Competition between thermal decomposition and hydrolysis of 2,2'-azobis(2-amidinopropane) in aqueous solution

The thermal decomposition and hydrolysis of 2,2′-azobis(2-amidinopropane) were examined as functions of pH. The rate of decomposition decreased with increasing pH. The specific rates at 60°C were 3.85 × 10^?5 1/sec at pH 0.90 and 2.5 × 10^?5 1 see at pH ≥ 8.5. The hydrolysis in alkaline solution yielded 2,2′-azobis(2-carbamylpropane) which was stable to thermal decomposition. The relation between the specific rate of hydrolysis k_h′ and the concentration of hydroxyl ion was obtained as k_h′ = 4.0 × 10^?2 OH]^0.50 1/sec at 60°C. In alkaline solution, the rate of hydrolysis was considerably larger than that of thermal decomposition. A mechanism for this hydrolysis is propesed.