See image — IUPAC and Nomenclature Chemistry Question

💡 Solution & Explanation

Step 1: Identify the structure. The compound is a 5-carbon chain with the following substituents: CH3-CH(CH3)-CH(OH)-CH(OH)-CHO. Reading left to right: C5 is CH3, C4 bears a CH3 branch, C3 bears OH, C2 bears OH, C1 is CHO (aldehyde). Step 2: Identify the principal functional group. The aldehyde (CHO) is the highest-priority functional group and must be at C1. The parent chain must include the CHO carbon. Step 3: Number the chain. The longest chain including the CHO group: CHO-CH(OH)-CH(OH)-CH(CH3)-CH3. This gives a 5-carbon chain (pentanal) with the aldehyde at C1. Step 4: Assign locants to substituents. - C1: CHO (aldehyde, suffix: -al) - C2: OH (hydroxy) - C3: OH (hydroxy) - C4: CH3 (methyl branch) - C5: CH3 (end of chain) Step 5: Construct the IUPAC name. Parent chain = pentanal (5 carbons, aldehyde at C1). Substituents: 2,3-dihydroxy (two OH groups at C2 and C3), 4-methyl (methyl group at C4). Name: 2,3-Dihydroxy-4-methylpentanal. Step 6: Evaluate options. - (a) 2,3-Dihydroxy-4-methylpentanal — correct, matches our analysis. - (b) 1-oxo-2,3-Dihydroxy-4-methylpentane — incorrect, 'pentane' implies no aldehyde suffix; 'oxo' at C1 on a pentane would be a ketone-like nomenclature, wrong. - (c) 2,3-Dihydroxy-4-methylpentanone — incorrect, 'pentanone' implies a ketone, not an aldehyde. - (d) 1,2-Dihydroxy-3-methylbutanecarbaldehyde — incorrect locants and parent chain name; 'butanecarbaldehyde' would be a 5-carbon chain but OH positions are wrong. Therefore, the correct answer is A.