Copper catalyst with silicon

This reaction is carried out in tall fluidized beds of high L/dt ratio. Pressures up to 200 kPa are used at temperatures around 300°C. The copper catalyst is deposited onto the surface of the silicon metal particles. The product is a vapor-phase material and the particulate silicon is gradually consumed. As the particle diameter decreases the minimum fluidization velocity decreases also. While the linear velocity decreases, the mass velocity of the fluid increases with conversion. Therefore, the leftover small particles with the copper catalyst and some debris leave the reactor at the top exit. 

Enantioselective 1,4-reduction of enones can be done using a copper-BINAP catalyst in conjunction with silicon hydride donors.158 Polymethylhydrosilane (PMHS) is one reductants that is used. 

In the presence of water-free late transition metalphosphine cation complexes as Lewis acids, glyoxylatetosylamine imine reacted with silicon enolates stereoselectivity [23-26]. It was proposed that imine coordinated to the metal such as Ag(I), Pd(II), and Cu(I) in a bidentate manner [23]. The copper-based catalyst was the most effective, and the desired product was obtained in high yields with high enantioselectivities [(Eq. (4)]. 

The influence of Lewis acids on the 4 + 2-cycloaddition of (2ft,2/ft)-A,iV/-fumaro-ylbis[fenchane-8,2-sultam] with cyclopentadiene and cyclohexadiene was investigated by IR studies of the sultam compexes with various Lewis acids.101 The first enantios-elective silicon Lewis acid catalyst (91) catalysed the Diels-Alder cycloaddition of methacrolein and cyclopentadiene with 94% ee.102 [A1C13 + 2THF] is a new and efficient catalytic system for the Diels-Alder cycloaddition of a,/9-unsaturated carbonyl compounds with dienes under solvent-free conditions.103 Dendritic copper(II) triflate catalysts with a 2,2 -bipyridine core (92) increased the chemical yields of Diels-Alder adducts.104... 

Catalysts (coni.) copper, for reaction of methyl chloride with silicon, 3 56 iron, for preparation of sodium amide, 2 133 nickel powder, 5 197 silica gel for, or for supports,... 

Thus the function of the copper catalyst in the synthesis of methyl-chlorosilanes seems to be to transport the free methyl groups and to prolong their life in the form of copper methyl, and also to transfer the chlorine from methyl chloride to silicon. It is probable that copper acts similarly in the reaction of other hydrocarbon halides with silicon, and that similar metals also may undergo the same cycle of reactions. 

If ethylchlorosilanes are desired, they may be made by the direct method by the vapor-phase reaction of ethyl chloride with silicon at 300° C., using 10 per cent of copper as catalyst.8 The reactions follow the general plan indicated in the flow sheet for the corresponding methyl compounds (Fig. 2). 

Many studies on the direct reaction of methyl chloride with silicon-copper contact mass and other metal promoters added to the silicon-copper contact mass have focused on the reaction mechanisms.7,8 The reaction rate and the selectivity for dimethyldichlorosilane in this direct synthesis are influenced by metal additives, known as promoters, in low concentration. Aluminum, antimony, arsenic, bismuth, mercury, phosphorus, phosphine compounds34 and their metal complexes,35,36 Zinc,37 39 tin38-40 etc. are known to have beneficial effects as promoters for dimethyldichlorosilane formation.7,8 Promoters are not themselves good catalysts for the direct reaction at temperatures < 350 °C,6,8 but require the presence of copper to be effective. When zinc metal or zinc compounds (0.03-0.75 wt%) were added to silicon-copper contact mass, the reaction rate was potentiated and the selectivity of dimethyldichlorosilane was enhanced further.34 These materials are described as structural promoters because they alter the surface enrichment of silicon, increase the electron density of the surface of the catalyst modify the crystal structure of the copper-silicon solid phase, and affect the absorption of methyl chloride on the catalyst surface and the activation energy for the formation of dimethyldichlorosilane.38,39 Cadmium is also a structural promoter for this reaction, but cadmium presents serious toxicity problems in industrial use on a large scale.41,42 Other metals such as arsenic, mercury, etc. are also restricted because of such toxicity problems. In the direct reaction of methyl chloride, tin in... 

Allylsilanes are known as interesting and useful reagents for organic synthesis.85-88 Hurd first reported the direct reaction of elemental silicon with allyl chloride in the presence of copper catalyst to give a mixture of allylchlorosilanes and polymeric materials.15 Among the volatile compounds, allyltrichlorosilane, formed by the 1 1 1 reaction of allyl chloride, hydrogen chloride and elemental silicon, was observed as the major product instead of the normally expected diallyldichlorosilane. Since diallyldichlorosilane thermally polymerizes at temperatures above 130°C, the product mixture polymerized during the reaction or upon distillation. 

When elemental silicon was reacted with a mixture of allyl chloride and hydrogen chloride in the presence of copper catalyst using a stirred reactor equipped with a spiral band agitator (Fig. 1) at temperatures ranging from 220 to 320 °C, allyldichlorosilane was successfully obtained as the major product along with allyltrichlorosilane as a minor product. Allyldichlorosilane was produced by the 1 1 1 reaction of allyl chloride, hydrogen chloride, and elemental silicon (Eq. 12).27... 

A 1 1 mixture of allyl chloride and hydrogen chloride reacted with elemental silicon in the presence of copper catalyst (10 wt%) and cadmium promoter (0.5 wt%) to give allyl-containing compounds, allyldichlorosilane (31%) and allyltrichlorosilane (2%), and other volatile compounds, 2-methyl-1,1,4,4-tetrachloro-l,4-disilabutane (1 %) 1,1,5,5-tetrachloro-1,5-disilapentane (2%) 3-(dichlorosilyl)-1,1,5,5-tetrachloro-1,5-disilapentane (4%), etc. and polymeric materials.27... 

The direct reaction of elemental silicon with oc,of-dichlorotoluene in the presence of copper catalyst around 300 °C was unsuccessful due to the decomposition of a,a-dichlorotoluene on the silicon-copper contact mass.25 However, oc,a-bis(silyl)toluenes were obtained when a mixture of a,a-dichlorotoluene and hydrogen chloride was reacted with silicon-copper... 

Cadmium was a good promoter for this reaction, while zinc was found to be an inhibitor. Thus, the reaction of elemental silicon with a 1 4 gaseous mixture of methylene chloride and hydrogen chloride at 280 °C using copper catalyst and cadmium promoter afforded bis(silyl)methanes consisting of bis(dichlorosilyl)methane (36%), bis(dichlorosilyl)(trichloro-silyl)methane (31%), and bis(trichlorosilyl)methane (7%).22... 

The deactivation of elemental silicon and copper catalyst was a major problem due in part to the decomposition of the starting chloroform and in part to the high boiling polycarbosilanes produced. Considering some of the products contained Si-H bonds, hydrogen chloride was likely produced during the reaction and involved in the reaction with elemental silicon. 

Direct reaction of elemental silicon with a gaseous mixture of chloroform and hydrogen chloride has been studied in the presence of a copper catalyst... 

The direct reaction of (trichloromethyl)chlorosilanes was applied under the same reaction condition described in the direct reaction of elemental silicon with (dichloromethyl)chlorosilanes above. In this reaction, an admixed gases of hydrogen chloride and 40 wt% (trichloromethyl)chlorosilanes in toluene injected using a syringe pump in pre-heater zone was fed into a reactor charged with elemental silicon (90%) and copper catalyst (10%) (Fig. 1). This reaction afforded no tetrakis (chlorosilyl)methane instead, tris(silyl)methanes and bis(silyl)methanes were obtained, which were the same products derived from the reactions of (dichloromethyl)chlorosilanes or chloroform, and (chloromethyl)chlor-osilanes or methylene chloride, respectively. This result may be rationalized by decomposition of (trichloromethyl)chlorosilanes to (dichloromethyl)-chlorosilanes and (chloromethyl)chlorosilanes on silicon-copper contact mass during the reaction, followed by reaction with elemental silicon to afford the products or the decomposition tetrakis(silyl)methane products.16... 

Prior to analysis, the FCC catalyst samples were embedded in copper doped thermosetting epoxy to provide increased electrical conductivity. They were dry polished with silicon carbide to approximate cross-sections. 

Direct synthesis is the reaction of alkyl or aryl chloride and silicon in the presence of a proper catalyst. Mostly, methyl chloride is snbjected to the reaction at 250 350 °C in a flnid bed with fine particles of silicon mixed with a copper catalyst (eqnation 2). ... 

The Rochow Process. Rochow found that alkyl and aryl halides react directly with silicon when their vapors contacted silicon at elevated temperatures to produce complex mixtures of organosilicon halides. The reaction is promoted by a wide variety of metals from both the main group and the transition series, but the most efficient catalyst is copper. The most studied reaction of this type is the reaction between methyl chloride and silicon to give dimethyldichlorosilane and methyltrichlorosilane. Dimethyldichloro-silane is major feedstock silane for methylsilicon polymers. 

One conclusion can be drawn from the many studies [2c, 7] devoted to obtaining an understanding of the mechanism of the R.-M. synthesis the process proceeds by way of surface-confined chloromethylsilylene. Being confronted with such a complex system one should keep in mind that the formation of dichlorodimethylsilane from silicon and methyl chloride does not necessarily need the presence of copper. For instance, it was reported as early as 1966 that pyrophoric silicon, when suspended in paraffin oil, reacts at 200 °C in the absence of any catalyst with methyl chloride with generation of chloromethylsilanes [8],... 

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