72092-79-6Relevant academic research and scientific papers
Conjugation and proton exchange equilibria. Heteroconjugation constants in substituted phenol-piperidine systems in acetonitrile
Magonski, Jozef,Rajzer, Barbara
, p. 1181 - 1185 (2007/10/03)
It has been shown by mathematical transformations that the final equations and expressions required for determining equilibrium concentrations of major species in HA + B systems are analogous to those used previously for HA + A1- systems. Heteroconjugation constants K→AHB = [AHB]/([HA][B]) for eight substituted phenol (HA)-piperidine (B) systems in acetonitrile (AN) were determined from emf measurements. A fairly linear dependence between log K→AHB and ΔpKaAN = pKBH+AN - pKHAAN was observed with a slope of 0.52. The [KAHB2/(KAHA - KBHB+)]atδpKa=0 quotient appeared to be much greater than [KAHA1-2/(KAHA - KA1HA1-)]atΔpKa=0 calculated from results obtained previously for HA + A1- type systems. From this fact it has been concluded that the formation of AHB type complexes (relative to the AHA- and BHB+ type complexes) is likely to be favoured by their overall neutrality ensuring weaker peripheral interactions.
