1976 Volume 25 Issue 274 Pages 653-657
Silica gels were treated with optically active tartaric acid esters, i. e., L(+)tartaric acid dimethyl, diethyl and di-n-butyl esters. The numbers of surface group were estimated as 2∼3×1014cm-2 from the microanalysis and the argon surface areas of the surface-treated silica gels. The characteristic absorptions due to their surface groups were observed in their ir absorption spectra. These surface groups were easily hydrolysed and the aqueous solutions after hydrolysis of their surface-treated silica gels showed the same optically active and the same specific rotation as the ones of the tartaric acid esters used. From these results, the surface groups were confirmed to be composed of the tartaric acid esters used and they were also optically active. The reaction was also confirmed to proceed with the silyl fission as shown in the following scheme:
_??_Si_??_OH+HC-ROCOCHOH H_??_OCOOR→_??_SiOC-CHOHCOOR COORH+H2O
The surface-treated silica gels were dispersed into water. But these gels, except the silica gels treated with dimethyl tartarate, were flocculated and transferred into the interfacial region between the immiscible two liquids like n-hexane and water. The surface tensions of the surface-treated silica gels, γS, were estimated as γS>183erg/cm2 for the ones treated with dimethyl tartarate and 72.8>γS>80.9erg/cm2 for the other two kinds of silica gels.