question_answer

Which one of the following is one of the cross end products formed when a mixture of  acetone and acetaldehyde is heated after treating with aqueous sodium hydroxide?

A)  \[(C{{H}_{3}})C=CHCHO\]

B)  \[~{{(C{{H}_{3}})}_{2}}C=CHCOC{{H}_{3}}\]

C)  \[C{{H}_{3}}CH=CHCHO\]

D)  \[{{(C{{H}_{3}})}_{2}}CH(OH)\text{ }C{{H}_{2}}\text{ }COC{{H}_{3}}\]

Correct Answer: A

Solution :

                 When a mixture of acetone and acetaldehyde is treated with aqueous sodium hydroxide, aldol is formed which on heating gives \[\alpha ,\beta -\]unsaturated aldehyde as \[{{(C{{H}_{3}})}_{2}}\underset{\text{aldol}}{\mathop{\overset{OH}{\mathop{\overset{|}{\mathop{C}}\,}}\,-}}\,C{{H}_{2}}CHO\] \[\,\xrightarrow[-{{H}_{2}}o]{\Delta }{{(C{{H}_{3}})}_{2}}C=CHCHO\] This reaction is an example of crossed aldol condensation reaction.