| Abstrakt: |
The reaction of 1,8-cineole with 60% acetic acid at 70°C for 10 hours under stirring gave dl-a-terpineol (0.12%) and transterpin (0.03%). By the action of 21% sulfuric acid at 70°C for 3 hours, cineole yielded dl-a-terpineol (4.6%), terpin hydrate (0.20%), trans-terpin (0.12%) and monocyclic hydrocarbons (a small amount). On the other hand, the reaxtion of cineole with 0.6% sulfuric acid solution at 70°C for 10 hours gave dl-a-terpineol and trans-terpin in poor yields. In this case the reaction products are the same as in the case of 60% acetic acid.Next, terpin hydrate was treated with 64% acetic acid at 70°C for 10 hours. The reaction products were dl-a-terpineol (2.7%) and trans-terpin (trace). By the action of 21% sulfuric acid at 70°C, terpin hydrate was attacked easily, and after 15 minutes it was converted to dl-a-terpineol (17.8%), trans-terpin (0.20%), 1,8-cineole and monocyclic hydrocarbons (11%). The monocyclic hydrocarbons consisted of a-terpinene, dipentene, ?2,4(8)-p-menthadiene and p-cymene. trans-Terpin was, also, treated with 60% acetic acid at 70°C for 10 hours, the reaction product being dl-a-tepineol (1.8%).On the basis of the above experiments a reaction mechanism for the action of acid solutions on 1,8-cineole was proposed. |
