AAMC Sample Test C/P Q45

[663697]

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Although highly toxic, amygdalin has been investigated as a potential anti-cancer compound. When refluxed in H2SO4 (aq), amygdalin breaks down to produce glucoese (2 equivalents), HCN (1 equivalent), and benzaldehyde (C6H5CHO, 1 equivalent). Which structure most likely corresponds to amygdalin?

Spoiler: answer

Can somebody please explain why cyanohydrin and acetal functional groups hydrolyze in H2SO4 as the answer states? I checked my TPR book and the only thing it has relating to cyanohydrin is when it is used for nucleophilic attack on a carbonyl.

 

[aldol16]

Acids can catalyze hydrolysis by turning good leaving groups into great leaving groups via protonation. Protonation of an acetal makes an excellent leaving group (alcohol) from an okay leaving group (alkoxide). Similarly, protonation of the cyanohydrin causes the HCN to turn into a great leaving group. Therefore, water can attack and kick out the HCN, leaving you with an acetal. The O from the water can then collapse into a carbonyl and kick out the sugar.