The study of linear solvation energy relationship for the reactivity of carboxylic acids with diazodiphenylmethane in protic and aprotic solvents

Abstract

Solvent effects on the reactivity of cycloalkenecarboxylic, cycloalkeneacetic, 2-substituted cyclohex-1-enecarboxylic, 2-substituted benzoic, 2-substituted cyclohex-1-eneacetic, 2-substituted phenylacetic, 2-phenylcyclohex-1-enecarboxylic, 2-phenylbenzoic and 2-phenylacrylic acids with diazodiphenylmethane (DDM) were investigated. In order to explain the kinetic results through solvent effects, the second-order rate constants for the reaction of the examined acids with DDM were correlated using the Kamlet-Taft solvatochromic equation. The correlations of the kinetic data were realized by means of multiple linear regression analysis and the solvent effects on the reaction rates were analyzed in terms of the contributions of the initial and the transition state. The signs of the equation coefficients support the proposed mechanism. Solvation models for all the investigated acids are suggested. The quantitative relationship between the molecular structure and the chemical reactivity is also discussed.

Uticaj rastvarača na reaktivnost cikloalkenkarbonskih, cikloalkensirćetnih, 2-supstituisanih cikloheks-1-enkarbonskih, 2-supstituisanih cikloheks-1-ensirćetnih, 2-supstituisanih benzoevih, 2-supstituisanih fenilsirćetnih, 2-fenilcikloheks-1-enkarbonske, 2-fenilbenzoeve i 2-fenilakrilne kiseline sa diazodifenilmetanom je proučavan u nizu protičnih i aprotičnih rastvarača. Da bi se kinetički rezultati objasnili pomoću efekata rastvarača, dobijene konstante brzine reakcije drugog reda su korelisane pomoću Kamlet-Taftove solvatohromne jednačine. Korelacije kinetičkih podataka su izvršene pomoću metode višestruke linearne regresione analize, a efekti rastvarača su posebno analizirani u odnosu na osnovno i prelazno stanje. Aritmetički znaci ispred koeficijenata solvatohromnih parametara odgovaraju pretpostavljenom mehanizmu ispitivane reakcije. Predložen je solvatacioni model za sve proučavane kiseline, koji je pokazao da postoji kvantitativni odnos molekulske strukture i njihove reaktivnosti.