(a) A student was given a mixture of two unknown compounds and asked to separate and identify them. One of the compounds was an amine and the other was a neutral compound (neither appreciably acidic nor basic). Describe how you would go about separating the unknown amine from the neutral compound using extraction techniques involving diethyl ether and solutions of aqueous 5% HCl and 5% NaHCO3. The mixture as a whole was soluble in diethyl ether, but neither component was soluble in water at pH 7. Using R groups on a generic amine, write out the reactions for any acid-base steps you propose and explain why the compound of interest will be in the ether layer or aqueous layer at any given time during the process.

(b) Once the amine was successfully isolated and purified, it was analyzed by IR, NMR, and MS. The following data were obtained. On the basis of this information, deduce the structure of the unknown amine. Assign the spectral data to specific aspects of the structure you propose for the amine.

IR (cm−1): 3360, 3280, 3020, 2962, 1604, 1450, 1368, 1021, 855, 763, 700, 538

1H NMR (δ): 1.35 (d, 3H), 1.8 (bs, 2H), 4.1 (q, 1H), 7.3 (m, 5H)

MS (m/z): 121, 120, 118, 106 (base peak), 79, 77, 51, 44, 42, 28, 18, 15