<br>密度泛函理论与实验研究碱热预处理木质纤维素水解半纤维素的机理,The Journal of Organic Chemistry

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密度泛函理论与实验研究碱热预处理木质纤维素水解半纤维素的机理
The Journal of Organic Chemistry ( IF 3.3 ) Pub Date : 2024-01-08 , DOI: 10.1021/acs.joc.3c01668
Bobing Tian ₁ , Jiahua Mao ₁ , Mingfu Zu ₁ , Ruilin Wu ₁ , Chao Xiao ₁

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木质纤维素碱热预处理过程中，半纤维素的共价键断裂导致半纤维素水解，此前尚未有报道。采用密度泛函理论研究了半纤维素模型化合物在碱性条件下的水解机理。木糖形成有四种反应路径，其中能垒最低的反应路径是亲核试剂捕获H30生成水的反应路径。去质子化的羟基攻击糖苷键上的碳，导致糖苷键断裂并形成新的碳氧共价键，其能垒为154.2 kJ/mol。亲核试剂进一步攻击糖苷键，形成能量垒为 111.9 kJ/mol 的新木糖残基。当糖苷键断裂时，最大比例的轨道相互作用导致约0.511个电子从糖苷键氧转移到去质子化的羟基氧。原位傅里叶变换红外光谱用于碱热预处理过程中官能团的识别。随着温度升高，反应的可行性增加。该研究为木质纤维素碱热预处理技术的发展奠定了理论基础。

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Study of the Mechanism of Hydrolysis of Hemicellulose from Lignocellulose during Alkali Thermal Pretreatment by Density Functional Theory and Experiment

The covalent bond fracture of hemicellulose leads to hemicellulose hydrolysis during lignocellulosic alkali thermal pretreatment, which has not previously been reported. Density functional theory was used to study the mechanism of hydrolysis of the hemicellulose model compounds under alkali conditions. There are four reaction paths for xylose formation, among which the reaction path with the lowest energy barrier is that in which the nucleophile captures H30 to generate water. The deprotonated hydroxyl group attacks the carbon on the glycoside bond, resulting in the cleavage of the glycoside bond and the formation of a new carbon–oxygen covalent bond, with an energy barrier of 154.2 kJ/mol. The nucleophile further attacks the glycosidic bond to form a new xylose residue with an energy barrier of 111.9 kJ/mol. When the glycosidic bond breaks, the orbital interaction with the largest proportion causes the transfer of ∼0.511 electron from the glycosidic bond oxygen to the deprotonated hydroxy oxygen. In situ Fourier transform infrared spectroscopy is used for the identification of functional groups during the alkali thermal pretreatment. As the temperature increases, the feasibility of the reaction increases. This study lays a theoretical foundation for the development of the alkali thermal pretreatment of lignocellulose.

更新日期：2024-01-08

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