2-5-二氯苯酚的合成新工艺研究

2,5-二氯苯酚的合成新工艺研究The Study on Synthesis of 2,5-DichlorophenolAbstractDicamba,which trade name is Banvel and chemical name is 3,6-dichloro-2-methoxy-benzoic acid.Dicamba is a kind of high efficiency in the absorption of the type of herbicide,and it is mainly used for drill and crop weeding.There are several major methods ofpreparation.In industrial production,the most widely used methods is etherifying3,6-dichlorosilicylic acid to produce Dicamba.2,5-dichlorophenol is an important starting material to prepare 3,6-dichlorosalicylic acid.Generally use the methods of diazotizing and hydrolyzing 2,5-dichloroaniline to produceDicamba.1,4-Dichlorobenzene can be also oxidized to 2,5-dichlorophenol.In addition to that,the method of using 1,2,4-trichlorobenzene to occurs alcoholysis reaction in alkalineenvironment is also used.2,5-dichlorophenol in fine chemical production has important applications,and also beused in medicine,dyes and other fields.It can be used to make nitrogen fertilizer efficiencyand used as leather preservatives.In this paper,2,5-dichloroaniline was used to diazotize and hydrolyze in the solution ofsodium hydroxide to produce 2,5-dichlorophenol,and process was improved.Diazonium saltwas prepared of by hydrochloric acid instead of traditional sulfuric acid.Optimize thereaction conditions such as the sulfuric acid and raw materials ratio,the reaction temperature,the amount of sodium nitrite and other reaction conditions.And try to synthesize2,5-dichlorophenol by catalytic oxidation.When the molar ratio of 2,5-dichloroaniline andsulfuric acid reaches to 5:2,the molar ratio of sodium nitrite and raw material is between 1.6and 1.8,react at temperature of 145C,the yield can reach to 92.4%.Use high performanceliquid chromatography to analysis of the purity,and the purity of the results can reach to 997.5%Key Words:Dicamba;2,5-dichloroaniline;2,5-dichlorophenol;2,5-dichloroanisoleII-