ISSN:
0749-1581
Keywords:
Nitropyridines
;
Nitrobenzenes
;
1H and 13C NMR
;
Hydrogen bonding
;
Conformation MS
;
Chemistry
;
Analytical Chemistry and Spectroscopy
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The 1H and 13C NMR spectra of 3-nitro-, 5-nitro- and 3,5-dinitro-2-methoxypyridines have been determined. The results show the preferred cis conformation for the 2-methoxy group, and the importance of steric repulsion between the oxygen atom of this group and those of the o-nitro group which hinders conjugation in the 3-nitro-substituted derivatives. Similar steric inhibition of resonance is observable with 2-N-butylamine-, 2-N-cyclohexylamine- and 2-(N-piperidyl)-substituted nitropyridines, whose 1H and 13C NMR spectra were also determined. In the case of the secondary amines, a hydrogen bond between the amino proton and the 3-nitro group was clearly detected. 1H and 13C NMR spectra of 2,6-dinitro-, 2,4-dinitro- and 2,4,6-trinitro-2-R-benzenes (R = OCH3, NHC4H9, NH-cyclo-C6H11, NC5H10) were also recorded and compared with those of the pyridine derivatives. The electronic aza and nitro group effects are comparable if conjugation of the nitro group is not hindered.
Additional Material:
4 Tab.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/mrc.1260240607
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