The 12th Chemical Physics Congress, Karabük, Turkey, 12 - 13 October 2018, pp.22
Sulfonamide antibiotics are used as medicine for the treatment of bacterial diseases . These compounds have been used in high volumes for several decades because of their effectiveness and inexpensiveness  Distribution of these compounds in the environment is a serious problem because of their potential toxicity towards to aquatic life and human health . Therefore an effective elimination of them in aqueous medium is essential to protect human health. The aim of this study is to determine probable reaction path of sulfonamides degradation reactions. For this purpose sulfisoxazole was chosen as a model compound.
In this work, the reaction of sulfisoxazole with hydroxyl radical have been investigated theoretically. Geometry optimizations of the reactants, the product radicals and the transition state complexes were performed with the DFT method within the GAUSSIAN 09 package. The DFT calculations were carried out using the hybrid B3LYP functional, which combines HF and Becke exchange terms with the Lee-Yang-Parr correlation functional with 6-31+g (d,p) basis set. Solvent effect was computed by using CPCM as the solvation model. The solvent was water at 25 0C, with the dielectric constant 78.39.