Silicon dichloride

Spontaneous explosions have been observed [1] with this dangerously explosive material, especially when pure. A sample at 0°C exploded during removal of traces of benzene under high vacuum [2], A residue containing the tetraazide, silicon chloride triazide and probably silicon dichloride diazide, exploded on standing for 2 or 3 days, possibly owing to hydrazoic acid produced by hydrolysis. 

Catalytic alcoholysis of silanes by a variety of transition metal based catalysts is a useful method to form silyl ethers under mild conditions (Scheme 19). The process is atom-economical hydrogen gas is the only byproduct. This mild method has not been fully exploited for the preparation of unsymmetrical bis-alkoxysilanes. A catalytic synthesis using silicon alcoholysis would circumvent the need of bases (and the attendant formation of protic byproducts), and eliminate the need for excess silicon dichlorides in the first silyl ether formation. We sought catalytic methods that would ultimately allow formation of chiral tethers that are asymmetric at the silicon center (Scheme 20). Our method, once developed, should be easily transferable for use with high-value synthetic intermediates in a complex target-oriented synthesis therefore, it will be necessary to evaluate the scope and limitation of our new method. 

Livingston, R. L., and L. 0. Brockway The Molecular Structures of Dimethyl Silicon Dichloride, Methyl Silicon Trichloride and Trifluoro Silicon chloride. J. Amer. chem. Soc. 66, 94—98 (1944). 

Timms, P. L. Some reactions of silicon dichloride. Inorg. Chem. 7, 387-89 (1968). 

Diethyl silicon dichloride was prepared by Ladenburg by treating silicon diethyl ether with benzoyl chloride at 250° C. The body is identical with that obtained by the action of hydrogen iodide on silicon... 

Dibromoethyl silicon dichloride, (CH2Br.CH2)2SiCl2, is produced by heating together a mixture of two molecular proportions of ethylene bromide with 1 mol. of silicon tetrachloride dissolved in ether, and four molecular proportions of sodium and a little ethyl acetate. The product is a dark brown oil. Doubt has recently been expressed as to the existence of this compound. ... 

Dibenzylethylchlorosilicane occurs in the preparation of benzyl-ethyl silicon dichloride, using benzyl magnesium chloride on ethyl sihcon trichloride. It is a colourless oil, fuming in moist air, and is... 

Benzylethylisobutylchlorosilicane.2—By the action of isobutyl magnesium bromide on benzylethyl silicon dichloride the above compound is produced. It has the same properties as the preceding body, and boils at 198° to 202° C. 

Dibenzyl silicon dichloride.—In the preparation of benzylethyl silicon dichloride an oily by-product is formed, which in addition to dibenzyl and other silicon compounds contains dibenzyl silicon dichloride. It melts at 50° to 52° C., fumes in air, and decomposes with water, giving the dioL By mercuric oxide it is transformed to a polymrised form of SiBzgO, soluble in ether, acetone, or benzene. ... 

Phenylethyl silicon dichloride is prepared from ethyl silicon trichloride and phenyl magnesium bromide. It boils at 228° to 282° C. and is a highly refractive liquid, fuming strongly in moist air,... 

Benzylethyl silicon dichloride is obtained as above, using the benzyl Grignard reagent. To avoid formation of too much dibenzyl, the reaction is carried out at 0° C. The two products obtained are benzylethyl silicon diehloride and dihemylethyl silicon chloride. The former is a mobile, fuming liquid, B.pt. 160° C. at 100 mm. 

PhenylmethylethylsiiicoL —Phenylethylsilicone is first prepared from phenylethyl silicon dichloride by hydrolysis, and the silicone then allowed to interact with methyl magnesium iodide. The product is contained in the fraction boiling at 115° C. at 17 mm. It is a colourless, mobile liquid, practically insoluble in water, and on standing slowly passes to the oxide which produces a turbidity. 

Diphenylsilicanediol in the presence of acids or alkalis very easily undergoes condensation. This accounts for the glue-like substances obtained in the preparation of the diol from diphenyl silicon dichloride by various methods, and they consist of a mixture of any of the four following condensation products —... 

Dibenzyl silicon dichloride is melted carefully and dropped into a... 

Benzylethylsilicanediol is prepared from pure benzyletliyl silicon dichloride, using ice-cold aqueous ammonium hydroxide under"the conditions used in the preparation of phenylethylsilicanodiol. The ethereal solution is allowed to evaporate spontaneously, when colourless needles... 

BenzylethylisobutylsUicyl chloride, see Benzylethyk sobutylchlorosiiicane. Benzylethyldichlorosilicane, see Benzylethyl silicon dichloride. Benzylethyldipropylsilicane, 264. 

Both Neish and Speakman Nature, 1945, 156, 176) and Wolsey and Alexander (Brit. Pat. 594901, 1947), showed that wool could be made unshrinkable by depositing upon it a silicon polymer. Alexander (J.S.D.C., 1950, 66, 349) considers that this is the only example of true masking of the scales with no spot welding involved. The process is described in detail by Alexander, Carter, and Earland J.S.D.C., 1949, 65, 107). The wool was treated with a substance of the general formula R.R. SiCl in an organic solvent such as carbon tetrachloride. The experiments were carried out with dimethyl silicon dichloride. The goods were immersed in the solution, hydroextracted, and then soaked in water at room temperature and dried, when the silicon compound was deposited on the surface of the fibres as an insoluble polymer. 

The effect has been studied391 of the nature of the stationary phase, and the solid support, the duration of stationary phase, the rate of flow and moisture content of the carrier gas, and the column temperature on the gas-liquid chromotographic separation of the components of a mixture obtained in the preparation of methylchlorosilanes including hydrogen chloride, methyl chloride, silicon tetrachloride, trimethylsilicon chloride, dimethyl silicon dichloride and methyl silicon trichloride. A column containing nitrobenzene on firebrick was used. 

Using a 10-p sample and a thermal conductivity detector, phenyl silicon trifluoride can be accurately determined in phenyl silicon dichloride down to 0.01%. The same procedure is applicable to the separation of high boiling chlorosilanes, which are difficult to separate otherwise, and also achieved the separation of various cyanopropylmethyl-chlorosilanes. 

More recently, stable silylenes which are structurally the repeating unit of a polysilane chain have been prepared and characterized [14-15]. Their synthesis involves the reduction of silicon dichlorides. Two methods of synthesis are shown in the Fig. 7.7. Both of these procedures involve the preparation of cyclic compounds containing Si(II). Although these compounds are highly interesting from the point of view of their chemistry, they have not been shown to serve as precursors for polymers. 

Exchange reactions between two different metal chlorides and alkoxides have been employed for the synthesis of a wide variety of homo- and heteroleptic metal alkoxides. For example, Bradley and Hill" observed that a mixture of excess titanium tetrachloride and silicon dichloride diethoxide at O C deposited a crystalline product which was characterized as titanium trichloride monoethoxide ... 

Palamarchuk et al S studied the separation of mixtures of di and trichlorisilane, silicon tetrachloride, methylchloride and also various methylchlorosilanes on columns (270 - 350mm x 0.4cm) operated at 30°C and containing 10% of benzyl benzoate, dibutyl phthalate or diethylphthalate supported on Celite or on diatomite brick previously treated with methyl silicon dichloride vapour. Helium was used as a carrier gas with a katharometer detector. 

Thrash et al studied the analysis of phenylmethyldichloro-silane by reaction chromatography with sodium fluosilicate involving an on column conversation in a pre-column to the corresponding fluorosilanes which are then separated on the chromatographic column. Due to the similarity of their boiling points, phenyl methyl silicon dichloride and phenyl silicon trichloride cannot be separated by normal chromatographic procedures. 

A 10 y1 sample was injected into the injection port with a 50 yl Hamilton syringe. The sample is immediately flashed into the sodium silicofluoride packed precolumn (6ft x inch maintained at 175°C), where the chlorosilanes are converted to fluorosilanes as previously mentioned. The volatile reaction products are then swept by the carrier into the analytical column where the components are separated. The results are calculated by comparison of the unknown samples with a standard sample containing a known amount of phenyl silicon trichloride and phenyl methyl silicon dichloride, which is analyses using identical techniques. 

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