ISSN:
0021-8383
Keywords:
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
1H-N. M. R., 13C—N. M. R., and I. R.-Investigations Concerning Tautomerism of 15N-Labeled 3-Methyl-1-phenyl-Δ2-pyrazolin-5-oneThe behaviour of the 15N-mono and dilabeled compound in dependence on temperature and solvent polarity is described. Chemical shifts, nJ(15N—1H), and nJ(15N—13C) coupling constants (n = 1 - 3) have been determined. In the cases of 2, 2, 2-trifluoroethanole and hexafluoroisopropanole the Δ4-pyrazolin-3-one is stabilized and detected by 3J(15N—2—H—4) = 3 Hz, 1J(13C—3—15N—2) = 11, 0 Hz and δ(13C—5). In HMPT the 5-hydroxypyrazole form predominates and is characterized by 3J(15N—1—H—4) = 5, 1 Hz and δ (13C—5).Coupling constants 3J(15N—2—H—4) and J(13C—3—15N—2) could not be observed in this solvent.In accordance with 1H- and 13C-n. m. r.-parameters i. r. measurements in dependence on temperature lead to the conclusion that in DMSO and THF for instance all three tautomers are present and variation of temperature does not change the equilibrium between the tautomers.A good relationship between the content of the CH2, OH and NH forms and the Donor Numbers (DN) and Acceptor Numbers (AN) by Gutmann has been found.
Additional Material:
3 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/prac.19833250209
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