2.1. General remarks
PW (N99%) and other reagents and solvents were commercially
available and purchased from Fluka, Merck, and Aldrich chemical
companies. Oleic acid (79 wt.%) was obtained from Carlo Erba. 1
H
NMR spectra were recorded on a Bruker Avance 200 MHz NMR spectrometer with D2O as solvent and TMS as internal standard. FTIR
spectra were recorded with KBr pellets using a Bruker ALPHA FT-IR
spectrometer. UV–vis spectra were obtained with an Agilent
(8453) UV–vis diode-array spectrometer using quartz cells of 1 cm
optical path. Melting points were determined using a digital
Gallenkamp apparatus. The potential variation was measured with
a Hanna 302 pH meter. The feedstock and products were analyzed
by the gas chromatographic-mass spectroscopy (GC-MS) using an
Agilent GC-6890 N/MS-5973 with a HP-5 capillary column (30 m
length, 0.32 mm i.d., 0.25 mm film thickness).