On the Formation of Borneol from Turpentine Oil. II.

Abstract

It was shown in the first report (this journal No. 498, 637-44 [1923]) that the formation of borned from turpentine oil by heating with organic acids depends upon the kind of acid used. And with trichloracetic acid and exsiccated oxalic acid good results were obtained. In continuation of the work various experiments were carried out with following catalyzers : AlCl₃, SnCl₄, ZnCl₂, FeCl₃, Japanese fuller's earth and wood charcoal. (compare D.R.P. 208487). As the material for investigation an American turpentine oil d₁₅ 0.8733, [α] -5.56°(94.1mm), was distilled over sodium and the fracton b. 158-61°was used. It had d₁₅0.8644 and [α]-6.00°(94.1mm). (1) With exsiccatec oxalic acid and AlCl₃. 400 g Oil diluted with 800 g CCl₄ were treated with 200 g acids and 20 g AlCl₂. After washed with dilute Na₂CO₃ solution the product was distilled with steam and the residue, a heavy oil, was saponified with alkali and again distilled with steam. The solidified distillate (crude borneol), when purified with petroleum ether, melts at 204°and is optically inactive. The average yield from 5 preparations being 22.3%. (2) With exsiccated oxalic acid and SnCl₄. By treating a mixture of 200 g oil and 400 g CCl₄. with 40 g acid and 5 g SnCl₄ gave 64 g (32%) crude borneol ; the average yield being 23%. (3) With exsiccated oxalic acid and ZnCl₂. By treating a mixture of 300 g of oil and 600 g CCl₄ with 80 g acid and 20 g ZnCl₂ gave 31 g (10.3%) crude borneol ; average yield being 11.5%. (4) With exsiccated oxalic acid and FeCl₃. By treating a mixture of 400 g oil and 800 g CCl₄, with 80 g acid and 20 g FeCl₃. (anhydrous) gave 118 g crude borneol; the av rage yield being 25%. (5) With exsiocated oxalic acid and japanese fuller's earth. By treating a mixture of 400 g oil and 800 g CCl₄, with 100 g acid and 100 g of the earth gave 32 g crude borneol; the average yield being 11%. (6) With exsiccated oxalic acid and wood charcoal. By treating a mixture of 400 g oil and 800 g CCl₄, with 80 g acid and 120 g of the charcoal gave 32 g crude borneol; the average yield being 6.6% (Tokio Hygienie Laboratory of the Department of Home Affairs).