氯化铯催化氢氧化钾促进二烷基二硒醚的合成

The Synthesis of Dialkyl Diselenides Promoted by Potassium Hydroxid Catalyzed by Cesium Chloride

针对氢氧化钠作用下水合肼还原硒形成Na2Se2与磺酸酯反应制备二烷基二硒醚需要在高温(100℃)下才能有效进行,且仅适用于制备不含官能团的二烷基二硒醚的问题.由于铯离子体积大,与阴离子之间的静电作用弱,使与之键合的阴离子表现出强的碱性和亲核性,利用铯碱作缩合剂,能显著降低反应的活化能,使许多反应在温和条件下就能有效进行.根据离子交换原理,采用氯化铯和TBAI作催化剂,以无水DMF作溶剂,4A分子筛作吸水剂,氢氧化钾促进肼还原硒,随后与含官能团的卤代烃或磺酸酯反应,高收率地形成对应的二烷基二硒醚.本方法不仅可以合成含官能团的二硒醚,而且具有反应条件温和、产率高等优点.

The preparation of dialkyl diselenides by the reaction of tosylates with disodium diselenide derived from hydrazine reduction of selenium promoted by sodium hydroxide needs high temperature（100 ℃）,and this method is only suitable for preparation of the diselenides without functional group.Cesium ion（Cs＋） is bulky,and the electrostatic interaction between cesium ion（Cs＋） and anion is very weak.So the anion attached to Cs＋ has strong alkality and nucleophilicity.The reaction proceeds more readily under mild reactive conditions using alkali of cesium as a catalyst because of the remarkable decline in activation energy.However,CsOH is very expensive compared to KOH.In this paper,according to the principle of ion exchange,using cesium chloride（CsCl） and TBAI as catalysts and dry DMF as solvent,hydrazine reduced selenium promoted by potassium hydroxide,followed by treatment with functional alkyl halide or tosylates at room temperature to afford corresponding diaryl diselenides in high yields.The method not only prepares diselenides containing functional group but has the advantages of mild conditions and high yields.