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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >FTIR Spectroscopy and DFT Calculations to Probe the Kinetics of beta-Carotene Thermal Degradation
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FTIR Spectroscopy and DFT Calculations to Probe the Kinetics of beta-Carotene Thermal Degradation

机译：FTIR光谱和DFT计算探测β-胡萝卜素热降解的动力学

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摘要

The thermal degradation of beta-carotene in air was investigated. The sample was heated at different temperatures (90, 100, 115, and 130 degrees C) for periods of up to 8 h to perform a complete kinetic study, the product analysis having been carried out via infrared spectroscopy in attenuated total reflectance mode coupled to density functional theory (DFT) calculations. The kinetics of this thermal degradation process was found to follow a first-order scheme, with rate coefficients varying from k(90) (degrees C) = (2.0 0.3) X 10(-3) to k(130) (degrees C) = (11.0 +/- 0.7) X 10(-3) min(-1), the experimental activation energy having been calculated as (52 +/- 1) kJ mol(-1). This E-a value is close to the DFT energies corresponding to a C15-15' or a C13-14 cis-trans isomerization, followed by the formation of a carotene-oxygen diradical, which was characterized for the first time. Comparison between the experimental and calculated infrared data confirmed the C15-15'-cis rupture as the predominant reaction pathway and retinal as the major degradation product.
机译：研究了空气中β-胡萝卜素的热降解。在不同温度（90,100,115和130℃）的时期在多达8小时的不同温度（90,100,115和130℃）中加热样品，以进行完整的动力学研究，该研究通过红外光谱进行了通过红外光谱来进行的，其耦合到密度泛函理论（DFT）计算。发现该热降解过程的动力学遵循一阶方案，速率系数从k（90）（℃）=（2.0 0.3）×10（-3）到K（130）（℃） =（11.0 +/- 0.7）×10（-3）min（-1），实验激活能量已经计算为（52 +/- 1）kJ mol（-1）。该E-A值接近对应于C15-15'或C13-14顺式反式异构化的DFT能量，然后形成第一次表征的胡萝卜素 - 氧。实验和计算的红外数据之间的比较证实了C15-15'-CIS破裂作为主要的反应途径和视网膜作为主要的降解产物。

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