The Research On The Catalyst Of Cesium Chloride Of Esterification, Azide And The Addtion Reaction Of Sodium Arylselenolate

Cesium cation owns unique properties for example cesium cation radius is bigger than other alkali metals; the density of charge of the surface is lower, which makes the cesium cation easier to be polarized. At the same time the anion which links to the cation can be actived by cesium cation. This can improve the nucleophilic capacity of the anion of reactant.Cesium compounds have widely used in all kinds of organic synthesis , especially cesium carbonate, cesium hydroxyl and cesium fluoride. But sometime the supply of strong bases has disadvantage to the yield. In order to avoid the defects and make use of the speciality of cesium cation simultaneity. Cesium chloride was used as ion-exchange reagent to enhance the rate of organic synthesis. My work mainly includes four parts:(1) The synthesis ofα-alkyloxyacylmethyl ester by the reaction between carboxylate salt andα-chloroacetate ester. The traditional methods need polar solvents like DMF such solvents prolonged the reaction time. In the presence of catalytic amounts of cesium chloride the addition of sodium carboxylic acid to alkyl halides occurred at room temperature in DMF and gave the product in good yield.(2) The synthesis of carboxylic acid ester by the reaction between alkyl halides and salt carboxylic acid. The traditional methods are similar to the partⅠ. Recently the work which make use of cesium carbonate to catalyst the esterification has been reported ,but this method improve the supply of carbonate salt, and the cost is promoted, also cesium fluoride or potassium fluoride was used to improve the esterification reaction ,but this reaction is required to heat to above 100℃, which can decompose the compound unstable to heat. So we explore a mild method to synthesize carboxyl acid ester. In the presence of catalytic amounts of cesium chloride the addition of sodium carboxylic acid to alkyl halides occurred at 40℃in DMF and gave the product in good yield.(3) The synthesis of organic azides by the reaction between sodium azide and alkyl halides. Organic azides are widely used to fine chemicals and medicine field. Many organic azides have important bioactive. On the other hand organic azide is one of the important intermediates in organic synthesis which can be reduced to amine or used to synthesize 1,2,3 -triazoles by 1,3-dipolar cycloaddition reaction. These classic methods often encounter many difficulties such as the system is heated to reflux ; phase transfer catalyst such as surfactant pillared clay or 18-crown-6 these methods need to be heated to reflux and because of the existence of water , the compounds sensitive to heat or water will be discomposed . In the presence of catalytic amounts of cesium chloride the addition of sodium azide to alkyl halides readily occurred at room temperature or heated to 40℃in DMF and gave the product in good yield.(4) The synthesis of (Z)-1,2-bis(arylseleno)-1-alkene by the reaction between sodium arylselenolate and alkynyl selenide. Organoselenium compounds have attracted considerable interests as reagent and intermediates as well as their biological activity. The nucleophilic addition of sodium arylselenoate to alkynyl selenide is one of the paths of preparation of bis(arylseleno)alkene. But the reactions do not easily occur at room temperature due to weak nucleophilicity of sodium arylselenoate. Under heating condition, the reaction could occur effectively, however it gave a mixture consisted of cis, trans and gem-bis(phenylseleno) alkenes. Herein, we wish to report the stereoslective synthesis of (Z)-1,2-bis(arylseleno)-1-alkene by addition of sodium arylselenolate to alkynyl selenide catalyzed by cesium chloride. In the presence of catalytic amounts of cesium chloride the addition of sodium arylselenolate to alkynyl selenide readily occurred at room temperature in DMF and gave the (Z)-1, 2- bis(arylseleno)-1-alkene in good yield.