Question

The major organic product formed from the following reaction is:

A.

B.

C.

D.

Answer 1

Hint:To determine the major organic product formed from the reaction, we need to know what type of reactions are taking place. We can see that the reactant ketone is first reacted with a primary amine and the product formed is further reacted with reducing agent lithium aluminum hydride.

Complete step-by-step answer:In the given reaction, the reactant is 3-methylbutan-2-one. It is a ketone and is also known as methyl isopropyl ketone. It is an uncommon solvent.
When a ketone is reacted with a primary amine, it first undergoes nucleophilic addition to give carbinolamine and then further undergoes elimination and dehydrates to form a substituted imine.

So, 3-dimethylbutan-2-imine is formed when 3-methylbutan-2-one is reacted with methylamine. This imine formed can be further reduced to an amine.
Now when a nitrile or a substituted imine is reacted with lithium aluminum hydride in the presence of water, the electrophilic carbon is attacked by the nucleophilic hydride to form an anion which is converted into a secondary amine upon addition of water.
Lithium aluminum hydride $LiAl{H}_4$ or LAH is an inorganic compound that is often used as a reducing agent, especially to reduce amides, carboxylic acids, and esters.

So, 3-dimethylbutan-2-amine is formed. It is a secondary amine.

The major organic product formed from the following reaction is option (B) 3-dimethylbutan-2-amine.

Note:It should be noted that the reaction between the ketone and the primary amine is carried out in an acidic buffer. This is done so that the carboxyl C=O group can be activated and the dehydration can be facilitated without the nucleophile being inhibited.