Do carboxylic acid and it's derivatives such as esters, amides, acid halides and anhydrides show Wolff-Kishner reductions and why?
$\begingroup$
$\endgroup$
Add a comment
|
1 Answer
$\begingroup$
$\endgroup$
0
Wolf-Kishner reduction of ketones and aldehydes proceeds by nucleophilic attack of hydrazine on the carbonyl compound followed by elimination of water to form the intermediate hydrazone mechanism here
Nucleophilic attack of hydrazine on esters, acyl halides and anhydrides gives the acyl hydrazide which is a stable species. See the second step of the reaction scheme below. If it does get deprotonated under W-K reaction conditions the anion is stable (note the NH next to the carbonyl group is the more acidic).
Image from Beck et.al..[1]
Nucleophilic acid of hydrazine on carboxylic acids does not occur, instead the hydrazine salt of the acid is formed which is stable. If this salt is then exposed to strong base, free hydrazine is formed and the salt of acid.
References:
- Beck, P.; Santos, J. M. d.; Kuhn, B. L.; Moreira, D. N.; Flores, A. F. C.; Martins, M. A. P.; D'oca, M. G. M.; Piovesan, L. A. Regiospecific synthesis of new fatty N-acyl trihalomethylated pyrazoline derivatives from fatty acid methyl esters (FAMEs). J. Braz. Chem. Soc. 2012, 23 (11), 2122–2127. DOI: 10.1590/S0103-50532012005000071.
answered Mar 25, 2020 at 18:05