A Revisited Picture of the Mechanism of Glycerol Dehydration
A Revisited Picture of the Mechanism of Glycerol Dehydration
复制标题
DOI：
10.1021/jp201078e
复制
发表时间：
2011-04-21
影响因子：
2.9
通讯作者：
Stolz, Steffen
中科院分区：
文献类型：
--
作者：
Laino, Teodoro;Tuma, Christian;Stolz, Steffen
通过元动力学模拟研究了中性甘油在气相中的脱水机理。计算了热解过程中涉及的不同步骤的结构、振动频率、吉布斯自由能垒和 800 K 下的速率常数。在本文中，我们提供了一种中性甘油脱水的新机制，通过形成屏障为 66.8 kcal/mol 的缩水甘油来进行。缩水甘油的形成是整个分解过程的限速步骤。一旦形成，缩水甘油就会转化为 3-羟基丙醛，其屏障为 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，其屏障分别为53.9和35.3 kcal/mol。这些发现为基于同位素标记的甘油热解研究以及热解条件下甘油和糖的化学解释的现有实验数据提供了新的见解。
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.