One equivalent of CH3MgBr is added to 4-hydroxybutanal, HO-CH2CH2CH2-CHO, in ether. The main immediate process is

deprotonation of the OH group with evolution of methane

addition of methyl to the aldehyde carbon to give pentane-1,4-diol

deprotonation of the OH group with evolution of methane

reduction of the aldehyde by hydride transfer

MolSynapse / Question bank / Organic Reaction Mechanisms I: Nucleophiles and Carbonyl Addition / Nucleophilic addition to aldehydes and ketones

JEE Main levelSingle correct optionDifficulty 2 of 3o1072

One equivalent of $CH X_{3} MgBr$ is added to 4-hydroxybutanal, $HO - CH X_{2} CH X_{2} CH X_{2} - CHO$ , in ether. The main immediate process is

Aaddition of methyl to the aldehyde carbon to give pentane-1,4-diol
Bsubstitution of OH by methyl
Cdeprotonation of the OH group with evolution of methane
Dreduction of the aldehyde by hydride transfer

Answer: C

Grignard reagents are very strong bases and react with alcohol O-H (pKa about 16) much faster than they add to C=O. The first equivalent is consumed in an acid-base step, giving

CH X_{4}

and the magnesium alkoxide, leaving the aldehyde largely untouched.

Practice Organic Reaction Mechanisms I: Nucleophiles and Carbonyl Addition More on Nucleophilic addition to aldehydes and ketones

Previous questionNext question

One equivalent of CHX3​MgBr is added to 4-hydroxybutanal, HO−CHX2​CHX2​CHX2​−CHO, in ether. The main immediate process is

Answer: C

More questions on Nucleophilic addition to aldehydes and ketones

One equivalent of $CH X_{3} MgBr$ is added to 4-hydroxybutanal, $HO - CH X_{2} CH X_{2} CH X_{2} - CHO$ , in ether. The main immediate process is