Fuels, Volume 89, Issue 3, 2009, Pages 685-690
| Solvent assisted decomposition of the tetrahedral intermediate of the transesterification reaction to biodiesel production. A density functional study | |
| Emmanuela F. de Lima, José Walkimar de M. Carneiro, C. Fenollar-Ferrer, Stanislav Miertus, Sergey Zinoviev, Neyda C. Om Tapanes, Donato A.G. Aranda | |
| 29 August 2009 | |
| Hardcopy |
Abstract
B3LYP/6-31+G(d) and B3LYP/6-31G(d) calculations were employed to investigate the mechanism of the transesterification reaction between a model monoglyceride and the methoxide and ethoxide anions. The gas-phase results reveal that both reactions have essentially the same activation energy (5.9 kcal.mol) for decomposition of the key tetrahedral intermediate. Solvent effects were included by means of both microsolvation and the polarizable continuum solvation model CPCM. Both solvent approaches reduce the activation energy, however, only the microsolvation model is able to introduce some differentiation between methanol and ethanol, yielding a lower activation energy for decomposition of the tetrahedral intermediate in the reaction with methanol (3.7 kcal.mol-1) than for the corresponding reaction with ethanol (4.7 kcal.mol-1), in line with experimental evidences. Analysis of the individual energy components within the CPCM approach reveals that electrostatic interactions is the main contribution to stabilization of the transition state. http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6V3B-4X3V4JY-1&_user=10&_coverDate=08%2F29%2F2009&_alid=1064318718&_rdoc=1&_fmt=high&_orig=search&_cdi=5726&_sort=r&_docanchor=&view=c&_ct=2&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=071cbecdcb46c2125a5a8476d14e0c63