A-LevelChemistryHydroxy compounds9701/42 · May/June 2019 · Q810 Marks

Compound R is shown. [Figure X.X]

(a)State the systematic name of compound R.[1]
(b)(i)R is dissolved in CDCl₃ and analysed using carbon-13 and proton NMR spectroscopy. • Predict the number of peaks that are seen in the carbon-13 NMR spectrum of R. • Predict the number of peaks that are seen in the proton NMR spectrum of R.[2]
(b)(ii)A separate sample of R is dissolved in D₂O. The proton NMR spectrum of this solution shows one less peak than is obtained in CDCl₃. Explain why.[1]
(c)Compound R reacts separately with the four reagents shown in the table. Complete the table by • drawing the structures of the organic products formed, • stating the type of reaction. [Table with reagents Na, CH₃COCl, Br₂(aq), benzenediazonium ion. Empty columns for organic product structure and type of reaction.][6]

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Mark scheme

Marking points from the official mark scheme (May/June 2019). The mark or mark type is shown in brackets.

[1] 4-chloro-3,5-dimethylphenol OR 3,5-dimethyl-4-chlorophenol ALLOW 2,6-dimethyl-4-hydroxychlorobenzene and 2-chloro-5-hydroxy-1,3-dimethylbenzene
[1] carbon-13 NMR = 5 peaks
[1] proton NMR = 3 peaks
[1] OH proton had disappeared due to proton exchange with D / D₂O ALLOW OH + D₂O → OD + HOD
[6] each structure [1] × 4; type of reaction • • [2]

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