octa(3-aminopropyl)silsesquioxane

Octa(3-aminopropyl)silsesquioxane hydrochloride (OAS) was first described in a patent from Wacker-Chemie GmbH.¹ However, this document does not describe the method of its preparation, nor the spectroscopic data allowing its full identification.² Seven years late F. Feher³ investigated the hydrolytic condensation of (3-aminopropyl) triethoxysilane in a methanolic solution using hydrochloric acid as a catalyst to obtain octakis (3-aminopropyl) octasilsesquioxane chloride salt. The yield of the reaction under these conditions is 30%, and the duration is 4 weeks. Modifications to this procedure can be found in the literature based on the change of the hydrolysable group to the methoxy group or the addition of PtCl₄ cocatalyst. However, these treatments do not significantly increase the yield of the reaction.^4–6 Kaneko and co-workers achieved another valuable approach.⁷ They investigated the hydrolytic condensation of APTMS using a number of different acid catalysts. The best effectiveness was proved using trifluoromethanesulfonic acid. OAS-POSS-CF₃SO₃ was prepared after 5-6 hours in ca. 90% overall yield. However, authors observed the presence of deca-substituted polyhedral silsesquioxane as a minor by-product.⁸ Also Janeta et all developed a modified method using commercially available (3-aminopropyl)triethoxysilane (APTES). Compounds 1-3 (scheme below) can be obtained in a one-step hydrolytic condensation using commercially available (3-aminopropyl)triethoxysilane (APTES) and appropriate amount (relative to APTES) of hydrochloric HCl (3.6 eq), trifluoromethanesulfon yield and avoiding the formation of deca and others that are difficult to separate substituted polyhedral silsesquioxane.⁹

Synthesis of [OAS-POSS-NH₃]X (Chemistry - A European Journal 2014, 20, 15966-15974)


(1) Weidner, R.; Zeller, N.; Deubzer, B.; Frey, V. Organooligosilsesquioxanes. 5047492, 1991.
(2) Hill, A. F.; Fink, M. J. Advances in Organometallic Chemistry; Academic Press, 2011.
(3) Feher, F. J.; Wyndham, K. D. Amine and Ester-Substituted Silsesquioxanes: Synthesis, Characterization and Use as a Core for Starburst Dendrimers. Chem. Commun. 1998, No. 3, 323–324.
(4) Gravel, M.-C.; Zhang, C.; Dinderman, M.; Laine, R. M. Octa(3-Chloroammoniumpropyl) Octasilsesquioxane. Appl. Organomet. Chem. 1999, 13, 329–336.
(5) Feher, F. J.; Wyndham, K. D.; Soulivong, D.; Nguyen, F. Syntheses of Highly Functionalized Cube-Octameric Polyhedral Oligosilsesquioxanes (R8Si8O12). J. Chem. Soc. Dalton Trans. 1999, 1491–1498.
(6) Gültek, A.; Seçkın, T.; Adigüzel, H. İ. Design and Characterization of Amino and Chloro Functionalized Rhombohedral Silsesquioxanes. Turk. J. Chem. 2005, 29, 391–399.
(7) Kaneko, Y.; Shoiriki, M.; Mizumo, T. Preparation of Cage-like Octa(3-Aminopropyl)Silsesquioxane Trifluoromethanesulfonate in Higher Yield with a Shorter Reaction Time. J. Mater. Chem. 2012, 22, 14475–14478.
(8) Tokunaga, T.; Shoiriki, M.; Mizumo, T.; Kaneko, Y. Preparation of Low-Crystalline POSS Containing Two Types of Alkylammonium Groups and Its Optically Transparent Film. J. Mater. Chem. C 2014, 2, 2496–2501.
(9) Janeta, M.; John, Ł.; Ejfler, J.; Szafert, S. High-Yield Synthesis of Amido-Functionalized Polyoctahedral Oligomeric Silsesquioxanes by Using Acyl Chlorides. Chem. – Eur. J. 2014, 20, 15966–15974.