Problem 2
Draw the structures of the following amines: (a) 2 -hexylamine; (b) 3,3 -dimethyl-1-heptylamine; (c) triethylamine; (d) dimethylamine; (e) 1,4 -butanediamine; (f) isopropylamine; (g) \(N, N\) -dimethylbutylamine; (h) 1 -octylamine; (i) benzylamine. Classify each compound as a primary, secondary or tertiary amine.
Problem 3
Give structural representations of the following salts: (a) tetraethylammonium chloride; (b) tetrabutylammonium bromide; (c) diethylammonium sulfate; (d) \(N, N\) -dimethylbenzylammonium bromide.
Problem 4
Explain why racemates of salts of chiral quaternary ammonium ions can usually be resolved whereas this is not generally true for chiral amines in which the chiral centre is the \(\mathrm{N}\) atom.
Problem 5
(a) Suggest how the reaction of \(\mathrm{NH}_{3}\) with 1-bromopropane might proceed. (b) Suggest a method of preparing 1-hexylamine in high yield from 1-bromohexane.
Problem 8
Give the products expected from the reductive amination using \(\mathrm{NH}_{3}\) of (a) butanone; (b) propanal; (c) pentane- 2,4 -dione; (d) cyclohexanone.
Problem 9
How would you expect the boiling points of the following series of compounds to vary? Rationalize your answers. (a) Pentane; 1-pentylamine; 2-pentylamine. (b) \(1-\) Butylamine; 2 -methyl- 1 -propylamine 2-methyl-2-propylamine. (c) Ethane; butane; 1-propylamine; 1, 2-ethanediamine.
Problem 10
Write down the equilibria to which the following \(\mathrm{p} K_{\mathrm{a}}\) and \(\mathrm{p} K_{\mathrm{b}}\) values refer: \((\mathrm{a}) \mathrm{p} K_{\mathrm{b}}\) for methylamine (b) \(\mathrm{p} K_{\mathrm{a}}\) values for the conjugate acids of \(1,3-\) propanediamine; (c) \(\mathrm{p} K_{\mathrm{a}}\) for triethylammonium ion; (d) \(\mathrm{p} K_{\mathrm{b}}\) for benzylamine; (e) \(\mathrm{p} K_{\mathrm{a}}\) for the conjugate acid of 1-butylamine.
Problem 14
What problems would be encountered if you used the reaction of 1 -bromohexane with \(\mathrm{NH}_{3}\) as a route to 1-hexylamine?
Problem 19
The mass spectrum of a compound \(\mathbf{X}\) has a parent peak at \(m / z=69 .\) The \(^{13} \mathrm{C}\) NMR spectrum of X has signals at \(\delta 119.9,19.3,19.0\) and \(13.3 \mathrm{ppm}\) Treatment of \(\mathbf{X}\) with \(\mathrm{LiAlH}_{4}\) gives compound \(\mathbf{Y}\), the mass spectrum of which contains major peaks at \(m / z=73\) and \(31 .\) The \(^{13} \mathrm{C}\) NMR spectrum of \(\mathbf{Y}\) shows signals at \(\delta 42.0,36.1,20.1\) and \(13.9 \mathrm{ppm}\) Elemental analytical data for \(\mathbf{X}\) and \(\mathbf{Y}\) are: \(\mathbf{X}, 69.6 \%\) \(\mathrm{C}, 20.3 \% \mathrm{N}, 10.1 \% \mathrm{H} ; \mathrm{Y}, 65.7 \% \mathrm{C}, 19.2 \% \mathrm{N}, 15.1 \%\) H. Compound \(\mathbf{Z}\) is an isomer of \(\mathbf{X} ;\) its \(^{1}\) H NMR spectrum contains signals at \(\delta 1.3\) (doublet, \(6 \mathrm{H}\) ), 2.7 (septet, 1 H) ppm. Suggest identities for \(\mathbf{X}, \mathbf{Y}\) and \(\mathbf{Z}\) How would Y react with (a) \(\mathrm{H}_{2} \mathrm{SO}_{4},\) (b) an excess of MeI and (c) butanoyl chloride, \(\mathrm{C}_{3} \mathrm{H}_{7} \mathrm{COCl} ?\)
