A-LevelChemistryCarbonyl compounds9701/21 · May/June 2019 · Q57 Marks
Ethanal reacts with a mixture of HCN and NaCN to make 2-hydroxypropanenitrile, CH3CH(OH)CN. The reaction mechanism is nucleophilic addition.
- (a)Explain the meaning of the term nucleophile and identify the species which acts as the nucleophile during this reaction.[2]
- (b)(i)Name the type of stereoisomerism shown by CH3CH(OH)CN.[1]
- (b)(ii)Draw three-dimensional diagrams of this pair of stereoisomers. Indicate with an asterisk (*) the chiral centre on one of the structures drawn.[3]
- (c)Give the structure of the organic product of the reaction of CH3CH(OH)CN with dilute sulfuric acid.[1]
Mark scheme
Marking points from the official mark scheme (May/June 2019). The mark or mark type is shown in brackets.
- [1] M1 a lone pair / electron pair donor
- [1] M2 (:)CN-/-(:)CN / cyanide ion
- [1] optical
- [1] M1 one 3-D structure of correct molecule shown.
- [1] M2 a mirror image of the molecule drawn in M1 OR same profile with two groups swapped
- [1] M3 central chiral C shown as *
- [1] CH3CH(OH)CO2H OR HO2CCH(OH)CH3
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