Chapter 18, Problem 47P

(a)

Interpretation Introduction

Interpretation: The structure of given compounds has to be drawn.

ethylacetoacetate

Concept introduction: The ${\text{CO}}_{\text{2}}$ group is attached to a carbon that is adjacent to a carbon, the ${\text{CO}}_{\text{2}}$ group can be removed because the electrons left behind can be delocalized onto the carbonyl oxygen.

Carboxylate ion with a carbonyl group at the 3-position loses ${\text{CO}}_{\text{2}}$ when they are heated. Loss of ${\text{CO}}_{\text{2}}$ from a molecule is called decarboxylation.

Answer to Problem 47P

The structure of ethyl acetoacetae is,

Explanation of Solution

The name given compound ethyl acetoacetate ends with ate.  This means the given compound must contain an ester group.  The name of compound starts with ethyl group, this means ethyl group is attached to the oxygen of an ester group.  The acetone group is attached with the carbonyl carbon of an ester group.  The structure of ethyl acetoacetae is,

(b)

Interpretation Introduction

Interpretation: The structure of given compounds has to be drawn.

α-methylmalonicacid

Concept introduction: The ${\text{CO}}_{\text{2}}$ group is attached to a carbon that is adjacent to a carbon, the ${\text{CO}}_{\text{2}}$ group can be removed because the electrons left behind can be delocalized onto the carbonyl oxygen.

Carboxylate ion with a carbonyl group at the 3-position loses ${\text{CO}}_{\text{2}}$ when they are heated. Loss of ${\text{CO}}_{\text{2}}$ from a molecule is called decarboxylation.

Answer to Problem 47P

The structure of α-methylmalonic acid is,

Explanation of Solution

The structure of malonic acid is two carboxylic acid is attached with a methyl group.  The structure of α-methylmalonic acid is one methyl group is attached with an α carbon of malonic acid.  The structure of α-methylmalonic acid is,

(c)

Interpretation Introduction

Interpretation: The structure of given compounds has to be drawn.

β-keto ester

Concept introduction: The ${\text{CO}}_{\text{2}}$ group is attached to a carbon that is adjacent to a carbon, the ${\text{CO}}_{\text{2}}$ group can be removed because the electrons left behind can be delocalized onto the carbonyl oxygen.

Carboxylate ion with a carbonyl group at the 3-position loses ${\text{CO}}_{\text{2}}$ when they are heated. Loss of ${\text{CO}}_{\text{2}}$ from a molecule is called decarboxylation.

Answer to Problem 47P

The structure of β-keto ester is,

Explanation of Solution

The given compound β-keto ester contains a keto group and an ester group.  The structure of β-keto ester is,

(d)

Interpretation Introduction

Interpretation: The structure of given compounds has to be drawn.

The carboxylic acid obtained from malonic ester synthesis when the alkyl halide is propyl bromide

Concept introduction: The ${\text{CO}}_{\text{2}}$ group is attached to a carbon that is adjacent to a carbon, the ${\text{CO}}_{\text{2}}$ group can be removed because the electrons left behind can be delocalized onto the carbonyl oxygen.

Carboxylate ion with a carbonyl group at the 3-position loses ${\text{CO}}_{\text{2}}$ when they are heated. Loss of ${\text{CO}}_{\text{2}}$ from a molecule is called decarboxylation.

Answer to Problem 47P

The structure of enol form of cyclopentanone is,

Explanation of Solution

The compound cyclopentanone contain a keto group.  After the keto enol tautomerism the keto compound converted into an alcohol and a double bond.  The structure of enol form of cyclopentanone is,

(e)

Interpretation Introduction

Interpretation: The structure of given compounds has to be drawn.:

The structure of enol form of cyclopentanone

Concept introduction: The ${\text{CO}}_{\text{2}}$ group is attached to a carbon that is adjacent to a carbon, the ${\text{CO}}_{\text{2}}$ group can be removed because the electrons left behind can be delocalized onto the carbonyl oxygen.

Carboxylate ion with a carbonyl group at the 3-position loses ${\text{CO}}_{\text{2}}$ when they are heated. Loss of ${\text{CO}}_{\text{2}}$ from a molecule is called decarboxylation.

Answer to Problem 47P

The structure of the carboxylic acid obtained from malonic ester synthesis by using propyl bromide is,

Explanation of Solution

The proton removed from the alpha carbon of malonic ester by the base.  Then, there is a nucleophilic substitution reaction takes place between the propyl bromide and carbanion of malonic ester.  The third step is acidic hydrolysis of an ester to form carboxylic acid. The fourth step is decarboxylation of the compound to form the desired product.  The reaction and structure of given compound is,