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An acyl-diazomethane can react with an aldehyde to form a β-diketone in the presence of a transition metal catalyst (SnCl 2 in the example shown below). β-Diketones are common biological products, and as such, their synthesis is relevant to biochemical research.
Diazomethane is an organic chemical compound with the formula CH 2 N 2, discovered by German chemist Hans von Pechmann in 1894. It is the simplest diazo compound.In the pure form at room temperature, it is an extremely sensitive explosive yellow gas; thus, it is almost universally used as a solution in diethyl ether.
As such they are used in cyclopropanation for example in the reaction of ethyl diazoacetate with styrene. [22] Certain diazo compounds can couple to form alkenes in a formal carbene dimerization reaction. Diazo compounds are intermediates in the Bamford–Stevens reaction of tosylhydrazones to alkenes, again with a carbene intermediate:
The acid chloride then reacts with diazomethane (R 2 = H), or occasionally a diazoalkyl, via the Arndt-Eistert procedure, to generate an α-diazo ketone, which will undergo a metal-catalyzed or photolyzed Wolff rearrangement, to give a ketene. The ketene can be trapped with any weak acid, such as an alcohol or amine, to form the ester or amide.
In organic chemistry, a homologation reaction, also known as homologization, is any chemical reaction that converts the reactant into the next member of the homologous series. A homologous series is a group of compounds that differ by a constant unit, generally a methylene ( −CH 2 − ) group.
The reaction process begins with diazotization of the amine by nitrous acid. The diazonium group is a good leaving group , forming nitrogen gas when displaced from the organic structure. This displacement can occur via a rearrangement (path A), in which one of the sigma bonds adjacent to the diazo group migrates.
This reaction goes by the German name Phenolverkochung ("cooking down to yield phenols"). The phenol formed may react with the diazonium salt and hence the reaction is carried in the presence of an acid which suppresses this further reaction. [33] A Sandmeyer-type hydroxylation is also possible using Cu 2 O and Cu 2+ in water.
If excess diazomethane is present during the reaction, it can act as a base, abstracting a hydrogen from the diazonium-salt intermediate. The result is a neutral diazoketone, which does not react with the chloride. Instead, the byproduct, diazonium-methyl from the other diazomethane molecule, can be attacked by the chloride to produce ...