Silicon and Aluminum Complexes:
5- and 6-coordinate silico- and alumino-
glycolates
Tech ID: WTC-90-1
Researchers at the University of Washington have developed simple, direct,
and extremely economical methods of transforming silica and alumina into
reactive glycolato compounds. These well characterized and easily prepared
glycolates have proven to be useful and versatile intermediates in the synthesis
of zeolites and ion conducting polymers, and have great potential as progenitors
to a wide range of glasses, ceramics, gels, and other novel polymers.
Background:
At present, the preparation of silicon containing
materials relies on the high temperature carbo-thermal reduction of silica to
silicon metal. The resulting, high grade, silicon is typically further processed
to make useful products. For example, silicon may be treated with chlorine or
hydrochloric acid to generate SiCl4 or, alternatively, combined with simple
organo-chlorines over a copper/tin catalyst at 200-350 OC to generate
organosilanes that may then be further processed to other, more complex,
organosilanes. Organosilicon compounds are useful and versatile intermediates in
a wide range of fields, including organic synthesis, ceramics, and electronics.
Therefore, new routes to these materials that avoid the use of the initial
energy- and equipment-intensive carbothermal reduction step would be highly
desirable. We present here a direct and highly efficacious, one step, route to
reactive silico- and alumino-glycolato compounds based on the reaction of silica
or alumina with a diol in the presence of base.
Description:
Silica, silica gel, or sand is combined with 1.1
equivalents of a metal hydroxide, an excess of an aliphatic diol and heated
under N2 for several hours with concomitant distillation of excess diol and the
water formed during the course of the reaction. Cooling, followed by
recrystallization from methanol/acetonitrile and drying, affords the glycolato
compounds as white powders in >80% yield. Use of a metal oxide results in the
formation of the 6 coordinate species, while the aluminum glycolate is
conveniently formed from alumina, lithium hydroxide, and a diol.
All alkali and alkaline earth hydroxides have been used to prepare the
5-coordinates silicon species; MgO, CaO, and BaO having been used to generate
the 6-coordinate complexes. Many 1,2 diols and some 1,3 diols have been used in
this reaction.
Applications:
* Low cost, uses silica as inorganic source of
silicon; alumina as source of aluminum.
* Ready, one-step entry to highly
functionalized and easily prepared organosilanes.
* Provides versatile
intermediates for possible use as polymers, glasses, ceramics, zeolites, or in
organic synthesis.
Publications:
Many aspects of this work have been published. In
addition, several workers have begun to explore the rich chemistry of these
compounds. Leading references are as follows:
Synthesis of glycolate complexes:
Blohowiak et al., Chem. Mater., 1994, 6,
2177.
Laine, et al., Nature, 1991, 353, 642.
Hoppe, et al., Angew. Chem.
Int. Ed. Engl., 1993, 32, 287.
Patents:
US 5,099,052 (Silicon and Aluminum Complexes);
US 5,216,155
(Silicon and Aluminum Complexes)
As precursors to silicate glasses and ceramics:
Kansal and Laine, J. Am.
Ceram. Soc., 1994, 77, 875.
Kansal and Laine, J. Am. Ceram. Soc., 1995, 78,
529.
Synthesis of zeolites:
Herreros, et al., Science, 1994, 263, 1585.
Herreros and Klinowski, Chem. Phys. Lett., 1994, 220, 478.
Herreros and Klinowski, J. Chem. Soc. Faraday Trans., 1995, 91, 1147.
Synthesis of inorganic polymers:
US 5,440,011 (Ion Conducting Polymers).
Youngdahl, et al., in Inorganic and Organometallic Polymers
with Special Properties, Laine (ed.), Kluwer Academic Publishers, 1992, p. 99.
Spectroscopic studies:
Herreros, et al., J. Phys. Chem., 1994, 98,
4570.
Status:
The synthesis and composition of the 5- and 6-coordinate
silico- and alumino-glycolates are the subject of United States Patents
#5,099,052 and #5,216,155. The Washington Research Foundation is seeking
qualified commercial partners capable of developing and commercializing this
technology under license.
For additional information, please contact:
Beth G. Etscheid, Ph.D.
Director of Licensing
Washington Research Foundation
2815 Eastlake Avenue E, Suite 300
Seattle, WA 98102
Tel: 206.336.5600 Fax: 206.336.5615
betschei@wrfseattle.org
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