The reactivity of α,β-unsaturated carboxylic acids. Part XVI. The kinetics of the reaction of cycloalkenecarboxylic and cycloalkenylacetic acids with diazodiphenylmethane in various alcohols

Abstract

The rate constants for the reaction of diazodiphenylmethane with 1-cyclopentenecarboxylic, 1-cycloheptenecarboxylic, cyclopent-1-enylacetic and cyclohept-1-enylacetic acids were determined in eight alcohols at 30 ºC using the appropriate UV-spectroscopic method. In order to explain the kinetic results through solvent effects, the second order rate constants of the examined acids were correlated using a total solvatochromic equation, of the form: log k = A0+ s¶*+aα+ bβ, where ¶* is a measure of the solvent polarity, βrepresents the scale of solvent hydrogen bond acceptor basicities and β represents the scale of solvent hydrogen bond donor acidities. The correlations of the kinetic data were carried out by means of multiple linear regression analysis. The opposite sings of the electrophilic and the nucleophilic parameters are in agreement with the well-known reaction mechanism. The results presented in this paper were compared with the kinetic data for 1-cyclohexenecarboxylic and cyclohex-1-enylacetic acids obtained under the same experimental conditions.

Konstante brzina za reakciju između diazodifenilmetana (DDM) i 1-ciklopentenkarbonske, 1-cikloheptenkarbonske, ciklopent-1-enilsirćetne i ciklohept-1-enilsirćetne kiseline su određene u osam alkoholnih rastvarača na 30 ºC odgovarajućim UV-spektrofotometrijskim metodom. Da bi se dobijeni kinetički rezultati objasnili kroz efekte rastvarača konstante brizna reakcije (k) su korelisane totalnom solvatohromnom jednačinom oblika: log k = A0+ s¶*+aα+ bβ, gde je ¶* mera polarnosti rastvarača, βpredstavlja skalu baznosti rastvarača kao akceptora protona u vodoničnoj vezi, a αskalu kiselosti rastvarača kao donora protona u vodoničnoj vezi. Korelacija kinetičkih parametara je izvršena metodom višestruke linearne regresione analize. Suprotni znaci uz elektrofilni i nukleofilni parametear u saglasnosti su sa izvedenim mehanizmom reakcije. Rezultati prikazani u ovom radu su upoređeni sa kinetičkim podacima za 1-cikloheksenkarbonsku i cikloheks-1-enilsirćetnu kiselinu, dobijenim pod istim eksperimentalnim uslovima.