Experimental Study On Dkr By Lipase Catalysis

With the acceleration of the pace of life,depression has become a common disease in modern people.Tomoxetine is the best-selling antidepressant because of its remarkable efficacy and few adverse reactions.（R）-3-chloro-1-phenylpropanol is an important intermediate in the synthesis of R-tomoxetine.The kinetic resolution of biocatalysis and the reduction of latent chiral ketones have been used to prepare chiral3-chloro-1-phenylpropanol,but the main problems are low utilization rate of raw materials,environmental pollution,long reaction time and low conversion rate,which greatly increase the production cost and limit its application.Therefore,it is of great practical significance to find an economical and efficient green synthesis method for the production of tomoxetine.In this paper,the efficient DKR system of immobilized lipase coupled with immobilized VOSO₄ metal catalyst was established,which solved the problem of poor compatibility between enzyme and metal catalyst and low catalytic efficiency.Transesterification method can avoid hydrolysis reaction and reduce the occurrence of reverse reaction.One-pot method can effectively reduce separation and purification steps,reduce waste generation and energy consumption,and improve reactivity and selectivity by promoting balanced reactions.This process has high yield,easy operation,easy access to raw materials and environmental friendliness.This technique can also be used in the synthesis of other chiral phenylpropanols.In the selective acylation reaction catalyzed by lipase,3-chloro-1-phenylpropanol was used as substrate and isopropylacetate as acyl donor.In-situ racemization reaction was carried out by racemic catalyst（VOSO₄）catalyzing inferior isomer.The kinetic resolution（KR）of racemic 3-chloro-1-phenylpropanol catalyzed by lipase was studied.The effects of solvent,the type of acyl donor,addition amount,temperature,substrate concentration,enzyme addition amount,external diffusion and water activity on KR were studied,and the optimal reaction conditions were determined.Based on this condition,DKR reaction was studied in depth,and response surface optimization was carried out for the key parameters such as reaction temperature,reaction time and substrate concentration that affect DKR.In order to realize efficient coordination between KR and in-situ racemization reaction,the addition of VOSO₄ was studied emphatically.Combined with KR experiment and DKR separation reaction,the optimal reaction conditions were determined by the study of each factor:With n-hexane as solvent,0.125mmol/m L 3-chloro-1-phenylpropanol,0.0625mmol/m L isopropylacetate and immobilize lipase by saturated K₂CO₃ solution were balanced for 24h 0.1g and immobilize VOSO₄ 6mg.The reaction was performed at 50℃for 48h.Under these conditions,the maximum conversion rate and the e.e value of the product were 91.6%and 95.5%,respectively.The average conversion rate and e.e value were 93.7%and95.1%,respectively,under the optimal conditions.