question_answer

Which of the following compounds forms an addition compound with \[\text{C}{{\text{H}}_{\text{3}}}\text{MgBr,}\]which on hydrolysis produce a secondary alcohol?

A) \[HCHO\]

B)  \[C{{H}_{3}}CHO\]

C) \[C{{H}_{3}}OC{{H}_{3}}\]

D)  \[C{{H}_{3}}COC{{H}_{3}}\]

Correct Answer: B

Solution :

 Key Idea: \[HCHO+Grignard\,reagent\,\,\xrightarrow{\text{Hydrolysis}}{{1}^{o}}\,alcohol\]\[Any\,other\,aldehdye+Grignard\,reagent\] \[\xrightarrow{\text{Hydrolysis}}{{\text{2}}^{\text{o}}}\text{alcohol}\] \[Ketone+Grignard\,reagent\xrightarrow{Hydrolysis}{{3}^{o}}alcohol.\] \[\underset{\text{(a)}}{\mathop{\text{HCHO}}}\,\,\underset{\text{aldehyde}}{\mathop{\underset{\text{(b)}}{\mathop{\,\text{C}{{\text{H}}_{\text{3}}}\text{CHO}}}\,}}\,\,\,\underset{\text{ether}}{\mathop{\underset{\text{(c)}}{\mathop{\text{C}{{\text{H}}_{\text{3}}}\text{OC}{{\text{H}}_{\text{3}}}}}\,}}\,\,\,\underset{\text{ketone}}{\mathop{\underset{\text{(d)}}{\mathop{\text{C}{{\text{H}}_{\text{3}}}\text{COC}{{\text{H}}_{\text{3}}}}}\,}}\,\] \[\therefore \]\[C{{H}_{3}}CHO\]is correct choice. \[C{{H}_{3}}CHO+C{{H}_{3}}MgBr\xrightarrow{{}}C{{H}_{3}}-\underset{C{{H}_{3}}}{\overset{OMgBr}{\mathop{\underset{|}{\overset{|}{\mathop{C}}}\,}}}\,-H\]