Question
Illustrate the following name reaction giving suitable example in each case:
(i) Clemmensen reduction
(ii) Hell-Volhard-Zelinsky reaction
Solution
(i) Clemmensen Reduction
The carbonyl group of aldehydes and ketones is reduced to the CH2 group on treatment with zinc amalgam and concentrated hydrochloric acid. This is known as Clemmensen reduction.
(ii) Hell-Volhard-Zelinsky (HVZ )reaction.
Carboxylic acids having a 
hydrogen are halogenated at the 
position on treatment with chlorine or bromine in the presence of small amount of red phosphorus to give 
halocarboxylic acids. The reaction is known as Hell-Volhard-Zelinsky reaction.
