Question

Which of the following compounds will react with two moles of $CH_3MgBr$ ?

• A. $C_2H_5COOH$
• B. $CH_3COOH$
• C. $CH _{3} C \equiv CCH _{3}$
• D. $HC \equiv C - CH _{2} OH$

Answer 1

Answer: (D)

$HC \equiv C - CH _{2} OH$

Answer 2

Reaction of carboxylic acid with Grignard is shown above.
It'll only consume 1 mole of $CH _{3} MgBr$.
$CH _{3} C \equiv CCH _{3}$ won't react with Grignard reagent because it doesn't have active H-atom.
In $HC \equiv C - CH _{2} OH$ two active hydrogen atoms are present, hence it will react with two moles of $CH _{3} MgBr$ (Grignard reagent) as shown below.
$HC \equiv C - CH _{2} OH +2 CH _{3} MgBr \rightarrow 2 CH _{4}+ BrMgC \equiv CCH _{2} OMgBr$