The oxidative coupling of methyl benzoate
The oxidative coupling of methyl benzoate
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DOI：
10.1006/jcat.2000.2865
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发表时间：
2000-07-01
影响因子：
7.3
通讯作者：
Schiraldi, DA
中科院分区：
文献类型：
--
作者：
Iretskii, AV;Sherman, SC;Schiraldi, DA
在可溶性钯催化剂[PdLL2‘](L=phen，bipy，dppe；L’=OAc，TFA)作用下，苯甲酸甲酯与加压(50atm)人工空气(50mol%O-2-N-2混合物)在150-200℃下反应生成了二甲基联苯甲酸(DMBBA)。不同的因素影响该过程的反应性和区域选择性。三氟甲磺酸可以增强反应活性，可以说是通过质子化激活芳环的C-H键。温度的升高不仅提高了反应速率(E-A=5.5kcal/mol)，而且有利于邻位偶联产物的形成。具有较强反式影响的配体(L=phen、bipy或dppe)直接使氧化偶联远离2，X‘-异构体(X=2、3或4)。总体而言，钯催化剂的电子性质比同一催化剂的空间位阻对改变MBA偶联的活性和区域选择性更为重要。(C)2000年学术出版社。
The reaction of methyl benzoate (MBA) with pressurized (50 atm) artificial air (50 mol% O-2-N-2 mixture) at 150-200 degrees C over a soluble palladium catalyst [PdLL2'] (L = phen, bipy, dppe; L' = OAc, TFA) afforded isomeric dimethyl bibenzoic acid eaters (DMBBA). Different factors affect the reactivity and regioselectivity of the process. The reactivity is enhanced by trifluoromethanesulfonic acid, arguably by activating the C-H bond of the aromatic ring by its protonation. The increase of temperature not only increases the reaction rate (E-A = 5.5 kcal/mol) but also favors a formation of an ortho-coupled product. Ligands with strong trans influence (L = phen, bipy, or dppe) direct the oxidative coupling away from 2,X'-isomers (X = 2, 3, or 4). Overall, electronic properties of a palladium catalyst are more important than steric restriction of the same catalyst for altering the activity and regioselectivity for MBA coupling. (C) 2000 Academic Press.