AN EXTENDED FORM OF THE EVANS-POLANYI EQUATION - A SIMPLE EMPIRICAL RELATIONSHIP FOR THE PREDICTION OF ACTIVATION-ENERGIES FOR HYDROGEN-ATOM TRANSFER-REACTIONS

被引:116
作者
ROBERTS, BP
STEEL, AJ
机构
[1] Christopher Ingold Laboratories, Department of Chemistry, University College London, London, WC1H 0AJ
来源
JOURNAL OF THE CHEMICAL SOCIETY-PERKIN TRANSACTIONS 2 | 1994年 / 10期
关键词
D O I
10.1039/p29940002155
中图分类号
O62 [有机化学];
学科分类号
070303 ; 081704 ;
摘要
An empirical approach has been used to devise a simple relationship [eqn. (B)] between the activation energy for an elementary hydrogen-atom transfer reaction (A) and ground state properties (A): A' + H-B --> A-H + B' (B): E(a) = E(o)f + alpha Delta H-o(1 - d) + beta Delta chi(AB)(2) + gamma(S-A + S-B) of the reactants and products. The role of polar effects, which operate in the transition state, is emphasised and described quantitatively-in terms of the. difference in Mulliken electronegativities (Delta chi(AB)) Of the radicals A' and B'. on. (B) reproduces the activation energies for 65 reactions. taken from the literature, within a standard error of +/- 2.0 kJ mol(-1) and with a correlation coefficient of 0.988. Reactions of widely differing types are included and no distinction is made between gasphase reactions and-those which take place in non-polar solvents. Examples of hydrogen-atom transfer reactions which are not treated satisfactorily by eqn. (B) are discussed.
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收藏
页码:2155 / 2162
页数:8
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共 128 条
[1]   REACTION OF CF3 RADICALS WITH C2H6 [J].
ARICAN, H ;
ARTHUR, NL .
INTERNATIONAL JOURNAL OF CHEMICAL KINETICS, 1986, 18 (04) :437-443
[2]  
ARICAN H, 1973, J CHEM SOC F1, V69, P1811
[3]   METHYL AND TRIFLUOROMETHYL RADICAL ATTACK ON ETHERS [J].
ARTHUR, NL ;
GRAY, P ;
HEROD, AA .
CANADIAN JOURNAL OF CHEMISTRY, 1969, 47 (08) :1347-&
[4]   BEBO CALCULATIONS .4. ARRHENIUS PARAMETERS AND KINETIC ISOTOPE-EFFECTS FOR REACTIONS OF CH3 AND CF3 RADICALS WITH H2 AND D2 [J].
ARTHUR, NL ;
DONCHI, KF ;
MCDONELL, JA .
JOURNAL OF THE CHEMICAL SOCIETY-FARADAY TRANSACTIONS I, 1975, 71 :2431-2441
[5]   SOLVENT EFFECTS ON THE COMPETITIVE BETA-SCISSION AND HYDROGEN-ATOM ABSTRACTION REACTIONS OF THE CUMYLOXYL RADICAL - RESOLUTION OF A LONG-STANDING PROBLEM [J].
AVILA, DV ;
BROWN, CE ;
INGOLD, KU ;
LUSZTYK, J .
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 1993, 115 (02) :466-470
[6]   LASER FLASH-PHOTOLYSIS ELECTRON-SPIN-RESONANCE KINETIC-STUDIES OF HOMOLYTIC REACTIONS IN SOLUTION [J].
BABAN, JA ;
GODDARD, JP ;
ROBERTS, BP .
JOURNAL OF THE CHEMICAL SOCIETY-PERKIN TRANSACTIONS 2, 1986, (08) :1269-1274
[7]   ADDITION OF C3H8, NORMAL AND I-C4H10 TO SLOWLY REACTING MIXTURES OF HYDROGEN AND OXYGEN AT 480 DEGREES C - REACTIONS OF H AND OH RADICALS WITH ADDITIVE [J].
BAKER, RR ;
BALDWIN, RR ;
WALKER, RW .
TRANSACTIONS OF THE FARADAY SOCIETY, 1970, 66 (575) :2812-&
[8]   ACTIVATION-ENERGIES OF HYDROGEN-ATOM ABSTRACTIONS FROM ALKANES BY FREE-RADICALS [J].
BALDWIN, RR ;
WALKER, RW .
JOURNAL OF THE CHEMICAL SOCIETY-PERKIN TRANSACTIONS 2, 1973, (04) :361-365
[9]   PERTURBATION MOLECULAR-ORBITAL TREATMENT OF FREE-RADICAL HYDROGEN-ABSTRACTION REACTIONS [J].
BARTELS, H ;
EICHEL, W ;
RIEMENSCHNEIDER, K ;
BOLDT, P .
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 1978, 100 (24) :7739-7740
[10]   LIQUID-PHASE REACTIONS OF CCL3 RADICALS WITH TRIMETHYLSILANE AND TRIETHYLSILANE [J].
BARUCH, G ;
HOROWITZ, A .
JOURNAL OF PHYSICAL CHEMISTRY, 1980, 84 (20) :2535-2539