Grignard process

Similar reactions can also be written for the alkoxysilanes but in commercial practice the chlorosilanes are favoured. These materials may be prepared by many routes, of which four appear to be of commercial value, the Grignard process, the direct process, the olefin addition method and the sodium condensation method. 

The reaction products must then be fractionated as in the Grignard process. 

The direct process is less flexible than the Grignard process and is restricted primarily to the production of the, nevertheless all-important, methyl- and phenyl-chlorosilanes. The main reason for this is that higher alkyl halides than methyl chloride decompose at the reaction temperature and give poor yields of the desired products and also the fact that the copper catalyst is only really effective with methyl chloride. 

The direct process involves significantly fewer steps than the Grignard process and is more economical in the use of raw materials. This may be seen by considering the production of chlorosilanes by both processes starting from the basic raw materials. For the Grignard process the basic materials will normally be sand, coke, chlorine and methane and the following steps will be necessary before the actual Grignard reaction ... 

Rochow has summed the entire Grignard process from basic raw material to polymer as ... 

Finally, yield improvements were also reported for industrial process developments. For the Merck Grignard process, a yield of 95% was obtained by a micro mixer-based process, while the industrial batch process (6 m stirred vessel) had only a 72% yield (5 h, at -20 °C) [11]. The laboratory-scale batch process (0.5 1 flask ... 

Boeseken, J., The Use of Boric Acid for the Determination of the Configuration of Carbohydrates, IV, 189-210 Bonner, William A., Friedel-Crafts and Grignard Processes in the Carbohydrate Series, VI, 251-289 Bourne, E. J., and Peat, Stanley, The Methyl Ethers of D-Glucose, V, 145-190 Bourne, E. J. See also, Barker, S. A. 

Friedel-Crafts and Grignard processes applied to, VI, 251-289 halogen oxidation of simple, III, 129-184... 

Grid-type couplings, for pumps, 27 80 Grignard plant flow diagram, 12 826 Grignard process, 22 547 Grignard reaction mixture, hydrolysis of, 12 827... 

Friedel-Crafts and Grignard processes applied to, 6, 251-289 gas-liquid chromatography of derivatives of, 19, 95-147 gel chromatography of, 25, 13-51 halogen oxidation of simple, 3,129-184 halogenated, 22, 177-227 infrared spectra of, 12, 13-33 infrared spectroscopy of, 19, 23-49 mass spectrometry of derivatives of,... 

Glycosyl fluorides, 16, 85-103 Glycosyl halides, and their derivatives, 10, 207-256 Goepp, Rudolph Maximilian, Jr., obituary of, 3, xv-xxiii Grignard process, in the carbohydrate series, 6, 251-289... 

The entire area of organosilicon chemistry blossomed with Kipping s preparation of such compounds by the more convenient Grignard process. These silanes turned out to be of paramount importance since they hydrolyzed readily to form compounds containing Si-0 bonds, both linear and cyclic.12,22,24 28 These new materials were first called silicoketones or silicones by analogy with ketones in the organic area. Structural studies, however, showed that they did not contain the Si=0 double bond. Thus, the silicone name is a misnomer, but it has persisted, at least in casual usage. However, the terms siloxanes and polysiloxanes are preferred. 

The precursor is generally a perfluoroalkyl iodide, and the preferred solvent dimethylformamide (DMF).21,22 Since a two-step Grignard process would give rise to difficulties, the one-step reaction was preferred giving good yields, which are still improved by sonochemical activation, minimizing 3-elimination.23,24 Perfluoroalkyl carboxylic acids can be prepared by running the reaction in the presence of carbon dioxide. 

Nalco Chemical Company does not use the batch alloy process for tetramethyllead in their plant at Freeport, Texas. Instead, they developed an electrolytic Grignard process in 1963 53,162,289,290). Tetraethyllead is not manufactured. The tetramethyllead process is based on the use... 

William A. Bonner, Friedel-Crafts and Grignard Processes in the Carbohydrate... 

FRIEDEL-CRAFTS AND GRIGNARD PROCESSES IN THE CARBOHYDRATE SERIES... 

Grignard process. Six steps remain necessary the three operations given in equations 1, 2, and 3, plus the preparations of magnesium, silicon tetrachloride, and methyl chloride. 

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