Aldehydes, Ketones and Carboxylic Acids
Carbonyl Group – Nomenclature and Structure
In the IUPAC system, aliphatic carboxylic acids are named as follows:
By replacing the ending ‘− e’ in the name of the corresponding alkane with ‘− oic acid’
Carboxylic carbon is numbered one.
If more than one carboxyl groups are present, then the ending ‘− e’ of the alkane is retained.
The number of carboxyl groups is indicated by adding prefix, di, tri, etc. to the term ‘oic’.
The given table lists the common and IUPAC names and structures of some carboxylic acids.
Names and Structures of Some Carboxylic Acids
Propane-1, 2, 3-
Structure of Carboxyl Group
Carboxyl carbon is less electrophilic than carbonyl carbon because of resonance.
Bonds to the carboxyl carbon lie in one plane and are separated by about 120°.
Methods of Preparation of Carboxylic Acid
From primary alcohols
Oxidising agents − HNO3, KMnO4, K2Cr2O7 and mild oxidising agents as well like Tollen’s reagent and Fehling’s reagent.
From alkyl benzenes
1° and 2° alkyl benzene are oxidised in this manner.
Tertiary group is not affected.
From nitriles and amides
From Grignard reagents
From acyl halides
From acid anhydrides
Ester Carboxylic acid + Alcohol
Common Names of Aldehydes
Often called by their common names instead of IUPAC names
Derived from the common names of the carboxylic acids by replacing the ending ‘−ic’ of the acid with aldehyde
Location of the substituent in the carbon chain is indicated by the Greek letters α, β, γ, δ, etc.
Common Names of Ketones
Derived by naming two alkyl or aryl groups bonded to the carbonyl group
Locations of substituents are indicated by the Greek Letters, α, α′, β, β′, and so on
The simplest dimethyl ketone is called acetone.
Alkyl phenyl ketones are usually named by adding the acyl group as prefix to phenone.
For open-chain aliphatic aldehydes and ketones, IUPAC names are derived from the names of the corresponding alkanes by replacing the ending ‘−e’ with ‘−al’ and ‘−one’ respectively.
In the case of aldehydes, the longest chain is numbered starting from the carbon of the aldehydic group.
In the case of ketones, the numbering begins from the end nearer to the carbonyl gro…
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