THE TAUTOMERISM OF 3(5)-PHENYLPYRAZOLES - AN EXPERIMENTAL (H-1, C-13, N-15 NMR AND X-RAY CRYSTALLOGRAPHY) STUDY

被引:89
作者
AGUILARPARRILLA, F
CATIVIELA, C
DEVILLEGAS, MDD
ELGUERO, J
FOCESFOCES, C
LAUREIRO, JIG
CANO, FH
LIMBACH, HH
SMITH, JAS
TOIRON, C
机构
[1] FREE UNIV BERLIN,INST ORGAN CHEM,FACHBEREICH CHEM,TAKUSTR 3,W-1000 BERLIN 33,GERMANY
[2] UNIV ZARAGOZA,FAC CIENCIAS,ICMA,DEPT QUIM ORGAN,E-50009 ZARAGOZA,SPAIN
[3] INST QUIM MED,E-28006 MADRID,SPAIN
[4] CSIC,INST QUIM FIS ROCASOLANO,UEI CRISTALOG,E-28006 MADRID,SPAIN
[5] UNIV LONDON KINGS COLL,DEPT CHEM,LONDON WC2R 2LS,ENGLAND
来源
JOURNAL OF THE CHEMICAL SOCIETY-PERKIN TRANSACTIONS 2 | 1992年 / 10期
关键词
D O I
10.1039/p29920001737
中图分类号
O62 [有机化学];
学科分类号
070303 ; 081704 ;
摘要
3(5)-Phenyl- and 5(3)-methyl-3(5)-phenylpyrazole have been studied using multinuclear NMR spectroscopy at low temperature to determine the tautomeric equilibrium constants in the slow proton exchange regime by simple signal integration. In order to compare the results in solution with those in the solid state, the X-ray structure of a derivative of the first, namely 4-bromo-3-phenylpyrazole was determined [triclinic, P1BAR, a = 13.0867(8), b = 13.2546(7), c = 7.8079(3)angstrom, alpha = 100.01 5(4), beta = 93.648(3), gamma = 84.923(5)-degrees, Z = 6]. The conclusions are that 3(5)-phenylpyrazoles exist in solution as mixtures rich in the 3-phenyl tautomer which is also the tautomer present in the solid state, whereas they form monomers which are hydrogen bonded to the solvent in liquids like TH F and self associate in inert solvents.
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页码:1737 / 1742
页数:6
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