CA1244235A - Hydrocarbon-soluble dialkylmagnesium composition - Google Patents

Abstract

HYDROCARBON SOLUBLE DIALKYLMAGNESIUM COMPOSITIONS

Abstract of the Disclosure Hydrocarbon soluble compositions comprising at least three dialkylmagnesium compounds, in which at least two of said compounds con-tain straight-chain alkyl groups having from 1 to 4 carbon atoms each, and at least one additional compound contains alkyl groups having from 5 to 20 carbon atoms each.

Description

3s PR~705~A
HYDRi:)CAR~N SOI,WBLE DIALKYLM~GNESIUM COM[`0'~7ITIO~IS

8ackground of the Invention Diorganomagnesium ccmpounds are well known for their usefulness in a wide variety of chemical reactions. As reagents, these compounds can be used for the reduction of ketones, the metalation of aromatic com-pounds, and the alkylation of metal halides or oxides to the corresponding metal alkyls. ~s catalysts, diorganomagnesium comFounds are useful in the dimerization and polymerization of olefins, see British Pat. 1,251jl77;
the polymerization of epoxides, see U.S. Pat. 3,444,102; and the prepara-tion of telomers, see U.S. Pat. 3,742,077. While they perform many of-the same types o~ ~unctions performed by Grignard reagents, diorganomagnesium co~pounds, owing to differences in electronic and steric factors, are re reactive than Grignard reagents toward c~rtain types of asmFounds. In general, see also U.S. Patènts 3,646,231 and 3,822,219.

The utility o diorgancmagnesium ccm~ounds is lessened by the fact that man~ are either solids or highly viscous liquids and all are un~able on exposure t~ moisture and air. Ihis probl~m is generally cver~
come either by dissolving the c~mpound in an inert hy~rocarbsn solvent or by solvating the ccm~ound and by ha~dl mg u~der ~n inert a ~ sp~.ere. MbLny 2U diorgancmagnesium compounds, particularly those with straight chain lower aIk~l groups with a chain length of up bo our carbon atcms, are insoluble by th~selves in hy~rocarbon solvents and ~hus re~uire solubilizing agents which will form a soluble complex E~amples of such solubilizing asents are alkyllithium oo~pou~ds, see U.S. Pat~ 3,742,077; diaLkyl 2inC COmr Eounds, see U.S. Pat. 3,444,10~; alkali metal h~drides, see U~S. Pat.
3,655,790; and organoaluminum compounds, see UDS. Pat. 3,737,393.

Solvation involves the use of an ether or an or~anic base mole-c~le to associate di~ectly with the magnesium atcm, thus rendering a liquid-phase ccmplex. The solvated foLm is undesirable, however, since `

~ ~5,~ L~L 9LZ 3 5 solvation seriously inhibits the effectiveness of the compound, particu-larly when the con~ound is used as a Ziegler-type catalyst. The use of ether is particularly undesirable due to considerations of flammability and explosibility, and because it introduces soluble RMgX according to the Schlenk equilibrium ~ Mg ~ MgX2 = 2 RMgX
where R is alkyl and X is halogen.

Solubilization also serves to reduce the viscosity of reaction mixtures whose high viscosity w~uld otherwise inhibit the progress of the reaction and cause difficulty in handling and transferring. This problem is only partially solved by the use of chloroaryl solvents to form low viscosity suspensions of the insoluble compounds, as described in U.S.
Pat. 3,264,360.

In addition, the insolubility of the lower alkyl magnesium com-pounds makes preparation of them in a form free of undesirable halides difficult. In particular, the direct reaction of magnesium metal with an organic halide is disclosed in Glaze and Selman, Journal of Crganometallic Ch~mistry, Vol. 5, p.477 (1966), and W.N. Smith, Journal of Organo-etallic Chem~ y, Vol. 64, p. 25 (1974). These articles deal with the preparation of diorganomagnesium compounds having straight chain alkyl groups of 5 carbon atoms and higher. Such compounds are soluble in hydro-carbon solvents and thus separable from the concurrently produced magnesium halide and unreacted magnesium. When lower straight chain aIkyls are used in this process, the desired diorganomagnesium compound is formed but is insoluble and exists as a slurry in the solvent together with the mag-nesium halide and unreacted magnesium metal. m us a solubilizing agent is required when this prooe ss is used to make lower alkyl diorganomagnesium oompounds. The latter are particularly desirable as reagents and cata-lysts owing to their relatively high magnesium content on a weight basis.

Other methods of preparation include the mercury-magnesium exchange method, as disclosed in Cowan and Mosher~ Journal of Organic , Vol. 27, p. 1 (1962), and the dioxanate~precipitation method, as disclos d in Schlenk, Berichte der Deutschen Chemischen Gesellschaf~, Vol.64, p. 734 (1931). The mercury method, .~Z~3S

R2Hg -~ Mg ---- ~ R2Mg ~
where R is alkyl, is limited by the high cost oE dialkylmerc~ry compounds, and the health hazards inv~lved in their use. The reaction itself is hazardous since it proceeds rapidly and exothermically after an inhibition period.

~le dioxanate-precipitation method, 2RMgX + C4H802 ~ R2Mg -~ C4H802 MgX2 where R -s alkyl and X is halogen, involves removal of magnesium halide from ether solutions of Grignard reagents by precipitation of a complex which the dioxane forms with the halide. This is a tedious process and results in an etherated dialkylmagnesium complex from which the e-ther must be removed prior to use as a catalyst.

Dialkylmagnesiums can also be prepared from alkyllithiums, see U.S. Pat. 3,646,231, by recipitation of lithium halide, MgX2 + 2LiR -~ Mg + 2LiX
where R is alkyl and X is halogen. m is process is unsuitable for straight-chain lower dialkylmagnesiums which are insoluble in hydrocarbon solvents, since separation will be impossible. me use of basic solvents renders separation possible but requires subsequent desolvation. m is reference also discloses the use of a hydrocarbonsoluble diorganomagnesium to solubilize an insoluble diorganomagnesium. The solubilizina r~ers shown in this reference, however, invariably oontain brached chain alkyl groups. Such brached-chain diorganomagnesium compounds cannot be pre-pared by the Glaze and Selman m~thod mentioned above. This fact is estab-lished in the w~rk of Kamienski and Eastham, ~ournal of Organic Chemlstry, ~o~ 34, p. 1116 (1968). Thus, resort to the lithium halide precipitation method is required.

A similar process is described in U.S. Pat. 3,742,077. Again, the solubilizing agent must be a hydrocarbon soluble secondary-branched dialkylmagnesium such as di-tert-butylmagnesium or di-sec-butylmagnesium.

me general i lubility of straight chain lower alkyl magnesium oomp~unds is thought to be due to interm~lecular association r~sulting in the formation of a polymer-type macro-structure wherein each magnesium ~ r 3~ 3~

atom is tetrahedrally surrounded by four alkyl groups. Known methods of solubilizing these compounds presumably operate to break some of the intermolecular bonds and thereby break down the macro-structure into smaller units. Solvation or complexing as descrlbed above are thouyht to bring about this effect.

Alkylmagnesium compounds containing either brached-chain alkyl groups or straight-chain alkyl groups of five carbon atoms or more, known to be effective as solubilizing ager.ts, are also thought to operate by breaking the intermolecular bonds. With alkylmagnesium compounds, how-ever, the effect is thought to occur by way of alkyl interchange and re-association, whereby the solubilizing alkyl groups exchange positions with some of the straight-chain .lower alkyls. Polymerization i5 thus sterically hindered/ either because the substituted groups are unwieldy for a tetrahedral fit around the magnesium atom, or because the groups have some inherent solubility of their own.

U.S. Patent 4,069,267 discloses the use of longer chain dialkyl-magnesium compounds to stabilize (prevent precipitation of) di-n-butyl-magnesium/di-sec-butylmagnesium and di-n-butylmagnesium~di-tert-butyl-magnesium compositions. The longer chain dialkylmagnesium co~pounds have 6 carbons or greater in the alkyl groups, preferably 8 or 10 carbons. The pro oe ss involves the use of relatively expensive brached-chain aIkyl-lithium compounds such assec~butyllithium and tert-butyllithium, which are added to the reaction product of n-butyl chloride with magnesium metal in the presence of a higher aikyl chloride~ Though brached-chain di~
alkyomagnesium compounds (such as di-sec-butyl and di-tert-butylmagnesium) are kn~wn to be highly soluble in hydrocarbon solvents and serve as highly effective solubili~ing agents for insoluble dialkylmagnesium o~mpounds (such as di-n-butylmag~esium), these brached-chain magnesium alkyls cannot be made by direct reaction of the corresponding secondary or tertiary alkyl halide with magnesium metal in hydrocarbon medio. Also, the three-component magnesium alkyl compositions disclosed in U.S. Pat.
4,069,267 contain two diaIkylmagnesium oom~ounds that are indep~ndetly soluble in hydrocarbon solvents; hence it is not surprising that the three-component systems are highly soluble in such solvents.

5 ~ 23~

Sev~ral other U.S. pa-ten-ts disclose hydrocarbon soluble dialkyl-magnesium systems containing two or three components in which the alkyl groups are Cl-C4 straight-chain alky:L and ~he alkyl groups in the different dialkylmagnesium oompounds differ by more than one carbon atom.

U.S. Patent 4,127,507 describes such compositions comprising di-n-butyLmagnesium and diethylmagnesiumO U.S. Patent 4,207,207 describes such compositions comprising di-n-propylmagnesium and dimethylmagnesium.
U.S. Patent 4,222,969 discloses such compositions comprising di-n-butyl-mangesium and dimethylmagnesium. U.S. Patent 4,207,207 also describes a three-component hydrocarbon soluble magnesium alkyl system comprising di-n-propyl-, diethyl- and dimethylmagnesiums. However, yields of soluble diaLkylmagnesium in this three-component system were relatively low, at most about 25%.

Additionally, when working with tw~-component lower alkyl magne-sium compostions as described in these three patents, it has been found that best results in terms of percetage yield of a hydrocarbon soluble diaLkylmagnesium composition are obtained within relatively narrow ranges of mole ratios of the starting two alkyl halides. Thus, in U.S. Patent 4,127,507 it is whown from the disclosure, and particularly from Examples

2-8, that the greatest yield of soluble dialkylmagnesium composition is obtained with a mole ratio of n-butyl:ethyl chloride of between about 0.8:1 and about 1.25:1, and particularly at approximately equimolar ratios. On the other hand, when the mole ratio is varied to about 3:1 in favor of either n-butyl or ethyl chloride, the yield of soluble diaIkyl-magnesium drops to about one-half of that at the optImum ratio, and decreases to only a few percent yield at ratios of approximately 10:1 in favor of either chloride. Similar performance occurs with combinations of di-n-propyl/dimethyl and di-n-butyl/dimethyl magnesiums.

Furthermore, U.S. Patent 4S222~69 also discloses (Examples 3-5) that when two diaIkylmagnesium compounds differ by only one carbon atom in the alkyl groups, a hydrocarbon soluble composition is not obtained.

In some instances, depending on the process in which a hydro-carbon soluble dialkylmagnesium composition is to be utilized, it may be . . . ~ .

lZ3~

advantageous to prepare such a composition dominating in one of the two alkyl groups. For instance, if the dialkylmagnesium compound is to be utilized as an alkylating agent in a hydro-carbon solution environment, it would be preferable to obtain a hydrocarbon soluble composition high in the desired alkyl-magnesium. In production of certain polymerization catalysts, it may also be desirable to have a dialkylmagnesium composition high in one or another dialkylmagnesium of such a two-component composition. If the ob~ective is to obtain a hydro-carbon soluble dialkylmagnesium composition with a highmagnesium content, it would be preferable to have such a composition predominantly comprising the dialkylmagnesium with a smaller alkyl group.
It is also desirable to provide a process for the production of such compositions.
Summary of the Invention According to this invention, there is provided a process for the production of a hydrocarbon solution of a composition comprising di-(n-butyl)magneisum and diethylmagnesium, in which the di-(n-butyl~ and diethylmagnesium are present in respective molax amounts of from about 70 to about 93 mole percent of di-(n-butyl)magnesium and from about 2 to about 20 mole percent of diethylmagnesium, which process comprises:
(a) reacting in the presence of a hydrocarbon solvent, magnesium metal, with an alkyl halide in which the alkyl group is a straight chain alkyl having from 5 to 20 carbon atoms;
(b) either simultaneously with step (a~ or subsequent thereto, reacting, in the presence of the solvent of step (a) further magnesium metal, with an n-butyl halide;
~c) either simultaneously with step (a) and/or step ~b) or subsequent thereto, reacting with further magnesium metal, an ethyl halide, to form a mixture of a hydrocarhon solution containing dialkylmagnesium compounds and undissolved solids;
and f235 (d) separating the hydrocarbon solution from the undissolved solids, all steps being conducted in the substantial absence of both moisture ancl oxygen.
Detailed Description of the Invention The present invention pertains to dialk~lmagnesium compositions comprising three or more dialkylmagnesium compounds, which compositions are soluble in hydrocarbon solvents.
Preferably, such compositions contain three dialkylmagnesiums - two lower dialkyl compounds and one higher dialkyl.
The term "hydrocarbon solvent" is used herein to designate aliphatic, cycloaliphatic, and aromatic hydrocarbons.
Illustrative of aliphatic solvents are n-pentane, isopentane, n-hexane, n-heptane, n-octane, isooctane, pentamethylheptane, and gasoline and other petroleum fractions. Illustrative o~
cycloaliphatic solvents are cyclohexane, methylcyclohexane, methylcyclopentane, cycloheptane, and cyclooctane. Illustrative of aromatic solvents are ben7ene, toluene, xylenes, ethylben2ene, tetralin, and -methylnaphthalene. Preferred solvents are those containing 5 to 20 carbon atoms, inclusive. More preferred are `
those containing 6 to 15 carbon atoms, inclusive. Particularly preferred solvents are those which having boiling points between about 69C and about 110C.
The concentration of dialkylmagnesium in the solvent is not critical and the compounds are generally soluble over a wide range of concentration. The solution viscosity incrPases with concentration, however. For greater ease of handling, there~ore, the dialkylmagnesium concentration is normally from about 0.2 to about 15.0 weight percent, and preferably from about 1.0 to about 5.0 weight percent, in terms of magnesium. Howe~er, if the solution has a higher dialkyl-magnesium concentration, its viscosity can be reduced as mentioned below.

3~

A n~ber of techniques may be utilized for producing solutiolls of the mul-tiple component dialkylmagnesium compounds in the desired hydro-carbon solvent.

In one type of process, the solution is prepared by phsically combining the dialkylmagnesium compounds as such with the hydrocarbon sol-vent. me dialkylmagnesium campounds may ke utilized in their relatively pure form, or as solids or slurries resulting from their manufact.ure.
When utilized in either fashion, the dialkylmagnesium compounds may be in their individual states, (for instance, an insoluble form of di-n-butyl~
magnesium, an insoluble form of diethylmagnesium and solid di-n-hexylmag-nesium) or tWD or more of the dialkylmagnesiums may have been prepared in combined form which is mixed according to the invention in a hydrocarbon solvent with a higher diaLkylmagnesium, such as di-n-hexylmagnesium. A
clear solution results which is separable from any insolubles retained with the compounds. Thus, for instance, di-n-butylmagnesium, as a solid or slurry, existing in admixture with magnesium halides, other insoluble by-products of the manufacturing process, or unreacted starting materials, can be contacted with a hydrocarbon solvent in the presence of, for instance, diethylmagnesium and, for instance, di-n-hexylmagnesium~ to pro~
duce a solution containing the dialkylmagnesium compounds as solutes, substantially free of the other ingredients. Solubilization can be hastened by heating the solution to a temperature of about 50C or higher.
me rate of solubilization increases as the temperature is raised. Once the oompounds are dissol~7ed, they will remain in solution on an~ subse-quent lowering of te~perature.

If desired, separation of the solution from the remaining undis-solved solids can be enhanced by the use of any of the variety of viscosi-ty reducing agents known m the art. Examples of such viscosity reducing agents are organoaluminum compounds such as trialkylaluminums, diaIkyl-aluminum halides and aLkylaluminum dihalides.

Alternati~ely, the dialkylmagnesium comFounds can be prepared directly in the solvent in a common vessel by either simultaneous or sub~
sequent reactions. Any reaction is suitable in which neither the by-products nor the unreacted starting materials are soluble in the final ~;~

mlxture. The insolubles can thus be easily filtered off. One such tech-nique involves the direct reaction ketween metallic maynesium and the appropriate alkyl halides. The concurrently produced magnesi~ chloride form~s a precipitate which is readily removed from the solution together with any unreacted magnesium still present. Another technique involves the use of a Grignard reagent to supply one alkyl group. The Grignard reagent is preferably freed of all ether used in its preparation prior to its use in the present rection. The desired solution of dialkylmagnesium oompounds is then obtained by reaction of the desolvated Griynard reagent with the reaction product of the other alkyl llalides with magnesium metal.

When magnesium is reacted directly with an alkyl halide, commercial g.rade magnesium turnings or shavings can be used. It is preferable, however, to use a form of magnesium with a higher surface area than either of the above. This can be acoomplished by milling, but it is most prefer-able to use the metal in a finely divided state, for instance, as a powder with a particle size equal to or less than about 150 microns.

If the magnesium is to ke reacted sequentially with the appro-priate halides, it is preferable to first react the magnesium with the aLkvl halide containing the greatest numker of carbon ato~s, that is an alkyl halide which oontains straight-chain alkyl groups of 5 or more carbon atoms, then with the alkyl halide having the next higher number of carbon atoms and so on, down to the alkyl halide having the fewest number of carbon atoms. ~ magnesium activating agent may be employed to initiate the reaction. Because the higher alkyl halides are more reactive with magnesium than the lower aLkyl halides, some care should be taken to pre-vent an unoontrolled reaction. This may be achieved, for instance, by utilizing a large amDunt of solvent, extra agitation, a slow rate of alkyl halide addition, or further addition of excess magnesium.

The term ~Imagnesium activating agent" is used herein to denote heat or any substance which, when contacted with magnesium, will cause the magnesium to react with the alkyl halide at a substantially faster rate.
Many activating agents are know in the art. Typical examples are AlC13, AlC13-ether o~mplexes, N,N-dimethylaniline, molecular iodine, alkyl halides of at least 3 carbon atoms, and Grignard reagents. A small .~

~2~'~Z35 quantity of a higher alkyl dialkylmagnesium, such as di-n-hexyLmagnesium itself can serve as an ac-tivatLng agent, as metnioned in U.S. Pat.

4,207,207, Example 2.

Thermal activation may also be utilized, and is generally per-formed at temperatures ketween about 125C and about 350C, preferably from about 150C to about 250C, and most preferably from about 150C to about 200C. Once the magnesium is activated, the magnesium/alkyl halide reaction can proceed at lower temperatures. Although reaction can occur over a wide temperature range once the magnesium is activated, it will be most convenient to operate between about 80C and a~out 130C. At least 10~ by weight of alkyl halide based on the weight of magnesium metal must be present during thermal activation.

The temperature ranges quoted above are not critical to any of the reactions. The minimum temperature is dictated largely by process economics, while the maximum temperature is limit d only by the possibility of alkyl halide decomposition and considerations of energy conservation.

Preferably, the compositions are manufactured by a process in which the various aIkyl halides are reacted simNltaneously, in the desired proportions, with the magnesium. Alternatively, the higher alkyl halide is first contacted with the magnesium, and then the remaining alkyl halides are added as a mixture.

Follow~ng any of the above procedures, the solids can be removed from the reaction nu~ture b~ any conventional technique, for ~xample, oe ntrifuging, decanting, or filtration. me resulting solution of dialkylmagnesium compounds can then be diluted or concentrated to give the concentration desired for purposes of reactivity, viscosity, or economic considerations.

me term "halide" as used herein denotes chloride, bromide, or iodide, or oombinations thereof. Chlorides are generally pref~rred for reasons of economy.

LZ3~i I'he mole ratio of magnesium to alkyl halide can ke varied over a wide range. No particular range is critical to the performance of any of the reactions. Normally, however, the starting materials will be such that the mole ratio of magnesi~ to total ~lides is from akout 1.0 to cikout 2.0, preferably from akout 1.1 to about 1.3. The excess magnesium inherent in mole ratios greater than 1.0 is effective in minimizing Wurtz coupling reactions.

The hydrocæbon solvent may be added before, during, or after the reaction. It will be most convenient to add the solvent prior to or during the reaction of the first added alkyl halide with magnesium so that further reaction is less inhibited by viscosity.

Magnesium aLkyls æe p~rophoric substances, capable of spontane-ous ignition upon contact with air. To prevent such ignition, and also to prevent oxidation of the dialkylmagnesiums, the reactions must be carried out in the absence of more than trace amounts of oxygen. Thus, the reac-tions are normally carried out in an atmosphere of inert gas such as nitrogen or ægon~ or in an atm~sphere of an aIkyl halide gas. me reac-tions must also be conducted in the substantial absence of water, due to the reactivity of dialkylmagnesiums with water.

me pressure un~er which the reactions are conducted is not critical and pressures ranging from atmospheric to elevated pressures of several atm~spheres can be employed. me reactions will be most conve-niently run at least in slight excess of atnospheric in order to keep the aIkyl halides in solution. The preferred pressure range is about 8 psig ~1.6 x 105 pascals) to akout 100 psig (8.0 x 105 pascals)~

The lower dialkylmagnesium compounds in the compositions of this invention contain straight-chain alkyl groups having from 1 to 4 car~on atoms each. Examples of such o~mFounds are dimethylmagnesium, diethyl-magnesium, di-n-propylmagnesium, di-n-butylmagnesium, and combinations of alkyl ma~nesiums such as n-butlethylmagnesium, n-propylmethylmagnesium, methylethylmagnesium, and the like. me oampositions of the present invention contain at least tw~ of such lower dialkylmagnesiums.

.
-The higher dialkylmagnesium~s contain straight-chain alkyl groups of 5 carbons or greater, preferably 5 to 20 carbon atoms and most prefer-ably, 5 to 12 carbon atoms. Examples of such compourlds are di-n-amylmagnesium, di-~n-hexylmagnesium, di-n-oetylmagnesium and the like.
In these compounds, the two alkyl groups are preferably identical.

The hydrocarbon soluble compositions oE this invention in gener-al contain a total of from about 75 to about 95 mole percent of lower diaIkylmagnesium oompounds (two or more such eompounds) and from about 5 to about 25 mole pereent of at least one higher dialkylmagnesium compound.
Preferably, the compositions will predominate in a selected lower dialkyl-magnesium 03mpound, and will contain from about 70 to about 93, most pre-ferably 70 to about 90, mole percent of one lower dialkylmagnesium compound, from about 2 to about 20, most preferably from about 5 to 20, mole pereent of a second lower dialkylmagnesium compound, and from 5 to about 25 mole percent of a higher dialkylmagnesium. For instance, a oompostlon aecording tothis invention eontaining diethyl-, di-n-butyl-, and di-n-hexyl magnesiums, could have as little as 5 mole percent di-n-hexylmagne-sium and as much as 93 mole pereent of either di-n-butyl- or diethylmagne-sium, withthe other lower dialkylmagneisum being present in as little as 2 pereent. Most preferably, for use as a polymerization eatalyst, the composition will contain a high amount of di-n-butylmagnesium and a lower a~ount of diethylmagnesium.

The ecmpositions aceording to this invention may eontain lower dialkylmagnesiums whieh differ only by one earbon atom in the aIkyl groups. Sueh eombinations ~uld inelude for instanee, dLmethyl~diethyl magnesiums, di-n-propyl/di-n-butyl magnesiums or diethyl/di-n-propyl magnesiums. As shown in Examples 3-5 of U.S. Patent 4,222,969, two~ eom-ponent eompositions eontaining only these types of dialkylmagnesiums were insoluble in hydroearbon solvents. The present invention, however, pro-vides for the first time hydroearbon soluble eompositions oontainingeombinations of sueh dialkylmagnesiums with no other metal present.

The invetion is further illustrated by the follcwing example.

~ .

~2~ 3S

EXAMPI.E 1 (Com~arlson Example) This exc~mple demonstrates the production of a m;.xture of di-methyl and diethyl magnesiums according to the prlor art, and corresponds to Example 5 of V.S. Patent 4,222,969.

A pressure bottle equipped with a varlable diptube, thermowell and stirrer was immersed in an oil bath, purged with nitrogen and charged with 13.0 grams (g) (0.53 g-atom) of magnesium powder. A small amount (0.24 g) of di n-hexylmagnesium was added to activate the metal and take up any m~isture present, together with 184 g of heptane, and the bottle was heated to 100-110C. While this temperature was maintained, 13.3 g (0.21 mole) of ethyl chloride was adlded slowly over a period of tw~ hours.

Following the ethyl chloride addition, the system temperature was raised to 130-136C and methyl chloride was added in a quantity of 6.6 g (0.13 mole) over a period of two hours. The reaction mixture was then held at 130C for six hours.

The solids in the reaction mixture were then allowed to settle and the clear hydrocarbon phase was sampled. Analysis of the sample indi-cated only 0.03 weight p~rcent magnesium, or about 1.5% of theoretical yield.

The solids were then solubilized by the addition of tri-n-octyl-alumunum. Analysis of the resulting solution indicated 0 83 weight per-cent magnesium, or about 40% yield, with a methane:ethane mols ratio of 0.3:1 in the hydrolysis gas, indicating that both dimethylma~nesium and diethylmagnesium had been made as a insoluble mixture.

Production of a Compostion Comprising .
Dimethyl-, Diethyl- and Di-n-amyl Magnesiums Using the apparatus and general procedure described in Example 1, the following alkyl chorides were charged to the pressure bottle, in the order and relative mole percent listed: n-amly chloride (19%~, ethyl chloride tl9%), methyl chloride (62%). Analysis of the visoous supernatant liquid sh~wed a magnesium content of 1.18%, corresponding to a yield of soluble . r 35~

magnesium a.Lkyls of 41%. Analysis of the volatile hydrocarbons resul.king from hydrolysis showed 43% methane, 35% ethane, and 22% n-pen-tane. The calculated amount of magnesium in this soluble dimethyl/
diethyl/di-n-amyl magnesium composition is 27.4%. The lower dialkylmangesiums in -this composition o~mprise 81 mole percent, and -the di-n-amylmagnesium, 19 mole percent.

Following the same procedure described above, the following experiments were performed using mixtures of ethyl, n-butyl and n-hexyl chlorides, and for comparison, mixtures containing only ethyl and n-butyl chlorides. In all such mixtures, the mole ratio of ethyl:n-butyl chlorides ranged frc~m 1:3 up to 1:18, that is, quite disproportionate as compared tothe preferred ratio of 1:1 in U.S. Patent 4,127,507. As can be seen from the results, addition of relatively small amounts of n-hexyl chloride (ranging from 5 to 13 mole percent) resulted in substantially higher yields of soluble magnesium alkyl as compared to experiments without n-hexyl chloride.

Mble % Alkyl Chloride Charged . . .... . . Ethyl ~Bu~yl. n--Hexyl Yield of Soluble Exam~le No. Chloride ChlorideChlorideMagnesium aIkyl, %
3 (comparisorl) 27 73 0 38 4 (invention) 12 75 13 76

5 (CQmparison) 11 89 0 5

6 (invention) 5 90 5 68

7 ~inventicn) 2 92 6 70 Thus, in Example 5 for instance, an attempt to make a dialkyl-magnesium composition containing di-n-butyl and diethyl magnesiums at a mole ratio of approxlmately 8:1 produced only a 5% yield soluble magnesium alkyls without the addition o~ a higher alkyl compoundO However, as shown by Example 6, the inclusion in the reaction mixture of only 5 m~le percent n-hexyl chloride resulted in the production of a good yield of a hydrocarbon soluble dialkylmagnesium composition containing a very high content (90 mole ~) of di-n-butylmagnesium.

Claims (3)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A process for the production of a hydrocarbon solution of a composition comprising di-(n-butyl)magnesium and diethylmagnesium, in which the di-(n-butyl) and diethylmagnesium are present in respective molar amounts of: fram about 70 to about 93 mole percent of di-(n-butyl)-magnesium and from about 2 to about 20 mole percent of diethylmagnesium, which process comprises:

(a) reacting in the presence of a hydrocarbon solvent, magnesium metal, with an alkyl halide in which the alkyl group is a straight chain alkyl having from 5 to 20 carbon atoms;
(b) either simultaneously with step (a) or subsequent thereto, reacting, in the presence of the solvent of step (a) further magnesium metal, with an n-butyl halide;
(c) either simultaneously with step (a) and/or step (b) or sub-sequent thereto, reacting with further magnesium metal, an ethyl halide, to form a mixture of a hydrocarbon solution containing dialkylmagnesium compounds and undissolved solids; and (d) separating the hydrocarbon solution from the undissolved solids, all steps being conducted in the substantial absence of both mois-ture and oxygen.

2. A process according to Claim 1 in which the hydrocarbon solvent is selected from the group consisting of aliphatic, cycloaliphatic and aromatic hydrocarbons containing 5 to 20 carbon atoms, inclusive.

3. A process according to Claim 1 in which the alkyl halides are alkyl chlorides.