The inhibition effect of N-(8-bromo-3H-phenoxazin-3-ylidene)-N,N’-dimethylaminium (DPhDMA) on the corrosion behavior of mild steel in 1.0 M HCl solution has been studied. Weight loss measurements, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and quantum chemical calculations were used in this study. Electrochemical results revealed that DPhDMA is an effective mixed type inhibitor for mild steel in 1.0 M HCl solution, and its inhibition efficiency increased with increasing its concentration and with the immersion time of the samples in the corrosive media. The adsorption of DPhDMA also led to a reduction in electric double layer capacitance and an increase in charge transfer resistance confirming its inhibitive effect on the corrosion behavior of mild steel samples. The thermodynamic parameters governing the adsorption process showed that DPhDMA was adsorbed spontaneously on mild steel surface through a combination of physical and chemical mechanisms following Langmuir adsorption isotherm. Quantum chemical calculations were used to correlate the performance of DPhDMA with its electronic structural parameters. تفاصيل المقالة

Sulfonic acid functionalized nanoporous silica (SBA-Pr-SO3H) with a pore size of 6 nm catalyzed three component coupling of aromatic aldehydes, urea and ethyl acetoacetate to afford the corresponding dihydropyrimidinones under solvent free condition. This new protocol for Biginelli reaction has important advantages such as green synthesis, short reaction time, easy isolation and high yields of products and reusability of the catalyst. SBA-Pr-SO3H was proved to be an efficient heterogeneous nanoporous solid acid catalyst which could be easily handled and removed from the reaction mixture by simple filtration and can be recovered and reused for several times without any loss of activity. تفاصيل المقالة