JEE Main 2020 · 6 September · evening · Single correct · +4 / −1
The IUPAC name of the following compound is :
- (a) 2-nitro-4-hydroxymethyl-5-amino benzaldehyde
- (b) 3-amino-4-hydroxymethyl-5-nitro benzaldehyde
- (c) 4-amino-2-formyl-5-hydroxymehtyl nitrobenzene
- (d) 5-amino-4-hydroxymethyl-2-nitro benzaldehyde
Answer and solution
Answer (d) 5-amino-4-hydroxymethyl-2-nitro benzaldehyde
Solution
Chemistry ma’am · 4 steps
CHO outranks the rest: it names the parent, takes C1, and the other groups go in as A to Z prefixes.
- Pick the parent. Of -CHO, -CH₂OH, -NH₂ and -NO₂, the aldehyde has the highest priority. So the parent is benzaldehyde and the ring carbon carrying -CHO is C1. Nitro is never a suffix; it is always a prefix.
- Choose the direction. From C1, go around the ring both ways and compare the locants of the three substituents. Pick the set with the lower number at the first point of difference.
Direction from C1 NO₂ CH₂OH NH₂ Locant set Towards NO₂ 2 4 5 {2, 4, 5} Away from NO₂ 6 4 3 {3, 4, 6} - Alphabetical order. The first difference is 2 against 3, so the set {2, 4, 5} wins. Now write the prefixes alphabetically: amino, hydroxymethyl, nitro.
- So. The name is 5-amino-4-hydroxymethyl-2-nitrobenzaldehyde, option (d).
The idea to keep. Find the principal group first: it fixes the parent name and C1. Use lowest locants to choose the direction, then list prefixes alphabetically, whatever their numbers.
Answer from the NTA final answer key. Solution by PrepWiser.