Chapter 20, Problem 71A

(a)

Interpretation Introduction

Interpretation:The structure of 2-methylpentanal has to be drawn.

Concept Introduction : Aldehydes contains the carbonyl group.

  

In aldehydes, the carbonyl group is attached at the end of the hydrocarbon chain. The carbonyl carbon is bonded to atleast one hydrogen.

Aldehydes have a general formula of $R-CHO.$ The general structure of an aldehyde is,

  

Answer to Problem 71A

The structure of 2-methylpentanal is,

  

Explanation of Solution

The compound 2-methylpentanal is an aldehyde. Aldehydes are organic compounds that have a carbonyl carbon attached to atleast one hydrogen atom. The general formula of aldehyde is $R-CHO.$

The general structure of an aldehyde is,

  

Where,

  $R$ represents hydrocarbon fragment.

In 2-methylpentanal,

The parent chain is pentane (five carbon atoms), since it is an aldehyde it becomes pentanal.

The carbonyl carbon occupies the first position

The substituent methyl is placed in the second position.

The structure of 2-methylpentanal is,

  

(b)

Interpretation Introduction

Interpretation: The structure of 3-hydroxybutanoic acid has to be drawn.

Concept Introduction : Carboxylic acid consists of carboxyl group, which contains two functional groups namely carbonyl and hydroxyl group.

  

In carboxylic acid, the second oxygen atom is attached to a hydrogen atom.

The general formula for carboxylic acid is $\text{R-COOH}\text{.}$

Answer to Problem 71A

The structure of 3-hydroxybutanoic acid is,

  

Explanation of Solution

The compound 3-hydroxybutanoic acid is a carboxylic acid. Carboxylic acid consist of carboxyl group. The general formula of carboxylic acid $R-COOH.$ The general structure of carboxylic acid is,

  

Where,

  $R$ represents the hydrocarbon fragment.

In 3-hydroxybutanoic acid,

The parent carbon chain is butane (four carbon atoms), since it is a carboxylic acid, it becomes butanoic acid.

The carboxyl group occupies the first position and a hydroxyl group is attached in the third position.

The structure of 3-hydroxybutanoic acid is,

  

(c)

Interpretation Introduction

Interpretation:Interpretation:The structure of 2-aminopropanal has to be drawn.

Concept Introduction : Aldehydes contains the carbonyl group.

  

In aldehydes, the carbonyl group is attached at the end of the hydrocarbon chain. The carbonyl carbon has to be bonded to atleast one hydrogen.

Aldehydes have a general formula of $R-CHO.$ The general structure of an aldehyde is,

  

Answer to Problem 71A

The structure of 2-aminopropanal is,

  

Explanation of Solution

The compound 2-aminopropanal is an aldehyde.Aldehydes are organic compounds that have a carbonyl carbon attached to atleast one hydrogen atom. The general formula of aldehyde is $R-CHO.$

The general structure of an aldehyde is,

  

Where,

  $R$ represents hydrocarbon fragment.

In 2-aminopropanal,

The parent carbon chain is propane (three carbon atoms), since it is an aldehyde, the name becomes propanal.

The carbonyl group occupies the first position and the substituent amino group is attached to the carbon at second position.

The structure of 2-aminopropanal is,

  

(d)

Interpretation Introduction

Interpretation:The structure of 2,4-hexanedione has to be drawn.

Concept Introduction:Ketones contain carbonyl group.

  

In ketones, the carbonyl group is bond to two carbon atoms. The general formula of a ketone is $RCOO{R}^{\text{'}}.$ The general structure of ketone is,

  

In a ketone, the carbonyl group is not present at the end of the hydrocarbon chain.

Answer to Problem 71A

The structure of 2,4-hexanedione is,

  

Explanation of Solution

The compound 2,4-hexanedione is a ketone. Ketones contain carbonyl group.

  

In ketones, the carbonyl group is bond to two carbon atoms. The general formula of a ketone is $RCOO{R}^{\text{'}}.$ The general structure of ketone is,

  

Where,

  $R,R^{\text{'}}$ represents hydrocarbon fragment. $R,R^{\text{'}}$ may or may not be the same groups.

In a ketone, the carbonyl group is not present at the end of the hydrocarbon chain.

In 2,4-hexanedione, there would be two keto groups (carbonyl groups) present the carbon-2 and carbon-4.

The parent carbon chain is hexane (six carbon atoms), since it is ketone consisting of two carbonyl groups, it is named as hexanedione.

The structure of 2,4-hexanedione is,

  

(e)

Interpretation Introduction

Interpretation:The structure of 3-methylbenzaldehyde has to be drawn.

Concept Introduction:Aldehydes contains the carbonyl group.

  

In aldehydes, the carbonyl group is attached at the end of the hydrocarbon chain. The carbonyl carbon has to be bonded to atleast one hydrogen.

Aldehydes have a general formula of $R-CHO.$ The general structure of an aldehyde is,

  

Answer to Problem 71A

The structure of 3-methylbenzaldehyde is,

  

Explanation of Solution

The compound 3-methylbenzaldehyde is an aldehyde.Aldehydes contain the carbonyl group.

  

In aldehydes, the carbonyl group is attached at the end of the hydrocarbon chain. The carbonyl carbon has to be bonded to atleast one hydrogen.

Aldehydes have a general formula of $R-CHO.$ The general structure of an aldehyde is,

  

Where,

  $R$ represents the alkyl group.

In 3-methylbenzaldehyde,

The carbonyl group is attached to the benzene ring and the carbonyl group occupies the first position.

The substituent methyl group is attached to carbon in the third position.

The structure of 3-methylbenzaldehyde is,