Beryllium dialkyls

Beryllium dialkyls (BeR2, R = Me, Et, Pr", Pr, Bu etc.) can be made by reacting lithium alkyls or Grignard reagents with BeCl2 in ethereal solution, but the products are difficult to free from ether and, when pure compounds rather than solutions are required, a better route is by heating Be metal with the appropriate mercury dialkyl ... 

Reaction of beryllium dialkyls with an excess of alcohol yields the alkoxides Be OR)2. The methoxide and ethoxide are insoluble and... 

Beryllium dialkyls BeR2 are best made by one of the most general preparative methods for organometallics, by heating elemental beryllium with the corresponding mercury alkyl HgR2 ... 

From the facts of the formation of beryllium dialkyls by the continuous heating of alkylberyllium halides and of the formation of the latter when beryllium dialkyls are treated with beryllium halides (99), the following equilibrium was suggested (R = alkyl, X=halogen) ... 

The actual isolation of beryllium dialkyls in a pure state has only just been accomplished by Gilman and Schulze, and their work throws doubt upon the accurac of that of previous investigators. Their method of procedure is the one suggested by Krause and Wendt. In 1926, Durand claimed to have prepared beryllium methyl iodide, but the work has since been disproved by Gilman and Schulze. These workers have isolated beryllium alkyl halides by heating beryllium, alkyl halides, and ether in the presence of catalysts, such as mercuric chloride, beryllium chloride, or free bromine. The first aryl compound, beryllium phenyl iodide, has been prepared by a similar process. 

The ethereal solutions of these iodides do not fume in air, and removal of the solvent gives a liquid, which on further heating evolves dense white fumes, probably of beryllium oxide. Heating changes the alkyl beryllium halides to beryllium dialkyls. All the alkyl halide compounds are decomposed by water, with formation of the corresponding hydrocarbon. When carbon dioxide is passed through ethereal beryllium methyl iodide for three hours, the solution still gives a positive test and no acetic acid is found after hydrolysis. Acetanilide is formed from beryllium methyl iodide and phenyl isocyanate. 

Organo -Ca, -Sr and -Ba derivatives are prepared from the metals. With Be, however, the compounds are produced from anhydr BeCl2 and organomagnesium-halide reagents or lithium alkyls. In principle, RBe derivatives can also be formed from Be metal. Thus, a Be mirror disappears by the effect of alkyl radicals, but such reactions cannot be used in practice. Beryllium dialkyls also can be prepared from olefins and Hj with the metal in the presence of small amounts of Br2 or I2, and by the electrolysis of M[A1R3R ] complexes (M = Na, K R = alkyl R = alkyl, alkoxy) using anodes of pure Be. However, laboratory application is limited owing to the lack of detailed information and the need for expensive apparatus. 

The Mg—C distance in the bridge are somewhat longer than the Mg—C single-bond distances observed in the Grignard-type reagents, but comparisons cannot be made with a simple dialkyl since none of the structures have been reported. The Mg—Mg distance is about 2.70 A, which is relatively short and could permit metal-metal interaction for stabilization of the polymeric materials, as suggested for the beryllium derivatives, but neither sufficient experimental data nor theoretical calculations (90) are available to confirm or refute this possibility. 

Te tram eric alkyl beryllium, zinc and cadmium alkoxides are formed by controlled alcoholysis of the metal dialkyls,16U62 while cubanoid thallium alkoxides are obtained by reaction of the metal with refluxing ethanol, and alcohol metathesis.163 Reaction (4) affords a tin phosphide cubane in low yield 164... 

Lead, cadmium, mercury, cobalt, uranium, antimony, barium, beryllium, cesium, molybdenum, platinum, thallium, tungsten, organochlorine pesticides, organophospho-rus insecticides (dialkyl phosphate metabolites), (specific metabolites), pyrethroid pesticides, other pesticides (2-isopropoyxyphenol, carbofuranphenol), herbicides, phthalates, phytoestrogens, polycyclic aromatic hydrocarbons, polychlorinated dibenzo-p-dioxins and dibenzofurans, polychlorinated biphenyls, tobacco smoke... 

Dialkyl-beryllium und Trialkyl-aluminium bilden in der Haupt-sache dimere Assoziate. Trialkylaluminium mit voluminosen Resten, z. B. A1(CH2 CHRR)3 (Iso-butyl-Typ), ist dagegen praktisch uberhaupt nicht assoziiert 16). 

Although beryllium alkyls can be obtained by the interaction of BeCl2 with lithium alkyls or Grignard reagents, they are best made in a pure state by heating the metal and a mercury dialkyl, for example ... 

Beryllium compounds were obtained in 1860 by Cahours by heating metallic beryllium with mercury dialkyls at 130 to 135° C. in a sealed tube. Frankland also obtained beryllium diethyl and dipropyl by a similar method. In 1884, Lavroff also claimed to have obtained... 

Rather similar hydrides of zinc, cadmium, beryllium and magnesium have been made by reducing their dialkyls with lithium aluminium hydride dissolved in ether ... 

The compound [Mn(CH2SiM63)2], for example, is polymeric in the crystal, -with a structure (75) like those of dialkyls of beryllium and magnesium (MR2) (M = Be or Mg R = Me or Et), Each metal atom, tetrahedrally coordinated. 

Pyrolysis of dialkyls which possess jS-hydrogen atoms proceeds mainly by loss of alkene. This provides a route to the polymeric beryllium hydride itself or to alkylberyllium hydrides. At higher temperatures Bu2 e decomposes to the metal. It is possible to plate thin layers of beryllium on to surfaces at 280-300 "C in vacuo. 

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