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Diazo Transfer
In organic chemistry, the diazo group is an organic moiety consisting of two linked nitrogen atoms at the terminal position. Overall charge-neutral organic compounds containing the diazo group bound to a carbon atom are called diazo compounds or diazoalkanes and are described by the general structural formula . The simplest example of a diazo compound is diazomethane, . Diazo compounds () should not be confused with azo compounds () or with diazonium compounds (). Structure The electronic structure of diazo compounds is characterized by π electron density delocalized over the α-carbon and two nitrogen atoms, along with an orthogonal π system with electron density delocalized over only the terminal nitrogen atoms. Because all octet rule-satisfying resonance forms of diazo compounds have formal charges, they are members of a class of compounds known as 1,3-dipoles. Some of the most stable diazo compounds are α-diazo-β-diketones and α-diazo-β-diesters, in which the ele ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diazonium
Diazonium compounds or diazonium salts are a group of organic compounds sharing a common functional group where R can be any organic group, such as an alkyl or an aryl, and X is an inorganic or organic anion, such as a halide. The parent, compound where R is hydrogen, is diazenylium. Structure and general properties Arene derivatives According to X-ray crystallography the linkage is linear in typical diazonium salts. The bond distance in benzenediazonium tetrafluoroborate is 1.083(3) Å, which is almost identical to that for dinitrogen molecule (N≡N). The linear free energy constants σm and σp indicate that the diazonium group is strongly electron-withdrawing. Thus, the diazonio-substituted phenols and benzoic acids have greatly reduced p''K''a values compared to their unsubstituted counterparts. The p''K''a of phenolic proton of 4-hydroxybenzenediazonium is 3.4, versus 9.9 for phenol itself. In other words, the diazonium group raises the ionization constant ''K''a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dehydrogenation
In chemistry, dehydrogenation is a chemical reaction that involves the removal of hydrogen, usually from an organic molecule. It is the reverse of hydrogenation. Dehydrogenation is important, both as a useful reaction and a serious problem. At its simplest, it is a useful way of converting alkanes, which are relatively inert and thus low-valued, to olefins, which are reactive and thus more valuable. Alkenes are precursors to aldehydes (), alcohols (), polymers, and aromatics. As a problematic reaction, the fouling and inactivation of many catalysts arises via coking, which is the dehydrogenative polymerization of organic substrates. Enzymes that catalyze dehydrogenation are called dehydrogenases. In metal manufacturing and repairs, dehydrogenation is a thermal treatment which consists in removing the hydrogen absorbed by an object during an electrochemical or chemical process, performed in a specific oven at a temperature of for a minimum time of 2 hours. Heterogeneous cat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organic Oxidation
Organic reductions or organic oxidations or organic redox reactions are redox reactions that take place with organic compounds. In organic chemistry oxidations and reductions are different from ordinary redox reactions, because many reactions carry the name but do not actually involve electron transfer.March Jerry; (1985). Advanced Organic Chemistry reactions, mechanisms and structure (3rd ed.). New York: John Wiley & Sons, inc. Instead the relevant criterion for organic oxidation is gain of oxygen and/or loss of hydrogen.''Organic Redox Systems: Synthesis, Properties, and Applications'', Tohru Nishinaga 2016 Simple functional groups can be arranged in order of increasing oxidation state. The oxidation numbers are only an approximation: When methane is oxidized to carbon dioxide its oxidation number changes from −4 to +4. Classical reductions include alkene reduction to alkanes and classical oxidations include alcohol oxidation, oxidation of alcohols to aldehydes. In oxidation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrazone
Hydrazones are a class of organic compounds with the structure . They are related to ketones and aldehydes by the replacement of the oxygen =O with the = functional group. They are formed usually by the action of hydrazine on ketones or aldehydes. Synthesis Hydrazine, organohydrazines, and 1,1-diorganohydrazines react with aldehydes and ketones to give hydrazones. : Phenylhydrazine reacts with reducing sugars to form hydrazones known as osazones, which was developed by German chemist Emil Fischer as a test to differentiate monosaccharides. Uses image:Pigment Yellow 97.svg, left, Pigment Yellow 97, a popular yellow colorant, is a hydrazone., 160px Hydrazones are the basis for various analyses of ketones and aldehydes. For example, dinitrophenylhydrazine coated onto a silica sorbent is the basis of an adsorption cartridge. The hydrazones are then eluted and analyzed by high-performance liquid chromatography (HPLC) using a ultraviolet, UV detector. The compound carbonyl cyanide-p-t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nitrous Acid
Nitrous acid (molecular formula ) is a weak and monoprotic acid known only in solution, in the gas phase, and in the form of nitrite () salts. It was discovered by Carl Wilhelm Scheele, who called it " phlogisticated acid of niter". Nitrous acid is used to make diazonium salts from amines. The resulting diazonium salts are reagents in azo coupling reactions to give azo dyes. Structure In the gas phase, the planar nitrous acid molecule can adopt both a ''syn'' and an ''anti'' form. The ''anti'' form predominates at room temperature, and IR measurements indicate it is more stable by around 2.3 kJ/mol. p. 462. Image:Trans-nitrous-acid-2D-dimensions.png , Dimensions of the ''anti'' form(from the microwave spectrum) Image:Trans-nitrous-acid-3D-balls.png , Model of the ''anti'' form Image:Cis-nitrous-acid-3D-balls.png , ''syn'' form Preparation and decomposition Free, gaseous nitrous acid is unstable, rapidly disproportionating to nitric oxides: :2 HNO2 → NO2 + ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amine
In chemistry, amines (, ) are organic compounds that contain carbon-nitrogen bonds. Amines are formed when one or more hydrogen atoms in ammonia are replaced by alkyl or aryl groups. The nitrogen atom in an amine possesses a lone pair of electrons. Amines can also exist as hetero cyclic compounds. Aniline is the simplest aromatic amine, consisting of a benzene ring bonded to an amino group. Amines are classified into three types: primary (1°), secondary (2°), and tertiary (3°) amines. Primary amines (1°) contain one alkyl or aryl substituent and have the general formula RNH2. Secondary amines (2°) have two alkyl or aryl groups attached to the nitrogen atom, with the general formula R2NH. Tertiary amines (3°) contain three substituent groups bonded to the nitrogen atom, and are represented by the formula R3N. The functional group present in primary amines is called the amino group. Classification of amines Amines can be classified according to the nature and number o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MNNG
Methylnitronitrosoguanidine (MNNG or MNG, NTG when referred to colloquially as nitrosoguanidine) is a biochemical tool used experimentally as a carcinogen and mutagen. It acts by adding alkyl groups to the O6 of guanine and O4 of thymine, which can lead to transition mutations between GC and AT. These changes do not cause a heavy distortion in the double helix of DNA and thus are hard to detect by the DNA mismatch repair system. In organic chemistry, MNNG is used as a source of diazomethane when reacted with aqueous potassium hydroxide. MNNG is a probable human carcinogen listed as an IARC Group 2A carcinogen. |
Diazald
Diazald (''N''-methyl-''N''-nitroso-''p''-toluenesulfonamide) is used as a relatively safe and easily handled precursor to diazomethane, which is toxic and unstable. Diazald has become the favored commercially available precursor for the synthesis of diazomethane, compared to reagents like N-Nitroso-N-methylurea, ''N''-methyl''-N''-nitrosourea and Methylnitronitrosoguanidine, ''N''-methyl-''N'''-nitro-''N''-nitrosoguanidine, which are less thermally stable and more toxic and mutagenic, respectively. Upon the addition of a Base (chemistry), base such as sodium hydroxide or potassium hydroxide and mild heating (65–70 °C) in a mixture of water, diethyl ether, and a high boiling polar cosolvent (e.g., 2-(2-Methoxyethoxy)ethanol, diethylene glycol monomethyl ether), the ''N''-nitrososulfonamide undergoes successive elimination reactions to produce diazomethane (which is codistilled as an ethereal solution) as well as a P-Toluenesulfonic acid, ''p''-toluenesulfonate salt as a byp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diazo Synthesis
In organic chemistry, the diazo group is an organic moiety (chemistry), moiety consisting of two linked nitrogen atoms at the terminal position. Overall charge-neutral organic compounds containing the diazo group bound to a carbon atom are called diazo compounds or diazoalkanes and are described by the general structural formula . The simplest example of a diazo compound is diazomethane, . Diazo compounds () should not be confused with azo compounds () or with diazonium compounds (). Structure The electronic structure of diazo compounds is characterized by π electron density delocalized over the α-carbon and two nitrogen atoms, along with an orthogonal π system with electron density delocalized over only the terminal nitrogen atoms. Because all octet rule-satisfying resonance forms of diazo compounds have formal charges, they are members of a class of compounds known as 1,3-dipoles. Some of the most stable diazo compounds are α-diazo-β-diketones and α-diazo-β-dieste ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dehydration Reaction
In chemistry, a dehydration reaction is a chemical reaction that involves the loss of an H2O from the reacting molecule(s) or ion(s). This reaction results in the release of the H2O as water. When the reaction involves the coupling of two molecules into a single molecule it is referred to as a condensation reaction. Dehydration reactions are common processes in the manufacture of chemical compounds as well as naturally occurring within living organisms. The reverse of a dehydration reaction is called a hydration reaction. The reverse of a condensation reaction yielding water is called hydrolysis. Condensation reactions occurring in living organisms Condensation dehydration reactions are fundamental to the existence of life as this type of reaction produces proteins from amino acids, DNA and RNA from nucleotides, fats from fatty acids, and polysaccharides (eg. cellulose, starch, sugar, lactose) from monosaccharides (eg. glucose and fructose). The formation of the pyrophosphat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nitrosamine
Nitrosamines (or more formally ''N''-nitrosamines) are organic compounds produced by industrial processes. The chemical structure is , where R is usually an alkyl group. Nitrosamines have a nitroso group () that are "probable human carcinogens", bonded to a deprotonated amine. Most nitrosamines are carcinogenic in animals. A 2006 systematic review supports a "positive association between nitrite and nitrosamine intake and gastric cancer, between meat and processed meat intake and gastric cancer and oesophageal cancer, and between preserved fish, vegetable and smoked food intake and gastric cancer, but is not conclusive". Chemistry The organic chemistry of nitrosamines is well developed with regard to their syntheses, their structures, and their reactions. They usually are produced by the reaction of nitrous acid () and secondary amines, although other nitrosyl sources (e.g. , , Alkyl nitrite, RONO) have the same effect: : The nitrous acid usually arises from protonation of a nit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
