Researches on preparation and properties of sodium polysulphide as gold leaching agent

Synthesis and Characterization of Disiloxane Cross-Linked Polysulfides

“…Instrumentation. Solution-based NMR samples were dissolved in CDCl 3 and recorded using a Bruker Avance 400 MHz spectrometer for 1 H, 29 Si, and 13 C NMR spectroscopies, and all spectra were recorded in parts per million (ppm). The 1 H NMR spectra were calibrated using tetramethylsilane (TMS) and referenced to residual amounts of protium found in the NMR solvent (e.g.…”

“…Recycle delays were used to assure complete relaxation of the components present, and they were determined using 1 H saturation−recovery experiments. The 13 C chemical shift scale for all 13 C experiments was referenced using the 13 C signal of TMS (0 ppm). Data processing was carried out using the Bruker TopSpin software.…”

“…Data processing was carried out using the Bruker TopSpin software. The Mestrelab MNOVA 14.1.1−25024 NMR data processing software package was used to predict and make tentative peak assignments in the 13 C CP/MAS spectra. The software uses several machine learning procedures together with Increments and HOSE-code algorithms (Modgraph).…”

“…1 H NMR (400 MHz, CDCl 3 ) δ: 5.82−5.72 (m, CH, 2H), 4.89− 4.83 (m, CH 2 , 4H), 1.55 (d, 3 J HH = 8.2 Hz, CH 2 , 4H), 0.07 (s, CH 3 , 12H). 13 Synthesis of 1,1,3,3-Tetramethyl-1,3-divinyldisiloxane, DVDSi. Under N 2 , chloro(dimethyl)vinylsilane (5.52 mL, 40 mmol) was cooled to 0 °C using an ice bath.…”

“…12 This method, however, is not efficient as it is a two-step reaction, and the first step involves the synthesis of the sodium polysulfide known to cause the formation of side products such as sodium thiosulfate. 13 Polysulfides are also formed from elemental sulfur via ring opening polymerization (ROP) when heated above 159 °C. These polysulfides are not stable as they revert back to cyclic S 8 when cooled below the floor temperature.…”