白皮杉醇PIC与OH自由基反应机理的理论研究

Theoretical Study on the Mechanism of Reaction Between Piceatannol and Hydroxyl Radical

采用M05-2X/6-311++G(d,p)水平对白皮杉醇PIC清除OH自由基的气相反应机理进行了研究,并采用极化连续介质模型考察了极性溶剂对该反应机理的影响.结果表明,在气相和水溶液中OH自由基的抽氢反应均最易发生在B环的C4'OH位的酚羟基上,加成反应优先在乙烯双键和C4'原子上进行.在298 K的气相条件下,抽氢与加成反应主通道总速率常数kCVT/SCTTotal分别为5.46×1015和2.72×1014L·mol-1·s-1,抽氢反应为优势通道,且抽氢与加成反应均具有负温度效应.

At M05-2X / 6-311 ＋ ＋ G（ d,p） level,the reaction mechanisms between piceatannol and OH free radical were studied in gas phase,the effect of solvent polarity on the reaction mechanisms were also considered using the polarizable continuum model. The results show that the active position is C4＇ OH（ OH is connected with C4＇） with B ring both in the gas and aqueous phase for hydrogen atom transfer mechanism. For radical adduct formation mechanism,OH radical preferred to adduct on Cα,Cβand C4＇. At the temperature of298 K,the total rate constants of hydrogen atom transfer and radical adduct formation are 5. 46 × 10^15 and 2. 72×10^14L·mol^-1·s^-1,the more favorable channel is hydrogen atom transfer. Furthermore,the results also manifest that there is a negative correlation between the rate constants and temperature.