氟改变了醇在镍(100)表面上的氧化机理  

Conversion of Alcohol Oxidation on Ni(100) by Fluorine

作　　者：赵清[1] 翟光杰[2] ZAERA Francisco 

机构地区：[1]北京理工大学理学院物理系 [2]中国科学院空间科学与应用研究中心 [3]Department of Chemistry,University of California,Riverside 92521,California,USA

出　　处：《物理化学学报》2007年第9期1447-1450,共4页Acta Physico-Chimica Sinica

摘　　要：利用程序热脱附(TPD)实验研究了2-丙醇和三氟-2-丙醇在Ni(100)表面的吸附和热反应过程.实验结果表明,电负性大的氟原子取代丙醇中γ-位氢原子后,使丙醇从脱氢反应转化为脱水反应.在这两种化合物的TPD实验产物中发现,有以脱水反应生成的烯烃(丙烯,三氟丙烯),脱氢反应产生的酮类(丙酮,三氟丙酮)等分子析出.实验结果表明,氟原子取代γ-H后阻止了产生中间产物醇盐的β-H脱氢反应,打开了γ-H脱氢反应的通道,导致烯烃的产生.在2-丙醇吸附于镍表面的TPD实验中观察到了消去β-H产生丙酮的脱氢反应,而1,1,1-三氟-2-丙醇在镍表面上经过脱水反应则产生了3,3,3-三氟丙烯.The temperature-programmed desorption（TPD）was used to study the adsorption and thermal decomposition of 2-propanol and trifluoro-2-propanol on clean Ni（100）surface.The products of TPD in both cases were traced for molecular desorption and for the products of dehydration（alkene）and dehydrogenation（ketone）reactions.The results showed that a partial switch from alcohol dehydrogenation to alcohol dehydration was driven by substitution ofγ- hydrogen with more electronegative fluorine atoms.The inductive effect exerted by fluorine atoms substituted at theγposition led to a significant inhibition ofβ-hydride elimination from the alkoxide intermediates,and to the opening of a newγ-hydride elimination channel which eventually ended in alkene formation.While exclusive dehydrogenation to acetone viaβ-hydride elimination from 2-propoxide surface species was seen with 2-propanol,some dehydration to 3,3,3-trifluoropropene was observed with 1,1,1-trifluoro-2-propanol.

关 键 词：2-丙醇 三氟-2-丙醇 热脱附(TPD) NI(100) 

分 类 号：O621.2[理学—有机化学]