Thermal Degradation Rate of 2-Amino-2-methyl-1-propanol to Cyclic 4,4-Dimethyl-1,3-oxazolidin-2-one; Mechanistic Aspects and Kinetics Investigation

Industrial & Engineering Chemistry Research

5 years ago

Thermal Degradation Rate of 2-Amino-2-methyl-1-propanol to Cyclic 4,4-Dimethyl-1,3-oxazolidin-2-one; Mechanistic Aspects and Kinetics Investigation

Kunlei Liu, Femke M. Onneweer, Naser S. Matin, Jesse Thompson

Using initial rate data, the mechanistic investigation for the thermal degradation kinetics of 2-amino-2-methyl-1-propanol (AMP) to 4,4-dimethyl-1,3-oxazolidin-2-one (DMOZD) as a function of amine and CO₂ concentration in the solution was performed. Activation energies of different reaction steps in introduced mechanisms imply that the reaction between AMP and CO₂ to produce carbamate will happen close to equilibrium conditions, while the carbamate will tends to revert back to initial amine rather than convert to the DMOZD at lower temperatures. Investigation of different forms of reaction pathways and various reaction orders for reactants including AMP and CO₂ demonstrates that the actual reaction mechanism is complex. The closest and simplest mechanism to fit the experimental data provides noninteger reaction order with respect to AMP and CO₂ concentration in the rate equation, which indicated more complexity of the reaction mechanism. Through the degradation rate data, the activation energy and reaction rate constant for the reaction of AMP and CO₂ to form a zwitterion were also calculated. The obtained reaction parameters through a zwitterion mechanism were consistent with reported literature values, which were calculated through different approaches. However, the zwitterion formation in the degradation mechanism displayed no improvement in the experimental rate prediction ability of the model equation compared to more simplified pathways. Employing the long-term experimental concentration vs time data, the overall reaction between amine and CO₂ to produce DMOZD was analyzed. The DMOZD and reactant concentrations at the steady state were calculated through an apparent reaction rate model. The results show that, depending on the AMP concentrations, CO₂ loading, and solution temperature, at steady state conditions the percentage ratio of DMOZD concentration over AMP is between 0.5 and 7.

Publisher URL: http://dx.doi.org/10.1021/acs.iecr.7b01492

DOI: 10.1021/acs.iecr.7b01492