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 showing polyanhydride repeat unit]

1. (a)Compare the relative acidities of benzoic acid (C6H5COOH), phenylmethanol (C6H5CH2OH), and phenol (C6H5OH). 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 (x) 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 CH₃COOH + PCl₅ → C₆H₅COCl + reaction 2 CH₃COOH + 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. H₂O Cl products[4]
6. (d)(ii)Name the type of mechanism you showed in (d)(i).[1]
7. (e)(i)Acyl chlorides react with sodium carboxylates to form acid anhydrides as shown in Fig. 5.1. [Figure 5.1 showing general reaction] 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]

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