Reaction between Thiouracil derivatives and Chloroasetic acid in gas and soluble phases:A theoretical study

Thiouracilis a historically relevant anti-thyroid preparation. Because of its structure you can find it in various chemical reactions differently. In this study, the reaction of Thiouracil with Chloroacetic acid and the formation of their additive products has been investigated. This reaction is aconcerted process, and it has not been determined yet by exhaustive mechanisms. From the potential energy profile, two possible mechanisms as well as two NH bonds dissociations are examined. Density Functional Theory (DFT) was used to compare these mechanisms. Calculation results for comparing these two pass ways were indicated byB3LYP/6-311g (d,p) levels of theory. The activation energies to 2-(6-oxo-1,6-dihydropyrimidin-2-ylthio) acetic acid and 2-(4-oxo-1,4-dihydropyrimidin-2-ylthio) acetic acid formation were obtained 55.78 and 72.9 kcal.mol-1, respectively. These calculations were also carried out for ethyl and methyl Thiouracil derivatives. The calculation results indicate that removal of hydrogen from nitrogen to sulfur group at the ortho position is more favorable.