11589 14 Mesalazine, an anti-inflammatory drug which is used to treat bowel disease, can be synthesised from 2-hydroxybenzoic acid using the flow scheme below. OH C HO O NO2 OH C HO O NH2 OH C HO O NH+ 3Cl− OH C HO O Step 2 Step 1 2-hydroxybenzoic acid mesalazine (a) (i) State the reagents that could be used for Step 1 and Step 2. Step 1: Step 2: [2] (ii) Mesalazine can be converted into azo dyes through reaction with naphth-1-ol or resorcinol: OH naphth-1-ol OH HO resorcinol Draw the structure of the ion mesalazine must be converted into before the azo dye can be formed. [2] 11589 [Turn over (iii) Draw the structure of the azo dye produced by the reaction with resorcinol. [2] (iv) Explain why azo dyes are coloured and suggest why the azo dyes produced by resorcinol and naphth-1-ol have slightly different colours. [4] (b) 2-hydroxybenzoic acid can be converted into an ester by reacting with an equimolar amount of ethane-1,2-diol. Write an equation for this reaction. [2] (c) Polyethylene terephthalate can be produced from ethane-1,2-diol. (i) State a use for polyethylene terephthalate. [1] (ii) Explain why polyethylene terephthalate is biodegradable. [1]