Remote substituent effects on homolytic bond dissociation energies

被引：53

作者：

Fu, Y ^{[1
]}

Liu, L ^{[1
]}

Lin, BL ^{[1
]}

Mou, Y ^{[1
]}

Cheng, YH ^{[1
]}

Guo, QX ^{[1
]}

机构：

[1] Univ Sci & Technol China, Dept Chem, Hefei 230026, Peoples R China

来源：

JOURNAL OF ORGANIC CHEMISTRY | 2003年 / 68卷 / 12期

关键词：

RADICAL STABILIZATION ENERGIES; C-H BONDS; O-H; THERMODYNAMIC STABILITIES; PHENOLIC ANTIOXIDANTS; PHENOXYL RADICALS; CLEAVAGE ENERGIES; X X; ENTHALPIES; POLAR;

D O I：

10.1021/jo034094h

中图分类号：

O62 [有机化学];

学科分类号：

070303 ; 081704 ;

摘要：

In the study we tried to answer two questions. First, does X-Z homolytic bond dissociation energy (BDE) Of Y-C6H4-X-Z obey the Hammett relationship? Second, if it does what factors determine the magnitude and sign of the slope (rho(+)) of Hammett regression against substituent sigma(p)(+) constants? We collected a large number of X-Z BDEs for over one-thousand Y-C6H4-X-Z systems using the RMP2/6-311++G**// UB3LYP/6-31G* method. We found that remote substituent effects on X-Z BDEs are determined by both the ground effect (i.e. stabilization/destabilization of X-Z by the substituents) and the radical effect (i.e. stabilization/destabilization of X by the substituents). The ground or radical effect is determined by the electron demand of X-Z or X-. in the same way as the deprotonation enthalpy of HOOC-C6H4-X-Z or HOOC-C6H4-X-. is affected by X-Z or X-.. As a result, rho(+)(BDE) for X-Z bond homolysis can be quantitatively predicted by using the change in deprotonation enthalpy from HOOC-C6H4-X-Z to HOOC-C6H4-X-..

引用

页码：4657 / 4662

页数：6

共 59 条

[1]

Adam W, 1998, ADV PHOTOCH, V24, P205

[2]

Bordwell FG, 1998, J PHYS ORG CHEM, V11, P10, DOI 10.1002/(SICI)1099-1395(199801)11:1<10::AID-POC967>3.3.CO

[3]

2-6

[4] SUBSTITUENT EFFECTS ON THE STABILITIES OF PHENOXYL RADICALS AND THE ACIDITIES OF PHENOXYL RADICAL CATIONS [J].

BORDWELL, FG ;

CHENG, JP .

JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 1991, 113 (05) :1736-1743

[5] ASSESSMENT OF THE IMPORTANCE OF CHANGES IN GROUND-STATE ENERGIES ON THE BOND-DISSOCIATION ENTHALPIES OF THE O-H BONDS IN PHENOLS AND THE S-H BONDS IN THIOPHENOLS [J].

BORDWELL, FG ;

ZHANG, XM ;

SATISH, AV ;

CHENG, JP .

JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 1994, 116 (15) :6605-6610

[6] Determination of the substituent effect on the O-H bond dissociation enthalpies of phenolic antioxidants by the EPR radical equilibration technique [J].

Brigati, G ;

Lucarini, M ;

Mugnaini, V ;

Pedulli, GF .

JOURNAL OF ORGANIC CHEMISTRY, 2002, 67 (14) :4828-4832

[7] A computational analysis of substituent effects on the O-H bond dissociation energy in phenols: Polar versus radical effects [J].

Brinck, T ;

Haeberlein, M ;

Jonsson, M .

JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 1997, 119 (18) :4239-4244

[8] DIRECTIVE EFFECTS IN AROMATIC SUBSTITUTION .30. ELECTROPHILIC SUBSTITUENT CONSTANTS [J].

BROWN, HC ;

OKAMOTO, Y .

JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 1958, 80 (18) :4979-4987

[9]

Carey F.A., 1990, Advanced Organic Chemistry Part A: Structure and Mechanisms, V3

[10] Homolytic cleavage energies of R-H bonds centered on carbon atoms of high electronegativity:: First general observations of O-type variation on C-HBDEs and the implication for the governing factors leading to the distinct O/S patterns of radical substituent effects [J].

Cheng, JP ;

Liu, B ;

Zhao, YY ;

Wen, Z ;

Sun, YK .

JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 2000, 122 (41) :9987-9992

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