反应详情

For example, U.S. Pat. No. 4,217,285(hereinafter referred to as '285 patent), which is assigned to Nisshin, discloses the synthesis of DL-α-tocopherol in toluene or n-hexane solvent with ZnCl2 and silica-alumina (or silica-gel) in the presence of acid, especially HCl, asserting that tocopherol can be obtained with a purity of 95 to 96% at a production yield of 99% or higher. Also, U.S. Pat. Nos. 4,634,781 and 4,639,533, both assigned to BASF, disclose processes for producing DL-α-tocopherol in which isophytol is reacted with amines such as tridecylamine or octadecylamine and thereafter with TMHQ in the presence of ZnCl2 and HCl, which are somewhat complicated and inefficient. In those techniques, the tocopherol is described to be produced with a purity of 94 to 95% at a yield of 95 to 98%. Other preparation methods of DL-α-tocopherol can be found in U.S. Pat. Nos. 5,663,376 and 5,886,197, both assigned to Eisai Co., Ltd, in which isophytol is reacted with TMHQ in a mixed solvent system comprising a non-polar solvent and an alcohol or carbonate ester. It is described that DL-α-tocopherol can be produced at a yield of 94 to 98% with a purity of 92 to 97%.

1. customcan be obtained with a purity of 95 to 96% at a production yield of 99%