Question

What is the IUPAC name of diisopropyl ketone?

(a) 1,3-Diisopropylpropan-2-one

(b) 2,4-Dimethylpentan-3-one

(c) 2-Methyl-1-(1-methylethyl)propan-1-one

(d) 1,3-Dimethylpropan-2-one

I have been asked this question at a job interview.

The origin of the question is Nomenclature and Structure of Carbonyl Groups topic in portion Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12

Answer 1

The correct answer is (b) 2,4-Dimethylpentan-3-one

Explanation: The formula of diisopropyl ketone is (CH3)2CHCOCH(CH3)2 which consists of 7 carbon atoms. The longest parent chain including the keto group is of 5 carbon atoms, leaving out one C atom from the methyl group at each end. This is a symmetric ketone and the methyl groups are present at the second and fourth carbon starting from any one end and the C-O double bond is present at the third carbon.