Organomagnesium synthesis

The nucleophilic substitution reactions are still more limited in scope owing to the instability of the isoxazole ring toward nucleophilic reagents. Homolytic reactions appear to be unknown though some of the reactions being studied are possibly of this type. Besides those reactions which are characteristic of the reactivity of the isoxazole nucleus itself, we shall consider in this section some substitution reactions in the side chain organomagnesium synthesis in the isoxazole series, condensation reactions of the methyl groups of methyl-isoxazoles, and finally some miscellaneous reactions. 

An interesting example of the organomagnesium synthesis is to be found in the use of 1,4-addition of the Grignard reagent to 4-alkyl-ideneisoxazol-5-ones (91) to prepare saturated isoxazol-5-ones (92). 

In 1863 Friedel and Crafts were the first to use metalorganic compounds to synthesise silicone monomers. Industiy focused on organomagnesium synthesis (the Grignard technique), in which alkyl- or arylhalogenide interacts with metallic magnesium to form organomagnesium compounds ... 

The process of organomagnesium synthesis yields a mixture of al-kyl(aryl)chlorosilanes with various numbers of radicals attached to the silicon atom. However, by regulating the ratio of the parent components and changing the conditions of the process, one can shift the reaction towards the preferential formation of a certain monomer. 

Fig. 1. Production diagram of methylphenyldichlorosilane by organomagnesium-synthesis 1,2- dehydration boxes 3,4,7,11- batch boxes 5 - agitator 6, 9, 14 - coolers 8 - reactor of phenylmagnesiumchloride synthesis 10 - reactor of methylphenyldichlorosilane synthesis 12 — nutsch filter 13 — vacuum distill-ingtank 15-18- collectors 19- container.

The reviewed technique of organomagnesium synthesis has significant drawbacks. The process develops in the necessary direction only in a narrow temperature range and requires solvents, which results in the low effi-... 

Apart from the given common technique, one can prepare hydroxyorganosilanes by the breakdown of the organochlorosilane mixture (with an aqueous alkali solution) obtained by the organomagnesium synthesis ... 

Fig. 14. Reactor of the continuous organomagnesium synthesis of organoethoxysi-lanes 1 - cooling jacket 2 - rake element 3 - choke for loading off the products of the reaction 4 - choke for loading magnesium 5 - agitator shaft 6 - separator 7 -spiral (hollow pipe) 8 - thermocouple pocket 9 - choke for loading the reactive mixture 10 - casing of the reactor...

In recent years there has been a great interest to the continuous processes of organomagnesium synthesis of silicone monomers. This is caused by the increasing consumption scale of organomagnesium compounds and the synthesis of silicone monomers used in the production of poly-phenyldiethylsiloxanes. 

Tin alkylhalogenides can be prepared by several techniques, the most important of which are direct synthesis and organomagnesium synthesis. 

Of greater practical interest for the production of tin alkylhalogenides is organomagnesium synthesis, which is based on the interaction of alkyl-magnesiumhalogenides with tin tetrachloride. This technique can also yield tin tetraalkyl derivatives. Since these substances are semiproducts in the production of organic salts of dialkyl tin, their organomagnesium synthesis is described along with the production of diethyl tin dicaprylate. 

Continuous processes of the synthesis of organomagnesium compounds and organomagnesium synthesis of silicone monomers (1984) In series Elementorganic compounds and their application. NIITEKhim Moscow [in Russian]... 

Since 1926 the organomagnesium synthesis was also used for preparing more complex tetraorganylgermanes145,162,163,169,172,187-190 such as R3GeR R2GeR2 and R2GeR/R". 

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