Naslov
Lack of the neighboring group rate effect in solvolytic reactions that proceed via participation

Autori
Jurić, Sandra ; Kronja, Olga

Izvornik
Journal of Physical Organic Chemistry (0894-3230) 21 (2008), 2; 108-111

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

Ključne riječi
neighboring group assistance; extended participation; inverse neighboring group rate effect

Sažetak
In order to investigate the influence of solvent polarity on the rate effect of double bonds in reactions that proceed via an extended pi-participation mechanism, the solvolysis rates (k(U)) of the benzyl chloride derivative 1 and tertiary chloride 2 that have doubly unsaturated side chains were measured in absolute ethanol, 80% v/v. aq. ethanol and 97% wt. aq. trifluoroethanol. The rates of the corresponding saturated analogs IS and 2S (k(S)) were measured in 80% aq. ethanol and 97% wt. aq. trifluoroethanol, while those in pure ethanol were calculated according to LIFER equation log k = s(f) (E-f + N-f). In solvents with moderate ionizing power (ethanol and 80% aq. ethanol) the expected rate effects were obtained (k(U)/k(S)>1), while in solvent with high ionizing power (2, 2, 2-trifluoroethanol) absence of the rate effect was observed (k(U)/k(S) approximate to 1), indicating that in the ks process the solvation of the transition state is very important, while in k(Delta) process the breaking of the C-Cl bond is not appreciably developed in the transition state and the solvent effect is marginal.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

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