Aldehydes and Ketones
- CHO Group is called formyl group and -CO- Group is called carbonyl group.
When the -CHO group is attached to a hydrogen or carbon atom, it is called an aldehyde group. And the related compound is called aldehyde.
Example: -CHO group in HCHO is associated with H, so it contains aldehyde group and it is an aldehyde. In CH3CHO, -CHO is associated with group C, so it also has an aldehyde group and is also an aldehyde. -CHO group is present in HCOOH but it is associated with O, so aldehyde group is not present in this compound.
Compounds in which the -CHO group is attached to a hydrogen atom or an alkyl group are also called alkanal. The common formula of these compounds is CnH2nO.
The common formula of these compounds is RCHO where R is a hydrogen atom or an alkyl group. There is a difference of CH2 between the two consecutive alkanal.
Hence all alkanal are members of the same homogeneous category. The first member of these categories is formaldehyde (HCHO) and the second member is acetaldehyde (CH3CHO).
When the -CO-group is connected to carbon atoms on both sides, it is called keto group or Ketone group and the related compound is called Ketone.
Example: In CH3-CO-CH3 the -CO — group is connected to two methyl groups through carbon atoms, so a ketone group is present in it and it is a ketone. In CH3COOH, the -CO-group is present but on one hand it is connected to the -OH group with oxygen atom, so ketone group is not present in this compound.
The compounds in which the -CO- group is attached to the alkyl group on both sides are also called Alkanones. The common molecule of these compounds is the formula CnH2nO, where n has a value greater than 2 or 2.
The general structure of these compounds is the formula R1-CO-R2, where R1 and R2 are the alkyl group. R1 and R2 may be the same or different. The two consecutive alkanones have a difference of CH2. Hence all alkanone are members of the same homogeneous category. The first member of this category is acetone (CH3-CO-CH3) and the second member is methyl ethyl ketone(CH3-CO-C2H5).
The carbonyl group is present in both aldehydes and ketones compounds, hence both these types of compounds are also called carbonyl compounds.