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以咪唑类离子液体为N-杂环卡宾(NHC)催化剂的前体,应用于催化芳基氟化物和醛的亲核酰基化反应,成功地将酰基直接引入到缺电子的芳环上,制备出含吸电子基团的芳香酮.以对氟硝基苯和苯甲醛的反应制备对硝基二苯甲酮为模板,详细探讨了NHC催化的亲核酰基化反应的机理和反应规律,优化出最佳反应条件,并考察了催化剂的循环使用效果.实验结果表明,以DMSO为溶剂、离子液体1(R=n-C12H25)为催化剂前体、叔丁醇钾为碱,离子液体的用量为对氟硝基苯的33 mol%,离子液体和叔丁醇钾的物质的量比为1:4,反应温度为30℃,反应时间为6 h,对氟硝基苯的转化率可达93.0%,对硝基二苯甲酮的收率为88.6%.离子液体循环使用4次,对硝基二苯甲酮的收率仍在75%以上.
Imidazole ionic liquids as precursors for N-heterocyclic carbenes (NHC) catalysts were used to catalyze the nucleophilic acylation of aryl fluorides and aldehydes to successfully introduce acyl groups directly onto electron-deficient aromatic rings to prepare Aromatic ketones containing electron-withdrawing groups were synthesized.The p-nitrobenzophenone was prepared by the reaction of p-fluoronitrobenzene with benzaldehyde and the mechanism and reaction rules of NHC-catalyzed nucleophilic acylation reaction were optimized. The best reaction conditions were obtained and the effects of catalyst recycling were investigated.The experimental results show that with DMSO as solvent, ionic liquid 1 (R = n-C12H25) as catalyst precursor and potassium t-butoxide as base, ionic liquid dosage Is p-fluoronitrobenzene 33 mol%, ionic liquid and potassium tert-butoxide ratio of 1: 4, the reaction temperature is 30 ℃, the reaction time is 6 h, the conversion of p-fluoronitrobenzene up to 93.0%, the yield of p-nitrobenzophenone was 88.6% .The ionic liquid was recycled for 4 times, and the yield of p-nitrobenzophenone was still above 75%.