Synthesis and Properties of Surface-Active Compounds Containing Silicon Atoms. I.

Synthesis and Properties of Ethyleneoxide-Adducts of 4, 4, 6, 6-Tetramethyl-4, 6-disilheptanol

Abstract

Among the surface-active compounds containing silicon atoms in the hydrophobic group being widely studied recently, methylsiloxane-oxyalkylene copolymers are reported to have very exellent surface activity. But study on surfactants containing polysilmethylene group has never been reported yet. The authors synthesized such compounds and investigated their physical properties to examine the difference of property between silicon-oxgen bond and silicon-carbon bond and the effect of substitution of carbons in the alkyl chain by silicons.
Syntheses were carried out as follow;
4, 4, 6, 6-Tetramethyl-4, 6-disilheptanol was prepeard by the reaction of ethylene oxide with the Grignard reagent of 4, 4, 6, 6-tetramethyl-4, 6-disilpentyl chloride obtained by the reaction of trimethylsilylmethyl lithium with chloromethyl-dimethylchlorosilane.
Ethyleneoxide-adducts of this disilheptanol were obtained by the usual addition reaction with potassium hydroxide catalyst.
Surface tension, wetting power, dispersing power on carbon black in benzene and foaming power of the aqueous solution of the adducts were determined, and it was found that some gave low surface tention at 0.1% and 1.0% solution and good foaming power.
But dispersing power on carbon black in benzene and wetting ability to polyvinyl chloride were less.
These silmethylene-type compounds were inferior to siloxane-type compound in lowering surface tension and wetting power.
In conclusion, siloxane bond is more efficient in lowering surface energy than silmethylene bond, and the effect of substitution of only two carbons in the alkyl chain by silicons is not evident.