Anthracene, magnesium

Allylmagnesium halides are best prepared from 3-chloropropene and equimolar amounts of magnesium-anthracene THF complex (Table 1, method A)13 -15. Here, usually, the yields arc higher solvent and temperature have only minor influence13 14. A catalytic version is also possible13. 

Propenylmagnesium Chloride, Catalyzed by a Magnesium-Anthracene-THF Complex (Method A) Typical Procedure1,1 ... 

The finely divided hydride produced by pyrolysis is pyrophoric in air, while synthesis from the elements produces a substantially air-stable product [1]. That prepared by reduction of butylmagnesium bromide with lithium tetrahydroalumi-nate is pyrophoric and reacts violently with water and other protic compounds [2], The hydride produced from magnesium anthracene has a very large specific surface area and is pyrophoric [3], In the context of use of the hydride for energy storage purposes, ignition and combustion behaviour of 100-400 g portions were studied, as well as the reaction with water [4],... 

Highly reactive calcium can be readily prepared by the reduction of calcium halides in tetrahydrofuran solution with preformed lithium biphenylide under an argon atmosphere at room temperature.5 This colored calcium species seems to be reasonably soluble in THF. However, the reactive calcium complex prepared from preformed lithium naphthalenide was insoluble in THF solution and precipitated out of solution to give a highly reactive black solid. The exact nature of this black calcium complex has not been determined. Acid hydrolysis of the black material releases naphthalene as well as THF. Accordingly, the most likely structure of the black material is a Ca-naphthalene-THF complex similar in nature to the soluble magnesium-anthracene complex recently reported.6... 

Alkali metal reductions of metallic salts using an arene as electron carrier, lithium being the most used metallic component (Rieke method) . Although not belonging to this group of metals, magnesium-anthracene has found some apphcations in the activation of other metals . 

Although the formation of magnesium anthracene was discovered in 1965 and mentioned in a patent, the chemistry of magnesium anthracene systems began to develop thirteen years later, triggered by the discovery of a catalyst system for the hydrogenation of magnesium under mild conditions". ... 

Magnesium anthracene Ci4HioMg(THF)3 (118) can be prepared in high yield from the reaction of metallic magnesium and anthracene in THE (equation 12) . Kinetic measurements showed that a reversible temperature-dependent equilibrium exists between anthracene, magnesium and 118, the latter being favored at lower temperatures. This equilibrium opened a way to the preparation of elemental magnesium in a finely dispersed. 

Magnesium anthracene. Syntheses of organomagnesium compounds from the magnesium-anthracene adduct (see p. 40) proceed via dissociation of the adduct to give magnesium in a highly reactive form [9, 10]. Indeed, anthracene may be used to catalyse the reactions of other forms of magnesium (see below). 

Catalytically prepared magnesium hydride has been used as an alternative to magnesium anthracene [10]. 

---