催化分子氧氧化合成3-甲基-4-硝基苯甲酸  

Synthesis of 3-Methyl-4-nitrobenzoic Acid via Catalytic Oxidation with Molecular Oxygen

作　　者：岳彩波[1] 魏运洋[1] 邱水发[1] 孙翔兰[1] 

机构地区：[1]南京理工大学化工学院,南京210094

出　　处：《应用化学》2005年第12期1338-1341,共4页Chinese Journal of Applied Chemistry

摘　　要：由2,4-二甲基硝基苯的钴催化氧化合成了3-甲基-4-硝基苯甲酸,发现以分子氧作氧化剂时,在乙酸钴催化剂体系(乙酸钴/丁酮/乙酸)中加入助催化剂溴化钠,3-甲基-4-硝基苯甲酸的收率显著提高。在O2气压力为0.8 MPa,130℃下反应8 h,结果表明,当乙酸钴和溴化钠的用量各为反应物量的1.7%,引发剂的用量为反应物量的30%时,反应的转化率达99%,生成3-甲基-4-硝基苯甲酸的选择性为52%,3-甲基-4-硝基苯甲酸的收率为51%。根据反应必须在自由基引发剂存在下才能进行的实验事实,认为反应按自由基机理进行。溴化钠与Co(Ⅲ)作用,产生溴自由基,溴自由基夺取苄基氢,促进苄基自由基的生成,从而起到助催化作用。3-Methyl-4-nitrobenzoic acid was synthesized via oxidation of 2,4-dimethylnitrobenzene with molecular oxygen catalyzed by cobalt acetate in acetic acid in the presence of an initiator. It was found that the yield of 3-methyl-4-nitrobenzoic acid increased remarkably with the addition of sodium bromide as a co- catalyst. The reaction was carried out at 130℃ for 8 h at 0. 8 MPa of oxygen in the presence of 0. 017 mol of cobalt acetate, 0. 017 mol of sodium bromide, and 0. 30 mol of 2-butanone with 1.00 mole of 2,4-dimethylnitrobenzene. Under these conditions 99% of the reactant converted with a selectivity of 52% to 3-methyl-4- nitrobenzoic acid, and the yield of 3-methyl-4-nitrobenzoic acid was 51%. The reaction mechanism and the function of sodium bromide were discussed. According to the fact that the reaction could not proceed without the presence of an initiator, it was proposed that the reaction took place via a free radical mechanism, and sodium bromide reacted with Co （ In ） to generate bromine radicals, which promoted the formation of benzyl radicals .

关 键 词：液相氧化 二甲基硝基苯 甲基-硝基苯甲酸 合成 

分 类 号：O625.5[理学—有机化学]