The influence of the solvent on organic reactivity. Part II. Hydroxylic solvent effects on the reaction rates of diazodiphenylmethane with 2-(2-substituted cyclohex-1-enyl)acetic and 2-(2-substituted phenyl)acetic acid

Abstract

The rate constants for the reaction of diazodiphenylmethane with 2-(2-substituted cyclohex-1-enyl)acetic acids and 2-(2-substituted phenyl)acetic acids, previously determined in seven hydroxylic solvents, were correlated using the total solvatochromic equation, of the form logk = logk0 + s¶*+ aα + bβ, the two-parameter model, logk=logk0 + s¶*+ aα and a single parameter model logk = logk0 + bβ, where ¶*is a measure of the solvent polarity, α 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 and the solvent effects on the reaction rates were analyzed in terms of initial state and transition state contributions.

Konstante brzina za reakciju između diazodifenilmetana i 2-(2-supstituisanih cikloheksen-1-enil)sirćetnih i 2-(2-supstituisanih fenil)sirćetnih kiselina prethodno određene u sedam alkoholnih rastvarača na 30 ºC, korelisane su totalnom solvatohromnom jednačinom oblika: logk = logk0 + s¶*+ aα + bβ kao i dvoparametarskom logk=logk0 + s¶*+ aα i jednoparametarskom logk = logk0 + bβ, gde je ¶*mera polarnosti rastvarača, α predstavlja skalu baznosti rastvarača kao akceptora protona u vodoničnoj vezi, β 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 parametar su u skladu sa navedenim reakcionim mehanizmom. Slaganje eksperimentalno određenih konstanti brzina sa izračunatim vrednostima je potvrda ispravnosti primenjenog modela. Rezultati prikazani u ovom radu omogućuju kvantitativno razdvajanje i procenu ukupnih efekata rastvarača na polazno i prelazno stanje u reakciji karbonskih kiselina sa DDM-om u alkoholnim rastvaračima.