R.V.Lawrence研究了老化、加热和催化等对松香的枞酸型树脂酸所产生的异构化作用。枞酸的三种同分异构体系被枞酸包围而处于一种酸诱发平衡状态。用这四种酸的任何一种或几种的混合物作原料,在微酸性介质中加热至125-250℃,即可产生一种平衡混合物,其组成为:枞酸95％,新枞酸2％,长叶松酸3％。可以看出,左旋海松酸没有可以检出的 R.V. Lawrence studied the aging, heating and catalysis on the abscisic acid-type resin acid rosin produced by the isomerization. The three isomers of abietic acid are surrounded by abietic acid and are in an acid-induced equilibrium. Using a mixture of any one or more of these four acids as a starting material and heating to a temperature in the range of 125 to 250 ° C in a slightly acidic medium produces an equilibrium mixture consisting of 95% abietic acid, neoabietic acid 2 %, Palustric acid 3%. It can be seen that levopimaric acid is not detectable