Compounds P and R upon ozonolysis produce Q and S, respectively. The molecular formula of Q and S is C8H8O. Q undergoes Cannizzaro reaction but not haloform reaction, whereas S undergoes haloform reaction but not Cannizzaro reaction.
The option(s) with suitable combination of P and R, respectively, is(are)iii
(A)(see structure) and (see structure)AB✓ Correct
(B)(see structure) and (see structure)AB✓ Correct
(C)(see structure) and (see structure)AB
(D)(see structure) and (see structure)AB
Answer: (A), (B)
Solution
Q undergoes Cannizzaro (no α-H, must be an aldehyde) but not haloform (no methyl ketone). So Q is an aromatic aldehyde without α-hydrogens, likely benzaldehyde derivative.
S undergoes haloform (methyl ketone) but not Cannizzaro (has α-H). So S is an aromatic methyl ketone.
Both have formula C8H8O.
Q = 4-methylbenzaldehyde or 2-methylbenzaldehyde S = acetophenone derivative (phenyl methyl ketone)
Ozonolysis of alkenes produces carbonyl compounds. For P to give Q (aldehyde) and for R to give S (methyl ketone), we need appropriate alkene precursors.
[A] Correct: P = 4-methylstyrene → Q = 4-methylbenzaldehyde + formaldehyde; R = α-methylstyrene → S = acetophenone + formaldehyde.
[B] Correct: P = 3-methylstyrene → Q = 3-methylbenzaldehyde; R = isopropenylbenzene → S = acetophenone.
[C] and [D]: The carbon count doesn't match for C8H8O products.
JEE Advanced · 2017 · 21 May 2017 · Paper 2 · One or more correct options
