A Novel ion extraction materials derived from molecular recognition properties of silica surface modified benzoxazine local structure

Abstract

A series of silylbenzoxazines with different bulky group on benzene ring, i.e., 3-triethoxysilyl-n-propyl-3,4-dihydro-2H-1,3-benzoxazine (1), 3-triethoxysilyl-n-propyl-3,4-dihydo-6-methyl-2H-1,3-benzoxazine(2), and 3-triethoxysilyl-n-propyl-3,4-dihydo-6,8-dimethyl-2H-1,3-benzoxazine(3), were prepared. Silica surface modified benzoxazine was successfully achieved via silylbenzoxazine derivatives coupling onto silica gel in solventless system. The subtracted FTIR spectra between the silica surface modified silylbenzoxazine derivatives show two bands near 1050 and 770 cm-1 which are assigned to the formation of Si-O-Si linkages. Elemental analysis shows that almost all alkoxysilanes are coupled onto silica surface. The ion extraction studies of various alkali and alkaline earth metal ions by the column chromatography packed with silica-benzoxazine resin show that 3triethoxysilyl-n-propyl-3,4-dihydo-6,8-dimethyl-2H-1,3-benzoxazine coupled with silica(6) exhibits ion extraction efficiency at 82-95% while 3triethoxysilyl-n-propyl-3,4-dihydro-2H-1,3-benzoxazine coupled with silica(4) performs only 65-83%.