question_answer

Which of the following combinations can be used to synthesise ethanol?

A)  \[C{{H}_{3}}MgI\] and \[C{{H}_{3}}COC{{H}_{3}}\]

B)  \[C{{H}_{3}}MgI\] and \[{{C}_{2}}{{H}_{5}}OH\]

C)  \[C{{H}_{3}}MgI\] and \[CH{{H}_{3}}COO{{C}_{2}}{{H}_{5}}\]

D)  \[C{{H}_{3}}MgI\] and \[HCOO{{C}_{2}}{{H}_{5}}\]

Correct Answer: C

Solution :

When ethyl acetate is treated with excess\[C{{H}_{3}}MgI\], it gives f-butanol along with the elimination of ethanol                 \[C{{H}_{3}}-\overset{\begin{smallmatrix}  O \\  || \end{smallmatrix}}{\mathop{C}}\,-O{{C}_{2}}{{H}_{5}}+C{{H}_{3}}MgI\xrightarrow{{}}\]                 \[C{{H}_{3}}-\overset{\begin{smallmatrix}  OMgI \\  | \end{smallmatrix}}{\mathop{\underset{\begin{smallmatrix}  | \\  C{{H}_{3}} \end{smallmatrix}}{\mathop{C}}\,}}\,-O{{C}_{2}}{{H}_{5}}\xrightarrow[\begin{smallmatrix}  -{{C}_{2}}{{H}_{5}}OH \\  (ethanol) \end{smallmatrix}]{{{H}_{2}}O}\left[ C{{H}_{3}}-\overset{\begin{smallmatrix}  OH \\  | \end{smallmatrix}}{\mathop{\underset{\begin{smallmatrix}  | \\  C{{H}_{3}} \end{smallmatrix}}{\mathop{C}}\,}}\,-OH \right]\]                                                 \[\xrightarrow{C{{H}_{3}}MgI}C{{H}_{3}}-\overset{\begin{smallmatrix}  C{{H}_{3}} \\  | \end{smallmatrix}}{\mathop{\underset{\begin{smallmatrix}  | \\  C{{H}_{3}} \end{smallmatrix}}{\mathop{C}}\,}}\,-OMgI\xrightarrow{{{H}_{2}}O}\] \[\underset{t-bu\tan ol}{\mathop{C{{H}_{3}}-\overset{\begin{smallmatrix}  C{{H}_{3}} \\  | \end{smallmatrix}}{\mathop{\underset{\begin{smallmatrix}  | \\  C{{H}_{3}} \end{smallmatrix}}{\mathop{C}}\,}}\,-OH}}\,\]