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在室温下,以8.2%的二氧化氮为催化剂,反应管中残留的空气为氧化剂,分子溴为溴化试剂,研究了带有给电子取代基的苯和萘的氧化溴化.使用的低沸点非金属催化剂易于从产物中去除,很少玷污最终产品;但反应后有少量的苯环硝化副产物生成,这会造成催化剂二氧化氮的损耗.反应具有较高的原子经济性,大部分溴原子被转化到产物中.反应产物具有可控性:可通过改变溴源的用量,分别得到单溴化和二溴化产物.初步的机理分析结论为:反应可能经历分子溴和芳环的反应,生成溴代芳烃和溴化氢;然后在氧化氮类物种催化下,生成的溴化氢被氧气氧化为具有反应活性的溴.
At room temperature, the oxidative bromination of benzene and naphthalene with electron donating substituents was studied with 8.2% of nitrogen dioxide as catalyst, air remaining in reaction tube as oxidant and molecular bromine as brominating reagent. Boiling point Nonmetallic catalysts are easy to remove from the product and seldom pollute the final product; however, a small amount of benzene ring nitration by-products are formed after the reaction, which leads to the loss of the catalyst nitrogen dioxide. The reaction has high atomic economy and most The bromine atom is converted to the product.The reaction product is controllable: monobrominated and dibrominated products can be obtained separately by changing the amount of bromine source.The preliminary mechanistic analysis concludes that the reaction may proceed through molecular bromine and aromatic ring Reaction to generate brominated aromatics and hydrogen bromide; and then under the catalysis of nitrogen oxides species, the generated hydrogen bromide is oxidized by oxygen to a reactive bromine.