At present, industrial production mainly adopts a two-step synthesis process with turpentine as raw material. Turpentine is a kind of cheap and high-quality natural linalool oil. Its main components are α-pinene and β-pinene, among which α-pinene accounts for the vast majority, and the content is between 75% and 95%. α-Pinene can provide C 10 or C 15 molecular skeleton, and at the same time provide multi-ring and bridged rings, outer and inner double bonds, etc. It has active chemical properties and is a rare natural chemical raw material. The two-step method does not mean that there are only two steps in the reaction process, but refers to the process of first reacting turpentine to generate terpineol, and then synthesizing terpineol acetate from terpineol and acetic anhydride after rectification and purification. The reaction of terpineol goes through several processes.
The method of synthesizing terpineol can also be divided into two categories according to the technological process, namely one-step method and two-step method, or direct method or indirect method. The step rule is to react with water under the action of a catalyst to obtain hydrated terpene glycol, and then dehydrate or saponify to obtain α-terpineol. The existing literature has carried out a comprehensive review of the process route for the preparation of terpineol from turpentine, and will not be repeated in this paper. The process of synthesizing terpineol acetate from terpineol can be divided into the following categories according to the catalysts used: the first category is liquid acid catalysis, mainly using inorganic acids such as sulfuric acid and phosphoric acid and some organic acids; the second category is solid acid Catalytic methods, including ion exchange resin method, inorganic super acid method, heteropoly acid method, zeolite molecular sieve catalytic method, etc.; the third type is anhydrous potassium carbonate method.
