Gas-phase acidities and O-H bond dissociation enthalpies of phenol, 3-methylphenol, 2,4,6-trimethylphenol, and ethanoic acid
Gas-phase acidities and O-H bond dissociation enthalpies of phenol, 3-methylphenol, 2,4,6-trimethylphenol, and ethanoic acid
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DOI：
10.1021/jp0627426
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发表时间：
2006-09-07
影响因子：
2.9
通讯作者：
Ervin, Kent M.
中科院分区：
文献类型：
--
作者：
Angel, Laurence A.;Ervin, Kent M.
能量分辨，竞争阈值碰撞诱导解离（TCID）方法被用来测量气相酸度的苯酚，3-甲基苯酚，2，4，6-三甲基苯酚，和乙酸相对于氰化氢，硫化氢，和氢过氧自由基使用引导离子束串联质谱。Delta H-酸（298）的气相酸度（C6 H5 OH）= 1456 +/- 4 kJ/mol，Delta H-酸（298）δ H酸（298）（2，4，6-（CH_3）（3）C_6H_2OH）= 1456 +/-4kJ/mol，δ H酸（298）（CH_3COOH）= 1457 +/-6kJ/mol。利用已发表的C_6H_5O的电子亲和势实验值，导出了D-298（C_6 H_5 O-H）的O-H键离解焓= 361 +/-4kJ/mol，并报道了其它物种的热化学值。新的TCID值与文献中的实验值和理论值进行了比较。
Energy-resolved, competitive threshold collision-induced dissociation (TCID) methods are used to measure the gas-phase acidities of phenol, 3-methylphenol, 2,4,6-trimethylphenol, and ethanoic acid relative to hydrogen cyanide, hydrogen sulfide, and the hydroperoxyl radical using guided ion beam tandem mass spectrometry. The gas-phase acidities of Delta H-acid(298)(C6H5OH) = 1456 +/- 4 kJ/mol, Delta H-acid(298)(3-CH3C6H4OH) = 1457 +/- 5 kJ/mol, Delta H-acid(298)(2,4,6-(CH3)(3)C6H2OH) = 1456 +/- 4 kJ/mol, and Delta H-acid(298)(CH3COOH) = 1457 +/- 6 kJ/mol are determined. The O-H bond dissociation enthalpy of D-298(C6H5O-H) = 361 +/- 4 kJ/mol is derived using the previously published experimental electron affinity for C6H5O, and thermochemical values for the other species are reported. A comparison of the new TCID values with both experimental and theoretical values from the literature is presented.