Study On The Synthesis Methods Of Vitamin K₂

The special pharmacological effects of Vitamin K₂has great value in Medical Field.Based on the analysis of many previous synthesis methods of Vitamins K₂, the F-Calkylation method which was simple, economic and suitable for industrial productionwas studied. Taking β-methylnaphthalene and geraniol as the starting material, VitaminK_{2（10）}has been finally synthesized with the total yield of51.3%by the oxidationreaction, F-C alkylation reaction and oxidation reaction. And each step of reactions wasoptimized to find the optimum process conditions.The first reaction, β-methylnaphthalene was oxidized to prepare menadione withchromium trioxide as oxidant. The optimized conditions of the first reaction are:β-methylnaphthalene: chromium trioxide: glacial acetic acid=1:4.5:15（Moore ratio）, thetemperature of adding chromic acid aqueous solution to the system was35to40℃,yield was67.5%.The second reaction,2-methyl-1,4-naphthalenediol was prepared with menadioneas the raw material by sodium dithionite reduction method and catalytic hydrogenationreduction method respectively. The catalytically hydrogenation with palladium/activatedcarbon as the catalyst can gain the yield as high as98.1%, when menadione（mol）:catalyst （g）=1:8. The yield of sodium dithionite reduction method was a bitlower than the catalytic hydrogenation reduction method, but the operation was simpleand the reaction condition was mild. The optimized conditions of the sodium dithionitereduction method are: reaction time was2.5h, menadione: sodium dithionite=1:6.5（mole ratio）, yield was92.91%.The third reaction, Vitamin K_{2（10）}was prepared with2-methyl-1,4-naphthalenedioland geraniol as the raw material, water resistance Louis acid Sm（CF₃SO₃）₃as catalyst.The optimized conditions of the third reaction are:2-methyl-1,4-naphthalenediol:catalyst: geraniol: adding time=0.01mol:0.25g:12ml:40min, yield was77.4%.Compared with common Louis acid, the water resistance Louis acid Sm（CF₃SO₃）₃as the catalyst of F-C alkylation reaction brought a great increase of yield which was ashigh as77.4%from30%.