(e) Acyl chlorides react with sodium carboxylates to form acid anhydrides as shown in Fig. 5.1. [Figure 5.1] The condensation polymers, polyanhydride and polyester, are formed by similar methods. The repeat unit for a polyanhydride is shown in Fig. 5.2. [Figure 5.2]

1. (a)Compare the relative acidities of benzoic acid (CH5COOH), phenylmethanol (C8H5CH2OH), and phenol (CH5OH). Explain your reasoning. most acidic > ... > least acidic[3]
2. (b)A series of nine separate experiments is carried out as shown in Table 5.1. Complete the table by placing a tick (✓) in the relevant box if a reaction occurs. Place a cross (✗) in the box if no reaction occurs. Table 5.1 benzoic acid phenylmethanol phenol Na(s) NaOH(aq) Na2CO3(aq)[3]
3. (c)(i)Benzoyl chloride, C₆H₅COCl, can be synthesised by the reaction of benzoic acid with either PCl₅ or SOCl₂. Complete the equations for these reactions. reaction 1 C₆H₅COOH + PCl₅ → C₆H₅COCl + ... + ... reaction 2 C₆H₅COOH + SOCl₂ → C₆H₅COCl + ... + ...[1]
4. (c)(ii)Use your answer to (c)(i) to suggest why it is easier to isolate, in a pure form, the C₆H₅COCl from reaction 2 compared to reaction 1.[1]
5. (d)(i)Benzoyl chloride is hydrolysed by water at room temperature to form benzoic acid. Complete the diagram to show the mechanism for the reaction between C₆H₅COCl and H₂O. Include charges, dipoles, lone pairs of electrons and curly arrows as appropriate. [Diagram for mechanism][4]
6. (d)(ii)Name the type of mechanism you showed in (d)(i).[1]
7. (e)(i)Use Fig. 5.1 and Fig. 5.2 to suggest the structures of the two monomers used to make this polyanhydride.[2]
8. (e)(ii)Polyanhydrides are biodegradable polymers. Suggest how this polyanhydride can be degraded.[1]

This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.