Process Development Of Regioselective Hydrolysis 1-cyanocyclohexylacetonitrile For Production Of 1-cyanocyclohexaneacetic Acid

1-Cyanocyclohexaneacetic acid(1-CA)is a valuable intermediate for the synthesis of gabapentin [1-(aminomethyl)cyclohexaneacetic acid].Many documents concerning chemical synthesis of gabapentin were available,but chemical enzymatic synthesis of gabapentin were rarely reported.The synthesis of 1-CA which regioselective hydrolysis of 1-cyanocyclohexylacetonitrile(1-CN),solved the most critical step in the process of the synthesis reaction,with high conversion rate and mild conditions.In this work,we investigated 500 L fermentation to produce nitrilase,optimized the catalytic conditions of industrialization,separated 1-CA from bioreaction mixture,built complete separation process,finally based on the entire process designed process design of 200 t scale.This dissertation investigated 500 L amplification fermentor,based on the recombinant E.coli BL21(DE3)/pET28b(+)-NIT and 5 L fermentation parameters.Results indicated that the biomass and enzyme activity of 500 L fermentation similar to results of 5 L fermentation,illustrated the feasibility of the strategy of amplification with immutability of compression-ventilation ratio.Then industrialize recation of enzyme regioselective hydrolyze 1-CN to synthesized 1-CA was investigated: catalytic medium was tap water,catalytic volume amp 5 L to 10 L,and the catalytic efficiency still remain at 92%.Based on the problem of protein in the bioreaction mixture poisoning hydrogenation catalyst in the next reaction,the process route of removing protein and separating 1-CA was established.The finalized process route: extraction agent was ethanol,phase ratio was 1:4(v/v),operated with 150 rpm,time for extraction was 1 h.Ethanol was recycled at 40°C after the suction filter.The another process route: 3% polymeric ferric sulfate(PFS),operated with pH 7.0 at 30°C,150 rpm rapid mixing maked PFS fast distributed in solution,and continue to stir 1 h with 50 rpm.1-CA could be got though aciding pH to 2.0,filtering and drying at 50°C.Then using an ion-exchange(IEX)process investigated the isolation of 1-CA from the bioreaction mixture.Resin 201×7 has the largest adsorption capacity among seven anion exchange resins.The adsorption process was spontaneous,endothermic,and Freundlich model fitted the static equilibrium adsorption data well.Kinetic study revealed that the adsorption process followed the pseudo-second-order model.In the fixed bed experiments,flow rate of the sample 0.3 mL/min,eluent(ethanol:1.0 M HCl =5:5(v/v)),flow rate of eluent 0.3 mL/min,the separation yield of 1-CA was 91.34%.Finally,through the simple crystallization,the purity of 1-CA was over 99.5%.1-CA could be directly used to the next step of catalytic hydrogenation reaction synthesis of gabapentin.An annual output of 200 t 1-CA process route was designed based on results from laboratory and enlarging test.According to product cost calculation,annual output of 200 t 1-CA could cost 0.494 million yuan.