Question

Which of the following combination will give $3^o$ alcohol (tertiary alcohol) as a final product?

• A. $R-COCl\underset{2.H^{+}/H_{2}O}{\overset{1.C{H}_{3}MgBr}{\to }}$
• B. $O=C=O\underset{2.H^{+}/H_{2}O}{\overset{1.C{H}_{3}MgBr}{\to }}$
• C. $R-CO-R\underset{2.H^{+}/H_{2}O}{\overset{1.C{H}_{3}MgBr}{\to }}$
• D. None of there

Answer 1

Answer: (A), (C)

The correct options are
A $R-COCl\underset{2.H^{+}/H_{2}O}{\overset{1.C{H}_{3}MgBr}{\to }}$
C $R-CO-R\underset{2.H^{+}/H_{2}O}{\overset{1.C{H}_{3}MgBr}{\to }}$

The combinations of the reactions in the options (A) and (C) will give tertiary alcohol.
(A) An acid chloride reacts with a grignard reagent followed by acidic work up to form a tertiary alcohol.
Two moles of grignard reagent will react with 1 mole of acid chloride.
$R-COCl\underset{2.H^{+}/H_{2}O}{\overset{1.C{H}_{3}MgBr}{\to }}RC(C{H}_3{)}_2-OH$
(C) A ketone reacts with a grignard reagent followed by acidic work up to form a tertiary alcohol.
One mole of grignard reagent will react with 1 mole of ketone.
$R-CO-R\underset{2.H^{+}/H_{2}O}{\overset{1.C{H}_{3}MgBr}{\to }}{R}_2-C\left(C{H}_3\right)-OH$
Note:
(B) the reaction between CO2 and a grignard reagent followed by acidic workup gives a carboxylic acid.
$O=C=O\underset{2.H^{+}/H_{2}O}{\overset{1.C{H}_{3}MgBr}{\to }}C{H}_{3}COOH$