US3711529A - Complexes of aluminum alkyls and sodium fluoride - Google Patents

Abstract

IT IS DISCLODES THAT ALKYL ALUMINUM AND ALKALI METAL HALIDES FROM STABLE 2:1 COMPLEXES WHEREIN THE ALKYL GROUPS OF THE ALKYL ALUMINUM HAVE FROM ABOUT 6 TO ABOUT 20 CARBON ATOMS EACH. PROCESSES ARE DISCLOSED WHEREBY THE COMPOSITIONS OF THE PRESENT INVENTION ARE PRODUCED. SIMILAR 2:1 COMPLEXES OF SUCH ALKYL ALUMINUM AND OTHER COMPLEXING AGENTS ARE DISCLOSED.

Description

United States Patent 3,711,529 COMPLEXES OF ALUMINUM ALKYLS AND SODIUM FLUORIDE Lawrence H. Shepherd, Jr., Baton Rouge, La., assignor to Ethyl Corporation, New York, N.Y. No Drawing. Filed Nov. 23, 1970, Ser. No. 92,257 Int. Cl. C071? /06 US. Cl. 260-448 A 7 Claims ABSTRACT OF THE DISCLOSURE It is disclosed that alkyl aluminum and alkali metal halides form stable 2:1 complexes wherein the alkyl groups of the alkyl aluminum have from about 6 to about 20 carbon atoms each. Processes are disclosed whereby the compositions of the present invention are produced. Similar 2:1 complexes of such alkyl aluminum and other complexing agents are disclosed.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to the preparation of complexes of aluminum alkyls with alkali metal halides and related complexing agents. The molar ratio of aluminum alkyls in the complexes relative to the alkali metal halide type of materials is about 2:1 on a molecular basis.

Description of the prior art Complexes of triethyl aluminum and alkali metal halides are described in US. Pat. 3,415,862 wherein 1:1 molecular ratio complexes are reacted with mixtures of olefins and triethyl aluminum to form 2:1 complexes for the purpose of removing the triethyl aluminum from the olefins. Another example of prior art in this area is Annalen der Chemie, vol. 629, Nos. 1-3, March 1960, p. 34, lines 6-8, wherein it is stated that complexes containing aluminum trialkyl (C I-I Al are detectable where n is equal to 4 but that above n=6 the complexes are unstable. Further art in the area is US. Pat. 3,317,570 wherein aluminum alkyl complexes are used in chain growth and displacement operations. Although US. Pat. 3,317,570 might appear to be questionable in view of the teachings of the Annalen der Chemie article, or vice versa, it is pointd out that the efiluent from a chain growth process does not normally contain threehigher alkyl groups having six or more carbon atoms each per aluminum molecule since many of the alkyl groups in such mixtures are ethyl or butyl; or, in appropriate circumstances, propyl. Thus, while US. Pat. 3,317,570 may not be directly contradicted by the Annalen der Chemie article, neither is it a teaching with regard to complexes of trialkyl aluminum compounds wherein all of the alkyl groups are hexyl or higher.

SUMMARY OF THE INVENTION The present invention relates to a process for preparing 2:1 molar ratio complexes of alkyl aluminum whose alkyl groups have from about 6 to about 20 carbon atoms each With MX wherein M is alkali metal or tetraalkyl ammonium and X is halogen, cyanate, cyanide, azide, phenoxy or methoxy. In the process the trialkyl aluminum and the MX are heated together in molar proportions of about 2:1, respectively, at a temperature of from about 100 to about 175 C. for a period of time of from about 30 minutes to about 6 hours.

In a preferred aspect, the present process is performed at a temperature of from about 125 to about 150 C., more preferably from about 140 to about 150 C.

Patented Jan. 16, 1973 In a preferred aspect, the process of the present invention is conducted for a period of time of from about 1 to about 3 hours.

The present invention also relates specifically to the 2:1 molar complexes of alkyl aluminum with MX wherein each alkyl group of the aluminum has from about 6 to about 20 carbon atoms and wherein M is alkali metal or tetraalkyl ammonium with each alkyl group having up to about 8 carbon atoms and X is fluorine or cyanide.

In preferred aspects of the present compositions, M of the complexes is sodium or potassium and X of the complexes is fluorine or cyanide.

The present invention also relates to a process for utilizing the aluminum alkyl alkali metal halide and related complexes of the present invention wherein complexes having dissimilar alkyl groups or a diiferent distribution of similar alkyl groups are mixed in selected proportions to provide the desired distribution of alkyl groups in the product at a temperature from about to about 175 C. for a time from about 30 minutes to about 6 hours. Although trialkyl aluminum reactants are preferred, other suitable reactants include dialkyl aluminum halides (F, Cl, Br, I), dialkyl aluminum alkoxides (CH O- through C H O-) and dialkyl aluminum hydrides.

DISCUSSION Complexes of aluminum alkyls with alkali metal halides and related complexing agents are useful intermediates in chemical synthesis operations, for example, in the preparation of ole-fins by chain growth with ethylene and a lower trialkyl aluminum compound or in the separation of olefins from aluminum alkyl compounds having boiling points similar to those of the olefins. Such operations are discussed in several instances in the prior art as involving the formation and cleavage of 2:1 complexes to liberate trialkyl aluminum producing 1:1 complexes which can be recycled to reform 2:1 complexes picking up additional trialkyl aluminum. Such processes surfer from several disadvantages, particularly the severe conditions required for conversion of the 2:1 complex into the 1:1 complex. These severe conditions are conducive to the occurrence of side reactions producing undesired byproducts and losses of desired materials. A feature of the present invention is that it does not involve the conversion of complexes from one molecular ratio to another but rather in all instances, the complexes are treated under conditions which retain the 2:1 molecular ratio of aluminum alkyls to alkali metal halide or related complexing agent.

The preferred method of producing complexes in accordance with the present invention is by direct reaction of aluminum alkyls having the desired alkyl distribution or ratio of higher alkyl groups ranging from about 6 to about 20 carbon atoms per alkyl group with the alkali metal halide or related compound, such reaction being conducted at a temperature which is sufficiently high to permit the desired reaction to take place but which is not so high as to result in significant splitting off of olefins from the aluminum alkyls. In general, this requirement places a restriction of a maximum temperature of about C. on the operation; however, when the reaction is conducted for brief periods of time with care to avoid localized overheating, acceptable results are obtainable at temperatures up to about C.

Preferred compositions of matter in accordance with the presentinvention are of the formula 2(R Al):MX which designates complexes having two molecules of R Al per molecule of MX wherein the alkyl groups have from about 6 to about 20 carbon atoms each. The alkyl groups are straight chain or branched chain, (C H includ ing cyclic, alicyclic, alkaryl, aralkyl, cycloalkyl. and like alkyl ammonium wherein the alkyl groups are similar' to those previously set forth for R Al, but preferably are straight chain having up to about 8 carbon atoms each, typically ethyl and butyl. The M constituency includes substantially single M compounds as well as mixtures such as (molar) A2 Na /2 K; 4 Na'% K; Na-% K, etc.

Preferred X constituency of the complexes are halogen, particularly fluorine; and cyanide. Other X constituency is alkoxy radical having from about 2 to about 30 carbon atoms, cyanate, azide, substituted amide and mixtures of two or more thereof.

Typical preferred compositions of matter in accordance with the present invention are:

Other complexes are:

2(n-C H A1 Na benzyloxide 2 (n-C H A1: Na octenyloxide 2 (n-C H A1 Na xylyloxide 2 (n-C H A1: Na diphenyloxide 2 (II-'C8H17 A1 Na heptynyloxide 2 (n-C H 3 Al Na(4-cyclohexenyl oxide 2 n-C H A1 Na triacontyloxide 2(11-C3H17) A1 Na dimethylcyclohexoxide 2 (n-C H A1: Na cyclohexoxide 2 (n-C H A1 Na tolyloxide 2 (n-C H A1 Na vinyloxide 2 n-C H A1 Na octadecoxide 2(nC H Al:Na cumenyloxide Other typical complexes are:

NaF KF NaF (R=individual or mixture of two or more hydrocarbyl radicals having 6-30 carbon atoms each, average more than 6) Other typical complexes are:

Other typical complexes are:

The following examples indicate preferred embodiments of the present invention.

EXAMPLE I 165 millimols of tridecyl aluminum was stirred with 4.91 grams (117 millimols, 30 percent excess) of sodium fluoride for two hours at 144 C. After the stirring, the mixture was cooled to room temperature and the liquid was decanted from the solid residue. The residue and decanted liquid were weighed. Residual NaF was 1.17 grams thus 3.74 grams (89 millimols) of sodium fluoride dissolved. The ratio is 165/'89=1.85.

The product was stable when stored in a moisture-free environment.

EXAMPLE II 163 millimols of tridecyl aluminum was stirred for two hours at 136 C. with 6.56 grams (134 millimols) of sodium cyanide. The mixture was "allowed to cool to room temperature and the liquid was decanted. Residual NaCN was 2.44 grams thus 4.11 grams 84 millimols) of sodium cyanide dissolved during the stirring. The ratio is 134/84=1.94.

The product was stable when stored in a moisture-free environment.

EXAMPLE III 82.49 grams, 303 millimols of trihexyl aluminum was stirred for three hours at 145-155 C. with 6.3 grams, 155 mols of sodium fluoride. Substantially all the NaF dissolved and a clear solution resulted. On standing overnight at room temperature, no appreciable amount of solids precipitated.

I claim:

1. The process of preparing a 2:1 molar ratio complex of trialkyl aluminum in which each alkyl group has from 6 to about 20 carbon atoms with sodium fluoride which comprises heating the trialkyl aluminum and the sodium fluoride in molar proportions of about 2:1 at a temperature of from about to about 175 C. for a period of time of from about 30 minutes to about 6 hours, thereby preparing said complex.

2. The 2:1 molar complex of trialkyl aluminum with sodium fluoride wherein each alkyl group of the trialkyl aluminum has from 6 to about 20 carbon atoms.

3. A complex of the formula 2R Al:NaF wherein R is an individual or mixture of two or more alkyl radicals having 6-30 carbon atoms each and averaging more than 6 carbon atoms.

4. The process of claim 1 wherein the temperature is from about to about 150 C.

5. The process of claim 1 wherein the temperature is from about to about C.

6. The process of claim 1 wherein the time is from about one to about three hours.

7. The process of making 2:1 molar complexes of trialkyl aluminum with sodium fluoride, said complexes being characterized by having two or more different alkyl groups on the aluminum which comprises, forming two or more dissimilar complexes which together have the distribution of alkyl groups desired in the product and mixing said complexes at a temperature from about 100 to about 175 C. for a time from about 30 minutes to about 6 hours.

References Cited UNITED STATES PATENTS 6 3,280,025 10/1966 Poe et al. 260448 A X 3,317,570 5/1967 Kroll 260448 A X FOREIGN PATENTS 1,444,306 5/1966 France 260- 448 A OTHER REFERENCES Annalen der Chemie, vol 629, pp. 33-49 (1959). Farina, Gazzetta Chemica Italiana, vol. 89, pp. 2532-42 10 1959 H. M. S. SNEED, Primary Examiner