Question

Three bottles A, B, and C have been found, each of which contains a liquid and is labeled \"amine C₈H₁₁N.\" As an expert in amine chemistry, you have been hired as a consultant and asked to identify each compound. Compounds A and B give off a gas when they react with NaNO2 and HCl at 0 ℃; C does not. However, when the aqueous reaction mixture from the diazotization of C is warmed, a gas is evolved. Compound A is optically inactive, but when it reacts with ( )-tartaric acid, two isomeric salts with different physical properties are obtained. Titration of C with aqueous HCl reveals that its conjugate acid has a pKa = 5.1. Oxidation of C with H2O2 (a reagent known to oxidize amino groups to nitro groups), followed by vigorous oxidation with KMnO4 gives p-nitrobenzoic acid. Oxidation of B in a similar manner yields 1,4-benzenedicarboxylic acid (terephthalic acid), and oxidation of A yields benzoic acid. Identify compounds A, B, and C.

Answer 1

The compound A is an amine that produces N2 gas on diazotization. It is achiral. Oxidation of A with KMnO4 gives benzoic acid H3C NH2 NaNO2, HCl o °C NH COOH KMnO4 The compound B is an amine that produces N2 gas on diazotization. Oxidation of B with KMnO4 gives 1,4-benzenedicarboxylic acid NH NaNO2, HCI NH COOH KMnO4 CH OOH

The compound C is an amine that doesn't produce N2 gas on diazotization. Oxidation of C with H202 gives p-nitrobenzoic acid. CH3 COOH H202 NH2 NO2 Therefore, the three compounds are as follows: NH2 NH2 CH3 CH3 NH2 compound B compound C compound A