| 摘要 |
Aluminium is reacted with at least one primary alkyl halide (as defined below) in the presence of an inert solvent to form a sesquihalide, and the so-formed sesquihalide is reacted with an alkali-metal in the presence of an inert solvent to form an aluminium alkyl. Primary alkyl halides specified are methyl chloride, bromide and iodide, ethyl chloride, bromide and iodide, propyl bromide and iodide, n-butyl bromide and iodide and isobutyl iodide. In the first step a small quantity of the sesquihalide may be present as a reaction initiator. An alloy of magnesium and aluminium containing a low proportion of magnesium may be used. The temperature at which the first step is conducted should not exceed 50 DEG C., while the second step may be carried out at about 100 DEG to 150 DEG C. Solvents free from aromatic compounds such as paraffinic and alicyclic hydrocarbons are preferred (e.g. decalin, methyl cyclohexane). The sludge of alkali metal chloride and aluminium obtained in the second step may be recycled back to the first step with, if desired, addition of further aluminium. Any complex alkali metalaluminium-alkyl present in the sludge reacts with the aluminium sesquihalide to give the alkali metal halide and the desired aluminium alkyl. The reactions should be conducted in the absence of moisture using dry materials and in an inert atmosphere, e.g. nitrogen. Example 1 describes the preparation of aluminium triethyl from aluminium and ethyl bromide in methyl cyclohexane to give ethyl aluminium sesquibromide, which is reacted with a sodium-potassium alloy to give the desired product. The Provisional Specifications are not restricted to the preparation of aluminium alkyls, but the process of the invention is applicable to the preparation of alkyls, aryls and aralkyls of metals of Group III of the Periodic Table (aluminium, gallium, indium and thallium2). |
