Chapter 15, Problem 15.51EP

(a)

Interpretation Introduction

Interpretation:

The number of aldehydes and ketones that exist with the molecular formula ${\text{CH}}_{\text{2}}\text{O}$ has to be given.

Concept Introduction:

Isomers are the compounds that have same molecular formula but different structural formula.  The main difference lies in the way the atoms are arranged in the structure.  Isomers have different chemical and physical properties even when they have same molecular formula.  This is known as Isomerism.

If there is difference only in the connectivity of the atoms in the molecule, then it is known as constitutional isomerism.  The isomers are known as constitutional isomers.  They will have same molecular formula and same functional group, but they differ in the connectivity between the atoms in the molecule.

Aldehydes and ketones have constitutional isomers.  Functional group isomerism exists between aldehyde and ketones.  Aldehydes and ketones that have same degree of saturation and same number of carbon atoms are functional group isomers.  In aldehyde, skeletal isomerism is possible where the group attached to the carbonyl carbon atom connectivity is changed.  In ketones positional isomerism is possible where the carbonyl group is moved within the carbon chain.

(b)

Interpretation Introduction

Interpretation:

The number of aldehydes and ketones that exist with the molecular formula ${\text{C}}_{\text{3}}{\text{H}}_{\text{6}}\text{O}$ has to be given.

Concept Introduction:

Isomers are the compounds that have same molecular formula but different structural formula.  The main difference lies in the way the atoms are arranged in the structure.  Isomers have different chemical and physical properties even when they have same molecular formula.  This is known as Isomerism.

If there is difference only in the connectivity of the atoms in the molecule, then it is known as constitutional isomerism.  The isomers are known as constitutional isomers.  They will have same molecular formula and same functional group, but they differ in the connectivity between the atoms in the molecule.

Aldehydes and ketones have constitutional isomers.  Functional group isomerism exists between aldehyde and ketones.  Aldehydes and ketones that have same degree of saturation and same number of carbon atoms are functional group isomers.  In aldehyde, skeletal isomerism is possible where the group attached to the carbonyl carbon atom connectivity is changed.  In ketones positional isomerism is possible where the carbonyl group is moved within the carbon chain.