Reaction kinetics of carbonyl sulfide with aqueous ethylenediamine and diethylenetriamine

The reaction in aqueous solution between carbonyl sulfide (COS) and the polyamines ethylenediamine and diethylenetriamine has been studied experimentally using a conductimetric stopped-flow technique. The experimental results indicate that this reaction follows a zwitterion intermediate mechanism leading to: $\text{k}{}_{\mathrm{obs}}\text{=}\text{[Am]}\text{1}\text{k}{}_2\text{+}\text{1}\text{k}{}_{\mathrm{Am}}\text{[Am] +}\text{k}{}_{\mathrm{w}}\text{[H}{}_2\text{O]}$ Values of the rate constants k₂, k_Am and k_w at 298 K are reported for both ethylenediamine and diethylenetriamine. Activation energies for k₂, k_Am and k_w are also reported for diethylenetriamine.