LOW-TEMPERATURE PYROLYTIC TRANSFORMATIONS OF TRI-TERT-BUTOXYSILOXY DERIVATIVES OF ALUMINUM TO ALUMINOSILICATE MATERIALS

被引:63
作者
TERRY, KW [1 ]
GANZEL, PK [1 ]
TILLEY, TD [1 ]
机构
[1] UNIV CALIF SAN DIEGO,DEPT CHEM 0506,9500 GILMAN DR,LA JOLLA,CA 92093
关键词
D O I
10.1021/cm00024a032
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
The tri-tert-butoxysiloxy complex {Me2Al[mu-OSi(OtBu)3]}2 (1) Was prepared by the reaction of [AlMe3]2 with HOSi(OtBU)3. Crystals Of 1 are tetragonal (P4(2)nm) with a = 14.684 (3) angstrom, c = 9.463 (2) angstrom, V = 2041.8 (9) angstrom3, Z = 4, and R(F) = 5.77%. Molecules of 1 in the crystal have a folded Al2O2 core (156.2-degrees), probably because of steric interactions involving the bulky siloxy groups. A trimeric derivative, [Me(tBuO)AlO-Si(OtBu)3]3 (2), was obtained by addition of tert-butyl alcohol to 1. Compounds 1 and 2 were investigated as precursors to aluminosilicate materials. In the solid state, 1 undergoes thermolysis at low temperatures (150-200-degrees-C) by cleanly eliminating isobutylene (6 equiv), along with methane and water. Clean conversion to a A12O3.2SiO2 material is observed by thermal gravimetric analysis (TGA) and elemental analysis. Differential thermal analysis (DTA) and X-ray powder diffraction (XRD) show that mullite crystallizes at about 1000-degrees-C, and at 1200-degrees-C, mullite particles of about 15 nm are produced (as calculated from the Scherrer equation). Compound 2 exhibits similar pyrolytic conversions, except that much higher surface areas are observed for the aluminosilicates produced. For example, thermolysis of 2 at 200-degrees-C gives a sample with a BET surface area of 270 m2 g-1, compared to a surface area of only 30 M2 g-1 for a sample obtained similarly from 1. Compound 2 also cleanly decomposes by elimination of isobutylene (12 equiv). The network-forming thermolyses of 1 and 2 are facile enough to be conveniently carried out in solution. For example, 1 is pyrolyzed in refluxing toluene, resulting in a polymerization that resembles the sol-gel process. A gel powder obtained from this procedure had a surface area of 210 m2 g-1 and was composed of small particles (ca. 500 nm in diameter) consisting of much smaller grains (by transmission electron microscopy, TEM). Heating this sample to 800-degrees-C increased the BET surface area to 280 m2 g-1, and further heating to 1200-degrees-C produced mullite particles (average size 18 nm, by XRD) that were densely packed into an amorphous silica matrix (by TEM).
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页码:1290 / 1295
页数:6
相关论文
共 40 条
[1]   ALKOXYSILANES .2. PREPARATION OF TRIBUTOXYSILOXYCHLOROSILANES SILANOLS AND THEIR POLYMERIC SUBSTANCES [J].
ABE, Y ;
KIJIMA, I .
BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN, 1969, 42 (04) :1118-+
[2]   SYNTHESIS AND CHARACTERIZATION OF TRIETHYLSILOXY-SUBSTITUTED ALUMOXANES - THEIR STRUCTURAL RELATIONSHIP TO THE MINERALS BOEHMITE AND DIASPORE [J].
APBLETT, AW ;
WARREN, AC ;
BARRON, AR .
CHEMISTRY OF MATERIALS, 1992, 4 (01) :167-182
[3]   1ST-EXAMPLE OF AN ORGANOGALLIUM COMPOUND CONTAINING A GALLIUM-TELLURIUM BOND - SYNTHESIS, PROPERTIES, AND MOLECULAR-STRUCTURE OF [(ME3CCH2)2GATEPH]2 [J].
BANKS, MA ;
BEACHLEY, OT ;
GYSLING, HJ ;
LUSS, HR .
ORGANOMETALLICS, 1990, 9 (06) :1979-1982
[4]  
BOILOT JP, 1988, MATER RES SOC S P, V121, P121
[5]   THE PYROLYSIS OF METAL ALKOXIDES .2. KINETIC STUDIES ON ZIRCONIUM TETRA-TERT-AMYLOXIDE [J].
BRADLEY, DC ;
FAKTOR, MM .
TRANSACTIONS OF THE FARADAY SOCIETY, 1959, 55 (12) :2117-2123
[6]   METAL ALKOXIDES AS PRECURSORS FOR ELECTRONIC AND CERAMIC MATERIALS [J].
BRADLEY, DC .
CHEMICAL REVIEWS, 1989, 89 (06) :1317-1322
[7]   ETHYLENE POLYMERIZATION WITH SUPPORTED BIS(TRIPHENYLSILYL) CHROMATE CATALYSTS [J].
CARRICK, WL ;
KARAPINK.GL ;
KAROL, FJ ;
TURBETT, RJ ;
JOHNSON, RN ;
FOX, AS .
JOURNAL OF POLYMER SCIENCE PART A-1-POLYMER CHEMISTRY, 1972, 10 (09) :2609-&
[8]   CRYSTAL AND MOLECULAR-STRUCTURE OF AL2(O-T-BU)6 - COMMENTS ON THE EXTENT OF M-O-PI BONDING IN GROUP-6 AND GROUP-13 ALKOXIDES [J].
CAYTON, RH ;
CHISHOLM, MH ;
DAVIDSON, ER ;
DISTASI, VF ;
DU, P ;
HUFFMAN, JC .
INORGANIC CHEMISTRY, 1991, 30 (05) :1020-1024
[9]   BUTYL METAL ARYLOXIDES, ARYLAMIDES, AND SULFUR AND PHOSPHORUS ANALOGS .2. SYNTHESIS AND CHARACTERIZATION OF NOVEL BULKY ALKOXIDES AND ARYLOXIDES OF ALUMINUM - X-RAY STRUCTURE OF [AL(MU-OCH2C6H2BU3TERT-2,4,6)ME2]2 [J].
CETINKAYA, B ;
HITCHCOCK, PB ;
JASIM, HA ;
LAPPERT, MF ;
WILLIAMS, HD .
POLYHEDRON, 1990, 9 (2-3) :239-243
[10]   Preparation and Structure of Aluminosilicate Aerogels [J].
Chaput, F. ;
Lecomte, A. ;
Dauger, A. ;
Boilot, J. P. .
CHEMISTRY OF MATERIALS, 1989, 1 (02) :199-201