question_answer

In the given compound which of the following hydrogens is most acidic? \[\underset{(a)}{\mathop{C{{H}_{3}}}}\,-\underset{(b)}{\mathop{C}}\,{{H}_{2}}-\overset{\begin{smallmatrix}  O \\  || \end{smallmatrix}}{\mathop{C}}\,-\underset{(C)}{\mathop{C{{H}_{3}}}}\,\]

A)  Only [a]

B)  Only [b]

C)  Only [c]

D)  Both [b] and [c]

Correct Answer: B

Solution :

\[\underset{a}{\mathop{C{{H}_{3}}}}\,-\underset{b}{\mathop{C}}\,{{H}_{2}}-\overset{\begin{smallmatrix}  O \\  || \end{smallmatrix}}{\mathop{C}}\,-\underset{c}{\mathop{C{{H}_{3}}}}\,\] This compound undergoes embolization by the following mechanism \[\xrightarrow[-{{H}^{+}}]{{{H}_{2}}O}C{{H}_{3}}-CH=\overset{\begin{smallmatrix}  OH \\  | \end{smallmatrix}}{\mathop{C}}\,-C{{H}_{3}}\] Thus, hydrogen [b] is most acidic as it is attached with the active methylene group.