白术挥发油中苍术酮氧化反应的动力学  

Kinetics and Mechanism Studies on Oxidizing Reaction of Atractylon in Essential Oil from Aatractylodes Mmacrocephala Koidz

作　　者：王小芳[1] 王芳 张亚环[1] 郑晓晖[3] 

机构地区：[1]西北大学化学系,西安710069 [2]西北大学分析科学研究所,西安710069 [3]陕西省教育学院生化系

出　　处：《应用化学》2007年第3期301-305,共5页Chinese Journal of Applied Chemistry

基　　金：陕西省自然科学基金(2004C240)资助项目

摘　　要：利用GC/MS法跟踪分析了苍术酮纯品的分解过程,得到5种分解产物——与文献报道的苍术酮转变成2种产物存在较大的差异;研究了苍术酮的氧化反应机理:苍术酮与水易进行1,4加成反应,生成半羧醛羟基。水的存在使半羧醛羟基开环并导致C—O键断裂,生成羰基,羰基进一步被氧化成羧基。由于羧基上的碳原子为sp2杂化,羟基可从杂化轨道平面两侧进攻羧基,并与羧基进行分子内脱水反应,故而可生成白术内酯Ⅰ及表白术内酯Ⅰ,而白术内酯Ⅰ的7位C上的—H很活泼,易被—OH取代而生成白术内酯Ⅲ,白术内酯Ⅲ不稳定,易使分子内脱水生成白术内酯Ⅱ。此外,白术内酯Ⅲ与白术内酯Ⅰ可进行分子间脱水反应,生成双白术内酯。通过定量分析纯品和白术原药材中苍术酮在氧化过程中的相对含量,计算反应的动力学参数,得出苍术酮纯品的反应速率方程为Rate1=k′1[x]1.84,活化能为58.05kJ/mol;原药材中苍术酮的反应速率方程为Rate2=k′2[x]1.89,活化能为63.17kJ/mol。By using GC/MS, the process of oxidizing reaction of atractylone is studied, and live decomposition products are obtained, which is greatly different from the references-only two decomposition products, and the mechanism of oxidizing reaction of atractylone is investigated. The hypothesized mechanism of reaction is ： atractylone is readily to additively react with water and to generate the semiacetalhydroxyl at 1, 4-site. The loop of it is opened and lead to the cleavage of C-O bond because of the existence of water, the carbonyl is thus formed. The carbonyl is then oxidized to generate carboxylic group. As the carbon atom is sp^2 hybridization, carboxyl can be attacked by hydroxyl from both sides of hybrid orbital, in this reaction, water is removed, and the remaining atoms are joined to form atractylenolide Ⅰ and iso-atractylenolide Ⅰ While the proton of 7-carbon of atractylenolide Ⅰ is rather active and liable to be replaced by hydroxyl to form atractylenolidem and atractylenolidem is unstable and dehydrated within molecule to form atractylenolide Ⅱ. Moreover, atractylenolidem and atractylenolide Ⅰ are dehydrated between two molecules to generate biatractylolide. By quantitatively analyzing the percentage of pure atractylone and atractylone in herb, the kinetic parameter is obtained, and the equations are： Rat1 = k＇1 [x]^1.84, Rate2 = k＇2 [x]^1.89, the activation energy of each is 58.05 kJ/mol and 63. 17 kJ/mol respectively.

关 键 词：白术挥发油 苍术酮 动力学方程 活化能 反应机理 

分 类 号：O643.1[理学—物理化学] R284.2[理学—化学]