Glycerol, CH2(OH)CH(OH)CH2OH, is widely used in the food industry and in pharmaceuticals.

1. (a)(i)A series of reactions starting from glycerol is shown. P CH2OH HOOC Q COOH c=0 reaction 1 NaCN and HCN reaction 2 NC—C—ОН CH2OH HOOC COOH Suggest the reagent(s) and conditions for reaction 1.[2]
2. (a)(ii)Name the reaction mechanism for reaction 2.[1]
3. (a)(iii)Give the observation you would make when 2,4-dinitrophenylhydrazine is added to P.[1]
4. (a)(iv)Q does not show optical isomerism. Explain why.[1]
5. (a)(v)When Q is heated with excess aqueous ethanoic acid in the presence of a catalytic amount of sulfuric acid, two reactions take place to form compound R. R COOH HOOC—C—OCOCH3 COOH Identify the two types of reaction that occur. 1 2[2]
6. (b)(i)Glycerol can be used as a starting material in the manufacture of nitroglycerine, C3H5N3O9. Nitroglycerine decomposes rapidly on heating to form a mixture of gases. 4C3H5N3O9(l) → 12CO2(g) + 10H2O(g) + 6N2(g) + O2(g) A sample of nitroglycerine decomposes, releasing 1.06 dm3 of O2(g) at 850 K and 1.00 × 105 Pa. Calculate the mass of nitroglycerine that decomposes. mass of nitroglycerine =[3]
7. (b)(ii)Calculate the total volume of gas released by this decomposition at 850 K and 1.00 × 105 Pa. total volume of gas =[1]
8. (c)(i)Fats are compounds made from glycerol and unsaturated carboxylic acids. 4-pentenoic acid is an example of an unsaturated carboxylic acid. 4-pentenoic acid (CH2)2COOH H. H H Give the molecular formula of 4-pentenoic acid.[1]
9. (c)(ii)Draw the repeat unit of the addition polymer that can be formed from 4-pentenoic acid.[1]
10. (c)(iii)Unsaturated acids are often brominated before being added to soft drinks. Complete the mechanism for the addition of Br2 to 4-pentenoic acid. • Include the structures of the intermediate and the product of the reaction. • Include all charges, partial charges, lone pairs and curly arrows. In the mechanism, R has been used to represent (CH2)2COOH. R H H H Br Br[4]
11. (d)(i)A reaction of another unsaturated carboxylic acid, T, is shown. HOOC. T C6H13 Br HOOC. U C6H13 Br T is one of a pair of geometrical (cis-trans) isomers. Draw the other geometrical isomer of T and explain why the molecules exhibit this form of isomerism.[3]
12. (d)(ii)Identify the reagent used to convert T to U.[1]
13. (d)(iii)The C−Br bond has an absorption between 500 cm−¹ and 600 cm−¹ in an infrared spectrum. The infrared spectra for both T and U have absorptions between 2850 cm−1 and 2950 cm−1. These correspond to C–H bonds. Identify: • two other absorptions that would be seen in the infrared spectra of both T and U • one other absorption that would only be seen in the infrared spectrum of T. For each absorption, give the range of the absorption and the bonds that correspond to these absorptions. absorption 1 present in both spectra absorption 2 present in both spectra absorption only present in spectrum of T[3]

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