12201 20 Cinnamaldehyde is a pale yellow liquid that can be obtained from the bark of cinnamon trees. cinnamaldehyde C C H H CHO H5C6 (a) (i) Cinnamaldehyde is a geometric isomer. State and explain which geometric isomer cinnamaldehyde is. [2] (ii) Explain how a pale yellow oil suspected as being cinnamaldehyde, could be identified using 2,4-dinitrophenylhydrazine. Include in your answer experimental details of the preparation of cinnamaldehyde-2,4- dinitrophenylhydrazone. In this question you will be assessed on using your written communication skills including the use of specialist scientific terms. 12201 [Turn over [6] (b) Write an equation for the reduction of cinnamaldehyde with lithal using [H] to represent the reducing agent. [1] (c) Oxidation of cinnamaldehyde produces cinnamic acid which is a solid at room temperature with a melting point of 132–133 °C. Explain why cinnamic acid has a higher melting point than cinnamaldehyde. [3]