The names of many drugs used in medicine often include parts of the names of the functional groups their molecules contain.

1. (a)Suggest two functional groups present in a molecule of the drug named chloramphenicol. 1 2[1]
2. (b)(i)The drug named ketamine readily reacts with protons as shown. ketamine + H⁺ → [ketamine-H]⁺ State the role of ketamine in this reaction.[1]
3. (b)(ii)Ketamine gives an orange precipitate with 2,4-dinitrophenylhydrazine (2,4-DNPH). Suggest the functional group in the ketamine molecule responsible for this observation.[1]
4. (b)(iii)The mass spectrum of ketamine is determined. Two peaks close to the molecular ion peak, M, are observed with the relative abundances shown in the table. peak m/e relative abundance M 237 100.0 M+1 238 14.3 M+2 239 33.3 Use the numbers in the table to show that there are 13 carbon atoms in a ketamine molecule.[1]
5. (b)(iv)In addition to carbon and hydrogen atoms, each molecule of ketamine contains one atom of each of three different elements. These are called heteroatoms. One of these heteroatoms is a halogen. Use the figures in the table to suggest the identity of this halogen. Explain your answer.[1]
6. (b)(v)Another peak in the mass spectrum of ketamine has an m/e value of 240. Predict the relative abundance of this peak.[1]
7. (b)(vi)Use the information in (b) to complete the molecular formula of ketamine by working out the identities of the three different heteroatoms and the number of hydrogen atoms present. C13H[1]
8. (c)(i)Suggest the number of peaks in the carbon-13 NMR spectrum of neramexane.[1]
9. (c)(ii)The proton (¹H) NMR spectrum of neramexane in CDCl3 shows five peaks with the following chemical shifts (δ). δ/ppm number of protons responsible splitting pattern (singlet, doublet, triplet, quartet or multiplet) 0.9 singlet 1.2 3 1.4 2 1.7 4 2.2 broad singlet Complete the table.[4]
10. (c)(iii)Use the Data Booklet and the table in (c)(ii) to complete the assignment of the correct δ values to each of the circled hydrogen atoms on the structure of neramexane.[2]
11. (c)(iv)One of the peaks in the proton (¹H) NMR spectrum disappears when the sample is shaken with D₂O. Identify the peak and explain why it disappears.[1]

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