Detailed chemomechanistic sensitivity study on the alkoxylation of fatty amines

The mechanism of the autocatalytic alkoxylation of fatty amines was elucidated using a combined experimental and theoretical approach. The kinetic parameters of the elementary reaction steps are fitted to the experimental data gained in semibatch for propylene and butylene oxides with dodecylamine. A quality-of-fit sensitivity study was conducted to assess the robustness and accuracy of the model. Herein, we identified the kinetic parameters that are either crucial for a good fit or rate controlling in terms of the overall kinetics. It was found that the critical steps are the activation of the epoxide ring by a hydroxyl group present on either the intermediate or final product, highlighting the autocatalytic nature of the reaction. Furthermore, we introduced a so-called degree of conversion control to characterize the importance of each elementary reaction step toward the epoxide conversion. The degree of conversion control showed that the uncatalyzed route toward the secondary amine is only influential at low conversion. At higher conversion the route via the catalytic intermediate dominates. Alternative mechanisms were investigated as well but did not significantly improve the quality of fitting and were thus discarded.