Question

What is the IUPAC name of acetone?
A. Propanal
B. Propanone
C. Propanol
D. Propanoic acid

Answer 1

The word IUPAC refers to the International Union of Pure and Applied Chemistry. This gives a method for naming the organic compounds. The name acetone indicates that it is a ketone.

Complete step by step answer:
In order to find the IUPAC name of the given compound we have to know the rules of IUPAC for naming the ketones.
Following rules of the nomenclature of ketones, ketones are named by changing the suffix of the parent hydrocarbon. The name of hydrocarbon is finished with –ane but the ketones are finished by adding the suffix –anone. The position of the carbonyl is mentioned in the beginning or in the middle.
The above mentioned method of nomenclature is applied for symmetrical ketones which have the same alkyl group on either side of the carbonyl group. For unsymmetrical ketones, the nomenclature is done by naming the alkyl group present in alphabetical order followed by ketone. For example, ethyl methyl ketone has a methyl and an ethyl group on either side of the $C = O$ group.
Acetone is the simplest ketone. The alkyl group present on either side of $C = O$ is methyl. The total number of carbon atoms present is three for acetone. Thus acetone is a symmetrical ketone and the IUPAC name of acetone is $2$-propanone, i.e. option B is the correct answer.
Propanal is the name used for naming aldehydes. Propanol is used for naming alcohols. Propanoic acid is used for naming carboxylic acid.

Thus option B is the correct answer.

Note: The prefix keto- or oxo- are also used in some instances. It is a common practice to use suffixes like –anone and ketone after the parent hydrocarbon.