A-LevelChemistryIntroduction to organic chemistry9701/42 · May/June 2022 · Q99 Marks

The structure of cyclohexylamine is shown in Fig. 9.1. [Figure cyclohexylamine, Fig. 9.1]

(a)Compare the relative basicities of ammonia, cyclohexylamine and phenylamine. Explain your reasoning.[3]
(b)(i)Cyclohexylamine reacts with ethanoyl chloride to form the corresponding amide, L. [Figure Fig. 9.2 showing the reaction and product L] Name the mechanism for the reaction shown in Fig. 9.2.[1]
(b)(ii)Complete the mechanism of the reaction between cyclohexylamine and CH₃COCl. R-NH₂ is used to represent cyclohexylamine. Include all relevant lone pairs of electrons, curly arrows, charges and partial charges.[4]
(b)(iii)The reaction between cyclohexylamine and an excess of CH3COCl forms compound M. Compound M has the molecular formula C10H17NO2. Suggest and draw the structure of M.[1]

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Mark scheme

Marking points from the official mark scheme (May/June 2022). The mark or mark type is shown in brackets.

[3] M1 cyclohexylamine > ammonia > phenylamine
[3] M2 (order of basicity) linked to ability of N to accept a proton / donate its lone pair (to a proton)
[3] M3 alkyl / cyclo / hexyl group is electron donating group / positive inductive group (and increases electron density on N)
[3] M3 lone pair / p-orbital from N in phenylamine delocalised / overlaps with ring (and decreases electron density on N)
[1] (nucleophilic) addition-elimination
[4] M1/M2 lone pair on N; correct arrow from (lone pair) N to C (of C=O); dipole on C=O; correct arrow on C=O
[4] M3 correct intermediate
[4] M4 arrow from lone pair on O- to C-O bond AND arrow from C-Cl to Cl
[1] [Figure of N,N-diethanoylcyclohexylamine]

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