Aldehydes and Ketones Summary

Aldehydes

• Aldehydes are formed through the oxidation of primary alcohols.

• Primary Alcohol: A primary alcohol is one in which the carbon atom bearing the hydroxyl group (-OH) is attached to one other carbon atom.

• Example: Methanol (a primary alcohol) is oxidized to form Methanal (an aldehyde).

• Naming Convention:

  • Take the name of the corresponding alkane.
  • Add "-al" to the end.
  • Ethanol (alcohol) becomes Ethanal (aldehyde).
  • Propanol (alcohol) becomes Propanal (aldehyde).
  • Butanol (alcohol) becomes Butanal (aldehyde).

• Functional Group:

  • A carbon atom has a double bond to oxygen (O) and a single bond to hydrogen (H).
  • The short form is CHO. It's crucial to keep the order as CHO to avoid confusion with alcohols (where the OH group is present).

• Unsaturated Aldehydes:

  • These aldehydes contain double bonds within the carbon chain.
  • Example: If a double bond exists between the first two carbon atoms, the name is derived from the corresponding alkene.
  • Propenal is formed from propene by adding "-al".

• Nomenclature:

  • Aldehydes derived from alkanes are called Alkanals.
  • Aldehydes derived from alkenes are called Alkenals.

Ketones

• Ketones are formed through the oxidation of secondary alcohols.

• Secondary Alcohol: A secondary alcohol is one in which the carbon atom bearing the hydroxyl group (-OH) is attached to two other carbon atoms.

• Oxidation Process:

  • A secondary alcohol reacts with an oxygen molecule.

• Functional Group:

  • The central carbon atom has a double bond to an oxygen atom (O).
  • This is a key difference from alcohols where the carbon atom has a bond to OH.

• Naming Convention:

  • The name is based on the corresponding alkane name with the suffix "-on" added.
  • Example: Propan-2-ol (an alcohol with the OH group on the second carbon) becomes Propanone (a ketone).

• Ketones derived from alkanes are named by adding "-on" to the alkane name.