stabilization of the carbocation intermediate; the more stable carbocation (R 5 CH3) is formedfaster than the less stable one (R 5 H).17.25(a)The reaction as written is the reverse of cyanohydrin formation, and the principles that governequilibria in nucleophilic addition to carbonyl groups apply in reverse order to the dissocia-tion of cyanohydrins to aldehydes and ketones. Cyanohydrins of ketones dissociate more atequilibrium than do cyanohydrins of aldehydes. More strain due to crowding is relieved whena ketone cyanohydrin dissociates and a more stabilized carbonyl group is formed. The equi-librium constant Kdissis larger forthan it is for(b)Cyanohydrins of ketones have a more favorable equilibrium constant for dissociation than docyanohydrins of aldehydes. Crowding is relieved to a greater extent when a ketone cyanohydrindissociates and a more stable carbonyl group is formed.The measured dissociation constants are
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This note was uploaded on 09/28/2011 for the course CHM 2210 taught by Professor Reynolds during the Fall '01 term at University of Florida.