Swelling of Anion Exchangers in Mixed Solvents. III. A Calorimetric Study

The integral heat evolved on swelling of the anion exchange resin Dowex‐1 in chloride and perchlorate forms in water, methanol, ethanol, n‐propanol, acetone and formamide, and in aqueous mixtures of these solvents, was measured calorimetrically as a function of the cross‐linking of the resin (4,8 and 16% DVB) and the solvent composition. Heats of swelling (wetting) of the resin skeleton were also measured. These were found to be negligible compared with the heats of swelling of the exchangers which were in the range of 4–8 kcal/equiv. resin for the chloride form with water, methanol, ethanol and formamide, or their aqueous mixtures, but considerably smaller for the chloride form and solvents rich in propanol or acetone as well as for the perchlorate form. The heats of solution of the monomer analog, benzyltrimethylammonium chloride were found to be endothermic. Their relevance to the heat of swelling, and that of the heat of mixing of the solvents, was examined.