Question

1)  Draw the acetal produced when ethanol adds to ethanal.

2)  Draw the major organic product formed when 2-butanone undergoes a reaction with NaBH₄.

3)  Predict the organic product formed when heptan-3-one undergoes reaction with LiAlH₄.

4)  Reduction of 1-phenylpropan-1-one using NH2NH2 and HO-, heat:

Draw the structure of the product formed when 1-phenylpropan-1-one is heated with NH₂NH₂ under basic conditions.

Answer 1

Concepts and reason

The concept used in this question is based on the acid-catalyzed reaction of an aldehyde with alcohol for the formation of an acetal. Also, the concepts of the reducing agent and reduction of carbonyl compounds are used in this question.

Initially, the acetal is drawn which is produced when ethanol adds to ethanal by using the concept of the acid-catalyzed reaction of an aldehyde with alcohol for the formation of an acetal. Then, the major organic product formed when $2 - {\rm{butanone}}$ is treated with sodium borohydride $\left( {{\rm{NaB}}{{\rm{H}}_4}} \right)$ is drawn by using the concept of reduction of carbonyl compounds with a reducing agent. Lastly, the organic product formed is predicted when ${\rm{heptan}} - 3 - {\rm{one}}$ reacts with lithium aluminum hydride $\left( {{\rm{LiAl}}{{\rm{H}}_4}} \right)$ .

Fundamentals

Formation of acetal: The aldehydes on reaction with an alcohol in the presence of an acid catalyst gives rise to the formation of an acetal.

Reducing agent: A substance or compound which reduces the other substance or compound by oxidizing itself is known as a reducing agent.

The reduction of carbonyl compounds can be done by using a suitable reducing agent.

The reduction of carbonyl compounds to alcohols can be done by using sodium borohydride or lithium aluminum hydride as a reducing agent.

(1)

The reaction of ethanal with an ethanol yield ${\rm{1,1 - diethoxyethane}}$ as an acetal. The chemical reaction involved in this reaction is shown as follows.

(2)

When $2 - {\rm{butanone}}$ is treated with sodium borohydride $\left( {{\rm{NaB}}{{\rm{H}}_4}} \right)$ , the major organic product so formed is ${\rm{butan}} - 2 - {\rm{ol}}$ .

(3)

The reaction of ${\rm{heptan}} - 3 - {\rm{one}}$ with ${\rm{LiAl}}{{\rm{H}}_4}$ gives ${\rm{heptan}} - {\rm{3}} - {\rm{ol}}$ as the organic product which is shown as follows.

Ans: Part 1

The acetal formed for the given reaction is shown below.

Part 2

The major organic product formed for the given reaction is shown below.

Part 3

The organic product formed for the given reaction is shown below.