Magnesium alkyl

Magnesium dialkyls, R Mg, and the alkyl magnesium halides, RMgX (where R is an alkyl groups such as n-butyl or //-hexyl and X is a halogen) 

The Chemistry and Technology of Magnesia, by Mark A. Shand Copyright 2006 John Wiley Sons, Inc. 

TABLE 14.1 Physical Properties of Various Magnesium Salts 

Property 0t-Mg(C2H3O2)2 MgCl2-6H20 Mg(N03)2-6H20 MgS04-7H20 

Crystal system Orthorhombic Monoclinic Monoclinic Orthorhombic 

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Preparations. Magnesium alkyls maybe prepared from a Grignard reagent according to the following disproportionation reaction ... 

Magnesium haUde and alkyl magnesium haUde precipitate and the alkyl magnesium compound remains in solution. Filtration (qv) followed by drying the filtrate yields soHd magnesium alkyl (11). Another preparation method is that of metal exchange using mercury alkyl in ether. 

Magnesium alkyls can also be prepared by reaction of alkyl iodide and a calcium—magnesium ahoy in ether. 

Reactions. The most noted magnesium alkyl reactions involve the solvated Grignard reagents. The more common reactions involving unsolvated magnesium alkyl are as foUows (14,15). 

Uses. Magnesium alkyls are used as polymerization catalysts for alpha-alkenes and dienes, such as the polymerization of ethylene (qv), and in combination with aluminum alkyls and the transition-metal haUdes (16—18). Magnesium alkyls have been used in conjunction with other compounds in the polymerization of alkene oxides, alkene sulfides, acrylonitrile (qv), and polar vinyl monomers (19—22). Magnesium alkyls can be used as a Hquid detergents (23). Also, magnesium alkyls have been used as fuel additives and for the suppression of soot in combustion of residual furnace oil (24). 

MgCl2 obtained from magnesium alkyl haUdes (-P) = organic polymer residue present in MgCl2. 

On catalytic hydrogenation it furnishes mainly dihydroquinidine. Benzoyl chloride converts it into the enol benzoate, m.p. 114-5°, and on interaction with magnesium alkyl halides it forms alkylquinidines, e.g., methylquinidine, 2H2O, m.p, 105-12°, [a] ° -(- 168° (EtOH),... 

Atid aie pioduced by passing carbon dioxide into tlie ether bolution of the magnesium alkyl compound. 

The reactivity of the zinc alkyl derivatives [TpBut]ZnR is typically lower than that of the corresponding magnesium derivatives (Section III,A,2,c.). For example, whereas [TpBut]MgMe undergoes insertion of C02 into the Mg-C bond at room temperature, no reaction is observed between [TpBut]ZnMe and C02 at 140°C. Similarly, whereas the magnesium alkyl derivatives [TpBut]MgR (R = Me, Et, Pr1, Bul) react immediately with 02 at room temperature to give alkylperoxo derivatives [TpBut]MgOOR, solutions of the zinc derivative [TpBut]ZnEt are stable in the presence of 02 at 100°C. 

Mercury alkyls are readily obtained by the actions of Grignard reagents (magnesium alkyl halides) on mercury(II) chloride. Thus, mercury dimethyl is made from magnesium methyl chloride and mercury(II) chloride ... 

A number of metal alkyls add readily to double bonds. These include the titanium alkyls, chromium aryls and alkyls, the alkylmanganese carbonyls, acyl-cobalt carbonyls, alkali metal alkyls, the magnesium alkyls, and aluminum alkyls. 

McKenzie, A. CXXVII. — Studies in asymmetric synthesis. I. Reduction of menthyl benzoylformate. II. Action of magnesium alkyl haloids on menthyl benzoylformate. J. chem. Soc. [London] 85, 1249 (1904),... 

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