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Mercury oxide is sometimes used in the production of mercury as it decomposes quite easily. When it decomposes, oxygen gas is generated.
It is also used as a material for cathodes in mercury batteries. | 1 | Inorganic Reactions + Inorganic Compounds |
Rieche formylation is a type of formylation reaction. The substrates are electron rich aromatic compounds, such as mesitylene or phenols, with dichloromethyl methyl ether acting as the formyl source. The catalyst is titanium tetrachloride and the workup is acidic. The reaction is named after Alfred Rieche who discovered it in 1960. | 0 | Organic Reactions |
Metal borate thin films have been grown by a variety of techniques, including liquid-phase epitaxy (e.g. FeBO, β‐BaBO), electron-beam evaporation (e.g. CrBO, β‐BaBO), pulsed laser deposition (e.g. β‐BaBO, Eu(BO)), and atomic layer deposition (ALD). Growth by ALD was achieved using precursors composed of the tris(pyrazolyl)borate ligand and either ozone or water as the oxidant to deposit CaBO, SrBO, BaBO, Mn(BO), and CoBO films. | 1 | Inorganic Reactions + Inorganic Compounds |
In 1960, Vogel discovered that 1,2-divinylcyclopropane rearranges to cycloheptan-1,4-diene., After his discovery, a series of intense mechanistic investigations of the reaction followed in the 1960s, as researchers realized it bore resemblance (both structural and mechanistic) to the related rearrangement of vinylcyclopropane to cyclopentene. By the 1970s, the rearrangement had achieved synthetic utility and to this day it continues to be a useful method for the formation of seven-membered rings. Variations incorporating heteroatoms have been reported (see below).
Advantages: Being a rearrangement, the process exhibits ideal atom economy. It often proceeds spontaneously without the need for a catalyst. Competitive pathways are minimal for the all-carbon rearrangement.
Disadvantages: The configuration of the starting materials needs be controlled in many cases—trans-divinylcyclopropanes often require heating to facilitate isomerization before rearrangement will occur. Rearrangements involving heteroatoms can exhibit reduced yields due to the formation of side products. | 0 | Organic Reactions |
Bone ash is a key raw material for bone china. Constituting around 50% of the body, it reacts with other raw materials in the body during firing to form, amongst other phases, anorthite.
In preparation for use in bone china, bones undergo multiple processing stages, including:
* Removal of any meat before being degreased.
* Calcination to around 1000 °C (1832 °F). This will remove all organic, and the bone is left sterilised.
* Being ground with water to fine particle size.
* Being partially dewatered.
Since the 1990s, the use of synthetic alternatives to bone ash, which are based on dicalcium phosphate and tricalcium phosphate, has increased. Significant amounts of bone china is produced using these synthetic alternatives rather than bone ash. | 1 | Inorganic Reactions + Inorganic Compounds |
Glycosylation can also be effected using the tools of synthetic organic chemistry. Unlike the biochemical processes, synthetic glycochemistry relies heavily on protecting groups (e.g. the 4,6-O-benzylidene) in order to achieve desired regioselectivity. The other challenge of chemical glycosylation is the stereoselectivity that each glycosidic linkage has two stereo-outcomes, α/β or cis/trans. Generally, the α- or cis-glycoside is more challenging to synthesis. New methods have been developed based on solvent participation or the formation of bicyclic sulfonium ions as chiral-auxiliary groups. | 0 | Organic Reactions |
The silyl-Hilbert-Johnson reaction is the most commonly used method for the synthesis of nucleosides from heterocyclic and sugar-based starting materials. However, the reaction suffers from some issues that are not associated with other methods, such as unpredictable site selectivity in some cases (see below). This section describes both derivatives of and alternatives to the SHJ reaction that are used for the synthesis of nucleosides. | 0 | Organic Reactions |
The stereochemical result of a given reaction on a macrocycle capable of adopting several conformations can be modeled by a Curtin-Hammett scenario. In the diagram below, the two ground state conformations exist in an equilibrium, with some difference in their ground state energies. Conformation B is lower in energy than conformation A, and while possessing a similar energy barrier to its transition state in a hypothetical reaction, thus the product formed is predominantly product B (P B) arising from conformation B via transition state B (TS B). The inherent preference of a ring to exist in one conformation over another provides a tool for stereoselective control of reactions by biasing the ring into a given configuration in the ground state. The energy differences, ΔΔG and ΔG are significant considerations in this scenario. The preference for one conformation over another can be characterized by ΔG, the free energy difference, which can, at some level, be estimated from conformational analysis. The free energy difference between the two transition states of each conformation on its path to product formation is given by ΔΔG. The value of ΔG between not just one, but many accessible conformations is the underlying energetic impetus for reactions occurring from the most stable ground state conformation and is the crux of the peripheral attack model outlined below. | 0 | Organic Reactions |
Acidifiers are inorganic chemicals that, put into a human (or other mammalian) body, either produce or become acid.
These chemicals increase the level of gastric acid in the stomach when ingested, thus decreasing the stomach pH.
Out of many types of acidifiers, the main four are:
* Gastric acidifiers, these are the drugs which are used to restore temporarily the acidity of stomach in patient suffering from hypochlorhydria
* Urinary acidifiers, used to control pH in urine
* Systemic acidifiers, used to control pH in the overall body
* Acids, mostly used in laboratory experiments
Acidifier performance in distal stomach is debatable.
Patients who suffer from achlorhydria have deficient secretion of hydrochloric acid in their stomach. In such cases, acidifiers may provide sufficient acidity for proper digestion of food. Systemic acidifiers, usually given by injection, act by reducing the alkali reserve in the body, and are also useful in reducing metabolic alkalosis. | 1 | Inorganic Reactions + Inorganic Compounds |
The reaction is catalyzed by a base and a divalent metal such as calcium. The intermediary steps taking place are aldol reactions, reverse aldol reactions, and aldose-ketose isomerizations. Intermediates are glycolaldehyde, glyceraldehyde, dihydroxyacetone, and tetrose sugars. In 1959, Breslow proposed a mechanism for the reaction, consisting of the following steps:
The reaction exhibits an induction period, during which only the nonproductive Cannizzaro disproportionation of formaldehyde (to methanol and formate) occurs. The initial dimerization of formaldehyde to give glycolaldehyde (1) occurs via an unknown mechanism, possibly promoted by light or through a free radical process and is very slow. However, the reaction is autocatalytic: 1 catalyzes the condensation of two molecules of formaldehyde to produce an additional molecule of 1. Hence, even a trace (as low as 3 ppm) of glycolaldehyde is enough to initiate the reaction. The autocatalytic cycle begins with the aldol reaction of 1 with formaldehyde to make glyceraldehyde (2). An aldose-ketose isomerization of 2 forms dihydroxyacetone (3). A further aldol reaction of 3 with formaldehyde produces tetrulose (6), which undergoes another ketose-aldose isomerization to form aldotetrose 7 (either threose or erythrose). The retro-aldol reaction of 7 generates two molecules of 1, resulting in the net production of a molecule of 1 from two molecules of formaldehyde, catalyzed by 1 itself (autocatalysis). During this process, 3 can also react with 1 to form ribulose (4), which can isomerize to give rise to ribose (5), an important building block of ribonucleic acid. The reaction conditions must be carefully controlled, otherwise the alkaline conditions will cause the aldoses to undergo the Cannizzaro reaction.
The aldose-ketose isomerization steps are promoted by chelation to calcium. However, these steps have been shown to proceed through a hydride shift mechanism by isotope labeling studies, instead of via an intermediate enediolate, as previously proposed. | 0 | Organic Reactions |
Two limiting mechanisms, one operating under kinetic and the other thermodynamic control, have been identified for lateral lithiation reactions. The mechanisms of most lateral lithiations fall somewhere between these two limiting mechanisms, and the precise mechanism of a particular lithiation depends on two factors:
* The Lewis acidity of the organolithium reagent (RLi > LiNR)
* The Lewis basicity of the heteroatom substituent (N > O > S)
When both the Lewis acidity of the organolithium compound and the Lewis basicity of the substituent are high, as in lithiations of ortho-(dialkylamino)methyl toluenes with n-butyllithium in a non-coordinating solvent, coordination of the base to the heteroatom substituent takes place. Lithiation then occurs at the most kinetically accessible ortho benzylic position; ortho lithiation is slower in this case.
As either the Lewis acidity of the base or the coordinating ability of the substituent decrease, a mechanism involving purely inductive effects becomes more important. For instance, the lithiation of 1 with lithium di(isopropyl)amide (LDA) affords only the product of benzylic metalation 2; none of the ortho-lithiated product 3 is observed. This result is explained by a mechanism in which the amide substituent affects the acidity of the para benzylic position solely through inductive effects and coordination of the base is not operative. Deprotonation occurs to afford the most thermodynamically stable product.
In most cases, both mechanisms will lead to the same product, as the sites of kinetic and thermodynamic deprotonation will coincide. | 0 | Organic Reactions |
A number of metal borates are known. They can be obtained by treating boric acid or boron oxides with metal oxides. | 1 | Inorganic Reactions + Inorganic Compounds |
Transamination catalyzed by aminotransferase occurs in two stages. In the first step, the α amino group of an amino acid is transferred to the enzyme, producing the corresponding α-keto acid and the aminated enzyme. During the second stage, the amino group is transferred to the keto acid acceptor, forming the amino acid product while regenerating the enzyme. The chirality of an amino acid is determined during transamination. For the reaction to complete, aminotransferases require participation of aldehyde containing coenzyme, pyridoxal-5-phosphate (PLP), a derivative of Pyridoxine (Vitamin B). The amino group is accommodated by conversion of this coenzyme to pyridoxamine-5-phosphate (PMP). PLP is covalently attached to the enzyme via a Schiff Base linkage formed by the condensation of its aldehyde group with the ε-amino group of an enzymatic Lys residue. The Schiff base, which is conjugated to the enzyme's pyridinium ring, is the focus of the coenzyme activity.
:The product of transamination reactions depend on the availability of α-keto acids. The products usually are either alanine, aspartate or glutamate, since their corresponding alpha-keto acids are produced through metabolism of fuels. Being a major degradative aminoacid pathway, lysine, proline and threonine are the only three amino acids that do not always undergo transamination and rather use respective dehydrogenase.
:Alternative Mechanism
:A second type of transamination reaction can be described as a nucleophilic substitution of one amine or amide anion on an amine or ammonium salt. For example, the attack of a primary amine by a primary amide anion can be used to prepare secondary amines:
:RNH + RNH → RRNH + NH
:Symmetric secondary amines can be prepared using Raney nickel (2RNH → RNH + NH). And finally, quaternary ammonium salts can be dealkylated using ethanolamine:
:RN + NHCHCHOH → RN + RNHCHCHOH
:Aminonaphthalenes also undergo transaminations. | 0 | Organic Reactions |
Organic reactions are chemical reactions involving organic compounds. The basic organic chemistry reaction types are addition reactions, elimination reactions, substitution reactions, pericyclic reactions, rearrangement reactions, photochemical reactions and redox reactions. In organic synthesis, organic reactions are used in the construction of new organic molecules. The production of many man-made chemicals such as drugs, plastics, food additives, fabrics depend on organic reactions.
The oldest organic reactions are combustion of organic fuels and saponification of fats to make soap. Modern organic chemistry starts with the Wöhler synthesis in 1828. In the history of the Nobel Prize in Chemistry awards have been given for the invention of specific organic reactions such as the Grignard reaction in 1912, the Diels–Alder reaction in 1950, the Wittig reaction in 1979 and olefin metathesis in 2005. | 0 | Organic Reactions |
Other enzymes that may be used for asymmetric ester hydrolysis include electric eel acetylcholinesterase, chymotrypsin, and Baker's yeast. The substrate scope of these enzymes differs from PLE, and in some cases they may provide hydrolyzed products in higher yield or enantioselectivity than PLE. Microorganisms may also be used for enantioselective hydrolysis; however, difficulties associated with the handling of microorganisms have made these methods unpopular for organic synthesis.
Nonenzymatic methods for the differentiation of enantiotopic groups employ chiral catalysts or auxiliaries. For instance, the introduction of a chiral leaving group on both carboxylic acid groups of a meso diacid leads to selective attack by an achiral nucleophile at one of the (now) diastereotopic carbonyl groups. | 0 | Organic Reactions |
Cadmium sulfide is the inorganic compound with the formula CdS. Cadmium sulfide is a yellow salt. It occurs in nature with two different crystal structures as the rare minerals greenockite and hawleyite, but is more prevalent as an impurity substituent in the similarly structured zinc ores sphalerite and wurtzite, which are the major economic sources of cadmium. As a compound that is easy to isolate and purify, it is the principal source of cadmium for all commercial applications. Its vivid yellow color led to its adoption as a pigment for the yellow paint "cadmium yellow" in the 18th century. | 1 | Inorganic Reactions + Inorganic Compounds |
Ortho lithiation followed by methylation with methyl iodide is a convenient method for the synthesis of starting materials for lateral lithiations. Elaboration of the benzylic carbon through lateral lithiation and treatment with an electrophile provides a powerful synthetic alternative to direct electrophilic aromatic substitution (EAS). Although yields over the entire sequence are moderate, site selectivity is generally higher than analogous EAS reactions. | 0 | Organic Reactions |
Theoretically, any biomass can be converted into bio-oil using hydrothermal liquefaction regardless of water content, and various different biomasses have been tested, from forestry and agriculture residues, sewage sludges, food process wastes, to emerging non-food biomass such as algae. The composition of cellulose, hemicellulose, protein, and lignin in the feedstock influence the yield and quality of the oil from the process.
Zhang et al., at the University of Illinois, report on a hydrous pyrolysis process in which swine manure is converted to oil by heating the swine manure and water in the presence of carbon monoxide in a closed container. For that process they report that a temperatures of at least is required to convert the swine manure to oil, and temperatures above about reduces the amount of oil produced. The Zhang et al. process produces pressures of about 7 to 18 Mpa (1000 to 2600 psi - 69 to 178 atm), with higher temperatures producing higher pressures. Zhang et al. used a retention time of 120 minutes for the reported study, but report at higher temperatures a time of less than 30 minutes results in significant production of oil.
A commercialized process using hydrous pyrolysis (see the article Thermal depolymerization) used by Changing World Technologies, Inc. (CWT) and its subsidiary Renewable Environmental Solutions, LLC (RES) to convert turkey offal. As a two-stage process, the first stage to convert the turkey offal to hydrocarbons at a temperature of and a second stage to crack the oil into light hydrocarbons at a temperature of near . Adams et al. report only that the first stage heating is "under pressure"; Lemley, in a non-technical article on the CWT process, reports that for the first stage (for conversion) a temperature of about and a pressure of about 600 psi, with a time for the conversion of "usually about 15 minutes". For the second stage (cracking), Lemley reports a temperature of about . | 0 | Organic Reactions |
Outside of the industrial sector, cracking of C-C and C-H bonds are rare chemical reactions. In principle, ethane can undergo homolysis:
:CHCH → 2 CH•
Because C-C bond energy is so high (377 kJ/mol), this reaction is not observed under laboratory conditions. More common examples of cracking reactions involve retro-Diels-Alder reactions. Illustrative is the thermal cracking of dicyclopentadiene to produce cyclopentadiene. | 0 | Organic Reactions |
Electrophilic additions of allylsilanes generally occur via an anti S2 process. Allylsilanes react through a conformation in which the smallest substituent on the carbon attached to silicon is essentially eclipsing the double bond. The silyl moiety forces electrophilic attack on the face opposite the silyl group for steric and electronic reasons, although the effects are not large. This model predicts that when the double bond is 1,2-disubstituted, the Z isomer should exhibit greater selectivity than the E' isomer, and this has been observed
Vinylsilane additions proceed with retention of double bond configuration, and follow a similar principle. After addition of the electrophile to the top or bottom face of the double bond, the silyl moiety rotates to become parallel to the adjacent empty 2p orbital. The principle of least motion provides that the electrophile moves into a position close to that formerly occupied by the silyl group. Thus, the configuration of the double bond is retained after loss of the silyl group. | 0 | Organic Reactions |
This process was patented and sold to Hoffmann-La Roche in 1934. The first commercially sold vitamin C product was either Cebion from Merck or Redoxon from Hoffmann-La Roche.
Even today industrial methods for the production of ascorbic acid can be based on the Reichstein process. In modern methods however, sorbose is directly oxidized with a platinum catalyst (developed by Kurt Heyns (1908–2005) in 1942). This method avoids the use of protective groups. A side product with particular modification is 5-Keto-D-gluconic acid.
A shorter biotechnological synthesis of ascorbic acid was announced in 1988 by Genencor International and Eastman Chemical. Glucose is converted to 2-keto-L-gulonic acid in two steps (via 2,4-diketo-L-gulonic acid intermediate) as compared to five steps in the traditional process.
Though many organisms synthesize their own vitamin C, the steps can be different in plants and mammals. Smirnoff concluded that “..little is known about many of the enzymes involved in ascorbate biosynthesis or about the factors controlling flux through the pathways". There is interest in finding alternatives to the Reichstein process. Experiments suggest that genetically modified bacteria might be commercially usable. | 0 | Organic Reactions |
Magnesium oxalate can by synthesized by combining a magnesium salt or ion with an oxalate.
: Mg + CO → MgCO
A specific example of a synthesis would be mixing Mg(NO) and KOH and then adding that solution to dimethyl oxalate, (COOCH).
When heated, magnesium oxalate will decompose. First, the dihydrate will decompose at 150 °C into the anhydrous form.
: MgCO•2HO → MgCO + 2 HO
With additional heating the anhydrous form will decompose further into magnesium oxide and carbon oxides between 420 °C and 620 °C. First, carbon monoxide and magnesium carbonate form. The carbon monoxide then oxidizes to carbon dioxide, and the magnesium carbonate decomposes further to magnesium oxide and carbon dioxide.
: MgCO → MgCO + CO
: CO + 1/2 O → CO
: MgCO → MgO + CO
Magnesium oxalate dihydrate has also been used in the synthesis of nano sized particles of magnesium oxide, which have larger surface are to volume ratio than conventionally synthesized particles and are optimal for various applications, such as in catalysis. By using a sol-gel synthesis, which involves combining a magnesium salt, in this case magnesium oxalate, with a gelating agent, nano sized particles of magnesium oxide can be produced. | 1 | Inorganic Reactions + Inorganic Compounds |
Lead(II) azide is an inorganic compound. More so than other azides, it is explosive. It is used in detonators to initiate secondary explosives. In a commercially usable form, it is a white to buff powder. | 1 | Inorganic Reactions + Inorganic Compounds |
Desulfonylation reactions are chemical reactions leading to the removal of a sulfonyl group from organic compounds. As the sulfonyl functional group is electron-withdrawing, methods for cleaving the sulfur–carbon bonds of sulfones are typically reductive in nature. Olefination or replacement with hydrogen may be accomplished using reductive desulfonylation methods. | 0 | Organic Reactions |
The diphosphine ligands have received considerably more attention than the monophosphines and, perhaps as a consequence, have a much longer list of achievement. This class includes the first ligand to achieve high selectivity (DIOP), the first ligand to be used in industrial asymmetric synthesis (DIPAMP) and what is likely the best known chiral ligand (BINAP). Chiral diphosphine ligands are now ubiquitous in asymmetric hydrogenation.
<br /> | 0 | Organic Reactions |
Methanation is an important step in the creation of synthetic or substitute natural gas (SNG). Coal or wood undergo gasification which creates a producer gas that must undergo methanation in order to produce a usable gas that just needs to undergo a final purification step.
The first commercial synthetic gas plant opened in 1984 and is the Great Plains Synfuel plant in Beulah, North Dakota. It is still operational and produces 1500 MW worth of SNG using coal as the carbon source. In the years since its opening, other commercial facilities have been opened using other carbon sources such as wood chips.
In France, the AFUL Chantrerie, located in Nantes, started in November 2017 the demonstrator MINERVE. This methanation unit of 14 Nm3/day was carried out by Top Industrie, with the support of Leaf. This installation is used to feed a CNG station and to inject methane into the natural gas boiler. | 0 | Organic Reactions |
The amino radical may also be produced by reaction of e(aq) with hydroxylamine (). Several studies also utilized the redox system of for the production of amino radicals using electron paramagnetic resonance (ESR) spectroscopy and polarography. | 1 | Inorganic Reactions + Inorganic Compounds |
The water–gas shift reaction (WGSR) describes the reaction of carbon monoxide and water vapor to form carbon dioxide and hydrogen:
: CO + HO CO + H
The water gas shift reaction was discovered by Italian physicist Felice Fontana in 1780. It was not until much later that the industrial value of this reaction was realized. Before the early 20th century, hydrogen was obtained by reacting steam under high pressure with iron to produce iron oxide and hydrogen. With the development of industrial processes that required hydrogen, such as the Haber–Bosch ammonia synthesis, a less expensive and more efficient method of hydrogen production was needed. As a resolution to this problem, the WGSR was combined with the gasification of coal to produce hydrogen. | 1 | Inorganic Reactions + Inorganic Compounds |
When doped with a suitable transition metal such as manganese, GaN is a promising spintronics material (magnetic semiconductors). | 1 | Inorganic Reactions + Inorganic Compounds |
The synthesis of (±)-periplanone B is a prominent example of macrocyclic stereocontrol. Periplanone B is a sex pheromone of the American female cockroach, and has been the target of several synthetic attempts. Significantly, two reactions on the macrocyclic precursor to (±)-periplanone B were directed using only ground state conformational preferences and the peripheral attack model. Reacting from the most stable boat-chair-boat conformation, asymmetric epoxidation of the cis-internal olefin can be achieved without using a reagent-controlled epoxidation method or a directed epoxidation with an allylic alcohol.
Epoxidation of the ketone was achieved, and can be modeled by peripheral attack of the sulfur ylide on the carbonyl group in a Johnson-Corey-Chaykovsky reaction to yield the protected form of (±)-periplanone B. Deprotection of the alcohol followed by oxidation yielded the desired natural product. | 0 | Organic Reactions |
The Schöllkopf method or Schöllkopf Bis-Lactim Amino Acid Synthesis is a method in organic chemistry for the asymmetric synthesis of chiral amino acids. The method was established in 1981 by Ulrich Schöllkopf. In it glycine is a substrate, valine a chiral auxiliary and the reaction taking place an alkylation. | 0 | Organic Reactions |
Carbonatation is a slow process that occurs in concrete where lime (CaO, or Ca(OH)) in the cement reacts with carbon dioxide (CO) from the air and forms calcium carbonate.
The water in the pores of Portland cement concrete is normally alkaline with a pH in the range of 12.5 to 13.5. This highly alkaline environment is one in which the steel rebar is passivated and is protected from corrosion. According to the Pourbaix diagram for iron, the metal is passive when the pH is above 9.5.
The carbon dioxide in the air reacts with the alkali in the cement and makes the pore water more acidic, thus lowering the pH. Carbon dioxide will start to carbonatate the cement in the concrete from the moment the object is made. This carbonatation process will start at the surface, then slowly moves deeper and deeper into the concrete. The rate of carbonatation is dependent on the relative humidity of the concrete - a 50% relative humidity being optimal. If the object is cracked, the carbon dioxide in the air will be better able to penetrate into the concrete.
Eventually this may lead to corrosion of the rebar and structural damage or failure. | 1 | Inorganic Reactions + Inorganic Compounds |
Because they form a strong electrophile when treated with Lewis acids, acyl halides are commonly used as acylating agents. For example, Friedel–Crafts acylation uses acetyl chloride () as the agent and aluminum chloride () as a catalyst to add an acetyl group to benzene:
This reaction is an example of electrophilic aromatic substitution.
Acyl halides and acid anhydrides of carboxylic acids are also common acylating agents. In some cases, active esters exhibit comparable reactivity. All react with amines to form amides and with alcohols to form esters by nucleophilic acyl substitution.
Acylation can be used to prevent rearrangement reactions that would normally occur in alkylation. To do this an acylation reaction is performed, then the carbonyl is removed by Clemmensen reduction or a similar process. | 0 | Organic Reactions |
Labeling studies establish the following regiochemistry:
:RCDO + CH=CHR → RC(O)CHCHDR
In terms of the reaction mechanism, hydroacylation begins with oxidative addition of the aldehydic carbon-hydrogen bond. The resulting acyl hydride complex next binds the alkene. The sequence of oxidative addition and alkene coordination is often unclear. Via migratory insertion, the alkene inserts into either the metal-acyl or the metal-hydride bonds. In the final step, the resulting alkyl-acyl or beta-ketoalkyl-hydride complex undergoes reductive elimination. A competing side-reaction is decarbonylation of the aldehyde. This process also proceeds via the intermediacy of the acyl metal hydride:
:R"C(O)-ML-H → R"-M(CO)L-H
This step can be followed by reductive elimination of the alkane:
:R"-M(CO)L-H → R"-H + M(CO)L | 0 | Organic Reactions |
Compounds containing both a primary or secondary amine and carbonyl functional group are often labile. This guideline applies to amino aldehydes, amino-ketones, and amino-esters; indeed a molecule cannot carry simultaneously (unprotected) aldehyde and amine groups. Aminoacetone, the simplest amino ketone, cannot be isolated as a liquid or solid, and 2-aminobenzaldehyde oligomerizes in solution or in the melt. An α-formyl aziridine, reduced with DIBAL from the ester, reversibly dimerizes to an oxazolidine: | 0 | Organic Reactions |
The Class IIA HDACs includes HDAC4, HDAC5, HDAC7 and HDAC9. HDACs 4 and 5 have been found to most closely resemble each other while HDAC7 maintains a resemblance to both of them. There have been three discovered variants of HDAC9 including HDAC9a, HDAC9b and HDAC9c/HDRP, while more have been suspected. The variants of HDAC9 have been found to have similarities to the rest of the Class IIA HDACs. For HDAC9, the splicing variants can be seen as a way of creating a "fine-tuned mechanism" for differentiation expression levels in the cell. Different cell types may take advantage and utilize different isoforms of the HDAC9 enzyme allowing for different forms of regulation. HDACs 4, 5 and 7 have their catalytic domains located in the C-terminus along with an NLS region while HDAC9 has its catalytic domain located in the N-terminus. However, the HDAC9 variant HDAC9c/HDRP lacks a catalytic domain but has a 50% similarity to the N-terminus of HDACs 4 and 5.
For HDACs 4, 5 and 7, conserved binding domains have been discovered that bind for C-terminal binding protein (CtBP), myocyte enhancer factor 2 (MEF2) and 14-3-3. All three HDACs work to repress the myogenic transcription factor MEF2 which an essential role in muscle differentiation as a DNA binding transcription factor. Binding of HDACs to MEF2 inhibits muscle differentiation, which can be reversed by action of Ca/calmodulin-dependent kinase (CaMK) which works to dissociate the HDAC/MEF2 complex by phosphorylating the HDAC portion. They have been seen to be involved in cellular hypertrophy in muscle control differentiation as well as cellular hypertrophy in muscle and cartilage tissues. HDACs 5 and 7 have been shown to work in opposition to HDAC4 during muscle differentiation regulation so as to keep a proper level of expression. There has been evidence that these HDACs also interact with HDAC3 as a co-recruitment factor to the SMRT/N-CoR factors in the nucleus. Absence of the HDAC3 enzyme has shown to lead to inactivity which makes researchers believe that HDACs 4, 5 and 7 help the incorporation of DNA-binding recruiters for the HDAC3-containing HDAC complexes located in the nucleus. When HDAC4 is knocked out in mice, they suffer from a pronounced chondrocyte hypertrophy and die due to extreme ossification. HDAC7 has been shown to suppress Nur77-dependent apoptosis. This interaction leads to a role in clonal expansion of T cells. HDAC9 KO mice are shown to suffer from cardiac hypertrophy which is exacerbated in mice that are double KO for HDACs 9 and 5. | 0 | Organic Reactions |
The normal halide of boron is boron trifluoride|. Boron forms many subhalides: several , including diboron tetrafluoride|; also BF. Aluminium forms a variety of subhalides. For gallium, adducts of are known. Phosphorus subhalides include diphosphorus tetraiodide|, , and (structurally related to ). For bismuth, the compound originally described as bismuth monochloride was later shown to consist of clusters and chloride anions. There are many tellurium subhalides, including tritellurium dichloride|, ditellurium bromide| (X = Cl, Br, I), and two forms of TeI. | 1 | Inorganic Reactions + Inorganic Compounds |
Nucleotides can undergo enzyme-catalyzed intramolecular cyclization in order to produce several important biological molecules. These cyclizations typically proceed through an oxocarbenium intermediate. An example of this reaction can be seen in the cyclization cyclic ADP ribose, which is an important molecule for intracellular calcium signaling. | 0 | Organic Reactions |
Hexaamminenickel chloride is the chemical compound with the formula [Ni(NH)]Cl. It is the chloride salt of the metal ammine complex [Ni(NH)]. The cation features six ammonia (called ammines in coordination chemistry) ligands attached to the nickel(II) ion. | 1 | Inorganic Reactions + Inorganic Compounds |
LSAT has a Mohs hardness of 6.5, placing it between quartz and the mineral feldspar. Its relative dielectric constant is ~22 and it has a thermal expansion coefficient of 8~10×10/K. The thermal conductivity of LSAT is 5.1 WmK. LSAT's (cubic) lattice parameter of 3.868 Å makes it compatible for the growth of a wide range of perovskite oxides with a relatively low strain.
LSAT's melting temperature of 1,840C is lower compared to similar alternative substrates, such as LaAlO. This property enables the growth of LSAT single crystals using the Czochralski process (CZ), which has commercial advantages. | 1 | Inorganic Reactions + Inorganic Compounds |
CdS and CdSe form solid solutions with each other. Increasing amounts of cadmium selenide, gives pigments verging toward red, for example CI pigment orange 20 and CI pigment red 108.<br />Such solid solutions are components of photoresistors (light dependent resistors) sensitive to visible and near infrared light. | 1 | Inorganic Reactions + Inorganic Compounds |
The reaction involving benzaldehyde was discovered by Claisen using sodium benzylate as base. The reaction produces benzyl benzoate.
Enolizable aldehydes are not amenable to Claisen's conditions. Vyacheslav Tishchenko discovered that aluminium alkoxides allowed the conversion of enolizable aldehydes to esters. | 0 | Organic Reactions |
The synthesis of borjatriol involved the rare isolation of a migrated epoxide. The diastereomeric mixture of rearrangement products was carried through the remainder of the synthesis.
The final two steps in the total synthesis of spatol involved intramolecular electrophilic trapping of an alkoxide derived from a rearranged epoxide. Attack of the intermediate alkoxide on the adjacent mesylate afforded a bis(epoxide), and debenzylation provided the target compound. | 0 | Organic Reactions |
Deprotonation of enolizable ketones, aldehydes, and esters gives enolates. Enolates can be trapped by the addition of electrophiles at oxygen. Silylation gives silyl enol ether. Acylation gives
esters such as vinyl acetate. | 0 | Organic Reactions |
Single crystals of lanthanum aluminate are commercially available as a substrate for the epitaxial growth of perovskites, and particularly for cuprate superconductors. | 1 | Inorganic Reactions + Inorganic Compounds |
Blue, white and ultraviolet LEDs are grown on industrial scale by MOVPE. The precursors are ammonia with either trimethylgallium or triethylgallium, the carrier gas being nitrogen or hydrogen. Growth temperature ranges between . Introduction of trimethylaluminium and/or trimethylindium is necessary for growing quantum wells and other kinds of heterostructures. | 1 | Inorganic Reactions + Inorganic Compounds |
Hydrogen cyanide (also known as prussic acid) is a chemical compound with the formula HCN and structural formula . It is a colorless, extremely poisonous, and flammable liquid that boils slightly above room temperature, at . HCN is produced on an industrial scale and is a highly valued precursor to many chemical compounds ranging from polymers to pharmaceuticals. Large-scale applications are for the production of potassium cyanide and adiponitrile, used in mining and plastics, respectively. It is more toxic than solid cyanide compounds due to its volatile nature.
Whether hydrogen cyanide is an organic compound or not is a topic of debate among chemists, and opinions vary from author to author. Traditionally, it is considered inorganic by significant part of authors. Contrary to them, it is considered organic by other authors, because hydrogen cyanide belongs to the class of organic compounds known as nitriles which have the formula , where R is typically organyl group (e.g., alkyl or aryl) or hydrogen. In the case of hydrogen cyanide, the R group is hydrogen H, so the other names of hydrogen cyanide are methanenitrile and formonitrile. | 1 | Inorganic Reactions + Inorganic Compounds |
Among several variants of thermal cracking methods (variously known as the "Shukhov cracking process", "Burton cracking process", "Burton-Humphreys cracking process", and "Dubbs cracking process") Vladimir Shukhov, a Russian engineer, invented and patented, the first in 1891 (Russian Empire, patent no. 12926, November 7, 1891). One installation was used to a limited extent in Russia, but development was not followed up; In the first decade of the 20th century the American engineers William Merriam Burton and Robert E. Humphreys independently developed and patented a similar process as U.S. patent 1,049,667 on June 8, 1908. Among its advantages was that both the condenser and the boiler were continuously kept under pressure.
In its earlier versions it was a batch process, rather than continuous, and many patents were to follow in the US and Europe, though not all were practical. In 1924, a delegation from the American Sinclair Oil Corporation visited Shukhov. Sinclair Oil apparently wished to suggest that the patent of Burton and Humphreys, in use by Standard Oil, was derived from Shukhovs patent for oil cracking, as described in the Russian patent. If that could be established, it could strengthen the hand of rival American companies wishing to invalidate the Burton-Humphreys patent. In the event Shukhov satisfied the Americans that in principle Burtons method closely resembled his 1891 patents, though his own interest in the matter was primarily to establish that "the Russian oil industry could easily build a cracking apparatus according to any of the described systems without being accused by the Americans of borrowing for free".
At that time, just a few years after the Russian Revolution and brutal Russian Civil War, the Soviet Union was desperate to develop industry and earn foreign exchange, so their oil industry eventually did obtain much of their technology from foreign companies, largely American. At about that time, fluid catalytic cracking was being explored and developed and soon replaced most of the purely thermal cracking processes in the fossil fuel processing industry. The replacement was not complete; many types of cracking, including pure thermal cracking, still are in use, depending on the nature of the feedstock and the products required to satisfy market demands. Thermal cracking remains important, for example in producing naphtha, gas oil, and coke, and more sophisticated forms of thermal cracking have been developed for various purposes. These include visbreaking, steam cracking, and coking. | 0 | Organic Reactions |
Asymmetric hydrogenations are used in the production of several drugs, such as the antibacterial levofloxin, the antibiotic carbapenem, and the antipsychotic agent BMS181100.
Knowles' research into asymmetric hydrogenation and its application to the production scale synthesis of L-Dopa gave asymmetric hydrogenation a strong start in the industrial world. A 2001 review indicated that asymmetric hydrogenation accounted for 50% of production scale, 90% of pilot scale, and 74% of bench scale catalytic, enantioselective processes in industry, with the caveat that asymmetric catalytic methods in general were not yet widely used.
Asymmetric hydrogenation has replaced kinetic resolution based methods has resulted in substantial improvements in the processs efficiency. can be seen in a number of specific cases where the For example, Roches Catalysis Group was able to achieve the synthesis of (S,S)-Ro 67-8867 in 53% overall yield, a dramatic increase above the 3.5% that was achieved in the resolution based synthesis. Roche's synthesis of mibefradil was likewise improved by replacing resolution with asymmetric hydrogenation, reducing the step count by three and increasing the yield of a key intermediate to 80% from the original 70%.
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Noyori-inspired hydrogenation catalysts have been applied to the commercial synthesis of number of fine chemicals. (R)-1,2-Propandiol, precursor to the antibacterial levofloxacin, can be efficiently synthesized from hydroxyacetone using Noyori asymmetric hydrogenation:
Newer routes focus on the hydrogenation of (R)-methyl lactate.
An antibiotic carbapenem is also prepared using Noyori asymmetric hydrogenation via (2S,3R)-methyl 2-(benzamidomethyl)-3-hydroxybutanoate, which is synthesized from racemic methyl 2-(benzamidomethyl)-3-oxobutanoate by dynamic kinetic resolution.
An antipsychotic agent BMS 181100 is synthesized using BINAP/diamine-Ru catalyst. | 0 | Organic Reactions |
Cobalts trichloride was detected in 1952 by Schäfer and Krehl in the gas phase when cobalt(II) chloride is heated in an atmosphere of chlorine . The trichloride is formed through the equilibrium
At 918 K (below the melting point of , 999 K), the trichloride was the predominant cobalt species in the vapor, with partial pressure of 0.72 mm Hg versus 0.62 for the dichloride. However, equilibrium shifts to the left at higher temperatures. At 1073 K, the partial pressures were 7.3 and 31.3 mm Hg, respectively.
Cobalt trichloride, in amounts sufficient to study spectroscopically, was obtained by Green and others in 1983, by sputtering cobalt electrodes with chlorine atoms and trapping the resulting molecules in frozen argon at 14 K.
A report from 1969 claims that treatment of solid cobalt(III) hydroxide · with anhydrous ether saturated with at −20 °C produces a green solution (stable at −78 °C) with the characteristic spectrum of .
In a 1932 report, the compound was claimed to arise in the electrolysis of cobalt(II) chloride in anhydrous ethanol. | 1 | Inorganic Reactions + Inorganic Compounds |
Hydroalumination of alkynes may be either stereospecifically cis or trans depending on the conditions employed. When a dialkylalane such as di(isobutyl)aluminium hydride (DIBAL-H) is used, the hydrogen and aluminium delivered from the reagent end up cis in the resulting alkenylalane. This stereospecificity can be explained by invoking a concerted addition of the H–Al bond across the triple bond. In the transition state, partial positive charge builds up on the carbon forming a bond to hydrogen; thus, the carbon better able to stabilize a positive charge becomes attached to hydrogen in the product alkenylalane. Hydroaluminations of terminal alkynes typically produce terminal alkenylalanes as a result. Selectivity in hydroaluminations of internal alkynes is typically low, unless an electronic bias exists in the substrate (such as a phenyl ring in conjugation with the alkyne).
Stereospecific trans hydroalumination is possible through the use of lithium aluminium hydride. The mechanism of this transformation involves the addition of hydride to the carbon less able to stabilize the developing negative charge (viz., in the β position to an electron-withdrawing group). Coordination of aluminium to the resulting trans vinyl carbanion leads to the observed trans configuration of the product. | 0 | Organic Reactions |
In the compound, gallium has a +3 oxidation state. Gallium arsenide single crystals can be prepared by three industrial processes:
* The vertical gradient freeze (VGF) process.
* Crystal growth using a horizontal zone furnace in the Bridgman-Stockbarger technique, in which gallium and arsenic vapors react, and free molecules deposit on a seed crystal at the cooler end of the furnace.
* Liquid encapsulated Czochralski (LEC) growth is used for producing high-purity single crystals that can exhibit semi-insulating characteristics (see below). Most GaAs wafers are produced using this process.
Alternative methods for producing films of GaAs include:
* VPE reaction of gaseous gallium metal and arsenic trichloride: 2 Ga + 2 → 2 GaAs + 3
* MOCVD reaction of trimethylgallium and arsine: + → GaAs + 3
* Molecular beam epitaxy (MBE) of gallium and arsenic: 4 Ga + → 4 GaAs or 2 Ga + → 2 GaAs
Oxidation of GaAs occurs in air, degrading performance of the semiconductor. The surface can be passivated by depositing a cubic gallium(II) sulfide layer using a tert-butyl gallium sulfide compound such as (. | 1 | Inorganic Reactions + Inorganic Compounds |
Dialkyl (E)-enones have been most commonly epoxidized using either lanthanide/BINOL systems or a magnesium tartrate catalyst.
For alkyl aryl (E)-enones, both polypeptides and lanthanide/BINOL catalysts give good yields and enantioselectivities. The most common polypeptide employed is poly-L-leucine.
Aryl alkyl (E)-enones have been epoxidized with high enantioselectivity using stoichiometric zinc peroxide systems. Polyleucine may be used with these substrates as well; when an existing stereocenter in the substrate biases the sense of selectivity of the epoxidation, polyleucine is able to overcome this bias.
Phase-transfer catalysis has been applied successfully to epoxidations of diaryl (E)-enones (chalcones). Lanthanide/BINOL is effective for this class of substrates as well.
(Z)-Enones are difficult to epoxidize without intermediate bond rotation to afford trans-epoxides. Lanthanide catalysts do effectively prevent bond rotation, however, and provide access to cis epoxide products.
With the lone exception of methylidene tetralone substrates, no general methods are available for the asymmetric nucleophilic epoxidation of trisubstituted double bonds. | 0 | Organic Reactions |
The Kröhnke pyridine synthesis is reaction in organic synthesis between α-pyridinium methyl ketone salts and α, β-unsaturated carbonyl compounds used to generate highly functionalized pyridines. Pyridines occur widely in natural and synthetic products, so there is wide interest in routes for their synthesis. The method is named after Fritz Kröhnke. | 0 | Organic Reactions |
Enolate anions are electronically related to allyl anions. The anionic charge is delocalized over the oxygen and the two carbon sites. Thus they have the character of both an alkoxide and a carbanion.
Although they are often drawn as being simple salts, in fact they adopt complicated structures often featuring aggregates. | 0 | Organic Reactions |
Several other methods for the electrophilic formation of C-N bonds are available. Nitrites and nitrates can be used to form oximes and nitro compounds, respectively. Additionally, organoboranes can serve the role of the nucleophile and often provide higher yields with fewer complications than analogous carbanions. The Neber rearrangement offers an alternative to electrophilic amination through the intermediacy of an azirine. | 0 | Organic Reactions |
The Eschenmoser sulfide contraction method has been employed in a number of total synthesis efforts, like that of fuligocandin A and B, cocaine, diplodialide A and isoretronecanol
An example of general synthetic utility is the synthesis of novel carbapenems | 0 | Organic Reactions |
In order to take advantage of both the thermodynamics and kinetics of the reaction, the industrial scale water gas shift reaction is conducted in multiple adiabatic stages consisting of a high temperature shift (HTS) followed by a low temperature shift (LTS) with intersystem cooling. The initial HTS takes advantage of the high reaction rates, but results in incomplete conversion of carbon monoxide. A subsequent low temperature shift reactor lowers the carbon monoxide content to O/CO ratio where low ratios may lead to side reactions such as the formation of metallic iron, methanation, carbon deposition, and the Fischer–Tropsch reaction. | 1 | Inorganic Reactions + Inorganic Compounds |
In organic synthesis, vinyl oxocarbenium ions (structure on right) can be utilized in a wide range of cycloaddition reactions. They are commonly employed as dienophiles in the Diels–Alder reaction. An electron withdrawing ketone is often added to the dienophile to increase the rate of the reaction, and these ketones are often converted to vinyl oxocarbenium ions during the reaction It is not clear that an oxocarbenium ion necessarily will form, but Roush and co-workers demonstrated the oxocarbenium intermediate in the cyclization shown below. Two products were observed in this reaction, which could only form if the oxocarbenium ring is present as an intermediate. [4+3], [2+2], [3+2] and [5+2] cycloadditions with oxocarbenium intermediates have also been reported. | 0 | Organic Reactions |
Diazomethane and the safer analogue trimethylsilyldiazomethane methylate carboxylic acids, phenols, and even alcohols:
The method offers the advantage that the side products are easily removed from the product mixture. | 0 | Organic Reactions |
It is used in a wide range of applications. For example, it is used as a catalyst for the hydrochlorination of acetylene, or the oxidation of sulfides. | 1 | Inorganic Reactions + Inorganic Compounds |
Uranium tetrafluoride is the inorganic compound with the formula UF. It is a green solid with an insignificant vapor pressure and low solubility in water. Uranium in its tetravalent (uranous) state is important in various technological processes. In the uranium refining industry it is known as green salt. | 1 | Inorganic Reactions + Inorganic Compounds |
The formose reaction is of importance to the question of the origin of life, as it leads from simple formaldehyde to complex sugars like ribose, a building block of RNA. In one experiment simulating early Earth conditions, pentoses formed from mixtures of formaldehyde, glyceraldehyde, and borate minerals such as colemanite (CaBO5HO) or kernite (NaBO). However, issues remain with both the thermodynamic and kinetic feasibility of binding pre-made sugars to a pre-made nucleobase, as well as a method to selectively employ ribose from the mixture. Both formaldehyde and glycolaldehyde have been observed spectroscopically in outer space, making the formose reaction of particular interest to the field of astrobiology. | 0 | Organic Reactions |
There are a total of four classes that categorize Histone Deacetylases (HDACs). Class I includes HDACs 1, 2, 3, and 8. Class II is divided into two subgroups, Class IIA and Class IIB. Class IIA includes HDACs 4, 5, 7, and 9 while Class IIB includes HDACs 6 and 10. Class III contains the Sirtuins and Class IV contains only HDAC11. Classes of HDAC proteins are divided and grouped together based on the comparison to the sequence homologies of Rpd3, Hos1 and Hos2 for Class I HDACs, HDA1 and Hos3 for the Class II HDACs and the sirtuins for Class III HDACs. | 0 | Organic Reactions |
Hexachlorophosphazene reacts readily with alkali metal alkoxides and amides.
The nucleophilic polysubstitution of chloride by alkoxide proceeds via displacement of chloride at separate phosphorus centers:
The observed regioselectivity is due to the combined steric effects and oxygen lone pair π-backdonation (which deactivates already substituted P atoms). | 1 | Inorganic Reactions + Inorganic Compounds |
Dioxiranes may either be prepared in advance or generated in situ for epoxidation reactions. In most cases, a two-phase system must be set up for in situ epoxidations, as KHSO is not soluble in organic solvents. Thus, substrates or products sensitive to hydrolysis will not survive in situ epoxidations. This section describes epoxidation conditions for alkenes with electron-donating or -withdrawing substituents, both of which may be epoxidized with dioxiranes in either the stoichiometric or catalytic mode.
Although dioxiranes are highly electrophilic, they epoxidize both electron-rich and electron-poor alkenes in good yield (although the latter react much more slowly). Electron-poor epoxide products also exhibit enhanced hydrolytic stability, meaning that they can often survive in situ conditions. Epoxidations of electron-rich double bonds have yielded intermediates of Rubottom oxidation. Upon hydrolysis, these siloxyepoxides yield α-hydroxyketones.
Electron-poor double bonds take much longer to epoxidize. Heating may be used to encourage oxidation, although the reaction temperature should never exceed 50 °C, to avoid decomposition of the dioxirane.
Alkenes bound to both electron-withdrawing and -donating groups tend to behave like the former, requiring long oxidation times and occasionally some heating. Like electron-poor epoxides, epoxide products from this class of substrates are often stable with respect to hydrolysis.
In substrates containing multiple double bonds, the most electron-rich double bond can usually be selectively epoxidized.
Epoxidations employing aqueous Oxone and a catalytic amount of ketone are convenient if a specialized dioxirane must be used (as in asymmetric applications) or if isolation of the dioxirane is inconvenient. Hydrolytic decomposition of the epoxidation product may be used to good advantage. | 0 | Organic Reactions |
The compound is used in high-end electric and semiconductor products, and as a raw material to produce phosphor. Also it is used as a magnetic material and sputtering target material. | 1 | Inorganic Reactions + Inorganic Compounds |
Ammonia borane (also systematically named ammoniotrihydroborate), also called borazane, is the chemical compound with the formula . The colourless or white solid is the simplest molecular boron-nitrogen-hydride compound. It has attracted attention as a source of hydrogen fuel, but is otherwise primarily of academic interest. | 1 | Inorganic Reactions + Inorganic Compounds |
HBr can be prepared by distillation of a solution of sodium bromide or potassium bromide with phosphoric acid or sulfuric acid:
: KBr + HSO → KHSO + HBr
Concentrated sulfuric acid is less effective because it oxidizes HBr to bromine:
: 2 HBr + HSO → Br + SO + 2 HO
The acid may be prepared by:
* reaction of bromine with water and sulfur:
*: 2 Br + S + 2 HO → 4 HBr + SO
* bromination of tetralin:
*: CH + 4 Br → CHBr + 4 HBr
* reduction of bromine with phosphorous acid:
*: Br + HPO + HO → HPO + 2 HBr
Anhydrous hydrogen bromide can also be produced on a small scale by thermolysis of triphenylphosphonium bromide in refluxing xylene.
Hydrogen bromide prepared by the above methods can be contaminated with Br, which can be removed by passing the gas through a solution of phenol at room temperature in tetrachloromethane or other suitable solvent (producing 2,4,6-tribromophenol and generating more HBr in the process) or through copper turnings or copper gauze at high temperature. | 1 | Inorganic Reactions + Inorganic Compounds |
Carbene C−H insertion in organic chemistry concerns the insertion reaction of a carbene into a carbon–hydrogen bond. This organic reaction is of some importance in the synthesis of new organic compounds.
Simple carbenes such as the methylene and dichlorocarbene are not regioselective towards insertion. When the carbene is stabilized by a metal the selectivity increases. The compound dirhodium tetraacetate is found to be especially effective. In a typical reaction ethyl diazoacetate (a well-known carbene precursor) and dirhodium tetraacetate react with hexane; the insertion into a C−H bond occurs 1% on one of the methyl groups, 63% on the alpha-methylene unit and 33% on the beta-methylene unit.
The first such reaction was reported in 1981, and the general reaction mechanism proposed by Doyle in 1993. the metal that stabilizes the carbene, dissociates at the same time but not to the same degree as carbon–carbon bond formation and hydrogen atom migration. The reaction is distinct from a metal catalyzed C−H activation reaction (sensu stricto) in which the metal actually inserts itself between carbon and hydrogen to form a species with a metal–carbon bond. It does, however, serve as a premier example of a metal-catalyzed C–H functionalization reaction, which some authors also refer to as C–H activation (sensu lato).
The metal employed as a catalyst in this reaction historically was copper until superseded by rhodium. Other metals stabilize the carbene too much (e.g. molybdenum as in Fischer carbenes) or result in carbenes too reactive (e.g. gold, silver). Many dirhodium carboxylates and carboxamidates exist, including chiral ones. An effective chiral dirhodium catalyst is Rh(MPPIM) with MPPIM (Methyl PhenylPropyl IMidazolidinecarboxylato) asymmetric ligand.
Most successful reactions are intramolecular within geometrically rigid systems, as pioneered by Wenkert (1982) and Taber (1982). | 0 | Organic Reactions |
Stereocontrol for cyclohexane rings is well established in organic chemistry, in large part due to the axial/equatorial preferential positioning of substituents on the ring. Macrocyclic stereocontrol models the substitution and reactions of medium and large rings in organic chemistry, with remote stereogenic elements providing enough conformational influence to direct the outcome of a reaction.
Early assumptions towards macrocycles in synthetic chemistry considered them far too floppy to provide any degree of stereochemical or regiochemical control in a reaction. The experiments of W. Clark Still in the late 1970s and 1980s challenged this assumption, while several others found crystallographic data and NMR data that suggested macrocyclic rings were not the floppy, conformationally ill-defined species many assumed.
The degree to which a macrocyclic ring is either rigid or floppy depends significantly on the substitution of the ring and the overall size. Significantly, even small conformational preferences, such as those envisioned in floppy macrocycles, can profoundly influence the ground state of a given reaction, providing stereocontrol such as in the synthesis of miyakolide. Computational modeling can predict conformations of medium rings with reasonable accuracy, as Still used molecular mechanics modeling computations to predict ring conformations to determine potential reactivity and stereochemical outcomes.
Reaction classes used in synthesis of natural products under the macrocyclic stereocontrol model for obtaining a desired stereochemistry include: hydrogenations such as in neopeltolide and (±)-methynolide, epoxidations such as in (±)-periplanone B and lonomycin A, hydroborations such as in 9-dihydroerythronolide B, enolate alkylations such as in (±)-3-deoxyrosaranolide, dihydroxylations such as in cladiell-11-ene-3,6,7-triol, and reductions such as in eucannabinolide. | 0 | Organic Reactions |
A free-radical reaction is any chemical reaction involving free radicals. This reaction type is abundant in organic reactions. Two pioneering studies into free radical reactions have been the discovery of the triphenylmethyl radical by Moses Gomberg (1900) and the lead-mirror experiment described by Friedrich Paneth in 1927. In this last experiment tetramethyllead is decomposed at elevated temperatures to methyl radicals and elemental lead in a quartz tube. The gaseous methyl radicals are moved to another part of the chamber in a carrier gas where they react with lead in a mirror film which slowly disappears.
When radical reactions are part of organic synthesis the radicals are often generated from radical initiators such as peroxides or azobis compounds. Many radical reactions are chain reactions with a chain initiation step, a chain propagation step and a chain termination step. Reaction inhibitors slow down a radical reaction and radical disproportionation is a competing reaction. Radical reactions occur frequently in the gas phase, are often initiated by light, are rarely acid or base catalyzed and are not dependent on polarity of the reaction medium. Reactions are also similar whether in the gas phase or solution phase. | 0 | Organic Reactions |
The Kharasch addition is an organic reaction and a metal-catalysed free radical addition of CXCl compounds (X = Cl, Br, H) to alkenes. The reaction is used to append trichloromethyl or dichloromethyl groups to terminal alkenes. The method has attracted considerable interest, but it is of limited value because of narrow substrate scope and demanding conditions.
The basic reaction proceeds through the CXCl free radical. Examples of organohalides are carbon tetrachloride and chloroform. Radicals are often generated by abstraction of a halide radical by a metal ion. The addition is an anti-Markovnikov addition. Early work linked the addition to olefin polymerization and is therefore considered a first step into what was to become atom transfer radical polymerization.
An example of Kharasch addition is the synthesis of 1,1,3-trichloro-n-nonane from 1-octene and chloroform using an iron-based catalyst. | 0 | Organic Reactions |
Hydrothermal liquefaction is a fast process, resulting in low residence times for depolymerization to occur. Typical residence times are measured in minutes (15 to 60 minutes); however, the residence time is highly dependent on the reaction conditions, including feedstock, solvent ratio and temperature. As such, optimization of the residence time is necessary to ensure a complete depolymerization without allowing further reactions to occur. | 0 | Organic Reactions |
Beryllium oxalate is an inorganic compound, a salt of beryllium metal and oxalic acid with the chemical formula . It forms colorless crystals, dissolves in water, and also forms crystalline hydrates. The compound is used to prepare ultra-pure beryllium oxide by thermal decomposition. | 1 | Inorganic Reactions + Inorganic Compounds |
In the 1960s and 1970s it was speculated that aluminium was related to various neurological disorders, including Alzheimer's disease. Since then, multiple epidemiological studies have found no connection between exposure to environmental or swallowed aluminium and neurological disorders, though injected aluminium was not looked at in these studies.
Neural disorders were found in experiments on mice motivated by Gulf War illness (GWI). Aluminium hydroxide injected in doses equivalent to those administered to the United States military, showed increased reactive astrocytes, increased apoptosis of motor neurons and microglial proliferation within the spinal cord and cortex. | 1 | Inorganic Reactions + Inorganic Compounds |
In organic chemistry, hydroboration refers to the addition of a hydrogen-boron bond to certain double and triple bonds involving carbon (, , , and ). This chemical reaction is useful in the organic synthesis of organic compounds.
Hydroboration produces organoborane compounds that react with a variety of reagents to produce useful compounds, such as alcohols, amines, or alkyl halides. The most widely known reaction of the organoboranes is oxidation to produce alcohols typically by hydrogen peroxide. This type of reaction has promoted research on hydroboration because of its mild condition and a wide scope of tolerated alkenes. Another research subtheme is metal-catalysed hydroboration.
The development of this technology and the underlying concepts were recognized by the Nobel Prize in Chemistry to Herbert C. Brown. He shared the prize with Georg Wittig in 1979 for his pioneering research on organoboranes as important synthetic intermediates. A complement to hydroboration is carboboration, where a carbon moiety is incorporated rather than hydrogen. | 0 | Organic Reactions |
Carbonatation is a chemical reaction in which calcium hydroxide reacts with carbon dioxide and forms insoluble calcium carbonate:
The process of forming a carbonate is sometimes referred to as "carbonation", although this term usually refers to the process of dissolving carbon dioxide in water. | 1 | Inorganic Reactions + Inorganic Compounds |
Vanadates can behave as structural mimics of phosphates, and in this way they exhibit biological activity.
Ammonium metavanadate is used to prepare Mandelin reagent, a qualitative test for alkaloids. | 1 | Inorganic Reactions + Inorganic Compounds |
Enantiopure, planar chiral chromium arene complexes can be synthesized using several strategies. Diastereoselective complexation of a chiral, non-racemic arene to chromium is one such strategy. In the example in equation (5), enantioselective Corey-Itsuno reduction sets up a diastereoselective ligand substitution reaction. After complexation, the alcohol is reduced with triethylsilane.
A second strategy involves enantioselective ortho-lithiation and in situ quenching with an electrophile. Isolation of the lithium arene and subsequent treatment with TMSCl led to lower enantioselectivities.
Site-selective conjugate addition to chiral aryl hydrazone complexes can also be used for the enantioselective formation of planar chiral chromium arenes. Hydride abstraction neutralizes the addition product, and treatment with acid cleaves the hydrazone. | 0 | Organic Reactions |
The Bunsen reaction is a chemical reaction that describes water, sulfur dioxide, and iodine reacting to form sulfuric acid and hydrogen iodide:
: 2HO + SO + I → HSO + 2HI
This reaction is the first step in the sulfur-iodine cycle to produce hydrogen. The products separate into two aqueous layers, with the sulfuric acid floating on top, and a mixture of hydrogen iodide and unreacted iodine on the bottom. While the two layers are generally considered immiscible, small amounts of sulfuric acid may still remain in the hydrogen iodide layer and vice versa. This can lead to unwanted side reactions, one of which precipitates out sulfur, a potential obstruction to the reaction vessel. The reaction is named after Robert Bunsen, who discovered it in 1853.
A similar reaction is the basis for Karl Fischer titration.
Note that at sufficiently high temperatures, concentrated HSO may react with HI, giving I, SO and HO, which reverses the reaction. Many chemical processes are reversible reactions, such as ammonia production from N and H, and removing the desired product will shift equilibrium to the right of the equation favoring reaction products as per the Le Chatelier principle. | 1 | Inorganic Reactions + Inorganic Compounds |
Lanthanum hydroxide can be obtained by adding an alkali such as ammonia to aqueous solutions of lanthanum salts such as lanthanum nitrate. This produces a gel-like precipitate that can then be dried in air.
Alternatively, it can be produced by hydration reaction (addition of water) to lanthanum oxide. | 1 | Inorganic Reactions + Inorganic Compounds |
Copper(II) borate is an inorganic compound with the formula Cu(B O). It has previously studied due to its photocatalytic properties. | 1 | Inorganic Reactions + Inorganic Compounds |
Diborane can be produced in situ by reduction BF with NaBH (see for Flavopiridol). Usually however, borane dimethylsulfide complex BHS(CH) (BMS) is used as a source of BH. It can be obtained in highly concentrated forms.
The adduct BH(THF) is also commercially available as THF solutions wherein it exists as the 1:1 adduct. It degrades with time.
Borane adducts with phosphines and amines are also available, but are not widely used. Borane makes a strong adduct with triethylamine; using this adduct requires harsher conditions in hydroboration. This can be advantageous for cases such as hydroborating trienes to avoid polymerization. More sterically hindered tertiary and silyl amines can deliver borane to alkenes at room temperature. | 0 | Organic Reactions |
Reactions of organocopper reagents involve species containing copper-carbon bonds acting as nucleophiles in the presence of organic electrophiles. Organocopper reagents are now commonly used in organic synthesis as mild, selective nucleophiles for substitution and conjugate addition reactions.
Since the discovery that copper(I) halides catalyze the conjugate addition of Grignard reagents in 1941, organocopper reagents have emerged as weakly basic, nucleophilic reagents for substitution and addition reactions. The constitution of organocopper compounds depends on their method of preparation and the various kinds of organocopper reagents exhibit different reactivity profiles. As a result, the scope of reactions involving organocopper reagents is extremely broad.
* Organocopper complexes (RCu) are produced when a copper(I) halide and organolithium are combined. In conjunction with Lewis acidic additives such as boron trifluoride etherate, these reagents are used for conjugate addition reactions.
* Lower-order cuprates (RCuLi, also known as Gilman reagents) result when organocopper complexes are treated with an equivalent of organolithium. Alternatively, they may be formed by the treatment of a copper(I) halide with two equivalents of organolithium. They undergo substitution, conjugate addition, and carbocupration reactions in the presence of the appropriate organic substrates. Mixed Gilman reagents consist of two different R groups, one of which is typically a non-transferable "dummy" group.
* Lower-order cyanocuprates (RCu(CN)Li) are similarly derived from an organolithium compound and copper(I) cyanide; however, intermediate organocopper complexes do not form during this reaction and thus only a single equivalent of organolithium reagent is necessary. Cyanocuprates undergo S2' substitution in the presence of allyl electrophiles and conjugate addition reactions in the presence of enones.
* Higher-order cyanocuprates (RCu(CN)Li) are formed upon the reaction of two equivalents of organolithium with copper(I) cyanide. These reagents are more reactive towards substitution than the corresponding lower-order cyanocuprates. | 0 | Organic Reactions |
Fluorination by sulfur tetrafluoride produces organofluorine compounds from oxygen-containing organic functional groups using sulfur tetrafluoride. The reaction has broad scope, and SF is an inexpensive reagent. It is however hazardous gas whose handling requires specialized apparatus. Thus, for many laboratory scale fluorinations diethylaminosulfur trifluoride ("DAST") is used instead. | 0 | Organic Reactions |
The environment, health and safety aspects of gallium arsenide sources (such as trimethylgallium and arsine) and industrial hygiene monitoring studies of metalorganic precursors have been reported. California lists gallium arsenide as a carcinogen, as do IARC and ECA, and it is considered a known carcinogen in animals. On the other hand, a 2013 review (funded by industry) argued against these classifications, saying that when rats or mice inhale fine GaAs powders (as in previous studies), they get cancer from the resulting lung irritation and inflammation, rather than from a primary carcinogenic effect of the GaAs itself—and that, moreover, fine GaAs powders are unlikely to be created in the production or use of GaAs. | 1 | Inorganic Reactions + Inorganic Compounds |
(-)-C-demethyl arteannuin B is a structural analog of the antimalarial artemisinin. It exhibits potent antimalarial activity even against a drug-resistant strain. Little and coworkers obtained the alkylated hydrazone in diastereomerically pure form (de > 95%) through the Enders' alkylation reaction. This intermediate was then elaborated into (-)-C-demethyl arteannuin B. | 0 | Organic Reactions |
Dolomitization is a geological process by which the carbonate mineral dolomite is formed when magnesium ions replace calcium ions in another carbonate mineral, calcite. It is common for this mineral alteration into dolomite to take place due to evaporation of water in the sabkha area. Dolomitization involves substantial amount of recrystallization. This process is described by the stoichiometric equation:
:2 CaCO + Mg ↔ CaMg(CO) + Ca
Dolomitization depends on specific conditions which include low Ca:Mg ratio in solution, reactant surface area, the mineralogy of the reactant, high temperatures which represents the thermodynamic stability of the system, and the presence of kinetic inhibitors such as sulfate.
If the kinetic inhibitors and high temperatures are compatible, then dolomitization can take place in saline environments above thermodynamic and kinetic saturation with respect to dolomite. This type of environment includes, freshwater and seawater mixing zones, normal saline to hypersaline subtidal environments, schizohaline environments (fluctuating salinity: fresh-water to hypersaline conditions) and hypersaline supratidal environments. When requirements are fulfilled, dolomitization can take place in alkaline environments which are those under the influence of bacterial reduction and fermentation processes, and areas with high input alkaline continental groundwaters. Environments with high temperatures (about 50 °C) such as subsurface and hydrothermal environments are conducive to dolomitization. | 1 | Inorganic Reactions + Inorganic Compounds |
Metal halides are often readily available precursors for other inorganic compounds. Mentioned above, the halide compounds can be made anhydrous by heat, vacuum, or treatment with thionyl chloride.
Halide ligands may be abstracted by silver(I), often as the tetrafluoroborate or the hexafluorophosphate. In many transition metal compounds, the empty coordination site is stabilized by a coordinating solvent like tetrahydrofuran. Halide ligands may also be displaced by the alkali salt of an X-type ligand, such as a salen-type ligand. This reaction is formally a transmetallation, and the abstraction of the halide is driven by the precipitation of the resultant alkali halide in an organic solvent. The alkali halides generally have very high lattice energies.
For example, sodium cyclopentadienide reacts with ferrous chloride to yield ferrocene:
:2 NaCH + FeCl → Fe(CH) + 2 NaCl
While inorganic compounds used for catalysis may be prepared and isolated, they may at times be generated in situ by addition of the metal halide and the desired ligand. For example, palladium chloride and triphenylphosphine may be often be used in lieu of bis(triphenylphosphine)palladium(II) chloride for palladium-catalyzed coupling reactions. | 1 | Inorganic Reactions + Inorganic Compounds |
Glucuronidation occurs mainly in the liver, although the enzyme responsible for its catalysis, UDP-glucuronyltransferase, has been found in all major body organs (e.g., intestine, kidneys, brain, adrenal gland, spleen, and thymus). | 0 | Organic Reactions |
In 1929, the conversion of oleic acid to stearic acid in the presence of hydrazine was observed. The short-lived intermediate diimide was not implicated in this reductive process until the 1960s. Since that time, several methods of generating transient amounts of diimide have been developed. In the presence of unpolarized alkenes, alkynes or allenes, diimide is converted into dinitrogen with reduction (net addition of dihydrogen) of the unsaturated functionality. Diimide formation is the rate-limiting step of the process, and a concerted mechanism involving cis-diimide has been proposed. This reduction represents a metal-free alternative to catalytic hydrogenation reductions, and does not lead to the cleavage of sensitive O–O and N–O bonds. | 0 | Organic Reactions |
Various polysulfides - are components of liver of sulfur. Polysulfides, like sulfides, can induce stress corrosion cracking in carbon steel and stainless steel. | 1 | Inorganic Reactions + Inorganic Compounds |
Electrophilic substitution of unsaturated silanes involves attack of an electrophile on an allyl- or vinylsilane. An allyl or vinyl group is incorporated at the electrophilic center after loss of the silyl group. | 0 | Organic Reactions |
Anhydrous iron(II) oxalate is unknown among minerals as of 2020. However, the dihydrate is known as humboldtine. A related, though much more complex mineral is stepanovite,<br>
Na[Mg(HO)] [Fe(CO)]·3HO - an example of trioxalatoferrate(III). | 1 | Inorganic Reactions + Inorganic Compounds |
Amino radicals can be produced by reacting OH radical with ammonia in irradiated aqueous solutions. This reaction is formulated as a hydrogen abstraction reaction.
The rate constant (k) for this reaction was determined to be , while the parallel reaction of OH with was found to be much slower. This rate was redetermined by using two-pulse radiolysis competition methods with benzoate and thiocyanate ions at pH 11.4. A value of k = was obtained from both systems. While in acidic solution, the corresponding reaction of with is too slow to be observed by pulse radiolysis. | 1 | Inorganic Reactions + Inorganic Compounds |
Gallium nitride () is a binary III/V direct bandgap semiconductor commonly used in blue light-emitting diodes since the 1990s. The compound is a very hard material that has a Wurtzite crystal structure. Its wide band gap of 3.4 eV affords it special properties for applications in optoelectronic, high-power and high-frequency devices. For example, GaN is the substrate which makes violet (405 nm) laser diodes possible, without requiring nonlinear optical frequency-doubling.
Its sensitivity to ionizing radiation is low (like other group III nitrides), making it a suitable material for solar cell arrays for satellites. Military and space applications could also benefit as devices have shown stability in high radiation environments.
Because GaN transistors can operate at much higher temperatures and work at much higher voltages than gallium arsenide (GaAs) transistors, they make ideal power amplifiers at microwave frequencies. In addition, GaN offers promising characteristics for THz devices. Due to high power density and voltage breakdown limits GaN is also emerging as a promising candidate for 5G cellular base station applications. Since the early 2020s, GaN power transistors have come into increasing use in power supplies in electronic equipment, converting AC mains electricity to low-voltage DC. | 1 | Inorganic Reactions + Inorganic Compounds |
Trioxidane (systematically named dihydrogen trioxide,), also called hydrogen trioxide is an inorganic compound with the chemical formula (can be written as or ). It is one of the unstable hydrogen polyoxides. In aqueous solutions, trioxidane decomposes to form water and singlet oxygen:
The reverse reaction, the addition of singlet oxygen to water, typically does not occur in part due to the scarcity of singlet oxygen. In biological systems, however, ozone is known to be generated from singlet oxygen, and the presumed mechanism is an antibody-catalyzed production of trioxidane from singlet oxygen. | 1 | Inorganic Reactions + Inorganic Compounds |
In organic chemistry, annulation (; occasionally annelation) is a chemical reaction in which a new ring is constructed on a molecule.
Examples are the Robinson annulation, Danheiser annulation and certain cycloadditions. Annular molecules are constructed from side-on condensed cyclic segments, for example helicenes and acenes. In transannulation a bicyclic molecule is created by intramolecular carbon-carbon bond formation in a large monocyclic ring. An example is the samarium(II) iodide induced ketone - alkene cyclization of 5-methylenecyclooctanone which proceeds through a ketyl intermediate: | 0 | Organic Reactions |
The title complex is one of several platinum ammine complexes.
*Hexaammineplatinum(IV) chloride
*Trichlorotriammineplatinum(IV) chloride
*cis-Tetrachlorodiammineplatinum(IV)
*trans-Tetrachlorodiammineplatinum(IV) (RN 16986-23-5) | 1 | Inorganic Reactions + Inorganic Compounds |