Equilibrium Solubility Determination and Correlation of Isobutoxyphenylboronic Acids in Organic Solvents

The solubility of three isomers of isobutoxyphenylboronic acid in several organic solvents (chloroform, 3-pentanone, acetone, dipropyl ether, and methylcyclohexane) has been determined experimentally by a dynamic method, in which the disappearance of turbidity was determined by light intensity measurements using a luminance probe. The solubility of the ortho-isobutoxyphenylboronic acid is significantly higher than that of other isomers for all of the tested solvents. It can be explained by the differences in the structures of ortho compared with meta and para isomers. Introduction of the isobutoxy group into the phenylboronic acid ring generally increases the solubility in most solvents: it is higher for all of the investigated compounds in comparison with phenylboronic acid for all investigated solvents, except dipropyl ether. Experimental data were correlated by the λh-equation, which gave better results than other models.