Classical carbonium ions. Part 12. The deamination of 1- and 4-amino-n-octane

Abstract

The deamination products of 1- and 4-amino-octane in acetic acid were examined. The amines were treated with sodium nitrite directly, and also converted into alkylaryltriazenes derived from several arenediazonium cations, which were then acetolysed. N-Nitrosobutyramides were acetolysed, and N-nitrosoacetamides were butyrolysed, to allow the separate analysis of rearranged and unrearranged products from internal and external nucleophiles. It is concluded that the primary alkylamine is converted by all these different methods in high yield into a primary alkane diazonium ion RN2+, the properties of which are independent of its method of preparation in that the alkyl cation formed by its decomposition does not capture the leaving group which accompanies its formation, but reacts with solvent to give a constant set of products. The secondary alkylamine behaves differently. Its diazo-derivatives, RN2X, usually undergo effectively concerted decomposition to carbonium ions, nitrogen, and leaving group X. The cations show differing degrees of hydride shift, and capture the internal nucleophile X to a considerable but variable extent, after as well as before rearrangement. The acetolysis of 4-diazo-octane proceeds via a much less reactive intermediate, possibly an intimate ion-pair, giving mainly unrearranged 4-acetoxyoctane, plus an olefin mixture in which the substantial proportion of cis-isomers reflects the conformational preference of the starting material.