松香中海松酸型树脂酸热作用变化规律的研究

Study on Thermal Variation Rule of Pimaric-type Acids in Rosin

详细研究了脂松香中海松酸型树脂酸在惰性气体保护下,于180～270℃之间进行高温热处理1～4h的变化规律。结果表明,脂松香中原有的3种海松酸型树脂酸即海松酸、异海松酸、山达海松酸的含量总体呈下降趋势,初始含量越高、热处理温度越高、时间越长,其含量下降幅度越大。高温热处理过程中产生了松香原料中所没有的3种海松酸型树脂酸即8,15-异海松酸、8,15-海松酸和7,15-海松酸,其含量随热作用温度的提高和时间的延长呈上升趋势。270℃以下热处理1～3h时,海松酸型树脂酸主要发生以环内双键位置变化为主的异构反应,而分解反应很少,环外乙烯基则没有参与反应。对海松酸型树脂酸各成分立体结构分析结果表明,8,15-异海松酸应来源于异海松酸和山达海松酸的异构化,而8,15-海松酸和7,15-海松酸应来源于海松酸的异构反应。

The rule of thermal variation of pimaric-type acids in rosin was studied in detail through heat treatment at 180- 270℃ for 1-4 h in inert gas. As results, the contents of three original pimaric-type resin acids, namely pimaric, isopimaric and sandaracopimaric acids, generally decreased, the higher the initial content with the higher the temperature and longer time, the faster the content declined. Three new pimaric-type resin acids, namely 8,15-isopimaric, 8,15-pimaric and 7,15-pimaric acids that were not present in the raw materials, were created and detected by GC-MS, and their contents increased with increase of treating temperature or time. Below 270℃ for 1-3 h, the key reaction of pimaric-type acids is isomerization from change of double bond position in the ring, accompanied with only a small amount of degradation, and without any reaction of the vinyl group. According to steric structure analyses of pimaric-type acids, it is considered that the new compound 8,15-isopimaric acid should be originated from isomerization of isopimaric and sandaracopimaric acids; while new compounds 8,15-pimaric and 7, 15-pimaric acids should he originated from isomerization of pimaric acid.