Naslov
Solvolytic Behavior of Aliphatic Carboxylates

Autori
Matić, Mirela ; Denegri, Bernard ; Kronja, Olga

Izvornik
European journal of organic chemistry (1434-193X) (2014), 7; 1477-1486

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

Ključne riječi
carboxylate; benzhydryl; nucleofugality; solvolysis; inductive effect; Hammond postulate

Sažetak
The leaving group abilities (nucleofugalities) of a series of aliphatic carboxylates have been obtained by determining the nucleofuge-specific parameters (Nf and sf) from solvolysis rate constants of X, Y-substituted benzhydryl carboxylates in a series of aqueous ethanol mixtures by applying the linear free energy relationship (LFER) equation: log k = sf (Ef + Nf). Those can be employed to compare reactivities of carboxylates with reactivities of other leaving groups previously included in the nucleofugality scale, and also to estimate solvolysis rates of various carboxylates. It is confirmed that the inductive effect is the most important variable that determines the reactivities of halogenated carboxylates in solution. Moreover, both the Hammett correlation and solvolytic activation parameters have revealed a strong influence of the inductive effect on the nucleofugality of alkyl-substituted carboxylates. The reaction constants (sf) indicate that the carboxylate substrates with weaker leaving groups solvolyze via later, more carbocation-like transition states, which is in accord with the Hammond postulate. In addition, due to less demand for solvation of the transition states that produce more stabilized benzhydrylium ions, in which more efficient charge delocalization occurs, the reaction constants (sf) obtained with most of the leaving groups investigated here increase as the polarity of the solvent decreases.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

POVEZANOST RADA