Question

Write down the following reactions: (i) Aldol condensation (ii) HVZ reaction

Hint:

Aldol condensation requires \(\alpha\)-hydrogen atoms. HVZ reaction is used for \(\alpha\)-halogenation of carboxylic acids.

Answer 1

(i) Aldol Condensation: When acetaldehyde is treated with dilute NaOH: \[ 2\,\text{CH}_3\text{CHO} \xrightarrow{\text{dil. NaOH}} \text{CH}_3\text{CH(OH)CH}_2\text{CHO} \] (\(\beta\)-hydroxy aldehyde, aldol) On heating: \[ \text{CH}_3\text{CH(OH)CH}_2\text{CHO} \xrightarrow{\Delta} \text{CH}_3\text{CH=CHCHO} + \text{H}_2\text{O} \] (ii) HVZ Reaction: Carboxylic acids having \(\alpha\)-hydrogen react with halogen in the presence of red phosphorus: \[ \text{RCH}_2\text{COOH} \xrightarrow{\text{Br}_2/\text{Red P}} \text{RCHBrCOOH} \]