See image — IUPAC and Nomenclature Chemistry Question

💡 Solution & Explanation

Step 1: Identify the structure. The compound is: CH2(NH2) — CH(CH3) — CH2 — CH2(NH2). This is a four-carbon chain with NH2 groups on C1 and C4, and a methyl substituent on C2. Step 2: Determine the parent chain. The longest continuous carbon chain that contains both nitrogen-bearing carbons is 4 carbons: C1-C2-C3-C4. This makes it a butane backbone. Step 3: Number the chain to give the substituents the lowest locants. Numbering from the NH2 end: C1 has NH2, C2 has CH3, C3 is CH2, C4 has NH2. The two amino groups are at positions 1 and 4, and the methyl group is at position 2. Step 4: Name the compound. Parent chain = butane. Two amino groups at C1 and C4 = butane-1,4-diamine. Methyl substituent at C2 = 2-methyl. Full name: 2-Methylbutane-1,4-diamine. Step 5: Verify numbering. If numbered from the other end, the methyl would be at C3 and amines at C1 and C4, giving 3-Methylbutane-1,4-diamine — but the lower locant set {1,2,4} is preferred over {1,3,4}, so numbering giving methyl at C2 is correct. Step 6: Eliminate wrong options. (b) 3-Methylbutane-1,4-diamine incorrectly numbers from the wrong end. (c) and (d) use substitutive nomenclature that does not correctly represent the structure as a simple diamine with methyl substituent on the main chain. Therefore, the correct answer is A.