Abstract
Adduct formation was confirmed between dimethylamine and six sulfonamides (sulfadiazine, sulfisomidine, sulfamethoxypyridazine, sulfamethoxazole, sulfathiazole, and sulfisoxazole). The thermal, micromeritical and other physico-chemical properties of these adducts as well as their desorbed products were investigated by differential scanning calorimetry, thermogravimetry, thermomicroscopy, infrared spectroscopy, X-ray powder diffractometry, electron microscopy, and BET gas adsorption analysis. The composition of the sulfathiazole adduct was not clarified by any method ; however, the combining ratios of other adducts were found to be 1 : 1 except that sulfisomidine formed 1 : 2 adduct. As new absorption bands arising from NH2+ stretching vibration appeared in the infrared spectra of all the adducts, it was considered that ionic bonding force would principally participate in the adduct formation. Although desorption of dimethylamine from these adducts was rather difficult, the adducts of sulfadiazine, sulfisomidine, sulfamethoxypyridazine, and sulfamethoxazole released combined dimethylamine without liquefaction by heating under reduced pressure. The original sulfonamides thus recovered were effectively micronized and their specific surface areas were about twice larger those via the corresponding ammonia adducts. It was concluded that these findings would be explainable by the basic strength and the molecular volume of dimethylamine.
