chemistry 12th class cbse notes

Aldehydes & Ketones

Aldehydes and Ketones

Aldehydes and ketones are the simplest and most important carbonyl compounds.
There are two systems of nomenclature of aldehydes and ketones.

Aldehydes:

Common names of aldehydes:

The common names of aldehydes are derived from the common names of the corresponding carboxylic acids in which the ending ‘-ic’ is replaced with ‘-aldehyde’of acid with the aldehyde. For example:

Common names of aldehydesIUPAC names of aldehydes:

In IUPAC system, the suffix ‘e’ of the alkane is replaced by the ‘al’.

For example:

IUPAC names of aldehydes

Ketones

Common names of ketones:

The common names of ketones are derived by naming two alkyl or aryl groups bonded to the carbonyl group.

For example:

Common names of ketones

Alkyl phenyl ketones are usually named by adding the acyl group as a prefix to phenone. For example:

Alkyl phenyl ketones

IUPAC name of ketones:

In IUPAC system, the suffix ‘e’ of the alkane is replaced by the ‘one’. For example:

IUPAC name of ketones

Structure of the Carbonyl Group

  • The carbonyl carbon atom is sp2-hybridised and forms three sigma (σ) bonds. The fourth valence electron of carbon remains in its p-orbital and forms a π-bond with oxygen by overlap with p-orbital of an oxygen.
  • In addition, the oxygen atom also has two non-bonding electron pairs. Thus, the carbonyl carbon and the three atoms attached to it lie in the same plane and the π-electron cloud is above and below this plane.

Structure of the Carbonyl Group

  • The high polarity of the carbonyl group is explained on the basis of resonance involving a neutral (A) and a dipolar (B) structures.

Structure of the Carbonyl Group

 

How useful was this post?

Click on a star to rate it!

Average rating 5 / 5. Vote count: 1

No votes so far! Be the first to rate this post.

As you found this post useful...

Follow us on social media!

We are sorry that this post was not useful for you!

Let us improve this post!

Tell us how we can improve this post? Please mention your Email so that we can contact you for better feedback.

Leave a Reply