Merck dc alufolien kieselgel 60 f254

All reagents and solvents were from Merck (formerly Sigma-Aldrich, Darmstadt, Germany) and were purified by standard procedures. The organic solutions were dried over anhydrous magnesium sulphate and evaporated using a rotatory evaporator operating at a reduced pressure of about 10–20 mmHg. The melting ranges of the solid compounds in this study were determined on a 360 D melting point device with a resolution of 0.1 °C (MICROTECH S.R.L., Pozzuoli, Naples, Italy). The melting points and boiling points are uncorrected. Attenuated total reflectance (ATR), Fourier transform infrared (FTIR), ¹H and ¹³C NMR analyses were carried out on the same instruments as previously reported [41 (link)]. Column chromatography was performed on Merck silica gel (70–230 mesh). Potentiometric titrations were carried out using a Hanna Micro-processor Bench pH Meter (Hanna Instruments Italia srl, Ronchi di Villafranca Padovana, Padova, Italy), which was calibrated using standard solutions at pH = 4, 7, and 10 before titrations. Thin layer chromatography (TLC) was carried out using aluminum-backed silica gel plates (Merck DC-Alufolien Kieselgel 60 F254, Merck, Washington, DC, USA), and detection of spots was made by UV light (254 nm) using a Handheld UV Lamp, LW/SW, 6W, UVGL-58 (Science Company^®, Lakewood, CO, USA).

The ¹H and ¹³C NMR spectra of all compounds were measured using Bruker AVANCE III HD spectrometer at the 500 MHz transmitter frequency for ¹H at a temperature of 298 K. The spectra were measured at a temperature of 295 K in the CDCl₃ solution relatively to the TMS signal as a ¹H and ¹³C chemical shift standard. The NMR studies were measured using the results from one- and two-dimensional NMR spectroscopy: ¹H, ¹³C, HSQC, HMBC, and COSY. The ESI-MS spectra were recorded on a PE Biosystems Mariner mass spectrometer. The progress of the reaction was monitored by thin layer chromatography (TLC) with Merck DC-Alufolien Kieselgel 60 F₂₅₄. The chemicals and solvents were purchased from Fluka Company. Column chromatography was performed on Merck silica gel 60 (230–400 mesh).