Preparation of N-acyl sulfonamides (2a-j), (3a-m), (5a-f) and cyclic imides (3n-r)Under nitrogen atmosphere, a mixture of sulfonamide (1 mmol), acylating agent (2 mmol) and Cs 5 HP 2 W 18 O 62 catalyst (5 mmol %) in water (2 mL), was stirred at room temperature to obtain (2a-j), (3a-m), (5a-f) and under reflux for (3n-r). Reaction was monitored by TLC. After completion of the reaction, the catalyst was removed by filtration. The filtrate was washed by water (10 mL) and extracted with EtOAc (3x15 mL). The combined organic layers were dried over anhydrous Na 2 SO 4 , then the solvent was evaporated in vacuum, and the crude compound was purified by flash chromatography (Merck silica gel 60 H, CH 2 Cl 2 /MeOH, 9:1) to afford the corresponding products.. NMR data of N-acyl sulfonamide derivatives (2a-j) N-(N-butylsulfamoyl)acetamide (2a)

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In this study, the photocatalytic degradation of seven sulfur compounds (2-methylthiophene, 3-methylthiophene, 2-phenylthiophene, 3-phenylthiophene, 2,5-diphenylthiophene, 2-(2-thienyl) pyridine, and 2-(3-thienyl) pyridine in semiaqueous medium are compared to thiophene. The apparent-reaction-rate constant (k) is found to decrease in the following order: 2From the data obtained by UV light absorption (λ max ) measurements and electronic structure calculations (frontier orbitals energy, global hardness, and global softness), the kinetic parameters of the reaction have been determined. Among the studied compounds, thiophene with a high λ max and low calculated LUMO−HOMO gap energy has showed higher activity under UV irradiation. Interestingly, a lower activity is observed with low λ max and high LUMO−HOMO gap energy. This demonstrates, for the first time, that the reactivity depends essentially on the thermodynamic stability of the sulfur compound rather than on the nature or the position of the substituent on the ring.

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