Hydrogen-bond basicity pKHB scale of six-membered aromatic N-heterocycles

被引:86
作者
Berthelot, M [1 ]
Laurence, C [1 ]
Safar, M [1 ]
Besseau, F [1 ]
机构
[1] Univ Nantes, Fac Sci & Tech, Lab Spectrochim, F-44322 Nantes 3, France
来源
JOURNAL OF THE CHEMICAL SOCIETY-PERKIN TRANSACTIONS 2 | 1998年 / 02期
关键词
D O I
10.1039/a706696a
中图分类号
O62 [有机化学];
学科分类号
070303 ; 081704 ;
摘要
Using 4-fluorophenol as a reference hydrogen-bond donor, equilibrium constants, K-f, for the formation of 1:1 hydrogen-bonded complexes have been obtained by FTIR spectrometry for 65 six-membered N-heteroaromatics of widely differing structures, in CCl4 at 298 K. The pK(HB) scale shows that most N-sp2 bases are weaker hydrogen-bend bases than many oxygen bases. This scale extends from the hypobasic pentafluoropyridine, illustrating the electron-withdrawing held effect of fluoro substituents, to push-pull 4-NR2-pyridines, illustrating the resonance effect of the 4-NR2 substituents which donate electrons in the order NH2 < piperidino < NMe2 < NEt2 < pyrrolidino. A spectroscopic scale is constructed from the IR frequency shift Delta nu(OH) of methanol hydrogen-bonded to N-heteroaromatics. The thermodynamic pK(HB) scale correlates with the Delta nu(OH) scale, but 2-substituted pyridines deviate markedly, These deviations are attributed to, and allow the semi-quantitative determination of: (i) steric effects, most important in 7,8-benzoquinoline; (ii) lone pair-lone pair repulsions, most important in 1,2-diazines; and (iii) lone pair-bond pair repulsions, most important in 2,6-difluoropyridine. IR spectra show the fixation of 4-fluorophenol to the nitrile nitrogen of 2-, 3- and 4-cyanopyridines, to the carbonyl oxygen of 3-COOMe, 3-COPh and 4-COMe-pyridines, and to the ether oxygen of 2-methoxypyridine, in addition to the fixation to the pyridine nitrogen. A cyclic complex, with complex, with both NH ... O and OH ... N hydrogen bonds, is formed with 2-amino- and 2-methylamino-pyridines.
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页码:283 / 290
页数:8
相关论文
共 45 条
  • [1] POLARIZABILITY EFFECTS ON THE AQUEOUS-SOLUTION BASICITY OF SUBSTITUTED PYRIDINES
    ABBOUD, JLM
    CATALAN, J
    ELGUERO, J
    TAFT, RW
    [J]. JOURNAL OF ORGANIC CHEMISTRY, 1988, 53 (06) : 1137 - 1140
  • [2] HYDROGEN-BONDING .9. SOLUTE PROTON DONOR AND PROTON ACCEPTOR SCALES FOR USE IN DRUG DESIGN
    ABRAHAM, MH
    DUCE, PP
    PRIOR, DV
    BARRATT, DG
    MORRIS, JJ
    TAYLOR, PJ
    [J]. JOURNAL OF THE CHEMICAL SOCIETY-PERKIN TRANSACTIONS 2, 1989, (10): : 1355 - 1375
  • [3] HYDROGEN-BONDING .10. A SCALE OF SOLUTE HYDROGEN-BOND BASICITY USING LOG K VALUES FOR COMPLEXATION IN TETRACHLOROMETHANE
    ABRAHAM, MH
    GRELLIER, PL
    PRIOR, DV
    MORRIS, JJ
    TAYLOR, PJ
    [J]. JOURNAL OF THE CHEMICAL SOCIETY-PERKIN TRANSACTIONS 2, 1990, (04): : 521 - 529
  • [4] STUDIES OF HYDROGEN-BONDED COMPLEX FORMATION .3. THERMODYNAMICS OF COMPLEXING BY INFRARED SPECTROSCOPY AND CALORIMETRY
    ARNETT, EM
    JORIS, L
    MITCHELL, E
    MURTY, TSSR
    GORRIE, TM
    SCHLEYER, PV
    [J]. JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 1970, 92 (08) : 2365 - +
  • [5] BASICITY - COMPARISON OF HYDROGEN-BONDING AND PROTON-TRANSFER TO SOME LEWIS-BASES
    ARNETT, EM
    MITCHELL, EJ
    MURTY, TSSR
    [J]. JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 1974, 96 (12) : 3875 - 3891
  • [6] HYDROGEN-BOND BASICITY OF NITRILES
    BERTHELOT, M
    HELBERT, M
    LAURENCE, C
    LEQUESTEL, JY
    [J]. JOURNAL OF PHYSICAL ORGANIC CHEMISTRY, 1993, 6 (05) : 302 - 306
  • [7] GAS-PHASE BASICITY AND SITE OF PROTONATION OF POLYFUNCTIONAL MOLECULES OF BIOLOGICAL INTEREST - FT-ICR EXPERIMENTS AND AM1 CALCULATIONS ON NICOTINES, NICOTINIC-ACID DERIVATIVES, AND RELATED-COMPOUNDS
    BERTHELOT, M
    DECOUZON, M
    GAL, JF
    LAURENCE, C
    LEQUESTEL, JY
    MARIA, PC
    TORTAJADA, J
    [J]. JOURNAL OF ORGANIC CHEMISTRY, 1991, 56 (14) : 4490 - 4494
  • [8] Besseau F, 1996, B SOC CHIM FR, V133, P381
  • [9] HYDROGEN-BOND BASICITY OF ESTERS, LACTONES AND CARBONATES
    BESSEAU, F
    LAURENCE, C
    BERTHELOT, M
    [J]. JOURNAL OF THE CHEMICAL SOCIETY-PERKIN TRANSACTIONS 2, 1994, (03): : 485 - 489
  • [10] Chardin A, 1996, B SOC CHIM FR, V133, P389