22. Answer ALL parts of this question. (a) If ethyne is treated according to the following scheme, the final product is

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22 Answer All Parts Of This Question A If Ethyne Is Treated According To The Following Scheme The Final Product Is 1 (52.76 KiB) Viewed 8 times

22. Answer ALL parts of this question. (a) If ethyne is treated according to the following scheme, the final product is trans-pent-2-ene, as shown: H-CC-H (c) (i) NaNH, / NH (ii) CH,Br (iii) NaNH, / NH, (iv) CH₂CH₂Br (v) Na/NH3 H₂C H CH₂CH3 Show the structures of the intermediates formed after each of the first four steps and identify the mechanism involved in steps (ii) and (iv). (4 + 1 marks) (b) If cis-pent-2-ene was wanted as the final product, how would step (v) in the sequence above must be modified? (1 mark) The alkene shown in part (a) of this question could also be made by treating 2-bromopentane with base. It would be the major product out of three possible alkenes that could form. Give the structures of the two other alkenes that would form and comment on why trans-pent-2-ene is the major one that forms here. (4 marks)