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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 general features of this synthesis are: 1) the epoxidation of α,β-unsaturated ketones is achieved usually in basic conditions using hydrogen peroxide solution in high yield; 2) the epoxy ketone is treated with 2–3 equivalents of a hydrazine hydrate in presence of substoichiometric amounts of acetic acid. This reaction occurs rapidly at ...
Azines have been used as precursors to hydrazones: [4] [8] R 2 C=N-N=CR 2 + N 2 H 4 → 2 R 2 C=N-NH 2. They are also precursors to diazo compounds. [9] [8] [10] The coordination chemistry of azines (as ligands) has also been studied. [11] [12] [13] Acetone is used to derivatize hydrazine into acetone azine for analysis by gas chromatography.
Alcohol oxidation is a collection of oxidation reactions in organic chemistry that convert alcohols to aldehydes, ketones, carboxylic acids, and esters. The reaction mainly applies to primary and secondary alcohols. Secondary alcohols form ketones, while primary alcohols form aldehydes or carboxylic acids. [1] A variety of oxidants can be used.
When derived from hydrazine itself, hydrazones condense with a second equivalent of a carbonyl to give azines: [11] R 2 C=N−NH 2 + R 2 C=O → R 2 C=N−N=CR 2 + H 2 O. Hydrazones are intermediates in the Wolff–Kishner reduction. Hydrazones are reactants in hydrazone iodination, the Shapiro reaction, and the Bamford–Stevens reaction to ...
It condenses with ketones and aldehydes to form hydrazones, which can be further transformed into reactive intermediates such as diazo compounds or carbenes. N-heterocycles can be synthesized through 1,3-dipolar cycloaddition reactions. Ketone hydrazones are defunctionalized using mild reagents in a modified Wolff-Kishner reaction. [4]
Several side reactions are known to occur. In the case of ketones and especially aldehydes aldol condensations have been observed. Aldehydes with no α-hydrogens can undergo the Tishchenko reaction. [7] Finally, in some cases the alcohol generated by the reduction can be dehydrated giving an alkyl carbon.
Aldehyde structure. In organic chemistry, an aldehyde (/ ˈ æ l d ɪ h aɪ d /) is an organic compound containing a functional group with the structure R−CH=O. [1] The functional group itself (without the "R" side chain) can be referred to as an aldehyde but can also be classified as a formyl group. Aldehydes are a common motif in many ...