Notes On Aldehydes And Ketones: Nomenclature - CBSE Class 12 Chemistry

Aldehydes and Ketones also have two systems of nomenclature. They are:

a) The Common system

b) The IUPAC system

The common names of aldehydes are derived from the names of the corresponding carboxylic acids by replacing '-ic acid' by '-aldehyde'.

In the IUPAC system, aldehydes are named by replacing the 'e' of the corresponding alkane with '-al'.

In case of branched chain aldehydes, the longest chain carrying the aldehyde group is considered the parent structure and is numbered starting from the carbon of the aldehyde group.

When the aldehyde is attached to a ring system, the suffix - carbaldehyde is added after the full name of the ring.

In the common system, ketones are named simply by adding the suffix 'ketone' to the name of two alkyl groups.

In case of simple ketones, where both the alkyl groups are the same, the prefix 'di' is used for the alkyl group.

In case of mixed ketones, the two different alkyl groups - R and R' - are to named in alphabetical order.

Ex:

A ketone in which the acyl group is attached to a benzene ring is named a - phenone.

In the IUPAC system, ketones are named by replacing -e of the corresponding alkane with -one.

In certain poly-functional compounds, the presence of a carbonyl group can be indicated by the prefix 'oxo'.

If a molecule contains hydroxy, aldehyde and ketone groups then according to IUPAC rules the order of preference given to aldehyde followed by ketone and then hydroxyl group.

Summary

Aldehydes and Ketones also have two systems of nomenclature. They are:

a) The Common system

b) The IUPAC system

The common names of aldehydes are derived from the names of the corresponding carboxylic acids by replacing '-ic acid' by '-aldehyde'.

In the IUPAC system, aldehydes are named by replacing the 'e' of the corresponding alkane with '-al'.

In case of branched chain aldehydes, the longest chain carrying the aldehyde group is considered the parent structure and is numbered starting from the carbon of the aldehyde group.

When the aldehyde is attached to a ring system, the suffix - carbaldehyde is added after the full name of the ring.

In the common system, ketones are named simply by adding the suffix 'ketone' to the name of two alkyl groups.

In case of simple ketones, where both the alkyl groups are the same, the prefix 'di' is used for the alkyl group.

In case of mixed ketones, the two different alkyl groups - R and R' - are to named in alphabetical order.

Ex:

A ketone in which the acyl group is attached to a benzene ring is named a - phenone.

In the IUPAC system, ketones are named by replacing -e of the corresponding alkane with -one.

In certain poly-functional compounds, the presence of a carbonyl group can be indicated by the prefix 'oxo'.

If a molecule contains hydroxy, aldehyde and ketone groups then according to IUPAC rules the order of preference given to aldehyde followed by ketone and then hydroxyl group.

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