Terpinyl Acetate CAS 80-26-2

The so-called one-step method refers to the use of turpentine and acetic acid (or acetic anhydride) as raw materials, followed by separation and purification to obtain terpineyl acetate. Compared with the two-step method, the one-step method has the advantages of simplifying the production process, saving costs, and having a wide source of raw materials. The main difficulty of this method is to find a highly selective catalyst. Xia Jianling studied the reaction of α-pinene and glacial acetic acid to synthesize terpineol acetate under different catalysts, their dosage and reaction temperature, and obtained the following results. They first screened several different catalysts and got the results shown in Table 1. It can be seen from Table 1 that the yield of α-terpinene ester in the products catalyzed by Mn 2 (OAc) 3 +KBr and Mn(OAc) 2 4H 2 O +ZnO and H 2 SO 4 +ZnCl 2 is relatively high. However, the yield of α-terpineol acetate catalyzed by H 3 PO 4 , H 2 O and BF 3 Et 2 O is extremely low, and the content in the product is only about 3%. Then, under the conditions of the same reaction temperature, reaction time, same amount of α-pinene and solvent, different amounts of Mn 2 (OAC) 3 +KBr catalysts were added to the experiment. The content of oily esters increased first and then decreased, and the maximum value was about 20.5%. Bornyl acetate, terpineol, terpinene and limonene also had the same trend, while the raw material α-pinene and the product camphene had the opposite trend. Fenchol and p-cymene did not change much. They found that the contents of α-terpinene, terpineol, terpinene, limonene, etc. all increased with the increase of temperature. They believe that α-pinene has an extremely unstable four-membered ring, which leads to the extreme instability of its chemical properties. Increasing the temperature is conducive to the ring-opening reaction, and α-pinene is easy to ring-open into a single-ring product and The ring expands into other bicyclic systems. When there is a nucleophile, it is possible to capture the intermediate and form an adduct. As a result, the competition between the isomeric rearrangement reaction and the nucleophilic addition reaction is formed, resulting in the diversity of reaction products. Chen Meiyun reported the use of a high-selectivity composite catalyst, the amount of catalyst used was about 0.5% of the mass of turpentine, the molar ratio of turpentine to glacial acetic acid was 1:1.15, the reaction temperature was 95°C, and the reaction time was from the beginning of the reaction until the content of terpineyl acetate no longer increased. Until now (about 6 hours), the content of terpineol acetate in the small test product can reach about 60%, the content of by-products is only about 15%, and the residual α-pinene is 24%. The comparison of the synthesis results shows that when H 3 PO 4 is used as a catalyst, the selectivity is low, the content of terpineyl acetate is low, only 25.6%, and the content of by-products is as high as 42.9% (including other terpenes brought into the raw material turpentine), α – Pinene residue 31.5%. But this result is quite different from the lower yield results obtained by other researchers using H 3 PO 4 as catalyst. There is no industrial application report of this process route at present. Gainsford G J et al. used solid acid catalyst—H-type β molecular sieve as the catalyst to investigate the influence of ingredient ratio, reaction temperature, catalyst dosage and reaction time on product distribution. Their experimental results showed that low temperature is beneficial to increase the yield of terpineol acetate , and the high temperature significantly reduces the yield of terpineol acetate; the reaction rate is related to the ratio of silicon to aluminum of the catalyst, and the high silicon to aluminum ratio improves the reaction rate, but the high reaction rate cannot obtain more terpineol acetate; The reaction time should not be too long, as the yield of terpineol acetate will decrease if the time is long, the reaction should be stopped in good time. At room temperature (20°C) and liquid phase conditions, terpineyl acetate was successfully synthesized, and a good yield was obtained, the highest yield was about 29%. They believe that the yield of terpineol acetate prepared by one-step method using solid acid catalyst seems to be comparable to or even better than the result of two-step preparation process in industry. Lin Senshu from the Department of Chemistry, Sun Yat-Sen University found that the heteropolyacid-12-phosphotungstic acid was used in the synthesis of α-pinene and anhydrous acetic acid from the catalyst screening research on the direct catalytic esterification of α-pinene to borneol acetate. It has quite high catalytic activity in the reaction, and the conversion rate of ester is also relatively high. It has the advantages of less dosage and low reaction temperature in the esterification reaction. Using solid heteropolyacid-12-phosphotungstic acid as a catalyst, the main product of esterification is pine oil ester, and the yield can reach 25%.