Study On Synthesis,Separation And Hydrolysis Of M-dichlorobenzene To Resorcinol

As important basic organic chemical intermediates,m-dichlorobenzene and resorcinol are widely used in the fields of dyes,pharmaceuticals and plastics.At present,the main processes for the production of m-dichlorobenzene and resorcinol in China are o-dichlorobenzene isomerization and benzene sulfonated alkali melting,but the m-dichlorobenzene obtained by o-dichlorobenzene isomerization has low selectivity and severe reaction,so there are hidden dangers in safety.on the other hand,the benzene sulfonated alkali melting method has some shortcomings,such as easy consumption of concentrated sulfuric acid and sodium hydroxide,high production cost and serious waste pollution.In this paper,m-dichlorobenzene was synthesized by isomerization of p-dichlorobenzene with a suitable catalyst,then pure m-dichlorobenzene was obtained by tertiary eutectic,and finally resorcinol was synthesized by hydrolysis catalyzed by cuprous oxide.The structure of the compound was identified by FT-IR,MS,¹H NMR and ¹³C NMR.The process conditions of each step were optimized,and the mechanism of the reaction process was analyzed.（1）Using p-dichlorobenzene as raw material,a mixture of dichlorobenzene isomers containing a high concentration of m-dichlorobenzene was synthesized under the catalysis of composite catalyst Al Cl₃+Al Cl₃·6H₂O.The effects of the water content of catalyst,amount of composite catalyst,reaction temperature and time on the isomerization of p-dichlorobenzene were investigated by single factor method.The results showed that n（Al Cl₃）:n（Al Cl₃·6H₂O）in the composite catalyst was equal to 1:1,n（p-dichlorobenzene）:n（anhydrous Al Cl₃+Al Cl₃·6H₂O）=1:0.2,the reaction temperature is 150℃,reaction time is 90 min,magneton speed is 200 r·min^-1,the conversion of p-dichlorobenzene is 66.6%,the content of dichlorobenzene in dichlorobenzene mixture is 60.2%,and the selectivity of m-dichlorobenzene is 91.5%.（2）M-dichlorobenzene was obtained from the mixture of dichlorobenzene isomers by using 1-Bromo-4-chlorobenzene as a eutectic agent.The optimum conditions determined by the experiment are as follows:the tertiary eutectic temperature is 0℃,-20℃and-24℃respectively,and the dosage of tertiary eutectic agent is 30%,55%and 60%of the total feed,respectively.The yield of m-dichlorobenzene was 32.2%（based on the initial raw material）and the purity was 98.68%.Using X-ray single crystal diffraction,it is found that p-dichlorobenzene and 1-Bromo-4-chlorobenzene form eutectic at the ratio of 1:4,and chlorine and bromine atoms replace disorder by position.the eutectic crystal is kept stable by PD-typeπ-πstacking interaction between eutectic molecules.（3）Resorcinol was synthesized by hydrolysis of m-dichlorobenzene under acidic conditions using cuprous oxide as catalyst.Through the control variable method and response surface optimization experiment,the optimum experimental conditions were obtained as follows:the feed ratio n（m-dichlorobenzene）:n（anhydrous sodium acetate）:n（cuprous oxide）:n（deionized water）=1:3:0.2:70,reaction system p H≈4,reaction temperature 250℃,reaction time 11 h.The conversion of raw material is 85%,the yield of resorcinol is 65.48%,and the selectivity is 77%.