See image — IUPAC and Nomenclature Chemistry Question

💡 Solution & Explanation

Concept: IUPAC nomenclature of aromatic amines. The parent compound aniline (aminobenzene) has the preferred IUPAC name 'benzenamine' (phenylamine), where benzene is the parent chain and -amine is the principal characteristic group suffix. When two methyl groups are attached to the nitrogen atom, they are cited as N,N-dimethyl substituents on the parent name. Step 1: Identify the compound. The structure shows a benzene ring with a -N(CH3)2 group attached, i.e., N,N-dimethylaniline. Step 2: Determine the correct IUPAC name. According to IUPAC 2013 recommendations, the preferred IUPAC name for C6H5-NH2 is 'aniline' (retained name) or 'benzenamine'. For N,N-dimethyl substitution on nitrogen, the IUPAC name is N,N-dimethylbenzenamine. Step 3: Evaluate option (a): 'N,N-Dimethyl aminobenzene' — this is a semi-systematic/common name where 'aminobenzene' is used as the parent, but 'aminobenzene' itself is not a proper IUPAC parent name (it is a substitutive name for aniline, not an acceptable IUPAC parent for further substitution on N). This name is not the preferred IUPAC name. Step 4: Evaluate option (b): 'N,N-Dimethyl benzenamine' — 'benzenamine' is the IUPAC name for aniline (benzene as parent + amine suffix), and N,N-dimethyl correctly denotes two methyl groups on nitrogen. This is the correct IUPAC name. Step 5: Option (c) claims both are correct, but only (b) is the proper IUPAC name. Option (a) uses 'aminobenzene' which is not a valid IUPAC parent name for naming N-substituted derivatives. Therefore, the correct answer is B.