Metalation magnesium alkoxide

Many metal alkoxides are soluble ia the corresponding alcohols, but magnesium alkoxides are practically insoluble. Only the distillable alkoxides, like those of alumiaum, titanium, and zirconium, are soluble ia weaMy polar solvents. The double alkoxides are soluble ia alcohol K[Li(OC2Hy)2],... 

A related class of compounds are the alkyl-magnesium alkoxides these can be prepared by reaction of MgR2 with an alcohol or ketone or by reaction of Mg metal with the appropriate alcohol and alkyl chloride in methylcyclohexane solvent, e.g. ... 

Modified MPV-type reductions carried out with chiral magnesium alkoxides and with chiral Grignard reagents have been discussed in detail (1). These reagents differ from the aluminum alkoxides since the Grignard reaction is essentially irreversible. Chiral alkali metal alkoxides have also been used to effect asymmetric reductions (1). 

A recent breakthrough in this field was made by Kanemasa and co-workers (136-138), who outlined a method to overcome the low selectivity of the cycloaddition to allylic alcohols by converting the hydroxyl group to a magnesium alkoxide. Coordination of both reactants to the metal ion accelerates the cycloaddition, affording the isoxazoline product with good to excellent stereoselectivity (136). Two transition states were proposed as pathways to the anti (erythro) and syn... 

Supported precursors for Ziegler-Natta catalysts may be obtained, depending on the kind of support, in two ways by treatment of the support containing surface hydroxyl groups with a transition metal compound with chemical covalent bond formation, and by the treatment of a magnesium alkoxide or magnesium chloride support with a Lewis base and transition metal compound with coordination bond formation. 

Perfluoroalkyl carbinols were prepared in a Barbier reaction using magnesium (Eq. 55).262 This metal is not frequently used in sonochemical Barbier reactions. A reason seems to be the insolubility of the product, a magnesium alkoxide. In many cases, this product coats the metal as a gummy deposit, whose texture prevents an ultrasonic cleaning of the surface. 

Sodium ethoxide was the first metal alkoxide described in 1837 (1). The alkoxides of many transition metals were developed after World War II (2—5). Today some alkoxides, including those of sodium, potassium, magnesium, aluminum, zirconium, and titanium, are commercially important. The name metal alkoxides is preferred, although metal alcoholates is also used. 

Biodiesel is a mixture of methyl esters of fatty acids and is produced from vegetable oils by transesterification with methanol (Fig. 10.1). For every three moles of methyl esters one mole of glycerol is produced as a by-product, which is roughly 10 wt.% of the total product. Transesterification is usually catalyzed with base catalysts but there are also processes with acid catalysts. The base catalysts are the hydroxides and alkoxides of alkaline and alkaline earth metals. The acid catalysts are hydrochloride, sulfuric or sulfonic acid. Some metal-based catalysts can also be exploited, such as titanium alcoholates or oxides of tin, magnesium and zinc. All these catalyst acts as homogeneous catalysts and need to be removed from the product [16, 17]. The advantages of biodiesel as fuel are transportability, heat content (80% of diesel fuel), ready availability and renewability. The... 

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