Papers - Okamoto, Masaki

Disproportionation of triethoxysilane over KF/Al2O3 and heat-treated hydrotalcite

E Suzuki, Y Nomoto, M Okamoto, Y Ono

APPLIED CATALYSIS A-GENERAL (ELSEVIER SCIENCE BV)  167 ( 1 ) 7 - 10 1998.02

ISSN  0926-860X

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Under fixed-bed flow conditions, silane, diethoxysilane, and tetraethoxysilane are formed by the disproportionation of triethoxysilane over a KF/Al2O3 or a heat-treated hydrotalcite catalyst. The reactions at 393 K give preponderantly either silane with 17-21% yields or diethoxysilane with 5-10% yields. The preponderance depends on the contact time and the amount of KF loaded on Al2O3. (C) 1998 Elsevier Science B.V.

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Direct Synthesis of Organometallic Compounds by the Reaction of Metallic Silicon, Hydrogen Chloride and Alkene/Alkyne

MASAKI OKAMOTO, SATOSHI ONODERA, YUJI YAMAMOTO, EIICHI SUZUKI, Yoshio Ono

Silicon for the Chemical Industry IV    339 - 348 1998

Disproportionation of triethylsilane over CaY zeolite

E Suzuki, Y Nomoto, M Okamoto, Y Ono

CATALYSIS LETTERS (BALTZER SCI PUBL BV)  54 ( 4 ) 223 - 225 1998

ISSN  1011-372X

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The disproportionation of triethylsilane over CaY zeolite was examined using a fixed-bed flow reactor. The reactions at 673-723 K gave diethylsilane and tetraethylsilane, the conversion of triethylsilane being 50%. Practically no hydrocarbons were included in the product. The effects of the degree of Ca2+ exchange and the reaction variables on the catalytic performance were examined.

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Synthesis of titanium tetraalkoxides from hydrous titanium dioxide and dialkyl carbonates

E Suzuki, S Kusano, H Hatayama, M Okamoto, Y Ono

JOURNAL OF MATERIALS CHEMISTRY (ROYAL SOC CHEMISTRY)  7 ( 10 ) 2049 - 2051 1997.10

ISSN  0959-9428

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The reaction of hydrous titanium dioxide (TiO2 . nH(2)O, n = 0.15-1.23) and dialkyl carbonates at 453-573 K offers a convenient synthetic method for titanium tetraalkoxides which are free from chlorine-containing impurities. Thus, hydrous titanium dioxide was almost completely converted into Ti(OEt)(4) by its reaction with diethyl carbonate at 493 K for 16 h. The reaction proceeded faster in the presence of a sodium hydroxide catalyst. From the hydrous titanium dioxide and dipropyl carbonate, Ti(OPrn)(4) was obtained in a high yield.

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Intermediacy of surface silylene in the direct synthesis of methylchlorosilanes

M Okamoto, S Onodera, T Okano, E Suzuki, Y Ono

JOURNAL OF ORGANOMETALLIC CHEMISTRY (ELSEVIER SCIENCE SA LAUSANNE)  531 ( 1-2 ) 67 - 71 1997.03

ISSN  0022-328X

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The reaction of silicon with methyl chloride was carried out in the presence of butadiene. The products consisted of 1,1-dichlorosilacyclopent-3-ene, 1-methyl-1-chlorosilacyciopent-3-ene and 1-chlorosilacyclopent-3-ene besides methylchlorosilanes. Silacyclopent-3-enes accounted for 25% of the whole products. The high selectivity for silacyclopent-3-enes indicates that surface silylene is the intermediate in the reaction of silicon with methyl chloride.

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Diethoxysilane formation by the disproportionation of triethoxysilane over heat-treated calcium hydroxide

E Suzuki, Y Nomoto, M Okamoto, Y Ono

CATALYSIS LETTERS (BALTZER SCI PUBL BV)  48 ( 1-2 ) 75 - 78 1997

ISSN  1011-372X

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The disproportionation of triethoxysilane was carried out in a fixed-bed flow reactor over the solids obtained by heat-treating calcium hydroxide at various temperatures. In the disproportionation, the reaction proceeding to completeness to afford silane and tetraethoxysilane occurs to far lesser extent: predominantly diethoxysilane is obtained together with tetraethoxysilane. Dimethoxysilane is obtained by the disproportionation of trimethoxysilane also over the heat-treated calcium hydroxide.

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Methylation of pyridin-2-one with methanol over gamma-alumina in vapor phase

M Okamoto, M Tanaka, Y Ono

CATALYSIS LETTERS (BALTZER SCI PUBL BV)  46 ( 1-2 ) 123 - 125 1997

ISSN  1011-372X

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Pyridin-2-one reacts with methanol over gamma-alumina in the vapor phase to afford exclusively 1-methylpyridin-2-one. Thus, 1-methylpyridin-2-one was obtained in a 99% selectivity at a 100% conversion at 573 K.

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Selective synthesis of triphenoxysilane by the reaction of metallic silicon with phenol using copper(I) chloride as the catalyst

M Okamoto, N Watanabe, E Suzuki, Y Ono

JOURNAL OF ORGANOMETALLIC CHEMISTRY (ELSEVIER SCIENCE SA LAUSANNE)  515 ( 1-2 ) 51 - 55 1996.05

ISSN  0022-328X

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When copper(I) chloride was used as a catalyst in the reaction of silicon with phenol, a high selectivity for triphenoxysilane (HSi(OPh)(3)) (94%) was obtained, the other product being tetraphenoxysilane (Si(OPh)(4)). Addition of a small amount of propyl chloride to the feed for poisoning metallic copper enhanced the selectivity for HSi(OPh)(3) without affecting the rate of silicon consumption. This result indicates that HSi(OPh)(3) is an exclusive primary product and that Si(OPh)(4) is formed by the secondary reaction between HSi(OPh)(3) and phenol. The reaction mechanism involving surface silylene intermediate is proposed for the formation of HSi(OPh)(3) as the sole primary product. The intermediacy of surface silylene was confirmed by adding ethylene in the silicon-phenol reaction to give rise to the trapped product ethyldiphenoxysilane, obtained in a 5.8% selectivity.

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DIRECT SYNTHESIS OF ETHYLMETHOXYSILANES BY THE LIQUID-PHASE REACTION OF SILICON, METHANOL AND ETHYLENE

M OKAMOTO, N WATANABE, E SUZUKI, Y ONO

JOURNAL OF ORGANOMETALLIC CHEMISTRY (ELSEVIER SCIENCE SA LAUSANNE)  489 ( 1-2 ) C12 - C16 1995.03

ISSN  0022-328X

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The liquid-phase reactions of silicon, methanol and ethylene in an autoclave gave ethylmethoxysilanes (HSi(C2H5)(OCH3)(2) and Si(C2H5)(OCH3)(3)) besides HSi(OCH3)(3) and Si(OCH3)(4). The reaction conditions for obtaining a high selectivity for the ethylmethoxysilanes were examined. With the use of a high pressure of ethylene and a small amount of methanol in toluene as a solvent at 433 K, ethylmethoxysilanes were obtained in 26% selectivity at silicon conversion of 59%. The direct reaction of silicon with ethanol and ethylene gave HSi(C2H5)(OC2H5)(2) and Si(C2H5)(OC2H5)(3).

SYNTHESIS OF METHOXYSILANES BY THE REACTION OF METALLIC SILICON WITH METHANOL USING COPPER(II) ACETATE AS THE CATALYST

M OKAMOTO, N MIMURA, E SUZUKI, Y ONO

CATALYSIS LETTERS (BALTZER SCI PUBL BV)  33 ( 3-4 ) 421 - 427 1995

ISSN  1011-372X

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The reaction of methanol with silicon was studied using various copper compounds other than the halides. Copper(II) acetate and copper(I) oxide gave high silicon conversions (82%) though the selectivities for trimethoxysilane were low (<19%). The selectivity was appreciably improved by addition of a small amount of thiophene or propyl chloride to the methanol feed.

金属ケイ素からのアルコキシシランの直接合成

岡本昌樹, 鈴木榮一, 小野嘉夫

触媒 37 ( 7 ) 565 1995

SELECTIVE SYNTHESIS OF TRIALKOXYSILANES BY THE REACTION OF METALLIC SILICON WITH ALCOHOLS USING COPPER(I) CHLORIDE AS THE CATALYST

M OKAMOTO, K YAMAMOTO, E SUZUKI, Y ONO

JOURNAL OF CATALYSIS (ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS)  147 ( 1 ) 15 - 23 1994.05

ISSN  0021-9517

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The reactions of silicon with ethanol, propanols and butanols were studied using copper(I) chloride as the catalyst. Primary alcohols reacted with silicon, while secondary and tertiary alcohols did not. The reactions of silicon with ethanol, 1-propanol, and 1-butanol gave high silicon conversions of 95, 85, and 77%, respectively, at 513 K without heating treatment of the silicon-catalyst mixture. Under these conditions, the selectivities for trialkoxysilanes were very high (>99%). The pretreatment of the silicon-catalyst mixtures at high temperatures (i.e., 723 K) to facilitate the formation of Cu3Si Phase is not favorable for the reactions: Both the silicon conversion and the selectivity for trialkoxysilane are sharply depressed. Metallic copper is easily formed on the silicon surface during the reactions after high temperature pretreatment. The metallic copper catalyzes the dehydrogenation of alcohols to aldehydes, which inhibit the silicon-alcohol reactions. It also catalyzes the reaction of trialkoxysilane with alcohol to give tetraalkoxysilane. This brings about the decrease in the selectivity for the trialkoxysilane. However, the high silicon conversion together with high selectivity was obtained by adding thiophene or propyl chloride, which is a poison for copper catalysts, to the alcohol feed. Though 2-propanol does not react with silicon, dimethoxyisopropoxysilane and methoxydiisopropoxysilane were formed appreciably when 2-propanol was fed to the silicon together with methanol. This phenomenon was discussed in relevance of the mechanism of the silicon-alcohol reactions. (C) 1994 Academic Press, Inc.

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DIRECT FORMATION OF ORGANOSILICON COMPOUNDS FROM SILICON, METHANOL AND ALKENES

M OKAMOTO, E SUZUKI, Y ONO

JOURNAL OF THE CHEMICAL SOCIETY-CHEMICAL COMMUNICATIONS (ROYAL SOC CHEMISTRY)   ( 4 ) 507 - 508 1994.02

ISSN  0022-4936

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The reaction of metallic silicon with methanol in the presence of an allyl alkyl ether affords an organosilicon compound, the reaction giving a unique method of synthesizing organosilicon compounds without using organic halides.

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REACTION PATHWAY OF FORMATION OF METHOXYSILANES IN THE REACTION OF SILICON WITH METHANOL CATALYZED BY COPPER(I) CHLORIDE

M OKAMOTO, E SUZUKI, Y ONO

JOURNAL OF CATALYSIS (ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS)  145 ( 2 ) 537 - 543 1994.02

ISSN  0021-9517

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Direct Synthesis of Alkoxysilanes by Gas-solid Reactions

Eiichi Suzuki, Masaki Okamoto, Yoshio Ono

Journal of The Japan Petroleum Institute 37 ( 2 ) 103 - 111 1994

ISSN  0582-4664

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Alkoxysilanes can be synthesized from silicon or silicon oxide. For example, trimethoxysilane is formed directly from silicon by reaction with methanol vapor using copper(I) chloride as a catalyst. Silica gel supporting catalytic component, such as potassium hydroxide, reacts with dimethyl carbonate vapor to form tetramethoxysilane. Rice hull ash can also be used as a silica source, the ash reacting with dimethyl carbonate vapor, even in the absence of a catalyst. These reactions are gas-solid reactions. The rate of alkoxysilanes formation was measured and the effect of the reaction variables on the rate was examined. Together with the kinetic measurements, the microscopic measurement of the solid and the surface analysis techniques were employed to know the activation process of the solid surface by the catalysts. © 1994, The Japan Petroleum Institute. All rights reserved.

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Intermediacy of Surface Silylenes in the Direct Reaction of Silicon with Methanol or Methyl Chloride

Yoshio Ono, MASAKI OKAMOTO, TOMOKI OKANO, NAOTO WATANABE, EIICHI SUZUKI

Silicon for the Chemical Industry II    185 - 196 1994

EFFECT OF PRETREATMENT CONDITIONS OF SI-CUCL MIXTURES ON THE RATE AND SELECTIVITY IN THE REACTION OF SILICON WITH METHANOL USING COPPER(I) CHLORIDE CATALYST

M OKAMOTO, M OSAKA, K YAMAMOTO, E SUZUKI, Y ONO

JOURNAL OF CATALYSIS (ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS)  143 ( 1 ) 64 - 85 1993.09

ISSN  0021-9517

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EFFECT OF OXIDE LAYERS ON THE REACTION OF SILICON WITH METHANOL INTO TRIMETHOXYSILANE USING COPPER(I) CHLORIDE CATALYST

E SUZUKI, M OKAMOTO, Y ONO

SOLID STATE IONICS (ELSEVIER SCIENCE BV)  47 ( 1-2 ) 97 - 104 1991.08

ISSN  0167-2738

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When the SiO2-overlayer of silicon surface was removed by treating silicon grains with aqueous HF solution, the reactivity of silicon towards methanol increased. Thus, trimethoxysilane was formed with almost complete conversion of silicon in three hours and > 98% of selectivity, when the mixture of the silicon grains and a catalyst (copper(1) chloride) was preheated at 513 K and brought in contact with methanol at 513 K. When the silicon with the SiO2-overlayer was used for the reaction after its mixture with copper(I) chloride was heated at 513 K, the reaction started after a long induction period and the rate of the silicon conversion was very low. However, when the preheating was done at 723 K, the reaction proceeded without induction period, irrespective of the presence of the SiO2-overlayer. The selectivity for trimethoxysilane was only about 60%. X-ray photoelectron spectroscopy was used to evaluate the thickness of the oxide layers of silicon surface. The morphology of the reacting silicon grains was also examined by SEM.

A KINETIC-STUDY ON THE COPPER-CATALYZED REACTION OF SILICON WITH METHANOL INTO TRIMETHOXYSILANE

E SUZUKI, M OKAMOTO, Y ONO

CHEMISTRY LETTERS (CHEMICAL SOC JAPAN)   ( 2 ) 199 - 202 1991.02

ISSN  0366-7022

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The reaction of methanol with silicon was carried out in a fixed-bed reactor at 463-533 K. In order to determine the kinetics of the reaction per reaction site on the silicon surface, a pressure- (or temperature-) transition method was employed. The reaction order with respect to methanol was 1.0 and 1.4 for the Si-CuC1 mixture preheated at 513 and 723 K, respectively, indicating that the rate-determining step is not the diffusion of silicon or copper species to the reaction site, but the chemical process involving methanol. Kinetics also indicate that the nature of the reaction sites changes with the preheating conditions of the mixture.

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ACTIVE-SITE FORMATION IN COPPER-CATALYZED SYNTHESIS OF TRIMETHOXYSILANE FROM SILICON AND METHANOL

E SUZUKI, M OKAMOTO, Y ONO

CATALYTIC SCIENCE AND TECHNOLOGY, VOL 1 (KODANSHA LTD)  1   505 - 506 1991