11177 12 Malic acid is found in some apples, giving them a sour taste. COOH CHOH CH2 COOH malic acid (a) (i) Draw the structure of malic acid showing all the bonds present. [1] (ii) Suggest the IUPAC name for malic acid. [2] 11177 [Turn over (b) (i) Show the organic products for the reaction of malic acid with an excess of each of the following: PCI5, LiAlH4 and CH3CHOHCH3. COOH CHOH CH2 COOH PCl5 LiAlH4 (CH3)2CHOH [4] (ii) Name the organic product formed from the reaction with LiAlH4. [1] (c) Malic acid melts at 130 °C and has a solubility of 0.558 kg dm−3 at 20 °C. (i) Explain why malic acid has a relatively high melting point. [2] (ii) Calculate, to three significant figures, the molarity of a saturated solution of malic acid at 20 °C. [2] 11177 (d) Malic acid is produced industrially by the double hydration of maleic anhydride. Although malic acid contains an asymmetric centre, the product of this reaction is not optically active. COOH CHOH CH2 COOH O C CH O CH C O +  2H2O maleic anhydride (i) Explain what is meant by the term optically active. [2] (ii) On the above diagram circle the asymmetric centre on the malic acid. [1] (iii) What name is given to this type of optically inactive product? [1] (iv) Explain why the product in this reaction is not optically active. [1] BLANK PAGE DO NOT WRITE ON THIS PAGE (Questions continue overleaf) 11177 [Turn over