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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.
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.
The double bond of the side chain condensation product is reduced with sodium amalgam. The intermediate 4 is then converted to 2-methyl-5-hexylfuran 5 in a Wolff-Kishner reduction using hydrazine. An acid-catalyzed reaction at 120 °C (248 °F) cleaves the furan ring, producing 2,5-undecanedione 6. [1]
In 1910 he described the catalytic decomposition of alcylidenhydrazines, which was later named as the Wolff–Kishner reduction. [1] [3] [4] In 1912, Kischner later applied the catalytic decomposition to pyrazoline bases and developed a versatile method for the preparation of substituted cyclopropanes by thermal decomposition of pyrazolines.
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]
Even with the development of other variants of the Wolff-Kishner reaction, it remains a widely practiced version of the reaction today. Some other practical advantages include the simple experimental setup, inexpensive starting materials, and a reduced amount of solvent needed, factors which made the conditions suitable for use in China at the ...
Strange matter: A type of quark matter that may exist inside some neutron stars close to the Tolman–Oppenheimer–Volkoff limit (approximately 2–3 solar masses). May be stable at lower energy states once formed. Quark matter: Hypothetical phases of matter whose degrees of freedom include quarks and gluons Color-glass condensate
Superfluid helium-4 is a liquid rather than a gas, which means that the interactions between the atoms are relatively strong; the original theory of Bose–Einstein condensation must be heavily modified in order to describe it. Bose–Einstein condensation remains, however, fundamental to the superfluid properties of helium-4.