The Study On Microwave Synthesis Of Chloroacetic Acid With Acetic Anhydride Catalyzing Chlorination Of Acetic Acid

Monochloroactic acid,which is widely used in medicine,pesticide, spicery, oil chemical, paper making chemical, synthetic dyestuff files,is an important intermediate in organic chemical industry. At present,the annual production capacity of monochloroactic acid has reached about 70 million tons in China, which hold over 70% of the total worldwide production, And it is ability to increase 40～50 thousand tons annually.Amino acid,one of its downstream products,is consumed about 0.2 milliom tons annually and ranks first in the world in production.However, the monochloroactic acid production industry is still in a embarrassed situation generally in our country.And most of the companies are still adopting out-of-date production technology to produce the monochloroactic acid. It directly results in low quality production, high material consumption, intense labor and high environment pollution. To deal with those problems we mentioned above, searching for a new produce technology and developing new catalyze system are becoming to be first now.Chloridization is the key element for monochloroactic acid produce and the real catalyst is acetylchlorde, monochloroactic acid produce is the result of enolization of acetyl chloride. But acetyl chloride itself cannot restrain multchlorination. If some catalyst promoter is added, the quantity of production phytoremediation from severe Chloridization of monochloroactic acid will be effectively inhibited. Clearly the direction of the choroactic industry is depended on researching and developing the new catalyst promoter and reaction of microwave-assisted to increase the chloridization selectivity, control the Phytoremediation, produce high quality choroactical products, reduce the material consumption, and release the labor condense.The system of microwave assisted chlorination, followed by adding 98% concentrated sulfuric acid and anhydrous FeCl₃ catalyst to investigate the microwave and catalyst reactivity and reaction selectivity, respectively,And the photocatalytic mechanism is also discussed.This research is divided into three parts:The first part is free reflux microwave.After acetic acid and acetic anhydride catalyst are added,the chlorination reaction is studied by adjusting the microwave power.The results show that:Microwave relatively good selectivity and reactivity. When the microwave power is 160W, a yield of 94.84% chloroacetic acid and 2.88% dichloroacetic acid are got.The second part.The constant temperature by adjusting the microwave power and temperature of the circulating water tank to control the reaction temperature are used to examine the chlorination reaction.Meanwhile,different catalysts such as anhydrous FeCl₃ and concentrated sulfuric acid are also investigated.In the microwave and co-catalyst under the conditions existed, we investigate the influence of reaction and the reaction mechanism of the simple discussion. Experiments show that,in the microwave assisted reaction, the reaction optimum temperature is 95℃,which is decreased by 10℃than normal heating reaction.When anhydrous FeCl₃ is existed, a yield of 97.28% MCA and 2.10% dichloroacetic acid were got. If acetic anhydride is decreased to 15%, the yield will not be affected, which could lower the cost of production effectively.The third part. It provides some useful basis of continuous reaction according to the discussion of formation mechanism of chloroacetic acid and dichloroacetic.