Chapter 15, Problem 15.50EP

(a)

Interpretation Introduction

Interpretation:

IUPAC name has to be given for all unbranched-chain saturated compounds that can be named as hexanals.

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.

For naming an aldehyde in IUPAC nomenclature, the suffix “-al” is added to the parent alkane name.

IUPAC rules for naming an aldehyde:

• • The longest parent carbon chain is identified that includes the carbonyl group.
• • The parent chain name is changed by replacing the suffix “-e” with “-al”.
• • Numbering is done in a way that the carbonyl group is designated as number 1.  This is not indicated in the part of the name because for aldehyde, the carbonyl carbon is always numbered 1.
• • The identity and location of substituents if any has to be determined and this information has to be added in front of the IUPAC name.
• • If the carbonyl functional group is attached to a ring of carbon atoms, the ring is named and “-carbaldehyde” is added as suffix.

(b)

Interpretation Introduction

Interpretation:

IUPAC name for all possible saturated unbranched ketones that are named as hexanones 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.

For naming a ketone in IUPAC nomenclature, the suffix “-one” is added to the parent alkane name.

IUPAC rules for naming a ketone:

• • The longest parent carbon chain is identified that includes the carbonyl group.
• • The parent chain name is changed by replacing the suffix “-e” with “-one”.
• • Numbering is done in a way that the carbonyl group gets the least numbering.  The position of the carbonyl group is indicated in the name.
• • The identity and location of substituents if any has to be determined and this information has to be added in front of the IUPAC name.
• • Cyclic ketones are named by adding the suffix “-one” to the name of the carbon ring.  The substituents are numbered so that it gets the least numbering starting from the carbonyl group that is given the number 1.