13108 14 3-methylbutan-1-ol is one of eight alcohols with the molecular formula C5H12O. (a) (i) Complete the table below for some of the isomers of C5H12O. C C C C CH3 O H H H H H H H H H C C C C OH H H CH3 H H H H H H C C C C C OH H H H H H H H H H H H H C C C C OH H H H CH3 H H H H Structural formula Classification IUPAC name primary 3-methylbutan-1-ol primary pentan-2-ol tertiary secondary [5] 13108 [Turn over (ii) Some of the alcohol isomers are optically active. Define the term optically active. [2] (iii) Name the alcohols shown in the table in (a)(i) which exhibit optical activity. [2] (iv) Name the alcohol shown in the table in (a)(i) which can be oxidised to produce an optically active compound. Draw the structural formula of the optically active compound. Name: [2] 13108 (b) 3-methylbutan-1-ol undergoes an esterification reaction with ethanoic acid to form ‘banana oil’ which is used as a food flavouring. (i) Write an equation for this esterification reaction. [2] (ii) An impure sample of ‘banana oil’ was obtained in a round-bottomed flask by reacting 3-methylbutan-1-ol with ethanoic acid in the presence of a concentrated sulfuric acid catalyst. The impure sample of the ‘banana oil’ was collected by distillation. Describe how the sample could be further purified by removing acidic impurities and water. In this question you will be assessed on using your written communication skills including the use of specialist scientific terms. [6] 13108 [Turn over (c) Coconut oil contains a large proportion of the triglyceride, glyceryl trilaurate. The fatty acid in this triglyceride is lauric acid, CH3(CH2)10COOH. (i) Draw the structure of glyceryl trilaurate. [1] (ii) Explain why glyceryl trilaurate is a solid at room temperature. [2] (iii) Biodiesel can be produced from oils such as coconut oil by a transesterification reaction. Define the term transesterification. [2] 13108 (iv) An oil, with the general formula shown below, can be used in the formation of biodiesel. CH2 CH CH2 R1COO R2COO R3COO Write the equation for the formation of biodiesel by heating the oil with an excess of ethanol in the presence of a catalyst. [2]