The combined catalyst PCl5–HCl shows effective catalysis in the trimerization of some aromatic nitriles or trichloroacetonitrile to s-triazines (III). The scope and limitation of the trimerization, in comparison with other Lewis acids, and its mechanism were studied. It was confirmed that PCl5 is effective both in the formation of an intermediate, nitrile–HCl 2:2 adduct, and in the reaction of the 2:2 adduct with another nitrile to s-triazine.
The authors synthesized nonionic surfactants containing dimethylpolysilane, dimethylpolysilmethylene and dimethylpolysiloxane as the hydrophobic groups, and investigated their surface activities. In their ability to lower the aqueous surface tension, the polysiloxane surfactants were the most active, and there is little reason to choose between the other two kinds of surfactants. With regard to the ability of lowering the interfacial tension between water and silicone oil, the polysilmethylene surfaetants were most effective when the concentration of aqueous solution was below 0.5 wt %. Above this concentration, however, the polysiloxane surfactants were superior. Also investigated was the lowering of surface tension of nonaqueous polyols and their ability to wet low energy hydrophobic surfaces such as polyethylene.
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