Kinetics and mechanisms of the reactions of carbon dioxide with alkanolamines: a discussion concerning the cases of MDEA and DEA

A recent paper by Blauwhoff et al. (1984) has incited us to reexamine some of our previous results concerning the kinetics of reaction of CO₂ with methyldiethanolamine (MDEA). The results can be very satisfactorily interpreted if an amine-catalyzed reaction with a rate constant 3.2 ( ± 1.0) M ^?1 s ^?1 is introduced in the theoretical simulations. This value agrees fairly well with the value obtained by the authors mentioned above (4.8 M ^?1 s ^?1. The influence of the pK_A value of the amine on the theoretical simulation is also examined. The mechanism proposed by Blauwhoff et al. for the diethanolamine (DEA) reaction with CO₂ is discussed and the values of their kinetic constants are compared with our value.