Kinetics of the Reaction of Carbon Dioxide with Blends of Amines in Aqueous Media Using the Stopped-Flow Technique

摘要

The effect of mixing 2-amino-2-methyl-1 -propanol (AMP) with a primary amine,mo-noethanolamine (MEA),and a secondary amine,diethanolamine (DEA),on the kinetics of the reaction with carbon dioxide in aqueous media has been studied at 298,303,308,and 313 K over a range of blend composition and concentration.The direct stopped-flow conductimet-ric method has been used to measure the kinetics of these reactions.The proposed model representing the reaction of CO_2 with either of the blends studied is found to be satisfactory in determining the kinetics of the involved reactions.This model is based on the zwitterion mechanism for all the amines involved (AMP,MEA,and DEA).Blending AMP with either of the amines results in observed pseudo-first-order reaction rate constant values (K_o) that are greater than the sum of the k_o values of the respective pure amines.This is due to the role played by one amine in the deprotonation of the zwitterion of the other amine.Steric factor and basicity of the formed zwitterion and the deprotonating species have a great bearing in determining the rate of the reactions studied.