Insight into etherification of 1,3-dimethylol-2-imidazolidinone with the primary alcohols and the hydroxyl groups of cellulose chain (n = 1–4) in acidic condition

Abstract

Etherification of 1,3-dimethylol-2-imidazolidinone (DMEU) with the primary alcohols and the hydroxyl groups of cellulose chain (n = 1–4) in acidic condition were probed in both gas phase and water solvent by using the Onsager model and polarized continuum model (PCM). Geometry and energy of reactants, products, intermediate complexes, carbocation intermediate, and transition state (TS) structures were calculated by using the methods of MP2, B3LYP, PM3MM at the basis sets of 6-311+g (d), 6-311g (d,p). The computational results indicate that the etherification adheres to unimolecular nucleophilic substitution (SN1) mechanism; reactants and products can form the activated complexes with H+ ions in which H+ ions are occupied by the O-atom of CO group in the reactant complex and the product complex. Potential energy surface (PES) of the reaction has the triple-well shape. Effect of substituent R in primary alcohol R-CH2OH (R = H, CH3, CH2CH3, CH2OCH3, CH2F) on the reactivity is significant. The energy barrier of H+ ions releasing step is much higher than those of the activation steps. The calculational data is in the good agreement with the experimental data in the literature.