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The Wolff–Kishner reduction is a reaction used in organic chemistry to convert carbonyl functionalities into methylene groups. [1] [2] In the context of complex molecule synthesis, it is most frequently employed to remove a carbonyl group after it has served its synthetic purpose of activating an intermediate in a preceding step.
The 4-acetyl group could easily be converted to a 4-ethyl group by Wolff-Kishner reduction (hydrazine and alkali, heated); hydrogenolysis, or the use of diborane. Benzyl or tert-butyl acetoacetates also work well in this system, and with close temperature control, the tert-butyl system gives a very high yield (close to 80%). [10]
Mechanism of Wolff-Kishner reduction Aromatic carbonyls are more readily reduced to their respective alkanes than aliphatic compounds. [ 26 ] For example, ketones are reduced to their respective alkyl benzenes by catalytic hydrogenation [ 27 ] [ 28 ] or by Birch reduction [ 29 ] under mild conditions.
In organic chemistry, the Arndt–Eistert reaction is the conversion of a carboxylic acid to its homologue.It is named for the German chemists Fritz Arndt (1885–1969) and Bernd Eistert (1902–1978).
The vinylogous Wolff rearrangement yields a γ,δ-unsaturated carboxylic acid derivative, which is the same retron as for the Claisen rearrangement. The variant was discovered when it was noticed that thermolysis of 1-diazo-3,3,3-triarylpropan-2-ones gave unexpected isomeric products. [40] First example of vinylogous Wolff rearrangement.
If desired, the resulting ketone can be subsequently reduced to the corresponding alkane substituent by either Wolff–Kishner reduction or Clemmensen reduction. The net result is the same as the Friedel–Crafts alkylation except that rearrangement is not possible.
The Wharton olefin synthesis or the Wharton reaction is a chemical reaction that involves the reduction of α,β-epoxy ketones using hydrazine to give allylic alcohols. [1] [2] [3] This reaction, introduced in 1961 by P. S. Wharton, is an extension of the Wolff–Kishner reduction.
Condensation is the change of the state of matter from the gas phase into the liquid phase, and is the reverse of vaporization. The word most often refers to the water cycle . [ 1 ] It can also be defined as the change in the state of water vapor to liquid water when in contact with a liquid or solid surface or cloud condensation nuclei within ...