The hydrocarbon [A] adds one mole of hydrogen in the presence of a platinum catalyst to form n-hexane. When [A] is oxidised vigorously with `KMnO_(4)`, a single carboxylic acid containing three carbon atoms is isolated. Give the strucure of [A] and explain the reactions.

Explanation

(i)Since the hydrocarbon A adds one mole of `H_2` in presence of Pt to form n-hexane, therefore, A must be an hexene.
(ii)Since A on vigorous oxidation with `KMnO_4` gives a single carboxylic acid containing three carbon atoms, therefore A must be a symmetrical hexene, i.e., hex-3-ene.
`underset"Hex-3-ene (A)"(CH_3CH_2CH=CHCH_2CH_3) underset(KMnO_4)overset"[O]"to underset"Propionic acid"(2CH_3CH_2COOH)`
Thus, the given hydrocarbon A is hex-3-ene.