Mercapto Acids And Their Esters, And Replace The Synthesis Of Phenol

This dissertation consists of two parts:Part one:The preparation of mercaptoacetic acid and its estersMercaptoacetic acid and mercaptoacetic acid esters are a kind of important fine chemical compounds. They are highly versatile intermediates in organic synthesis such as pharmaceuticals ,pesticides and so on.With their applications becoming biger and biger, their consumption are increasing ,but their industry product in our country cann't meet the needs, almost all higher purity mercaptoacetic acid depends on import ,so the price is higher.Numerous methods were reported for the synthesis of these structures over the last few decades,although these methods were valuable for the preparation of mercapto compounds ,many were associated with drawbacks,such as unsatisfactory yieds ,ropy and toxic.Thus ,an improved practical for the preparation of these compounds is essential.In this paper ,we synthesised mercaptoacetic acid with sodium thiosulfate and chloracetic acid by Bunte salt formation ,hydrolysis of Bunte salt and its reduction processes to get higer purity and quality thioglycollic acid.To optimize the reaction conditions,the reaction time,temperature, reducing agent,extracting agent and so on were varied, The optimum process conditions were determined: n (chloracetic acid):n(sodium thiosulfate):n(sulfuric acid):n(Fe)=1.0:1.0:2.0:0.3,the heat chloracetic acid sodium was poured into the melted sodium thiosulfate by continuous agitation,synthesis Bunte salt at 70-75℃for one hour,then cooling to room temperature, hydrolysis of Bunte salt with sulfuric acid at 80-85℃for two hours , then cooling to room temperature,adding iron powder to reduce at 60-65℃for two hours,then disposing to get the products.Secondly, thioglycolic acid esters were studied. Bunte salt were synthsised with chloroactic acid ester and sodium thiosulfate,hydrolyzed by viriol,then reduced with iron powder.Then reacter conditions were discussed,the optimum conditions for the thioglycolic acid esters were determined: n (chloracetic acid ester):n(sodium thiosulfate):n(sulfuric acid):n(Fe)=1.0:1.0:2.5:0.2, Bunte salt were synthsised at 70-75℃for one hour with the solvent of alcohol and water,to hydrolyze at 85-90℃for two hours,to reduce at 55-60℃for two hours then post treatment and reduced pressure distillation to get products.The process has several advantages as following:(1) The manipulates are simple.(2) The cost is lower.(3) Less pollution to the environment is caused.(4) The yield and quality of produtions are optimized in this way.The structures of the substances were confirmed by 1HNMR, IR ,and elementary analysis .Part two:the preparation of substituted phenols.Substituted phenols are very important substants.They have broad practical usefulness as industry raw material and the intermediates of medicine , pesticides and dyestuffs etc.In this paper ,we synthesize a series of substituted phenols by hydrolyze diazonium salt, which make the reaction condition moderate, take the amount of material easily controlled, reduce the pollution to the environment and greatly enhance the purification and yield of the productions. Substituted phenols were prepared by the reaction of substituted phenylamine and sodium nitrite to give diazonium salt ,then hydrolyze under the catalyzed in the acid condition.The optimum process conditions were determined: n(substituted phenylamine):n(sulfuric acid):n(sodium nitite)=1.0:3.0:1.10, the concentration of acid of hydrolyze is 40%,reaction temperature 120℃,The mother liquor of hydrolyse is repetitive-used.In all the reaction processes ,reaction conditions are mild, operations are simple and the three wasters are less,while the yield was higher and the purity was good ,In conclusion,we have disclosed a practical and efficient synthesis of Substituted phenols from readily available starting materials .The products were assigned by IR,1HNMR and 13CNMR.