Patent GB-777701-A (GB)
Title: The manufacture of organic compounds of aluminium
IPC: C07F5/06
Filed: 1953-05-13
Abstract: Organo-aluminium compounds of the general formula AlRR1R11, wherein R represents a hydrocarbon residue and R1 and R11 are similar or dissimilar and each represent a hydrocarbon residue, hydrogen or a halogen, are prepared by reacting in a reaction cycle an organoaluminium compound of the above general formula with (a) an aluminium halide, alkylaluminium halide or alkylaluminium sesquihalide, (b) an alkali metal hydride, and (c) an olefin, in the appropriate order to produce an additional amount of organo-aluminium compound of the above general formula so that in effect, the compounds (a), (b) and (c) have yielded an organo-aluminium compound of said general formula.  It is possible to start with or to finish with any of the organo-aluminium compounds of the above general formula.  The reactions involved in the reaction cycle, which may be carried out as separate reaction steps or two or more of the reaction steps may be carried out simultaneously, are summarized as follows in which the hydrocarbon residues are ethyl radicals, the reactant (a) is aluminium chloride, the alkali metal hydride is sodium hydride and the olefin is ethylene: <FORM:0777701/IV(b)/1> <FORM:0777701/IV(b)/2> <FORM:0777701/IV(b)/3> In this type of cycle represented by equations (1), (2) and (3), the second and third stages may be combined.  Thus it is possible to arrive at the same end product, if, following reaction (1) above the diethylaluminium chloride or other alkylaluminium halide is gradually reacted, preferably at 100-120 DEG C., with a quantity of sodium hydride or other alkali metal hydride equivalent to its halogen content, and ethylene or other olefin is passed at the same time into the reaction mixture, and further there can be introduced into the reaction mixture, preferably at 110-120 DEG C., with simultaneous introduction of ethylene or other olefin, either alternately or simultaneously aluminium chloride or other aluminium halide and sodium hydride or other alkali metal hydride, if care is taken to ensure that the ethylene or other olefin in the gas space does not come into contact with the aluminium halide.  The reaction cycle represented by equations (1), (2) and (3) above can be applied to a process in which alkylaluminium dehalide such as ethylaluminium dichloride, alkylaluminium dihydride such as ethylaluminium dihydride, and trialkylaluminium such as triethylaluminium are formed at each stage respectively, and such a process can be modified to form alkylaluminium hydride halide such as ethylaluminium hydride chloride, at the end of the second stage by using equimolecular proportions of an alkali metal hydride and alkylaluminium dihalide.  The above three-stage cycle and the modifications thereof may be used, therefore, to prepare trialkylaluminiums, dialkylaluminium monohydrides and monohalides, monoalkylaluminium dihydrides and dihalides, and alkylaluminium hydride halides.  The reaction represented by equation (1) above may be modified in that an alkylaluminium dihalide or an alkylaluminium sesquihalide (a mixture of dialkylaluminium halide and alkylaluminium dihalide) may be used for reaction with the trialkylaluminium to form dialkylaluminium halide.  The dialkylaluminium halide portion of the alkylaluminium sesquihalide may be converted into alkylaluminium dihalide by reaction with aluminium halide, and the alkylaluminium dihalide may then be reacted in accordance with the process illustrated in equation (1) above.  Suitable alkali metal hydrides mentioned are sodium and lithium hydride, and suitable olefins mentioned are ethylene, propylene and isobutylene.  Aluminium trialkyls and alkylaluminium hydrides are capable of adding alkali metal hydrides to form complex compounds such as [HAlR3]Na, [HAlR3]Li, [H2AlR2]Na, [H2AlR2]Li and [H2AlR2]K, wherein R represents an alkyl radical, and it is useful to introduce the alkali metal hydrides into the reaction cycle in the form of such complex compounds as illustrated in the following equations: <FORM:0777701/IV(b)/4> <FORM:0777701/IV(b)/5> <FORM:0777701/IV(b)/6> wherein n is an integer and R represents an alkyl radical.  It is also possible to react the olefin with the complex compounds formed from alkylaluminium dihydrides, dialkylaluminium hydrides or trialkylaluminiums with alkali metal hydrides.  Such a reaction cycle is illustrated in the following equations: <FORM:0777701/IV(b)/7> <FORM:0777701/IV(b)/8> <FORM:0777701/IV(b)/9> The steps illustrated in equations (7) and (8) may be combined by heating together sodium hydride, tripropylaluminium and propylene. It is possible, therefore, to isolate the product in the form of a complex compound if the cycle is terminated, for example, at the step illustrated by equation (4), (7) or (8).  In the examples: (1) tripropylaluminium is prepared in a reaction cycle involving the reaction of tripropylaluminium, aluminium chloride, sodium hydride and propylene; (2) triisobutylaluminium is prepared in a reaction cycle involving the reaction of triisobutylaluminium etherate, aluminium chloride, lithium hydride, isobutylaluminium dichloride and isobutylene (lithium aluminium isobutyl trihydride is formed as an intermediate); (3) triethylaluminium is prepared by a reaction cycle involving the reaction of triethylaluminium, ethylaluminium sesquihalide (or aluminium chloride), sodium hydride and ethylene (sodium aluminium triethyl hydride is formed as an intermediate); (4) diethylaluminium hydride is prepared by a reaction cycle involving the reaction of diethylaluminium hydride, sodium hydride, triethylaluminium and ethylaluminium sesquichloride.  Specifications 763,824 and 774,516 are referred to.