Kinetics of the reaction of carbon dioxide (CO2) with cyclic amines using the stopped-flow technique

Abstract

Experimentally found kinetic values (pseudo-first order rate constants) for the reaction of CO2 in different types of aqueous amines using stopped-flow technique were compared at 303.15 K. (Primary amines–1-amino-propanol(1-AP), 3-amino-propanol(3-AP),Ethylaminoethanol(EAE); Secondary amines–Ethylene diamine(EDA), 1, 3-diamino propane(DAP), 2-(amino ethyl)ethanol amine (AEEA); Cyclic amine–Piperazine; Poly amine–N-(2-aminoethyl)-1, 3-propane diamine). It was observed that polyamines and cyclic amines are having higher reaction rate than primary, and secondary amines. Therefore, the kinetics of the reaction of carbon dioxide with six cyclic amines)) in aqueous solutions has been studied at (298.15 to 313.15) K over a concentration range of (20to120) mol⋅m−3 using the stopped-flow technique.(Piperazine (PZ),1-methyl piperazine (1-MPZ),2-methyl piperazine (2-MPZ),1-ethyl piperazine (1-EPZ),N-(2-hydroxyethyl) piperazine (1-HEPZ) and 3-morpholino propyl amine (3-MOPA). PZ has the highest reaction rate and 1-MPZ has the lowest. The trend of reaction rates are given as (PZ>2-MPZ>1-EPZ>3-MOPA>HEPZ>1-MPZ). All the studied cyclic amines were found to have fractional reaction order with respect to amine varying from 0.9 to 2.43.Termolecular mechanism and Zwitterion-mechanism were used for calculating the rate parameters by fitting the experimental data.