<sub> 0 </ Sub>. Coenzyme Q Synthesis And Optimization,

Coenzyme Qo (2,3-Dimethoxy-5-methyl-1,4-p-benzoquinone) is an important medical intermediate of Coenzyme Q10. Based on the literature search, a commercial and practical synthesis route with p-cresol as start material was chosen. Coenzyme Q0 was prepared by bromination of p-cresol, methoxylation of 2,6-dibromo-p-cresol, following methylation of 2,6-dimethoxy-p-cresol, then oxidation. The route was chosen by many excellences, for example, ordinary materials, short route , moderate and maneuverable conditions.A lot of experiments and some improvements were made . The condition of the first reaction was moderate. It was a measurable reaction. The yield of 2,6-dibromo-p-cresol was 98%. A better catalyst A was chosen for the second reaction, which increased the yield . The reaction conditions of the second reaction were optimized. The optimized conditions were :reaction temperature 110 , reaction time 2 hours. m(2.6-dibromi-p-cresol):m(catalyst A):m(sodium methanol)=l:0.28:3.4. The yield of 2,6-dimethoxy-p-cresol was 95%. Utilizing Phase Transfer Catalyst, 3,4,5-trimethoxy-toluene was synthesized. Methylation of 2,6-dimethoxy-p-cresol with Me2SO4 and KOH was rapid and yield was increased in the presence of PEG. The reaction conditions of the third reaction were optimized. The optimized conditions were : reaction temperature 90 , reaction time 2 hours, m(2,6-dimethoxy-p-cresol):m(PEG):m(KOH) = 1:0.20:0.86,m(KOH):m(Me2SO4)=l:1.50. The yield of 3.4.5-trimethoxy-toluene was 92.9%. The reaction conditions for synthesizing Coenzyme Qo from 3,4,5-trimethoxy-toluene were optimized with the uniform design method. The yield of Coenzyme Qo was 63.3%. Coenzyme Qo was purified by vacuum distillation instead of recrystallization, which can reclaim unreactive material and the losing of Coenzyme Qo was reduced. The purity of Coenzyme Q0 was >98%.