The non-covalent bindings of CF2Cl2 with NO and SO2

Ab initio calculations have been performed on the complexes of CF₂Cl₂ with NO and SO₂, and a set of stable configurations for CF₂Cl₂–NO and CF₂Cl₂–SO₂ were found with no imaginary frequencies by the MP2 method. In addition, the binding energy and the NBO analysis were used to evaluate the relative stability of the complexes. The calculated results indicate that the weak interactions in the CF₂Cl₂–NO and CF₂Cl₂–SO₂ systems involved are enhanced with the increase of the number of non-covalent bonds. Further studies predict that the CF₂Cl₂–SO₂ system may play a more important role than the CF₂Cl₂–NO system in environmental problem because the former offers a stronger interaction than the latter. Furthermore, the non-covalent binding interactions of Cl···N and Cl···O for CF₂Cl₂–NO system, Cl···O, Cl···S and F···S for CF₂Cl₂–SO₂ system, are the dominant forces, which seem to be very significant as a driving force influencing the arrangement of molecules, especially in CF₂Cl₂–SO₂ system.     

THE ROLE OF INTERFACIAL INTERACTIONS IN THE PARTICLE/BUBBLE ATTACHMENT

The Van Oss surface thermodynamic theory of polar and apolar interfacial interactions was extended to the interaction between mineral surfaces and bubbles across liquid media. The acid base (polar) interfacial interactions are supposed to be responsible for the hydration repulsion between a hydrophilic mineral and a bubble as well as for the hydrophobic attraction between a hydrophobic mineral and the bubble.     

Dispersion Mechanism of Superfine SiC Particles in the Different Condition Liquid

SiC@A1(OH)₃-Y(OH)₃ core-shell composite particles are synthesized by co-precipitation method for strengthening the antioxidation of SiC at high temperature. To reach better A1(OH)₃-Y(OH)₃ composite shell and higher coating ratio on the SiC particles surfaces, SiC particles must be adequately dispersed in the SiC suspension during the coating process. The dispersion mechanism of SiC particles is investigated by the sedimentation method. Through test and analysis, the optimum conditions of the dispersion of SiC particles in the SiC suspension are sedimentating for 10 minutes, ultrasonic dispersion for 10 minutes, the lower SiC concentration, pH = 9, the dispersant content for the 2% volume of SiC suspension and using the polyelectrolyte dispersant, respectively.     

Concurrent synthesis of vanillin and isovanillin

A method for concurrent synthesis of vanillin and isovanillin has been developed by a nonregioselective Vilsmeier–Haack reaction of O-alkyl guaiacols. O-Alkylation of guaiacol provided the corresponding O-alkyl guaiacol (1), which was then formylated with N-methylformanilide/phosphorus oxychloride to give a mixture of 4-alkoxy-3-methoxy-benzaldehyde (2) and 3-alkoxy-4-methoxybenzaldehyde (3). Finally, the obtained mixture underwent a selective dealkylation by anhydrous aluminium trichloride, while leaving methyl groups intact to simultaneously achieve the significant fine chemicals vanillin and isovanillin.     

Phosphonium salt induced stereoselective allylic rearrangement during chlorination of α-hydroxyallylphosphinates

α-Hydroxyallylphosphinates were stereoselectively converted to γ-chloro allylphosphinates when treated with Ph₃P and CCl₄, via substitution of hydroxyl and migration of double bond. The reaction was promoted by phosphonium cation that acted as Lewis acid.