question_answer

Cannizaro reaction is not given by

A)  methanol

B)  phenyl methanol

C)  2,2-dimethyl butanal

D)  phenyl ethanol

Correct Answer: D

Solution :

                Only those aldehydes in which a-hydrogen atoms are not present, give Cannizaro reaction. The structure of the given compounds is  \[\underset{\begin{smallmatrix}  methanal \\  (no\,\alpha -H) \end{smallmatrix}}{\mathop{HCHO}}\,\]                               \[\underset{(no\text{ }\alpha -H\text{ }atom)}{\mathop{C{{H}_{3}}C{{H}_{2}}\underset{\begin{smallmatrix}  | \\  C{{H}_{3}} \end{smallmatrix}}{\overset{\begin{smallmatrix}  C{{H}_{3}} \\  | \end{smallmatrix}}{\mathop{C\overset{\alpha }{\mathop{{}}}\,}}}\,CHO}}\,\]    Thus, phenyl ethanal because of the presence of\[\alpha -H\] atoms, does not give Cannizaro reaction.