SEMIPREPARATIVE SEPARATION OF MIXED SUBST ITUTED OCTA-(ORGANYLSILSESQUIOXANES) USING NORMAL-PHASE HPLC AND ITS SI-29 NMR SPECTROSCOPIC ANALYSIS

Cohydrolysis of organotrichloro or organotrimethoxy silanes yields the mixed octa-(organosilsesquioxanes), (Si8O12)R8-nR(n)' (n = 0, 1, 2 (3 isomers); R = n-C3H7, R' = 3-ClC3H6 (I), 3-HSC3H6 (III), C3H5 (IV) an d R = C2H5, R' = C2H3 (V)); they can be separated by normal phase HPLC . The degree of substitution and the substitution pattern can be recog nized by the distribution of Si-29-NMR signals, where a linear depende nce of the chemical shift of the R substituted silicon atoms on the nu mber of R' substituted neighbours is observed.