Problem 6

A, C₃H₇Cl, reacts with aqueous sodium hydroxide solution to give C, C₃H₈O. C reacts with phosphorus pentachloride to give steamy fumes, and can be oxidised with acidified potassium dichromate solution to give D, C₃H₆O, and then E, C₃H₆O₂. D reacts with both 2,4-dinitrophenylhydrazine and ammoniacal silver nitrate. E reacts with phosphorus pentachloride and with sodium hydrogen carbonate solution, in the latter case giving carbon dioxide.

A will react with benzene in the presence of anhydrous aluminium chloride to give B, C₉H₁₂. The structure of this compound is not what might have been expected from A. B can be made from benzene and F as the expected product, however, F being an isomer of A. Sodium hydroxide solution converts F to G, an isomer of C. G can be oxidised with acidified potassium dichromate solution to H, an isomer of D, but no further. H gives a positive result with the 2,4-DNP test but not the ammoniacal silver nitrate test; it also gives a positive result in the iodoform reaction.

On heating with alkaline potassium manganate(VII) solution B gives an aqueous solution of I, which on treatment with dilute sulphuric acid gives a white precipitate J.

(a) Identify all of the substances A – J, and explain each of the observations as fully as you can with supporting equations.

(b) Suggest why A and F give the same product with benzene.

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