Naslov
Influence of a Side-Chain on Deuterium Isotope Effects in C-13 NMR Spectra of Some Benzene Derivatives

Autori
Novak, Predrag ; Vikić-Topić, Dražen ; Meić, Zlatko ; Gacs-Baitz, Eszter

Izvornik
Magnetic Resonance in Chemistry (0749-1581) 34 (1996), 8; 610-615

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
C-13 NMR ; Deuterium isotope effects ; Toluene ; Benzoic acid ; Benzophenone

Sažetak
Deuterium-induced isotope effects on C-13 chemical shifts were measured in a series of benzene derivatives, viz, toluene, benzoic acid and benzophenone, The effects over two, three and four bonds reflect a dependence on the transmission pathway and the nature of the side-chain. Steric and inductive influences of side-chain lane pair electrons located at the P-position to the phenyl ring account for a lower magnitude and negative sign of some effects in the deuteriated phenyl ring. In monodeuteriated benzophenones isotope effects are transmitted to the second phenyl ring, e.g. in p-deuteriobenzophenone over up to nine bonds, Although the carbonyl group allows only a minor conjugation between the phenyl rings, the extent, the magnitude and the sign of isotope effects resemble those in fully conjugated molecules, indicating a similar transmission mechanism. In polydeuteriated isotopomers, the additivity of isotope effects holds for the majority of carbon atoms. However, in few cases significant deviations exist owing to perturbations in hydrogen-bond dynamics and redistribution of rotamer populations caused by deuteriation, For monodeuteriated isotopomers, a number of C-13-H-2 coupling constants through one and three bonds are also reported.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

POVEZANOST RADA