Work

Acidity Scale in 1,2-Difluorobenzene

Year: 2026

Type: article

Abstract: High Resolution Image Download MS PowerPoint Slide Equilibrium Brønsted acidity measurements have been established in 1,2-difluorobenzene (1,2-DFB), both in terms of acid p K a values measured using UV–vis spectrophotometry and unified pH (pH abs ) values measured using differential potentiometry. The p K a values of 137 acids were obtained in 1,2-DFB, of which 33 have been directly measured, spanning 15 orders of magnitude of acidity. The rest have been estimated using p K a values in other solvents (acetonitrile, 1,2-dichloroethane). The p K a values have been anchored to the computational p K a values of 9 compounds. An experimental pH abs scale spanning more than 10 orders of magnitude has been established and aligned with the aqueous pH scale, resulting in a p H a b s H 2 O range from −0.6 to 10.0. The potentiometrically measured p H a b s H 2 O values and p H a b s H 2 O values calculated independently from the experimental p K a values anchored to computational reference values agree well, which demonstrates the solid foundation of the underlying theory. These results open the possibility of quantitatively describing and measuring acid–base processes in 1,2-DFB, including potentiometric and UV–vis spectrophotometric p H a b s H 2 O measurement.

Source: ACS Omega

DOI: 10.1021/acsomega.6c02089