A method for improving the calculation accuracy of acid–base constants by inverse gas chromatography

In this paper, studies were conducted in order to improve the calculation accuracy of acid–base constants measured by inverse gas chromatography. The conventional a⋅(γld)0.5 parameters of DCM (dichloromethane), TCM (trichloromethane), and EtAcet (ethyl acetate) were corrected as 185, 212, and 235 Å2(mJ/m2)0.5 by analyzing the relationship between a⋅(γld)0.5 and the boiling temperature of the probe solvents, where a   is molecular area and γld is surface dispersive free energy of the probe solvents, respectively. To validate the availability of the new a⋅(γld)0.5 values, the acid–base constants of polystyrene were measured. It was found that when the new a⋅(γld)0.5 parameters were adopted, the final linear fit degree for the plot of −ΔHas/AN* versus DN/AN  * was enhanced from 0.993 to 0.999, and the standard deviation was decreased from 0.344 to 0.156. In addition, the availability of general application to improving the calculation accuracy of acid–base constants with the new a⋅(γld)0.5 parameters was also proved with a mathematical justification.

► Acid–base accuracy is enhanced by amending basic parameters of DCM, TCM, and EtAcet.
► Conventional a⋅(γld)0.5 of DCM, TCM, and EtAcet are amended as 185, 212, and 235 Å2(mJ/m2)0.5.
► Validity of the method is proved with IGC experiment and mathematics justification.