| 2-(p-chlorobenzyl) pyridine is a medical intermediate to product chlorphenamine maleate which is used as antihistamine. Because chlorphenamine maleate has important medical value, and 2-(p-chlorobenzyl) pyridine is the main intermediate to synthesize chlorphenamine maleate , the optimizing of 2-(p-chlorobenzyl) pyridine' s synthetic technics has a vital influence to the production of chlorphenamine maleate. The industrialized production technics has ripe technology, but long production steps and low yield. To shorten the synthesis route and increase the yield of 2-(p-chlorobenzyl) pyridine , another synthesis route-the condensation of 4-chlorobenzyl chloride and pyridine hydrochloride -was discussed , including the synthesis technics and apparent kinetics.At first , the synthesis route of 2-(p-cholorpenzyl) pyridine via 2-(p-chlorobenzyl) pyridine and pyridine was discussed . By means of the Uniformity Experiments , the different influence factors on the reaction were discussed , The Quantitative Correlation Equation about factors and molar yield was established . According to the equation , the reaction condition of this technics was optimized , and on the optimum condition , the molar yield of the aimed product , 2-(p-chlorobenzyl) pyridine , was predicted as 59.66% . The optimum conditions are shown as follows:material proportion : 1.6:1 (the molar proportion of 4-chlorobenzyl chloride and pyridine hydrochloride)catalyst quantity : 17%(the quantity percentage of pyridine hydrochloride)condensation reaction time :2h condensation reaction temperature:165℃ the persistent time of temperature :7h absolute pyridine quantity :10mlOn the base of the Uniformity Experiments , the material proportion , the catalyst quantity , the condensation reaction temperature and the persistent time of temperature were mainly discussed , and each factor was optimized , which got the similar results to the optimum reaction condition of the Uniformity Experiments .To validate the reliability of the optimum technologic condition , the technology of artificial neural network was adopted , and the artificial neural network model to predict the preferable technologic condition was established .The data of the Uniformity Experiments and single factor were used as training stylebooks to train the model . After the training , the most relative error between the simulative output and the training stylebooks was under 2. 5% . It means that the model could be used to predict the preferable condition .Then the range of each factor was broadened , and all the factors were fitted as varies stylebooks to input into the model . After that , the preferable technologic condition was established ,which consisted with the result of the Quantitative Correlation Equation , and predicted the yield as 60. 97% . At the optimum technologic condition , the average experimental yield of aimed product was 58. 11% , which consisted with the predicted yield of the two models . Compared with the industrialized technologic route which got the yield of 40% .according to the literature , the yield of this new route was increased by 20 percent .Secondly , the apparent reaction kinetics of the synthesis of 2-(p-chlorobenzyl) pyridine was discussed . Because of the complexity of this reaction (not only parallel reaction , but also continuous reaction ),only the kinetics of the control step - the second step of main reaction - was discussed . The kinetics equation was :Where CR is the molar concentration of 2-(p-chlorobenzyl) pyridine , mol/L , and Ceo is the molar concentration of the intermidiate, mol/L .In addition , a new method to analyze 2-(p-chlorobenzyl) pyridine and its isomeric compound by gas chromatography was founded, with the help of temperature programmable column oven . By this method, the resultants of the whole synthesis system could be analyzed well .In a word , employing the method of artificial intelligence in combination with experimental technology , we optimized the technologic condition of the synthesis of 2-(p... |
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