論文 - 岡本　昌樹

Encapsulation of cytochrome c in hollow mesoporous silica spheres by denaturation

Masaki Okamoto, Yuki Naito, Kiyoyuki Yamazaki, Shunsuke Odai, Hidehiro Ito, Toshiaki Kamachi

Microporous and Mesoporous Materials （Elsevier）  377   113216 2024年06月

研究論文（学術雑誌）, 共著, 筆頭著者, 責任著者, 査読有り

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Fabrication and Reinforcement of Macro- and Mesoporous Bimodal Materials from Mesoporous Silica-Alumina Spheres and Their Applications to Acid Catalysts and Adsorbents

Masaki Okamoto, Yuki Takahashi, Yusuke Takanaka

Catalysis Surveys from Asia （Springer Nature）  27   39 - 47 2023年

研究論文（学術雑誌）, 共著, 筆頭著者, 責任著者, 査読有り

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Interlayer-expanded MWW-type zeolite catalysts with carbon filler in expanded micropores for efficient microwave heating

Okamoto M., Sakatsume T., Tsubaki S., Wada Y.

Journal of Materials Chemistry A 10   14585 - 14593 2022年

ISSN  20507488

　概要を見る

Recently, microwave (MW) heating has been applied to chemical reactions instead of conventional heating because heating only catalysts by MW radiation is more energy-efficient than heating reaction systems by conventional heating. However, zeolites, which are widely used as catalysts in the chemical industry, can hardly be heated by MW radiation. Here, zeolite catalysts suitable for MW heating were prepared by filling carbon in the interlayer-expanded micropores of MWW-type zeolites. The carbon in the pores was readily heated by MW radiation. When the catalyst was heated in a nitrogen stream by MW radiation at 50 W of consumed electric power, the temperature reached 450 °C for 300 s. However, the temperatures of the MWW-type zeolite and the physical mixture of the MWW-type zeolite and graphite powder were 140 °C and 260 °C, respectively. This indicated that the carbon-filled interlayer-expanded MWW was suitable for MW heating. The methylation of toluene with methanol catalyzed using a proton-type C@expanded MWW by MW heating proceeded at a lower reaction temperature, compared with that of the methylation catalyzed using the physical mixture of the MWW-type zeolite and graphite. This indicated that the carbon-incorporated catalysts were suitable for MW heating and that the internal temperature of the catalyst particles was higher than the external temperature. This enhanced the shape selectivity because the reaction preferentially proceeded inside the pores.

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1,3-butadiene production by crotyl alcohol dehydration over solid acids and catalyst deactivation by water adsorption

Segawa A., Ichijo T., Kimura N., Tsuruta K., Yoshida N., Okamoto M.

Journal of the Japan Petroleum Institute （Journal of the Japan Petroleum Institute）  63 （ 2 ） 70 - 78 2020年

ISSN  13468804

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The synthesis of 1,3-butadiene via the dehydration of crotyl alcohol (2-buten-1-ol) over solid acids (six silica-alumina catalysts, two zeolite catalysts, and one γ-alumina catalyst) was assessed. Crotyl alcohol conversion and butadiene selectivity were both 95% or more over commercial silica-alumina catalysts. However, a sudden decrease in catalytic activity was observed during the reaction. Since the deactivated catalyst was regenerated by drying at 150°C -200°C, results showed that the main cause of the catalyst deactivation was the adsorption of water formed during the reaction and not the coke formation. An analysis of the deactivated catalyst indicated that, since the formation of Al-OH by the hydrolysis of the Al-O-Al bond increased the hydrophilicity of the catalyst surface, the adsorption of water on the catalyst surface was promoted, while that of crotyl alcohol was probably inhibited. Also, based on the catalyst characterization, the silica-alumina catalysts with few silanol groups, few alumina-rich zones, and a low Si/Al ratio were preferable.

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Synthesis of Short, Needle-Shaped Crystals of TON-Type Zeolite by Addition of Inhibitors of Crystal Growth along the [001] Direction

Okamoto M., Nishimura Y., Takahashi M., Chen W.

Crystal Growth and Design （Crystal Growth and Design）  18 （ 11 ） 6573 - 6580 2018年11月

ISSN  15287483

　概要を見る

TON-type zeolite crystals in the shape of short needles were synthesized using inhibitors of crystal growth along the [001] direction. When fluoride was used as a mineralizer, bulky amines incorporating structure-directing agents acted as inhibitors, while nonionic surfactants were more effective as inhibitors for decreasing the crystal length of TON-type zeolite. The amount of surfactant adsorbed on the zeolite increased with the surface area of the face containing pore mouths. This indicates that the surfactant was trapped in the pore mouths to inhibit crystal growth along the long axis of the needle-shaped crystals. By microscopic observation of the crystals, we confirmed inhibition of crystal growth by adsorption of the surfactant. After adsorption of Nile red, a lipophilic stain that is intensely fluorescent in surfactants, on as-synthesized zeolite, only the edges of the needle-shaped crystals were luminous, also indicating adsorption of the surfactant in pore mouths. When hydroxide was used as a mineralizer, the bulky amines acted as inhibitors. Nonionic surfactants, however, did not work. We used the obtained shorter crystals of TON-type zeolites as catalysts for hydroisomerization of n-tetradecane. Use of the shorter crystals improved the selectivity for skeletal isomerization.

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Acetaldehyde Production from Ethanol by Eco-Friendly Non-Chromium Catalysts Consisting of Copper and Calcium Silicate

Segawa A., Nakashima A., Nojima R., Yoshida N., Okamoto M.

Industrial and Engineering Chemistry Research （Industrial and Engineering Chemistry Research）  57 （ 35 ） 11852 - 11857 2018年09月

ISSN  08885885

　概要を見る

The authors developed eco-friendly non-chromium catalysts for acetaldehyde production through bioethanol dehydrogenation, consisting of copper and calcium silicate. Acetaldehyde selectivity was higher over copper calcium silicate catalysts with a CuO content of 40 wt % or more, because the number of acid sites on the calcium silicate was reduced, which helped prevent formation of byproducts. It was found that high ethanol conversion (39%-57%) and high acetaldehyde selectivity (91%-95%) could be achieved simultaneously at high temperature and high weight hourly space velocity conditions. Furthermore, it was shown that stable acetaldehyde production could be maintained over 20 h of time-on-stream. These catalysts were prepared from commercially available precursors and could be used in place of conventional copper chromite catalysts.

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Meerwein-Ponndorf-Verley Reduction of Crotonaldehyde over Supported Zirconium Oxide Catalysts Using Batch and Tubular Flow Reactors

Segawa A., Taniya K., Ichihashi Y., Nishiyama S., Yoshida N., Okamoto M.

Industrial and Engineering Chemistry Research （Industrial and Engineering Chemistry Research）  57 （ 1 ） 70 - 78 2018年01月

ISSN  08885885

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The authors studied Meerwein-Ponndorf-Verley (MPV) reduction of crotonaldehyde using batch and tubular flow reactors. Various ZrO2/SiO2 catalysts prepared from commercially available carriers and precursors were subjected to activity testing using autoclave batch reactors. To determine the degree of Zr dispersion in the ZrO2/SiO2 catalysts, X-ray photoelectron spectroscopy (XPS) measurements and the benzaldehyde-ammonia titration (BAT) method were carried out. The results suggested a positive correlation between Zr dispersion and crotonaldehyde conversion. Durability tests using tubular flow reactors were performed with the most suitable catalyst, which was selected through batch reactions and catalyst characterizations. Almost no degradation of the catalytic activity was observed over 2,200 h in a liquid-phase reaction, while catalyst durability was short in a gas-phase reaction. It was surmised that in the liquid-phase, 2-propanol (hydrogen donor) in the feed had dissolved the reaction byproducts to purge from the catalyst. In addition, a continuous process flow design that includes 2-propanol regeneration was proposed for industrial production.

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Base-resistant adsorbents prepared using diamino group-grafted mesoporous silica uniformly coated with zirconia

Masaki Okamoto, Haruka Satake, Hiroyuki Seki

Journal of Materials Chemistry A 5 （ 46 ） 24425 - 24432 2017年

ISSN  2050-7488

　概要を見る

The mesopore walls of ordered mesoporous silicas were coated with zirconia layers at room temperature using zirconia tetra-n-butoxide dissolved in dry toluene. It was found that coating the silicas three times with zirconia layers was sufficient to completely cover their pore walls with zirconia. The coated mesoporous silicas demonstrated high resistance to a 2 M sodium hydroxide solution at 0 °C. Prior to being coated three times with the zirconia layers, the silica walls were partially coated with 3-(2-aminoethylamino)propyltrimethoxysilane so that diamino groups could be grafted onto the pore walls; this was done so that they could be used as base-resistant adsorbents for copper(ii) ions that had been dissolved in basic solutions. The grafted diamino groups, which captured copper(ii) ions, were protected from the basic solution, as the silyl in the diamino groups was covered with zirconia layers.

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Preparation of Mesoporous Silica Uniformly Coated with Titania and Its Application to Hydrodesulfurization Catalyst

H. Satake, M. Okamoto, Y. Sakayori, S. Furudera, T. Kubota, H. Seki

J. Jpn. Inst. Energy 96   144 - 152 2017年

査読有り

Synthesis of hollow and rattle-type mesoporous silica spheres by treating layered mesoporous silica with a basic solution, and using the spheres as microreactors for two-phase reactions

Masaki Okamoto, Hiroyuki Tsukada, Syun Fukasawa, Aya Sakajiri

Journal of Materials Chemistry A 3 （ 22 ） 11880 - 11890 2015年06月

ISSN  2050-7488

　概要を見る

Hollow silica spheres with radially oriented mesopores were synthesized by treating core-shell structured mesoporous silica spheres (pure silica core and propyl group-grafted silica shell) with an ammonia solution in the presence of alkyltrimethylammonium chloride. The pure silica cores dissolved in the basic solution but the propyl groups and the surfactant adsorbed on the shells protected the mesopore walls in the shells from the basic solution. Treating mesoporous silica spheres with three-layered structures (silica with grafted propyl groups, pure silica, and then silica with grafted propyl groups) led to mesoporous spheres with rattle structures being formed. The hollow and rattle-type spheres acted as microreactors when they were added to two-phase reactions, halogen exchange reaction, hydroformylation and esterification, and the reaction rates were increased. Stirring caused the hollow spheres containing the aqueous phase to be transferred into the organic phase, causing the reaction rate to be increased. Modifying the mesopore walls with phenyl groups to make the spheres highly hydrophobic increased the amount of spheres that was present in the organic phase, increasing the reaction rate. A higher reaction rate was achieved using hollow spheres than that using non-hollow mesoporous silica spheres, indicating that the hollow structure was an important factor in increasing the reaction rate.

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Catalytic reactions enhanced under microwave-induced local thermal non-equilibrium in a core-shell, carbon-filled zeolite@zeolite

Dai Mochizuki, Ryo Sasaki, Masato M. Maitani, Masaki Okamoto, Eiichi Suzuki, Yuji Wada

JOURNAL OF CATALYSIS （ACADEMIC PRESS INC ELSEVIER SCIENCE）  323   1 - 9 2015年03月

査読有り,  ISSN  0021-9517

　概要を見る

A core-shell, carbon-filled zeolite@zeolite was created through the epitaxial growth of shell zeolite on a core zeolite filled with carbon. The catalytic dehydrations of alcohols on the core-shell structure were enhanced under microwave irradiation by comparison with conventional heating using an oil bath at the same solution temperatures; however, the dehydrations on the sole core zeolite were not enhanced under microwave irradiation, which indicated the presence of a higher temperature area in the shell near the border with the core. The core-shell structure exhibited thermal non-equilibrium with microwave irradiation because of the extremely different dielectric losses of the core and the shell; that is, the carbon in the core generated much heat from microwaves, but the shell did not. (C) 2014 Elsevier Inc. All rights reserved.

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Skeletal isomerization of tetradecane catalyzed by TON-type zeolites with a fragmented core-shell structure

Masaki Okamoto, Lili Huang, Midori Yamano, Sayuri Sawayama, Yohei Nishimura

APPLIED CATALYSIS A-GENERAL （ELSEVIER SCIENCE BV）  455   122 - 128 2013年03月

査読有り,  ISSN  0926-860X

　概要を見る

TON-type zeolites with a core-shell structure were synthesized by crystal overgrowth of an aluminum-free TON-type zeolite on an aluminum-containing TON-type zeolite in the presence of fluoride ion, which was used as a mineralizing reagent to restrain the formation of defects. The core-shell structured zeolite showed greater selectivity for skeletal isomerization in tetradecane hydroisomerization because the acid sites on the external surface of needle-shaped crystals were passivated to inhibit cracking. Breaking the needle-shaped crystals of the core-shell structure to create shorter crystal pieces effectively enhanced the catalytic activity and selectivity for isomerization because new pore entrances were formed. (c) 2013 Elsevier B.V. All rights reserved.

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Readily recyclable catalysts of zeolite nanoparticles linked with polymer chains

Masaki Okamoto, Satoshi Watanabe, Junya Nitta

Applied Catalysis A: General 467   55 - 60 2013年

ISSN  0926-860X

　概要を見る

Aggregates of zeolite nanoparticles were linked together with polypropylene oxide or polydimethylsiloxane polymer chains, and were used as catalysts for liquid-phase reactions. The polymer-linked catalysts showed high catalytic activity in esterification of acetic acid with 1-propanol and hydrolysis of ethyl acetate, and were readily separated from reaction mixtures by decantation. Moreover, the linkage with the polymer chains enhanced shape selectivity in esterification of acetic acid with cyclohexanol and dehydration of 1-phenylethanol because of passivating the external acid sites of the zeolite with the polymer. © 2013 Elsevier B.V. All rights reserved.

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Synthesis of core-shell structured porous materials and applications as catalysts and precursors for hollow porous materials

Masaki Okamoto

Journal of the Japan Petroleum Institute 56 （ 4 ） 198 - 205 2013年

ISSN  1346-8804

　概要を見る

Ordered porous materials such as zeolites and ordered mesoporous silicas have important physical characteristics based on their high surface area and well-defined pore size. Control of the structure or shape of the ordered porous materials will provide new functions. This review focuses on core-shell structure; especially fabrication methods of core-shell structured zeolites with minimal defects are introduced. As an example of applications, MFI and TON-type zeolites with core-shell structure used as catalysts have high shape selectivity in the methylation of toluene with methanol and skeletal isomerization of tetradecane, respectively. As another application, synthesis of hollow porous materials from core-shell porous materials is also described. Decomposition of silica with dimethyl carbonate catalyzed by an alkali metal salt impregnated in the core was an effective method for selective removal of the core from the core-shell structure. Hollow porous materials show promise as vessels for drug delivery, catalyst vessels and microreactors.

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Formation of hollow silica spheres with ordered mesoporous structure by treatment with dimethyl carbonate for selective decomposition of mesoporous silica core

Masaki Okamoto, Huimin Huang

Microporous and Mesoporous Materials 163   102 - 109 2012年11月

ISSN  1387-1811

　概要を見る

Hollow silica spheres containing ordered mesopores with radial orientation were synthesized from core-shell structured mesoporous silica spheres with pure silica core and propyl group-grafted silica shell. The silica core was selectively impregnated with sodium acetate owing to the hydrophilicity of the core. Sodium acetate acted as a catalyst for silica decomposition with dimethyl carbonate (DMC), and after impregnation, treatment with DMC was performed to remove the core by the reaction of silica with DMC. The obtained hollow spheres contain ordered mesopores with radial orientation and are mono-disperse. The final shell thickness could be controlled by changing the shell thickness of the initial core-shell spheres, as well as by modifying the degree of decomposition of the shell. 9-Phenylanthracene encapsulated in the hollow spheres was gradually released through the mesopores as vapor into an air stream by diffusion limitation. © 2012 Elsevier Inc. All rights reserved.

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MFI-type zeolite with a core-shell structure with minimal defects synthesized by crystal overgrowth of aluminum-free MFI-type zeolite on aluminum-containing zeolite and its catalytic performance

Masaki Okamoto, Yukio Osafune

Microporous and Mesoporous Materials 143 （ 2-3 ） 413 - 418 2011年09月

ISSN  1387-1811

　概要を見る

MFI-type zeolite with a core-shell structure and minimal defects was synthesized by crystal overgrowth of aluminum-free MFI-type zeolite on aluminum-containing MFI-type zeolite crystals. The purpose of the zeolite shell is to passivate acid sites on the external surface of the zeolite core. When both the shell and the core are synthesized in the presence of fluoride ion, defects are minimal. In the case of synthesizing the shell in the absence of fluoride ion, core growth does not occur. When the core is synthesized in the absence of fluoride ion, significant defects develop and cause mesopores to form in the core-shell zeolite. As catalysts for methylation of toluene with methanol, only the core-shell zeolite with minimal defects shows high selectivity for p-xylene (96%). © 2011 Elsevier Inc. All rights reserved.

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Polymers as novel modifiers for supported metal catalyst in hydrogenation of benzaldehydes

Masaki Okamoto, Tomoyuki Hirao, Tatsuya Yamaai

Journal of Catalysis 276 （ 2 ） 423 - 428 2010年12月

ISSN  0021-9517

　概要を見る

Polyethylene glycol (PEG) was impregnated on a palladium metal supported on silica gel and used in a catalyst for hydrogenation of benzaldehydes. In the vapor-phase flow reaction, the PEG modification improved catalytic activity and selectivity for a partially hydrogenated product, benzyl alcohol. In isoprene hydrogenation, selectivity for partially hydrogenated products, monoenes, was also enhanced. X-ray photoelectron spectroscopy (XPS) analysis of the modified catalysts revealed that the modification with PEG makes the palladium surface negatively charged, possibly leading to an increase in the selectivity for the partially hydrogenated product caused by enhancement of its desorption from the surface. In the liquid-phase hydrogenation of benzaldehyde, the PEG modification also increased the selectivity for benzyl alcohol. © 2010 Elsevier Inc. All rights reserved.

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東京工業大学・化学系専攻における安全教育

岡本昌樹

触媒 52 （ 1 ） 51 - 56 2010年

Effect of addition of alkali metal salts in hydrothermal synthesis and post heat-treatment on porosity of SBA-15

Masaki Okamoto, Yuko Fukukita, Masaki Haga, Kazuhisa Toyofuku, Naoki Mimura

JOURNAL OF POROUS MATERIALS （SPRINGER）  16 （ 2 ） 135 - 140 2009年04月

ISSN  1380-2224

　概要を見る

SBA-15 was hydrothermally synthesized at 80 A degrees C for 48 h, and then the surfactant template for mesopore formation was removed by extraction with ethanol, washing with nitric acid, and heating at 200 A degrees C. Addition of alkali metal chlorides to a synthesis gel of SBA-15 increased its mesopore diameter in the following order: no added salt < LiCl < KCl < CsCl. The micropore volume did not change with the addition of any alkali metal and was around 0.17 mL g(-1). These results suggest that alkali metal salt is inside the mesopore with a micelle template. When a small amount of potassium chloride was impregnated in SBA-15 after extraction and washing, micropore volume reduced almost to zero with heating at 400 A degrees C in dry air, and the mesopore diameter and pore wall thickness were reduced by a larger amount than for non-impregnated SBA-15. It is likely that the micropores in the mesopore wall vanish due to condensation of silanols and/or reconstruction of siloxane bonds on the micropore wall, which are catalyzed by alkali metal halides.

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Wacker-type oxidation in vapor phase using a palladium-copper chloride catalyst in a liquid polymer medium supported on silica gel

Masaki Okamoto, Yuichi Taniguchi

JOURNAL OF CATALYSIS （ACADEMIC PRESS INC ELSEVIER SCIENCE）  261 （ 2 ） 195 - 200 2009年01月

ISSN  0021-9517

　概要を見る

Pd(II) chloride and Cu(II) chloride in various liquid polymer media supported on silica gel were prepared and used in a catalyst system for vapor-phase synthesis of acetaldehyde by Wacker-type oxidation of ethylene. This catalyst system supported on silica gel prepared by impregnation was quickly deactivated, while use of polyethylene glycol (PEG) as a liquid polymer medium supported on silica gel showed stable catalytic activity. PEG inhibited the formation of Pd metal particles, which deactivate the catalyst system. Addition of alkali metal salts, especially LiCl, to the PdCl(2)-CuCl(2) catalyst system with PEG enhanced catalytic activity for 22 h, even when the I'd content was high, leading to high activity but poor stability. LiCl also inhibited the formation of metal particles. (C) 2008 Elsevier Inc. All rights reserved.

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Vapor-phase hydrosilylation using a transition metal complex catalyst in a liquid polymer medium supported on silica gel

Masaki Okamoto, Hironari Kiya, Akihiko Matsumura, Eiichi Suzuki

CATALYSIS LETTERS （SPRINGER）  123 （ 1-2 ） 72 - 79 2008年06月

ISSN  1011-372X

　概要を見る

Transition metal catalysts in various liquid polymer media supported on silica gel were prepared and used for vapor-phase hydrosilylation. Tetraammineplatinum(II) chloride and potassium hexachloroplatinate(IV) in a polyethylene glycol (PEG) medium showed high and stable activity. Deactivation of the catalyst was not observed unless a high platinum concentration in PEG was used. When the amount of PEG was 40 vol% of the pore volume of silica gel, PEG was coated on the pore walls of the silica gel, and did not block the pore openings. Active species in the PEG were formed only during the reaction.

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東京工業大学における安全管理と環境安全教育

日野出洋文, 岡本昌樹

安全工学 47 （ 6 ） 339 - 346 2008年

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Oxidative dehydrogenation of ethane over Cr/ZSM-5 catalysts using CO2 as an oxidant

Naoki Mimura, Masaki Okamoto, Hiromi Yamashita, S. Ted Oyama, Kazuhisa Murata

JOURNAL OF PHYSICAL CHEMISTRY B （AMER CHEMICAL SOC）  110 （ 43 ） 21764 - 21770 2006年11月

ISSN  1520-6106

　概要を見る

Highly active catalysts for oxidative dehydrogenation of ethane with CO2 were characterized by temperature-programmed reduction (TPR), temperature-programmed oxidation (TPO), Fourier transform infrared (FTIR) spectroscopy, and X-ray absorption fine-structure (XAFS) analysis. In the active catalysts, Cr/H-ZSM-5 (SiO2/Al2O3 > 190), Cr6+ = O, or possibly Cr5+ = O was the catalytic species on the zeolite support. In contrast, little Cr6+ (or Cr5+) was detected in the less-active catalysts. The Cr6+ (or Cr5+) species was reduced to an octahedral Cr3+ species by treatment with ethane at 773 K, and the reduced Cr species was reoxidized to the Cr6+ (or Cr5+) species by treatment with CO2 at 673-773 K. The Cr redox cycle played an important role in the catalyst's high activity.

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Intermediacy of silylene and germylene in direct synthesis of organosilanes and organogermanes

M Okamoto

RESEARCH ON CHEMICAL INTERMEDIATES （VSP BV）  32 （ 3-4 ） 317 - 330 2006年

ISSN  0922-6168

　概要を見る

In the direct synthesis of silicon compounds by reactions of elemental silicon with methyl chloride, methanol and hydrogen chloride, silylene formed on surface of silicon grains during the reaction is an intermediate. The reaction of surface silylene with a variety of unsaturated hydrocarbons provides new direct synthesis of organosilanes. In the direct synthesis of methylchlorogermanes from elemental germanium, surface germylene is not an intermediate, while tetrachlorogermane is synthesized by the direct reaction of germanium with hydrogen chloride via dichlorogermylene intermediate. Various unsaturated hydrocarbons or organic chlorides added to the system of tetrachlorogermane synthesis give new methods for the synthesis of organogermanes.

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東京工業大学における一日体験化学教室の内容と問題点

岡本昌樹

化学と教育 （公益社団法人 日本化学会）  53 （ 5 ） 268 - 271 2005年

ISSN  0386-2151

　概要を見る

東京工業大学では,工学部応用化学系学科,理学部化学科,総合理工学研究科化学系研究室の3つのグループが2年ずつ持ち回りで一日体験化学教室を開催している。初回開催の1990年から14年間を経て,現在の体験教室の形となった。本稿では,2004年に行った工学部応用化学系学科主催の一日体験化学教室の内容を紹介する。また,体験教室の準備段階で明らかとなった問題点とその解決策,および開催後に新たに明らかとなった問題点を示し,2005年の体験教室に向けての対策を紹介する。

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炭酸ジメチル処理によるSBA-15の細孔の三次元化

岡本昌樹, 福喜多祐子, 三村直樹

触媒 47 （ 6 ） 461 - 463 2005年

Polysiloxane depolymerization with dimethyl carbonate using alkali metal halide catalysts

M Okamoto, S Suzuki, E Suzuki

APPLIED CATALYSIS A-GENERAL （ELSEVIER SCIENCE BV）  261 （ 2 ） 239 - 245 2004年04月

ISSN  0926-860X

　概要を見る

Polydimethylsiloxane terminated by a methyl group was almost completely depolymerized in the mixture of dimethyl carbonate (DMC) and methanol using alkali metal halide catalysts to form dimethoxydimethylsilane (DMDMS) and methoxytrimethylsilane (MTMS) monomers. The various alkali metal halides tested as catalysts gave the same monomer yield. The depolymerization rate depended on the kind of alcohol but not on dialkyl carbonate. The results indicate that the siloxane bond is cleaved by methanol attack to form the corresponding monomers together with water and that dimethyl carbonate reacts with water formed as a byproduct to give methanol, whose amount is the same as that of the methanol consumed for cleavage of siloxane bonds. Therefore, dimethyl carbonate, not methanol, acts as the depolymerization reagent in the apparent reaction.
Depolymerization of poly(methylphenylsiloxane-ran-dimethylsiloxane) and poly(methylvinylsiloxane-ran-dimethylsiloxane) with dimethyl carbonate in methanol using potassium fluoride catalyst also proceeded to obtain dimethoxymethylphenylsilane and dimethoxymethylvinylsilane, respectively, together with dimethoxydimethylsilane and methoxytrimethylsilane from polydimethylsiloxane parts. Silicone rubber containing silica as an additive was also depolymerized to form dimethoxydimethylsilane together with a small amount of tetramethoxysilane formed from silica additive. Therefore, the depolymerization with DMC using alkali metal salt catalyst can be counted on for recycling silicone waste. (C) 2003 Elsevier B.V. All rights reserved.

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Direct synthesis of organotrichlorogermanes by the reaction of elemental germanium, hydrogen chloride, and alkene

Masaki Okamoto, Takehiko Chikamori, Takuya Asano, Eiichi Suzuki

Organometallics 23 （ 3 ） 595 - 599 2004年02月

ISSN  0276-7333

　概要を見る

The reaction of elemental germanium, hydrogen chloride, and ethylene with copper(I) chloride catalyst gave ethyltrichlorogermane with a 66% selectivity, tetrachlorogermane also being formed. The addition of tetrachlorogermane to the reaction system increased the formation rate of ethyltrichlorogermane. The reaction of germanium, tetrachlorogermane, and butadiene resulted in the formation of 1,1-dichlorogermacyclopent-3-ene. These results indicate the intermediacy of dichlorogermylene, which is formed by the reaction of elemental germanium with tetrachlorogermane. In place of ethylene, allyl chloride was fed with hydrogen chloride. Allyltrichlorogermane was obtained with a 92% selectivity together with a small amount of tetrachlorogermane. It is highly plausible that the formation of allyltrichlorogermane is caused by the insertion of dichlorogermylene intermediate to the carbon - chlorine bond of allyl chloride.

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Organotrichlorogermane synthesis by the reaction of elemental germanium, tetrachlorogermane and organic chloride via dichlorogermylene intermediate

M Okamoto, T Asano, E Suzuki

DALTON TRANSACTIONS （ROYAL SOC CHEMISTRY）   （ 15 ） 2372 - 2376 2004年

ISSN  1477-9226

　概要を見る

Organotrichlorogermanes were synthesized by the reaction of elemental germanium, tetrachlorogermane and organic chlorides, methyl, propyl, isopropyl and allyl chlorides. Dichlorogermylene formed by the reaction of elemental germanium with tetrachlorogermane was the reaction intermediate, which was inserted into the carbon-chlorine bond of the organic chloride to give organotrichlorogermane. When isopropyl or allyl chloride was used as an organic chloride, organotrichlorogermane was formed also in the absence of tetrachlorogermane. These chlorides were converted to hydrogen chloride, which subsequently reacted with elemental germanium to give the dichlorogermylene intermediate. The reaction of elemental germanium, tetrachlorogermane and organic chlorides provides a simple and easy method for synthesizing organotrichlorogermanes, and all the raw materials are easily available.

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Deoligomerization of cyclooligosiloxanes with dimethyl carbonate over solid-base catalysts

M Okamoto, K Miyazaki, A Kado, S Suzuki, E Suzuki

CATALYSIS LETTERS （KLUWER ACADEMIC/PLENUM PUBL）  88 （ 3-4 ） 115 - 118 2003年06月

ISSN  1011-372X

　概要を見る

Cyclooligosiloxanes, hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane and decamethylcyclopentasiloxane were efficiently deoligomerized with dimethyl carbonate using an alumina-supported potassium fluoride catalyst under a continuous vapor-phase flow condition to form dimethoxydimethylsilane monomer. In the deoligomerization of larger cyclooligosiloxanes, the catalyst was deactivated. The addition of a small amount of methanol suppressed the deactivation. These results strongly suggest a new method for recycling silicone via monomers.

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High-performance Cr/H-ZSM-5 catalysts for oxidative dehydrogenation of ethane to ethylene with CO2 as an oxidant

N Mimura, Takahara, I, M Inaba, M Okamoto, K Murata

CATALYSIS COMMUNICATIONS （ELSEVIER SCIENCE BV）  3 （ 6 ） 257 - 262 2002年06月

ISSN  1566-7367

　概要を見る

Cr/H-ZSM-5 (SiO2/Al(2)O(3)greater than or equal to190) catalyst effectively dehydrogenated ethane to ethylene in the presence of CO2 oxidant. The maximum rate of formation of ethylene at 923 K was 0.516 mmol g-catalyst(-1) min(-1) and selectivity was over 90%. Carbon dioxide maintained the activity of the catalyst by removing coke from the surface of the catalyst. TPR profiles of the Cr/H-ZSM-5 catalysts suggest that there are high oxidation states Cr species such as Cr(VI) on the catalyst, which is considered key of higher activity. (C) 2002 Elsevier Science B.V. All rights reserved.

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Direct synthesis of phenylchlorogermanes from metallic germanium and chlorobenzene using metal chloride catalysts

Masaki Okamoto, Takuya Asano, Eiichi Suzuki

Catalysis Letters 78 （ 1-4 ） 33 - 36 2002年03月

ISSN  1011-372X

　概要を見る

In the direct synthesis of phenylchlorogermanes, copper(I) chloride was the best catalyst among the metal chlorides tested, the products being diphenyldichlorogermane and phenyltrichlorogermane. The reaction mainly gave diphenyldichlorogermane
however at the beginning of the reaction, phenyltrichlorogermane was afforded by the reaction of chlorobenzene and dichlorogermylene formed from metallic germanium and chloride ion in the catalyst.

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A novel catalyst containing a platinum complex in polyethylene glycol medium supported on silica gel for vapor-phase hydrosilylation of acetylene with trichlorosilane or trimethoxysilane

M Okamoto, H Kiya, H Yamashita, E Suzuki

CHEMICAL COMMUNICATIONS （ROYAL SOC CHEMISTRY）   （ 15 ） 1634 - 1635 2002年

ISSN  1359-7345

　概要を見る

Hydrosilylation of acetylene with trichlorosilane or trimethoxysilane was carried out using a vapor-phase flow reactor with use of tetraammineplatinum(II) chloride in polyethylene glycol medium supported on silica gel as a catalyst, which is an active and thermally stable supported liquid-phase catalyst prepared readily from easily available materials, tetraammineplatinum(II) chloride, polyethylene glycol and silica gel.

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Phenyltrichlorogermane synthesis by the reaction of chlorobenzene and the dichlorogermylene intermediate formed from elemental germanium and tetrachlorogermane

M Okamoto, T Asano, E Suzuki

ORGANOMETALLICS （AMER CHEMICAL SOC）  20 （ 26 ） 5583 - 5585 2001年12月

ISSN  0276-7333

　概要を見る

Phenyltrichlorogermane was synthesized with high, selectivity, 96%, from elemental germanium, tetrachlorogermane, and chlorobenzene using no catalyst, almost all germanium and tetrachlorogermane being converted. Dichlorogermylene was formed as a reaction intermediate by the reaction of germanium with tetrachlorogermane and inserted into the C-Cl bond of chlorobenzene to yield phenyltrichlorogermane.

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Deoligomerization of siloxanes with dimethyl carbonate over solid-base catalysts

M Okamoto, K Miyazaki, A Kado, E Suzuki

CHEMICAL COMMUNICATIONS （ROYAL SOC CHEMISTRY）   （ 18 ） 1838 - 1839 2001年09月

ISSN  1359-7345

　概要を見る

Hexamethyldisiloxane and hexamethylcyclotrisiloxane were almost completely deoligomerized with dimethyl carbonate over alumina-supported potassium fluoride catalyst to form methoxytrimethylsilane (85% yield) and dimethoxydimethylsilane (94% yield), respectively, and moreover the addition of a small amount of methanol to the hexamethyldisiloxane deoligomerization reaction enhanced the methoxytrimethylsilane yield to 98%.

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Direct synthesis of alkyldialkoxysilanes by the reaction of silicon, alcohol and alkene using a high-pressure flow reactor

M Okamoto, J Komai, M Uematsu, E Suzuki, Y Ono

JOURNAL OF ORGANOMETALLIC CHEMISTRY （ELSEVIER SCIENCE SA）  619 （ 1-2 ） 235 - 240 2001年01月

ISSN  0022-328X

　概要を見る

In the reaction of silicon, methanol and ethylene, use of a high-pressure flow reactor operating at 240 degreesC at 0.86 MPa of ethylene and 0.18 MPa of methanol gave a 33% selectivity for ethyldimethoxysilane, which was much higher than that using an atmospheric-pressure flow reactor (8%) or using an autoclave (4%). The selectivity increased proportionally with the ethylene pressure below 0.5 MPa. This indicates that the addition of ethylene or methanol to a surface silylene intermediate determines the selectivity and that the ethylene addition is a first-order reaction. Above 0.5 MPa the slope of the selectivity change was smaller. By feeding propylene instead of ethylene, n- and iso-propyldimethoxysilanes were obtained as organosilanes with 15 and 2% of selectivity, respectively. The reaction of silicon, ethanol and ethylene resulted in 28% selectivity for ethyldiethoxysilane at 0.99 MPa of ethylene and 0.21 MPa of ethanol at 240 degreesC. (C) 2001 Elsevier Science B.V. All rights reserved.

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Direct synthesis of organodichlorosilanes by the reaction of metallic silicon, hydrogen chloride and alkene/alkyne and by the reaction of metallic silicon and alkyl chloride

Masaki Okamoto, Satoshi Onodera, Yuji Yamamoto, Eiichi Suzuki, Yoshio Ono

Journal of the Chemical Society, Dalton Transactions  （ 1 ） 71 - 78 2001年

査読有り,  ISSN  1470-479X

　概要を見る

Dichloroethylsilane was synthesized by the reaction of metallic silicon, hydrogen chloride and ethylene using copper(I) chloride as the catalyst, the silicon conversion and the selectivity for dichloroethylsilane being 36 and 47%, respectively. At a lower reaction temperature or at a higher ratio of ethylene: hydrogen chloride a higher selectivity was obtained, however the silicon conversion was lower. The silicon-carbon bond formation is caused by the reaction of a surface silylene intermediate with ethylene. The reaction with propylene in place of ethylene gave dichloroisopropylsilane (22% selectivity) and dichloro-n-propyl-silane (8% selectivity) together with chlorosilanes. A part of the dichloroisopropylsilane is formed by the reaction of silicon, hydrogen chloride and isopropyl chloride formed by hydrochlorination of propylene. Use of acetylene instead of alkenes resulted in dichlorovinylsilane formation with a 34% selectivity. Alkyldichlorosilanes were also produced directly from silicon with alkyl chlorides, propyl and butyl chlorides. During the reaction the alkyl chloride is dehydrochlorinated over the surface of copper originating from the catalyst to afford hydrogen chloride and alkene. The hydrogen chloride formed participates in the formation of the silicon-hydrogen bond in alkyldichlorosilane, and the reaction of silicon, hydrogen chloride and alkene also causes alkyldichlorosilane formation. The reaction with isopropyl chloride gave a very high selectivity (85%) for dichloroisopropylsilane, the silicon conversion being 86%. © The Royal Society of Chemistry 2001.

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Direct synthesis of methyldimethoxysilane from metallic silicon and methanol using copper(I) chloride catalyst

M Okamoto, H Abe, Y Kusama, E Suzuki, Y Ono

JOURNAL OF ORGANOMETALLIC CHEMISTRY （ELSEVIER SCIENCE SA）  616 （ 1-2 ） 74 - 79 2000年12月

ISSN  0022-328X

　概要を見る

When the reaction of metallic silicon with methanol in the presence of a small amount of thiophene was carried out at 653 K, methyldimethoxysilane was formed together with trimethoxysilane and tetramethoxysilane, the selectivity for methyldimethoxysilane:being 22%. Further adding a small amount of trioxane, trimer of formaldehyde, to the reaction system improved the selectivity for methyldimethoxysilane. This indicates that formaldehyde formed by the dehydrogenation of methanol takes part in methyldimethoxysilane formation. The reaction of silicon with ethanol also gave a 14% selectivity of ethyldiethoxysilane with a 43% silicon conversion. (C) 2000 Elsevier Science B.V. All rights reserved.

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Oxydehydrogenation of propane over vanadyl ion-containing VAPO-5 and CoAPO-5

M Okamoto, L Luo, JA Labinger, ME Davis

JOURNAL OF CATALYSIS （ACADEMIC PRESS INC）  192 （ 1 ） 128 - 136 2000年05月

ISSN  0021-9517

　概要を見る

Vanadyl ion-containing VAPO-5 and CoAPO-5 are prepared by contact with a vanadyl sulfate solution or by impregnation with aqueous vanadyl oxalate and characterized by powder X-ray diffraction, electron spin resonance spectroscopy, and temperature-programmed reduction (TPR). Treatment of VAPO-5 with vanadyl ion results in incorporation of up to 1.0 wt% total vanadium into the AFI framework by filling lattice vacancies. At vanadium contents above ca. 1 wt%, extraframework vanadium is also obtained. TPR results show that framework vanadium can be reduced by hydrogen at a lower temperature than extraframework vanadium and vanadium in bulk V2O5. Oxydehydrogenation of propane over VAPO-5 samples reveals that framework vanadium is the most active and selective species for propylene formation (at 400 degrees C and 5% conversion, the selectivity is 72%); extraframework vanadium species are less active and selective. (C) 2000 Academic Press.

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Direct synthesis of organochlorosilanes by the reaction of metallic silicon with hydrogen chloride and alkene/alkyne

M Okamoto, S Onodera, Y Yamamoto, E Suzuki, Y Ono

CHEMICAL COMMUNICATIONS （ROYAL SOC CHEMISTRY）   （ 12 ） 1275 - 1276 1998年06月

ISSN  1359-7345

　概要を見る

Organosilicon compounds were directly synthesized from metallic silicon, alkene/alkyne and HCl, EtHSiCl2 being obtained with 47% selectivity from Si, C2H4 and HCl ae 513 K, and CH2=CHSiHCl2 and EtHSiCl2 with 39 smd 23% selectivity, respectively, when C2H2 was used in place of C2H4.

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Disproportionation of triethoxysilane over KF/Al┣D22┫D2O┣D23┫D2 and heat-treated hydrotalcite

E. Suzuki, Y. Nomoto, M, Okamoto, Y. Ono

Appl. Catal. A : General （ELSEVIER SCIENCE BV）  167 （ 1 ） 7 - 10 1998年02月

ISSN  0926-860X

　概要を見る

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年

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年

ISSN  1011-372X

　概要を見る

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年10月

ISSN  0959-9428

　概要を見る

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年03月

ISSN  0022-328X

　概要を見る

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年

ISSN  1011-372X

　概要を見る

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 γ-alumina in vapor phase

M. Okamoto, M, Tanaka, Y. Ono

Catal. Lett. （BALTZER SCI PUBL BV）  46 （ 1-2 ） 123 - 125 1997年

ISSN  1011-372X

　概要を見る

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年05月

ISSN  0022-328X

　概要を見る

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年03月

ISSN  0022-328X

　概要を見る

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年

ISSN  1011-372X

　概要を見る

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年

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年05月

ISSN  0021-9517

　概要を見る

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年02月

ISSN  0022-4936

　概要を見る

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年02月

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年

ISSN  0582-4664

　概要を見る

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年

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年09月

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年08月

ISSN  0167-2738

　概要を見る

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年02月

ISSN  0366-7022

　概要を見る

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年

CATALYSIS BY HYDROTALCITE IN LIQUID-PHASE ORGANIC-REACTIONS

Y ONO, E SUZUKI, M OKAMOTO

CHEMISTRY OF MICROPOROUS CRYSTALS （ELSEVIER SCIENCE PUBL B V）  60   363 - 370 1991年

CATALYSIS BY SYNTHETIC HYDROTALCITE-LIKE MATERIALS IN HALIDE EXCHANGE BETWEEN ALKYL-HALIDES

E SUZUKI, M OKAMOTO, Y ONO

JOURNAL OF MOLECULAR CATALYSIS （ELSEVIER SCIENCE BV）  61 （ 3 ） 283 - 294 1990年09月

ISSN  0304-5102

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CATALYSIS BY INTERLAYER ANIONS OF A SYNTHETIC HYDROTALCITE-LIKE MINERAL IN A HALIDE EXCHANGE BETWEEN ORGANIC HALIDES

E SUZUKI, M OKAMOTO, Y ONO

CHEMISTRY LETTERS （CHEMICAL SOC JAPAN）   （ 8 ） 1485 - 1486 1989年08月

ISSN  0366-7022

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CATALYSIS BY SYNTHETIC HYDROTALCITE-LIKE MINERALS IN A DISPROPORTIONATION OF TRIMETHOXYSILANE

E SUZUKI, M OKAMOTO, Y ONO

CHEMISTRY LETTERS （CHEMICAL SOC JAPAN）   （ 8 ） 1487 - 1490 1989年08月

ISSN  0366-7022

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