Download (8Mb) - Etheses - Saurashtra University
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2.7 Experimental<br />
2.7.1 General Methods<br />
All chemical reagents were used without further purification. Solvents for column<br />
chromatography and TLC were laboratory grade and distilled before use. For thinlayer<br />
chromatography (TLC), analytical TLC plates (Alugram SIL G/UV254 (E. M.<br />
Merk) were used. Column chromatography was performed with flash silica gel (100-<br />
200 mesh) or neutral alumina oxide (50-200 micron). 1 H and 13 C NMR spectra were<br />
recorded on a Bruker Avance 300 (300 MHz) or a Bruker AMX-400 (400 MHz)<br />
spectrometers. NMR samples were run in the indicated solvents and were referenced<br />
internally. Chemical shift values were quoted in ppm and coupling constants were<br />
quoted in Hz. Chemical shift multiplicities were reported as s = singlet, d = doublet, t<br />
= triplet, q = quartet, m = multiplet and br = broad. Low-resolution mass spectra were<br />
recorded on a HEWLETT-PACKARD instrument (CI or EI) and LCQ Advantage<br />
instrument (ESI). High-resolution mass spectra (EI) were recorded on a KRATOS<br />
MS50TC instrument. Melting points were determined using Reichert-Jung Thermovar<br />
apparatus and were uncorrected.<br />
2.7.2 Microwave Irradiation Experiments<br />
Microwave irradiation experiments were carried out in a dedicated CEM-Discover<br />
mono-mode microwave apparatus or Milestone MicroSYNTH multi-mode microwave<br />
reactor (Laboratory Microwave Systems). Microwave apparatuses were used in the<br />
standard configuration as delivered, operating at a frequency 2.45 GHz with<br />
continuous irradiation power from 0 to 400 W. The reactions were carried out in 10,<br />
20, 30 and 50 mL glass tubes. The temperature was measured with an IR sensor on<br />
the outer surface of the process vial or fibre optic sensor inside the process vial. After<br />
the irradiation period, the reaction vessel was cooled rapidly (2-5 min) to ambient<br />
temperature by air jet cooling.