Research Progress on the Synthesis of o-Dimethoxybenzene
o-dimethoxybenzene is widely used in medicine,pesticides and chemical synthesis.Its main synthesis methods include o-aminoanisole method,guaiacol method and catechol method.The o-aminoanisole method and guaiacol method have obvious disadvantages,which limit their application.The catechol method is an ideal choice for industrial synthesis of o-phenylenediol due to its simple operation,easy availability of raw materials,mild reaction conditions and environmental friendliness.According to the different methylating agents,there are several methods for preparing o-dimethoxybenzene by catechol method.When methyl chloride is used as a methylating agent,the yield is high,but the control requirements of reaction conditions are high,and the product separation process is complicated.Dimethyl sulfate is a methylating agent with high reaction activity,which is suitable for batch production,but the raw materials are highly toxic,and the process will produce sulfuric acid,which is corrosive to equipment and operators,and a large amount of wastewater is produced,polluting the environment.When dimethyl carbonate is used as a green methylating agent,no alkali is required,and the process is environmentally friendly,but the choice of catalyst is crucial.When methanol is used as a methylating agent,the cost is low and the post-processing is simple,but the reaction activity is low,and a suitable catalyst needs to be selected to improve the selectivity of o-dimethoxybenzene.
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