松香中海松酸型树脂酸在酸作用下的组成变化规律

Study on Composition Variation Relationships of Pimaric-type Resin Acids in Rosin at Acidic Conditions

详细研究了在溶液状态下酸催化作用引起松香中海松酸型树脂酸组成变化的特征及规律,以甲苯、醋酸等作为溶剂,醋酸、盐酸、硫酸等作为催化剂,反应温度为保持良好回流,反应时间1～8h。研究结果表明,松香中的海松酸型树脂酸在醋酸作用下比较稳定,其组成没有发生明显的变化。在盐酸、硫酸作用下,松香中原有的海松酸、异海松酸、山达海松酸明显减少,初始质量分数越高、酸作用时间越长,减少越明显,与此同时产生了原料中没有的8,15-异海松酸、8,15-海松酸和7,15-海松酸,且随酸作用时间延长而增多。在质量分数为51.4%的硫酸催化作用下于甲苯中回流8h后,湿地松松香中的海松酸型树脂酸质量分数变化为:异海松酸由13.77%降至10.53%,山达海松酸由1.78%升至1.98%,8,15-异海松酸则从0升至5.05%;马尾松松香中的海松酸型树脂酸质量分数变化为:海松酸由7.45%降至3.02%,7,15-海松酸由0升至0.67%,8,15-海松酸则从0升至3.99%。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,很少发生分解反应,而环外乙烯基则没有参与反应,松香中各海松酸型树脂酸总质量分数基本不变。对海松酸型树脂酸各成分的立体结构分析及异构体之间的相关性分析结果表明,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化反应。

The composition variation relationships of pimaric-type resin acids in rosin dissolved in a solvent such as toluene, acidic acid, were studied in detail through an acidic treatment with AcOH, HCl,or H2SO4 at a refluxing temperature for 1 -8 h. As a result,pimaric-type resin acids are rather stable in AcOH without significant change, but the contents of three original pimaric-type resin acids, such as pimaric, isopimaric and sandaracopimaric acids, decreased remarkably while treated with HC1 or H2S04, and the higher initial content, the longer treating time, the faster rate of decrease in its content. There are three new pimaric-type resin acids, 8,15-isopimaric, 8,15-pimarie and 7,15-pimaric aeids,which have not been found in raw materials, and their contents increased accompanying with longer acidic treatment. After refluxing for 8 h with a solution of 51.4% H2SO4 in toluene ,the content variations of pimaric-type resin acids are as follows： isopimaric acid decreased from 13.77% to 10. 53%, sandaracopimaric acid increased from 1.78% to 1.98%, and 8,15-isopimaric acid increased from zero to 5.05% ,in Pinus elliottii rosin, respectively; as well as pimaric acid reduced from 7.45 % to 3.02% ,7,15-pimaric acid increased from zero to 0. 67% ,8,15-pimaric acid increased from zero to 3.99% in Pinus massoniana rosin, respectively. The main reaction is the isomerization among six pimaric-type acids with double bonds rearrangement, but without degradation or any Vinyl rearrangement, so the total amount of the pimaric-type resin acids is constant basically. According to analyzing steric structure of pimaric-type acids and correlation coefficients among their contents, it is considered that 8, 15-isopimaric acid should be originated from isomerization of isopimaric and sandaracopimaric acids, and that 8, 15-pimaric and 7, 15-pimaric acid should be originated from isomerization of pimaric acid.