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A tandem acetylene-activated SNAr-anionic cyclization strategy is presented for the synthesis of chalcogen-containing hetero[5]­helicenes. Oxa-, thia-, and selena[5]­helicenes are accessed from common ortho-fluoro-ethynylarene precursors, allowing the heteroatoms to be installed at the 1-position or 1- and 12-positions of the hetero[5]­helicene inner core surface.

Difluoromethane (R32) as a refrigerant with zero ozone depletion potential and low global warming potential has received extensive attention in the refrigeration industry. The phase behavior of refrigerant/lubricant mixtures has a critical effect on the performance and operation safety in a compression-refrigeration system. Using the isochoric saturation method, the solubilities of refrigerant R32 in POE75 and in PVE68 lubricant were measured from 278.15 to 348.15 K. The results indicate that there is no sediment, no color change, and no stratification during the whole experiment. The nonrandom two-fluid equation was used to correlate the experimental data. For both oils, solubilities of R32 increase with the decrease of temperature and increase of pressure. R32 is more soluble in PVE than in POE. In addition, the Henry's constants were calculated for R32 in both oils at different temperatures.

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