How many of the following will give faster rate of cyanohydrins formation than benzaldehyde? ___
(a) p-methoxy benzaldehyde
(b) p-cyano benzaldehyde
(c) p-nitrobenzaldehyde
(d) p-methylbenzaldehyde
How many of the following will give faster rate of cyanohydrins formation than benzaldehyde? ___
(a) p-methoxy benzaldehyde
(b) p-cyano benzaldehyde
(c) p-nitrobenzaldehyde
(d) p-methylbenzaldehyde
p-cyano benzaldehyde is most reactive towards the addition reaction of hydrogen cyanide to form the corresponding cyanohydrin.
Carbonyl C atom in p-cyano benzaldehyde is most electrophilic.
In aldehydes and ketones, the +I effect of alkyl groups decreases the electrophilic character of the carbonyl C atom. Lower is the electrophilic character, lower is the reactivity towards the addition reaction of hydrogen cyanide to form the corresponding cyanohydrin.
In p-cyanobenzaldehyde, the -CN group is a powerful electron-withdrawing group. It
withdraws electrons by inductive effect thereby decreasing the electron density on the carbon atom of the carboxyl group. This facilitates the attack of the nucleophile and hence makes it more reactive than benzaldehyde.
p-cyano benzaldehyde is most reactive towards the addition reaction of hydrogen cyanide to form the corresponding cyanohydrin.
Carbonyl C atom in p-cyano benzaldehyde is most electrophilic.
In aldehydes and ketones, the +I effect of alkyl groups decreases the electrophilic character of the carbonyl C atom. Lower is the electrophilic character, lower is the reactivity towards the addition reaction of hydrogen cyanide to form the corresponding cyanohydrin.
In p-cyanobenzaldehyde, the -CN group is a powerful electron-withdrawing group. It
withdraws electrons by inductive effect thereby decreasing the electron density on the carbon atom of the carboxyl group. This facilitates the attack of the nucleophile and hence makes it more reactive than benzaldehyde.
