Acidity order of selected Broensted acids in the gas phase of 300.deg. K
Acidity order of selected Broensted acids in the gas phase of 300.deg. K
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选定的布朗斯台德酸在气相中的酸度顺序为300℃。
DOI：
10.1021/ja00770a002
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发表时间：
1972
期刊：
影响因子：
--
通讯作者：
L. Young
中科院分区：
文献类型：
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作者：
D. Bohme;E. Lee‐Ruff;L. Young
本文研究了300 K下气相中A-+ BH B-+ AH型质子转移反应的动力学，得到了AH和BH酸在气相中酸强度不同的信息。使用流动余辉技术测量质子转移的正向和反向速率常数，然后用于计算极限或绝对值，p2 sTa（气体）的酸AH和BH的差的直接测量值的p2 sTa平衡常数。对58个涉及不同氧酸和碳酸的质子转移反应的动力学数据进行了分析，得到了下列酸度标度：n-C_4H_9SH> CH_3NO_2> C_5H_6> CHCl_3> CH_3COCH_3> CH_3CN> CH_2Cl_2，CH_3SOCH_3> C_2H_2，？-C3H7OH> C2H8OH> CH3OH> C3H4，C6H8CH（CH3）2> C6H8CH> C3H3> H2O> C6H> H2> NH3> C2H4，C6H12，（CH2）3，CH4。气相酸度级与溶液酸度级的比较进一步证明了某些酸的pK* 对溶剂化的极端敏感性。确定了ApATA从气相到溶液的符号的几个变化。质子转移的首选方向显示了适度高的反应性，在大多数的质子转移反应的调查。然而，在少数情况下，有一些空间阻碍的质子转移在气相中的证据。最后，质子转移的优选方向的识别允许化学上有用的限制值的一些烃基的电子亲和性和质子亲和性的一些有机阴离子的测定。
A study of the kinetics of proton-transfer reactions of the type A-+ BH B-+ AH proceeding in the gas phaseat 300 K has led to information regardingthe difference in acid strength of the acids AH and BH in the gas phase. Forward and reverse rate constants for protontransfer were measured using the flowing afterglow technique and then employed to calculate limits to, or absolute values for, the thermodynamicequilibrium constant which is a direct measure of the difference in p2sTa (gas) for the acids AH and BH. The kinetic data for 58 proton-transfer reactions involving various oxygen and carbon acids led to the following acidity scale:«-C4H9SH> CH3N02> C5H6> CHC13> CH3COCH3> CH3CN> CH2C12, CH3SOCH3> C2H2,? er/-C4H9OH,;-C3H7OH> C2HsOH> CH3OH> C3H4, CeHsCH (CH3) 2> CeHsCH> C3H3> H20> CeH> H2> NH3> C2H4, CeHi2,(CH2) 3, CH4. A comparison of the gas-phase acidity orderwith the solution order provided further evidence for the extreme sensitivity of the pK* of certain acids toward solvation. Several changes in the sign of ApATa in going from the gas phase to solution were identified. The preferred direction of proton transfer displayed a moderately high reactivity in the majority of the proton-transfer reactions investigated. However, in a few cases there was some evidence for steric hindrancetoward proton transfer in the gas phase. Finally, the identification of the preferred direction of proton transfer allowed the determination of chemically useful limiting values for the electron affinities of a number of hydrocarbon radicals and proton affinities of a number of organic anions.