a phosphine ligand followed by association of the alkene yields complex II, and migratory insertion of the alkene into the carbon-palladium bond establishes the key carbon-carbon bond.
Insertion takes place in a suprafacial fashion, but the dihedral angle between the alkene and palladium-carbon bond during insertion can vary from 0° to ~90°. After insertion, β-hydride elimination affords the product and a palladium(II)-hydrido complex IV, which is reduced by base back to palladium(0). | 0 | Organic Reactions |
The mechanism of the SHJ reaction begins with the formation of the key cyclic cation 1. Nucleophilic attack at the anomeric position by the most nucleophilic nitrogen (N) then occurs, yielding the desired β-nucleoside 2. A second reaction of this nucleoside with 1 generates bis(riboside) 3. Depending on the nature of the Lewis acid used, coordination of the nucleophile to the Lewis acid may be significant. Reaction of this "blocked" nucleophile with 1 results in undesired constitutional isomer 4, which may undergo further reaction to 3. Generally Lewis acid coordination is not a problem when a Lewis acid such as trimethylsilyl triflate is used; it is much more important when a stronger Lewis acid like tin(IV) chloride is employed.
2-Deoxysugars are unable to form the cyclic cation intermediate 1 because of their missing benzoyl group; instead, under Lewis acidic conditions they form a resonance-stabilized oxocarbenium ion. The diastereoselectivity of nucleophilic attack on this intermediate is much lower than the stereoselectivity of attack on cyclic cation 1. Because of this low stereoselectivity, deoxyribonucleosides are usually synthesized using methods other than the SHJ reaction. | 0 | Organic Reactions |
For trisubstituted alkenes such as 1, boron is predominantly placed on the less substituted carbon. The minor product, in which the boron atom is placed on the more substituted carbon, is usually produced in less than 10%. A notable case with lower regioselectivity is styrene, and the selectivity is strongly influenced by the substituent on the para position.
Hydroboration of 1,2-disubstituted alkenes, such as a cis or trans olefin, produces generally a mixture of the two organoboranes of comparable amounts, even if the substituents are very different in terms of steric bulk. For such 1,2-disubstituted olefins, regioselectivity can be observed only when one of the two substituents is a phenyl ring. In such cases, such as trans-1-phenylpropene, the boron atom is placed on the carbon adjacent to the phenyl ring. The observations above indicate that the addition of H-B bond to olefins is under electronic control rather than steric control. | 0 | Organic Reactions |
Methoxy groups heavily decorate the biopolymer lignin. Much interest has been shown in converting this abundant form of biomass into useful chemicals (aside from fuel). One step in such processing is demethylation.
The demethylation of vanillin, a derivative of lignin, requires and strong base. Pulp and paper industry]] digests lignin using aqueous sodium sulfide, which partially depolymerizes the lignin. Delignification is accompanied by extensive O-demethylation, yielding methanethiol, which is emitted by paper mills. | 0 | Organic Reactions |
Like other corrosive acids and alkalis, a few drops of sodium hydroxide solutions can readily decompose proteins and lipids in living tissues via amide hydrolysis and ester hydrolysis, which consequently cause chemical burns and may induce permanent blindness upon contact with eyes. Solid alkali can also express its corrosive nature if there is water, such as water vapor. Thus, protective equipment, like rubber gloves, safety clothing and eye protection, should always be used when handling this chemical or its solutions. The standard first aid measures for alkali spills on the skin is, as for other corrosives, irrigation with large quantities of water. Washing is continued for at least ten to fifteen minutes.
Moreover, dissolution of sodium hydroxide is highly exothermic, and the resulting heat may cause heat burns or ignite flammables. It also produces heat when reacted with acids.
Sodium hydroxide is mildly corrosive to glass, which can cause damage to glazing or cause ground glass joints to bind. Sodium hydroxide is corrosive to several metals, like aluminium which reacts with the alkali to produce flammable hydrogen gas on contact. | 1 | Inorganic Reactions + Inorganic Compounds |