Abstract:

In order to reduce the influence of middle distillate on the rectification of high-purity longifolene in real production, the mass fraction of middle distillate in the process of isolating longifolene from heavy turpentine was monitored, and the relative density and refractive index of the product were measured. The experimental results showed that longipinene and (+)-longicyclene existed in the whole process of longifolene rectification, and the effect of longipinene was significantly higher than that of (+)-longicyclene. Under the operating pressure of -0.1 MPa, the tower kettle temperature of 150 ℃, and the reflux ratio of 1∶7, the distillation of heavy turpentine was carried out. In this process, the influence of the middle distillate on the longifolene rectification could be minimized by adjusting the reflux ratio or lowering the temperature of the column kettle. When the d₂₀ of the top distillate was between 0.926 0 and 0.926 3 and the reflux ratio was adjusted to 10∶1(or the temperature of the tower reduced to 140-150 ℃ when the mass fraction of longifolene in the overhead distillate exceeded 30%), or the temperature of the tower increased to 150 ℃ when the d₂₀ of overhead distillate was greater than 0.933 5, more than 90% longifolene could be obtained, and the total mass fractions of longipinene and(+)-longicyclene was less than 1.5%.

Key words: heavy turpentine, longifolene, longipinene, (+)-longicyclene