Deamination and hydrolysis of tertiary systems

Abstract

This thesis reports the aqueous nitrous acid deamination of two tertiary carbinamines; 2-amino-2-methylpropane and 3-amino-3-methylpentane (at 80°C, pH4). The hydrolysis (at 80°C, pH4) of the two corresponding alkyldimethyl sulphonium salts; dimethyl-(2-methyl-2-propyl) sulphonium perchlorate and dimethyl-(3-methyl-3-pentyl) sulphonium perchlorate, is also reported. A comparison of the two types of reaction (deamination and hydrolysis) shows small but definite differences. Both deaminations produced a greater proportion of elimination than the corresponding hydrolyses. The deamination of 3-amino-3-methylpentane produced lower 2-ene/1-ene and trans/cis ratios than the corresponding hydrolysis. It is suggested that the deamination carbocations are short-lived and shielding by the departing nitrogen prevents complete loss of the “excess” energy acquired from the irreversible decomposition of the diazonium ions. The “excess” energy of the deamination product precursors relative to the hydrolysis analogs makes the higher energy product-forming pathways more favourable in deamination than hydrolysis.