Metal alkyl, solution

Gasoline, ether and lighter fluid are examples of flammable liquids, while fuel oil and many alcohols are combustible liquids. Metal alkyl solutions are, if of relatively high concentration, pyrophoric liquids. 

In laboratory, small amounts of metal alkyls may be destroyed by diluting the pure compounds or its more concentrated solutions to a concentration below 5% with a hydrocarbon solvent, such as hexane or toluene. Alternatively, a water-miscible solvent, such as ethanol or ferf-butanol may be used. Small volumes of such solutions are then slowly and cautiously added to water in wide-mouthed containers in a hood and swirled gently. The metal alkyls are converted into their oxides or hydroxides. The organic solvent, if immiscible in water, is separated and evaporated in a hood. The entire content may, alternatively, be placed in waste containers and labeled for disposal. The toxic oxides or hydroxides of the metals formed are disposed for landfill burial while the nontoxic metal oxides or hydroxides conld be flushed down the drain. Alternatively, the metal alkyl solution or its waste may be diluted to a concentration below 5% with toluene or heptane. The diluted solution is then placed in a labeled container under argon for waste disposal. 

Using a solution process, the choice of catalyst system is determined, among other things, by the nature of the third monomer and factors such as the width of the mol wt distribution to be realised in the product. A number of articles review the induence of catalyst systems on the stmctural features of the products obtained (3,5—7). The catalyst comprises two main components first, a transition-metal haHde, such as TiCl, VCl, VOCl, etc, of which VOCl is the most widely used second, a metal alkyl component such as (C2H )2A1C1 diethylalurninum chloride, or monoethyl aluminum dichloride, (C2H )AlCl2, or most commonly a mixture of the two, ie, ethyl aluminum sesquichloride, [(C2H )2Al2Cl2]. 

The above results are concordant with the recent finding" that saturated alkyl fiuorides are not reduced by alkali metals in liquid ammonia at — 33°, although unsaturated fiuorides are reduced rapidly. All types of fiuoro compounds are reported to be reduced by metal-ammonia solutions at 0-25°. 

Initiation presumably involves metal alkyls as the primary source of carbanions. These are immediately available from the Grignard reagents, organosodium compounds, or sodium amide used as catalysts when the alkali metal itself or its solution in liquid ammonia is used, addition to the monomer may precede actual initiation. ... 

A solid surface is coated with a metal alkyl-oxide solution. 

Leaving aside the autoxidations of d°-alkyls, which only formally yield O2 insertion products, there are a very few examples of reactions where migratory insertion of a coordinated O2 into a metal alkyl bond seems indicated. Thus, heating of Cp 2Ta( -02)Me (Sect. 2.1) in solution in the absence of any base results in its transformation into Cp 2Ta(0)0Me [1]. Lewis acids were noted to catalyze the reaction. While there is no direct evidence for the formation of an alkylperoxo intermediate, the final product could easily be rationaUzed as resulting from an a-alkoxide eUmination (Scheme 10). 

Again several alkyls add—molybdenum, chromium, iron, cobalt, nickel, the alkali metal alkyls and aluminum alkyls react. A tin alkoxide has recently been studied by Russian workers and found to add to acetylenes. Mercury chloride, of course, adds and two cobalt—cobalt bonded compounds add to acetylene. The second is questionable because it dissociates in solution and the reaction may be a radical reaction, one cobalt adding to each end of the triple bond. 

Lithium amides are the most important of the alkali metal amides. This is mainly due to the facility with which they can be prepared in solution by the simple reaction of the amine with commercially available LiBu". An analogous reaction with heavier metal alkyls is much more difficult due to the high reactivity of heavier alkali metal alkyls which attack many solvents. Another advantage of lithium amides is that they tend to be more soluble in hydrocarbons than their heavier element congeners. This is due to the small size (and hence greater polarizing power) of the lithium ion, which induces greater covalent character. 

Radioactivation analysis has been used to measure bromine in polymers (37—39) and recently a novel technique for trace oxygen has been reported (40). Any polymer or other material (e.g. metal alkyl) which is miscible with butyl lithium solutions may be analysed since the procedure involves the intermediate production of triton particles by the nuclear reaction 6Li (n, a) t. The tritons then act as nuclear projectiles for the activation of oxygen 0 (t, n) 18F and the radioactivity due to fluorine-18 is measured. A sensitivity of 1 x 10 g in a 0.5 g sample is claimed. 

Traditionally, the adducts have been prepared by adding stoichiometric amounts of the ligand to a solution of dimethylzinc (in diethyl ether or petroleum spirit) followed by removal of the solvent in vacuo. The compounds presented here were synthesized by direct reaction of the ligand and the electronic grade metal alkyl in the absence of any solvent. 

Trimethylaluminum is available from many commercial sources, including Aldrich (97%), which also supplies a 2.0-molar solution in hexanes which may be substituted for the neat metal alkyl. 

Because of the ease of removal of its single 4s electron (4.339 eV) and the difficulty of removing a second electron (31.66 eV) potassium is exclusively monovalent in its compounds, which are electrovalent (Some experimental work indicates that the potassium alkyls may be covalent, but even they form conducting solutions in other metal alkyls.)... 

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