Dimethyl silicon chloride

Silcones are important products of silicon. They may be prepared by hydrolyzing a silicon organic chloride, such as dimethyl silicon chloride. Hydrolysis and condensation of various substituted chlorosilanes can be used to produce a very great number of polymeric products, or silicones, ranging from liquids to hard, glasslike solids with many useful properties. 

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). 

The most straightforward solution to the problem of producing methyl-, ethyl-, and phenylchlorosilanes would be to adapt the classical laboratory methods of synthesis to large-scale operation. A logical choice would be the Grignard reaction, long a laboratory favorite because it is so universally applicable. For the preparation of dimethyl silicone from inethyl chloride by the Grignard method, the steps would be ... 

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. 

Figure 9-33. Selectivity of different polymer membranes to He-N2 separation as a function of nitrogen permeability (n, incm /(cm x atm x s)) (1) polyvinylidenechloride (2,4)polyethylene terephthalafe (3) polyvinylfluoride (5) polyvinylchloride (6) polyamide (7) plasfified polyvinylidene chloride (8) cellulose nitrate (9) polypropylene (lO)fluoroplast (26) (ll)co-polymer of isoprene (74%) and acryl-nitryl (26%) (12, 18, 20) different co-polymers of butadiene and acryl-rritryl (13) polyacrylate (14) polycarbonate (15) polyisobutylene (16) bulyl latex (17) co-polymer of vinyl chloride and vinyl acetate (19, 37) butyl acetate of cellulose (21) polyethylene vinyl acetate (22) polybutadiene (23) special polymer SKI-3 (24) natural latex (25) nitryl silicon latex (26) dimethyl silicon latex (27) special polymer SKS-30 (28) special polymer SKMS-50 (29) special polymer SKMS-30 (30, 34, 35) high-density, medium-densily, and low-density polyethylene (31) polyethylene with 5% soot (32) co-polymer of ethylene (90%) and propylene (10%) (33) co-polymer of ethylene (96.5%) and vinyl acetate (3.5%) (36) triacetate of cellulose (38) acetate cellulose (39) polystyrene.

Bouncing putty is prepared by heating a dimethyl silicone with ferric chloride and boric oxide or other boron compounds and adding suitable fillers and softeners to the resultant gum. The material is readily shaped by kneading and may be drawn into threads on application of moderate tension. When dropped on a hard surface, the material shows high elastic rebound it shatters, however, when given a sharp blow. 

Fluidized bed reactors do not have to perform poorly, but special conditions must be maintained for good performance. A basic process for silicone manufacturing, which is not practiced much anymore, is the reaction of silicon metal with methyl chloride to form dimethyl dichlorosilane ... 

Dimethyl-2-oxazoline is commercially available from Columbia Organic Chemicals, 912 Drake Street, Columbia, South Carolina, or may be prepared as follows. In a 250-ml., three-necked flask is placed 89.14 g. (1.0 mole) of 2-amino-2-methyl-l-propanol, and the flask is cooled in an ice bath. The amine is carefully neutralized with 52.3 g. (1.0 mole) of 90.6% formic acid over a 1-hour period. A magnetic stirring bar is added, the flask is fitted with a short path distillation head, and the reaction mixture is placed in a silicon oil bath which is rapidly heated to 220-250°. The azeotropic mixture of water and oxazoline distills over a period of 2-4 hours and is collected in an ioe-cooled flask containing ether. The aqueous layer is separated, saturated with sodium chloride, and extracted with three 50-ml. portions of ether. The combined ethereal extracts are dried over potassium carbonate, filtered to remove the drying agent, and the ether is removed at 35-40° at atmospheric pressure. The 4,4-dimethyl-2-oxazoline is collected as the temperature rises above 85°. The yield is 56.7-62.7 g. (57—63%) of a colorless mobile liquid, b.p. 99-100° (758 mm. Hg). 

Dimethyl(trimethylsilyl)phosphine (63) reacts with aluminium chlorides with cleavage of the silicon-phosphorus bond,58 as shown for aluminium trichloride. The same phosphine (63) reacts with the cobalt derivative (64) as shown.59... 

FIGURE 3 2 Solvent extraction efficiencies (EF) as functions of dielectric constants (D), solubility parameters (6), and polarity parameters (P and E -). Solvents studied silicon tetrachloride, carbon disulfide, n pentane. Freon 113, cyclopentane, n-hexane, carbon tetradiloride, diethylether, cyclohexane, isooctane, benzene (reference, EF 100), toluene, trichloroethylene, diethylamine, chloroform, triethylamine, methylene, chloride, tetra-hydrofuran, l,4 dioxane, pyridine, 2 propanol, acetone, ethanol, methanol, dimethyl sulfoxide, and water. Reprinted with permission from Grosjean. ... 

Methyllithium-Methylaluminum bis(2,4,6-tri-t-butylphenoxide), 203 Organolithium reagents, 221 Trityllithium, 338 Boron reagents Alkyldimesitylboranes, 8 Bis(2,4-dimethyl-3-pentyl) tartrate, 36 Chlorodimethoxyborane, 73 Silicon reagents Titanium(IV) chloride, 304 Tin reagents... 

FIG. 18.3 Activation energy of diffusion as a function of Tg for 21 different polymers from low to high temperatures, ( ) odd numbers (O) even numbers 1. Silicone rubber 2. Butadiene rubber 3. Hydropol (hydrogenated polybutadiene = amorphous polyethylene) 4. Styrene/butadiene rubber 5. Natural rubber 6. Butadiene/acrylonitrile rubber (80/20) 7. Butyl rubber 8. Ethylene/propylene rubber 9. Chloro-prene rubber (neoprene) 10. Poly(oxy methylene) 11. Butadiene/acrylonitrile rubber (60/40) 12. Polypropylene 13. Methyl rubber 14. Poly(viny[ acetate) 15. Nylon-11 16. Poly(ethyl methacrylate) 17. Polyethylene terephthalate) 18. Poly(vinyl chloride) 19. Polystyrene 20. Poly (bisphenol A carbonate) 21. Poly(2,6 dimethyl-p.phenylene oxide). 

The actual polymerization process involves a ring-opening reaction of dimethyl-substituted cyclic siloxanes. The preparation of the cyclic materials starts with the production of pure silicon via the reduction of quartz with coke in an electric arc furnace. The silicon metal then reacts with methyl chloride to give a mixture of silicones, from which dimethyldichlorosilane is removed by distillation.65 Subsequent hydrolysis gives the cyclic dimethylsiloxane. 

The formation of the expected 2,4,6-trisilaalkanes 2 can be explained by the 2 1 reaction of (chloromethyl)silanes 1 and elemental silicon. The byproducts, 1,3-disilaalkanes 3, were obtained from the reaction of (chloromethyl)silane reactant 1 and hydrogen chloride (or chlorine) with the same silicon atom, as methyldichlorosilane (or methyltrichlorosilane) was obtained from the methyl chloride reaction. This result indicates that some of the (chloromethyl)silane reactant decomposed under the reaction conditions and acted as a chlorine or hydrogen chloride source. In the direct reaction of (chloromethyl)dimethylchlorosilane (lc), a significant amount of starting material was recovered at temperatures below 300 °C, but the reaction went to completion above 320 °C. 2,6-Dimethyl-2,4,4,6-tetra-chloro-2,4,6-trisilaheptane (2c) was obtained in much higher yields than 3-methyl-l,l,l,3-tetrachloro-l,3-disilabutane (3c) at reaction temperatures ranging from 280 to 320 °C, but the ratio of both compounds reversed above 340 °C. 

In complete analogy to silicon, trialkyltin chlorides react with the lithiated ferrocenylalkyl amines to give the corresponding tin derivatives (Fig. 4-26, bottom) trimethyltin [129] and tributyltin substituents [106] have been introduced by this method. The tin compounds are more reactive towards transmetalation than the silicon analogues and are therefore useful intermediates in the preparation of other derivatives [129], e.g., by C —C coupling to give chiral biferrocenes [106]. Several racemic planar chiral derivatives of ferrocenyltriethylstannane have been prepared via lithiated N,lV-dimethyl-ferrocenylmethylamine and similar compounds [150]. 

Chloromethane can be produced by either chlorination of methane or reaction of methanol with hydrogen chloride. In an integrated production of silicones hydrogen chloride obtained by hydrolysis of methylchlorosilanes is recycled to the Direct Process via a chloromethane synthesis. The losses are compensated by make-up chloromethane or hydrogenchloride. Impurities, tike water, methanol, dimethyl ether or oxygen, must be kept at as low a level as possible. 

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