Determination and evaluation of acidity constants of some imidazole and thiazole linked acetamide compounds

In this work, the effect of substituents on the acidity constants of some acetamide derivatives was investigated. The acidity constants of nine acetamide derivatives were determined at 25 °C using a UV spectrophotometric method. When the molecules possessed different substituents the values of the acidity constants changed from 6.01 to 8.22 for the first protonation and from 3.07 to 4.73 for the second protonation. The first protonation under these circumstances was observed to occur on the nitrogen atom of the 2-mercaptoimidazole ring. The second protonation was observed to occur on the nitrogen atom of the thiazole ring.