Question

The IUPAC name of the following compound is
(A) 3-Hydroxy – 4 – methylpentaonic acid
(B) 4 – Methyl – 3 – hydroxypentanoic acid
(C) 2 – Methyl – 3 – hydroxylpentan-5-oic acid
(D) 4, 4 – Dimethyl – 3 – hydroxybutanoic acid

Answer 1

Answer:

option B

Explanation:

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Answer 2

The IUPAC name of the given compound is 3-hydroxy-4-methylpentanoic acid. Hence, the correct alternative is option (A).

• The given compound has two functional groups, namely, the OH group and the COOH group.

• The COOH functional group has the highest priority in the seniority table, and therefore, its carbon is numbered 1 in the chain.

• The longest straight chain in the structure comprises of five carbon atoms, starting from the COOH group.

• This chain of five carbon atoms counted from the carboxylic group (COOH) is designated as 'pentanoic acid' in the nomenclature.

• The fourth carbon atom in the structure is substituted with a methyl group, represented as '4-methyl' in the name of the structure.

• The OH group, having a lower priority, and being attached to the third carbon atom, is designated as '3-hydroxy' in the compound.

• Now, it is to be noted that the name of the substituents in the structure should be arranged alphabetically, i.e., 3-hydroxy should be written before 4-methyl.

• Thus, following all the rules of nomenclature, the IUPAC name of the compound can be given as 3-hydroxy-4-methylpentanoic acid.