Reaction of HCN with an aldehyde has higher yield than HCN with a ketone due to steric strain around the ketone. Then how about reaction yield of HCN with an aromatically conjugated aldehyde (like Ph-CHO) comparing with the previous two reactions? What I think: The yield be lower than just with regular aldehyde and higher than with ketone. Since the phenyl group is Electron donating, thus making the carbonyl carbon less Electrophilic. Tell me if I am right or wrong, thank you.