IBM Research-Zurich, Rüschlikon, Switzerland.
J Phys Chem A. 2011 Apr 21;115(15):3592-5. doi: 10.1021/jp201078e. Epub 2011 Mar 31.
The dehydration mechanism of neutral glycerol in the gas phase was investigated by means of metadynamics simulations. Structures, vibrational frequencies, Gibbs free energy barriers, and rate constants at 800 K were computed for the different steps involved in the pyrolytic process. In this article, we provide a novel mechanism for the dehydration of neutral glycerol, proceeding via formation of glycidol with a barrier of 66.8 kcal/mol. The formation of glycidol is the rate limiting step of the overall decomposition process. Once formed, glycidol converts into 3-hydroxypropanal with a barrier of 49.5 kcal/mol. 3-Hydroxypropanal can decompose further into acrolein or into formaldehyde and vinyl-alcohol with barriers of 53.9 and 35.3 kcal/mol, respectively. These findings offer new insights to available experimental data based on glycerol pyrolysis studies performed with isotopic labeling and on the interpretation of the chemistry of glycerol and sugars in pyrolytic conditions.
通过分子动力学模拟研究了中性甘油在气相中的脱水机制。计算了不同热解步骤涉及的结构、振动频率、吉布斯自由能势垒和 800 K 时的速率常数。在本文中，我们提供了一种新的中性甘油脱水机制，通过形成环氧丙烷进行，其势垒为 66.8 kcal/mol。环氧丙烷的形成是整个分解过程的限速步骤。一旦形成，环氧丙烷转化为 3-羟基丙醛，其势垒为 49.5 kcal/mol。3-羟基丙醛可以进一步分解为丙烯醛或甲醛和乙烯醇，其势垒分别为 53.9 和 35.3 kcal/mol。这些发现为基于甘油热解研究的可用实验数据提供了新的见解，这些研究使用同位素标记进行，并对甘油和糖在热解条件下的化学性质进行了解释。
