ALKALI-METAL DERIVATIVES HYDROCARBONS

See ALKALI-METAL DERIVATIVES OF HYDROCARBONS See Other METAL ACETYLIDES... 

Alkali-metal derivatives of aliphatic or aromatic hydrocarbons, such as methyl-lithium, ethylsodium or phenylpotassium, are the most reactive towards moisture and air, immediately igniting in the latter. Derivatives of benzyl compounds, such as benzylsodium, are of slightly lower activity, usually but not always igniting in... 

Metalation. Benzene reacts with alkali metal derivatives such as methyl or ethyUithium in hydrocarbon solvents to produce phenyllithium [591-51-5], C6H5Li, and methane or ethane. Chloro-, bromo-, or iodobenzene will react with magnesium metal in ethereal solvents to produce phenylmagnesium chloride [100-59-4], C6H5MgCl, bromide, or iodide (Grignard reagents) (32). 

The solid obtained by evaporation of the air-sensitive solution is pyrophoric in air. See ALKALI-METAL DERIVATIVES OF HYDROCARBONS... 

Metal diketonates, the salts of /3-diketones and /3-ketoimines, are of interest for their usefulness as reagents (principally the alkali metal derivatives) and as potential precursors (the alkaline-earth derivatives) for CVD. The latter are discussed in additional detail in Section 3.1.4.4.1(vi), and Group 2 /3-diketonates used for this purpose have been extensively reviewed.Considerable interest has been expressed in fluorinated derivatives, which can display substantially increased volatility relative to the hydrocarbon compounds. Commonly used /3-diketones and /3-ketoimines... 

The structural chemistry of solvated alkali metal derivatives of planar polycyclic hydrocarbon dianions has been well investigated. Monomeric complexes have been isolated with hydrocarbons such as naphthalene, anthracene, perylene, pentalene,... 

Didehydroaromatic species apparently were considered as possible intermediates only twice during the next 30 years and in one of those instances rejected as being too unlikely. A dipolar formulation (lb) of dehydrobenzene was suggested almost simultaneously by Wittig and Morton as an intermediate in the reactions of halobenzenes with alkali metal derivatives of hydrocarbons. A symmetrical structure (la) for dehydrobenzene was specifically rejected by Wittig based on some earlier erroneous experimental work. ... 

Alkali metal reduction is a widely employed method for the preparation of radicals derived from various classes of conjugated compounds such as hydrocarbons, heterocycles, nitro compounds, quinones, and nitriles. For... 

Electronic Effects in Metallocenes and Certain Related Systems, 10, 79 Electronic Structure of Alkali Metal Adducts of Aromatic Hydrocarbons, 2, 115 Fast Exchange Reactions of Group I, II, and III Organometallic Compounds, 8,167 Fluorocarbon Derivatives of Metals, 1, 143 Heterocyclic Organoboranes, 2, 257... 

Tri-(l-naphthyl)phosphine is cleaved by alkali metals in THF solution. " Reaction with sodium gives the naphthalene radical-ion, with lithium the perylene radical-ion, and with potassium the radical-ion (22). Hydrocarbon radical-ion formation was thought to occur via naphthalene derived from the metal naphthalenide. E.s.r. spectra of further examples of phosphorus-substituted picrylhydrazyl radicals have been reported. ... 

The reaction involves the transfer of an electron from the alkali metal to naphthalene. The radical nature of the anion-radical has been established from electron spin resonance spectroscopy and the carbanion nature by their reaction with carbon dioxide to form the carboxylic acid derivative. The equilibrium in Eq. 5-65 depends on the electron affinity of the hydrocarbon and the donor properties of the solvent. Biphenyl is less useful than naphthalene since its equilibrium is far less toward the anion-radical than for naphthalene. Anthracene is also less useful even though it easily forms the anion-radical. The anthracene anion-radical is too stable to initiate polymerization. Polar solvents are needed to stabilize the anion-radical, primarily via solvation of the cation. Sodium naphthalene is formed quantitatively in tetrahy-drofuran (THF), but dilution with hydrocarbons results in precipitation of sodium and regeneration of naphthalene. For the less electropositive alkaline-earth metals, an even more polar solent than THF [e.g., hexamethylphosphoramide (HMPA)] is needed. 

Alkali metals in liquid ammonia represent the most important class of the so-called dissolving-metal reductions of aromatics. First described in 1937, it is a highly efficient and convenient process to convert aromatic hydrocarbons to partially reduced derivatives.201 The recognition and extensive development of this electron-transfer reduction came from A. J. Birch,202,203 and the reaction bears his name. 

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