REACTION-KINETICS OF COS WITH PRIMARY AND SECONDARY-AMINES IN ALCOHOLIC SOLUTIONS

The reaction kinetics of carbonyl sulphide (COS) with primary (monoeth anolamine, diglycolamine and 2-amino-2-methyl- 1 -propanol) and second ary (diethanolamine, 2-(methylamino)ethanol, di-isopropanolamine and m orpholine) amines in alcoholic solutions were studied using a conducti metric stopped flow technique at 278-298 K. Solvents investigated incl uded methanol, isopropanol, ethylene glycol and propylene glycol. Expe rimental data obtained at various amine concentrations (0.1-1.5 kmol M -3) gave apparent orders in amine between 1 and 2, which confirms that thiocarbamate formation is not a single-step process but involves a z witterion intermediate. Quantitative rate data show that the reaction rates of COS in alcoholic solutions (particularly in glycols) are high er than those in water. This indicates that the COS selectivity of ind ustrial processes employing alcoholic solvents such as AMISOL is due n ot only to the increased physical solubilities but also to the increas ed reaction rates.