0028612 - UCHP-M 20050103 RIV GB eng J - Journal Article
Schraml, Jan - Tkadlecová, M. - Pataridis, S. - Soukupová, Ludmila - Blechta, Vratislav - Roithová, Jana - Exner, Otto
Ring-Substituted Benzohydroxamic Acids: 1H, 13C and 15N NMR Spectra and NHOH Proton Exchange.
[Benzhydroxamové kyseliny substituované na benzenovém jádře. 1H,13C, 15N NMR spektra a NHOH protonová výměna.]
Magnetic Resonance in Chemistry. Roč. 43, č. 7 (2005), s. 535-542. ISSN 0749-1581. E-ISSN 1097-458X
R&D Projects: GA ČR(CZ) GA203/03/1566; GA AV ČR(CZ) IAA4072605; GA AV ČR(CZ) IAA4072005; GA MŠMT(CZ) LB98233
Institutional research plan: CEZ:AV0Z40720504
Keywords : proton exchange * substituent effects * chemical shifts
Subject RIV: CC - Organic Chemistry
Impact factor: 1.553, year: 2005

NMR spectra (1H, 13C, 15N) of para- and meta-substituted benzohydroxamic acids were studied in dry dimethyl sulfoxide solutions. The 13C chemical shifts were very close to those found by cross-polarization magic angle spinning in solids, the hydroxamic (not hydroximic) structure of which is unambiguous. The hydroxamic structure of these acids in DMSO solutions was proved independently by their 15N chemical shifts. The 15N and 1H chemical shifts of the NHOH fragment showed excellent mutual dependences and dependences on the nature of the ring substituent. According to these dependences and ab initio energy calculations, all the acids assume the same Z conformation. Proton exchange between hydroxamic OH and NH groups in DMSO proceeded by both intra- and intermolecular exchange and the rates did not exhibit any simple relationship to the substituent constants.

Zmíněná NMR spektra byla studována v roztocích DMSO. Uvedené kyseliny maji hydroxamovou strukturu a nikoliv hydroximovou. Vyměna probiha jak intra- tak i inetermolekulárně.
Permanent Link: http://hdl.handle.net/11104/0118536