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Nitrogen NMR spectroscopy: Application to some substituted pyrroles
Author(s) -
King Michael M.,
Yeh Herman J. C.,
Dudek Gerald O.
Publication year - 1976
Publication title -
organic magnetic resonance
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0030-4921
DOI - 10.1002/mrc.1270080411
Subject(s) - tautomer , substituent , chemistry , nitrogen , chemical shift , molecule , solvent , spectroscopy , proton , nuclear magnetic resonance spectroscopy , computational chemistry , medicinal chemistry , stereochemistry , organic chemistry , physics , quantum mechanics
A series of 15 N labeled 2‐acylpyrroles was prepared and the nitrogen and proton n.m.r. spectra obtained. 15 N chemical shifts for these compounds are reported for the first time. No correlation between the nitrogen chemical shift and any Hammett substituent constant could be found. No variation in J ( 15 NH) was observed for any compound with changes in solvent, temperature or concentration, ruling out any observable tautomeric equilibria for these systems. An increase in J ( 15 NH) with the addition of electron withdrawing groups indicates increasing polarization of the NH bond and acidity of these molecules. Two and three bond 15 N couplings are also reported.