Does 4-methylbenzaldehyde give haloform and aldol reactions? The following question was asked in JEE Advanced 2017:


  


The answers given are option A and B. I was able to get B as the correct answer but A look like the wrong option to me.

My approach for option (A) and checking the reactions for Q:



Since (Q) of option (A) is able to give both haloform and aldol reaction, it should be incorrect. The reason I say that aldol reaction makes the option incorrect is that cannizaro reaction is given by aldehydes or ketones which have non enolisable hydrogen atoms. But aldol reaction requires enolisable hydrogen.

Can anyone confirm what should be the correct answer and why is my approach wrong if the answer given is right.
First, Cannizzaro reaction is not given by ketones (your statement says ketones give cannizzaro reaction).

Counter to your analysis, the following reaction will not occur since $\ce{H}$ bonded to methyl group is not sufficiently acidic for hydroxide ion to attack. Refer to $\mathrm{p}K_\mathrm{a}$ values given by Mathew Mahindaratne.

 

Under the given conditions  P on ozonnolysis gives formaldehyde and 4-methylbenzaldehyde. Both are nonenolizable aldehydes capable of undergoing Cannizzaro reaction. Both compounds do not undergo haloform reaction.

Scheme 1



Under the given conditions R gives acetophenone and formaldehyde. Acetophenone gives haloform test and it also undergoes aldol condensation, but not cannizaro reaction.

Scheme 2


Choice B also meets the conditions given.
Thus choices A &amp; B are correct.