US3324160A

US3324160A - Oxidation of hydrocarbyl-metallo compounds

Info

Publication number: US3324160A
Application number: US272517A
Authority: US
Inventors: William E Wright; John C Benstead; James D Shimmin
Original assignee: Shell Oil Co
Current assignee: Shell USA Inc
Priority date: 1963-04-12
Filing date: 1963-04-12
Publication date: 1967-06-06
Anticipated expiration: 1984-06-06

Description

United States Patent 3,324,160 OXIDATEGN OF HYDROCARBYL-METALLO CQMPOUNDS William E. Wright. John C. Benstead, and James D. Shimmin, Cheshire, England, assignors to Shell Gil Company, New York, N.Y., a corporation of Delaware No Drawing. Filed Apr. 12, 1963, Ser. No. 272,517 9 Claims. (Cl. 260-448) This invention relates to an improvement in the known methods of oxidizing hydrocarbyl compounds of metals of Groups IIIB and IVB of the Periodic Table. It deals with a process for carrying out such oxidations to produce the corresponding hydrocarboxy compounds efficiently and advantageously.

It has been known for some time that aluminum, boron, lead, silicon and tin compounds having one or more bydrocarbon groups (R) such as alkyl, aryl, alkaryl, aralkyl, and cycloalkyl groups linked directly to the metal atom can be oxidized to hydrocarboxy compounds in which one or more of these hydrocarbon groups is converted to a hydrocarboxy group (OR) directly linked to the metal atom. Thus, for example, aluminum and boron alkoxides can be made from the trialkyl aluminums and trialkyl borons, and aluminum and boron phenoxides can be made from triphenyl aluminum and triphenyl boron compounds. These oxidation products are particularly useful as intermediates for the alcohols and phenols into which they are converted on hydrolysis. Methods for carrying out these oxidations and hydrolyses are described in US. Patents 2,863,895, 2,873,290, 2,892,858, 3,016,397, and 3,048,612, for instance.

The prior methods for producing alcohols and phenols in this way have been found to give undesirably low yields with some of these hydrocarbyl compounds due chiefly to low conversions to the desired hydrocarboxy metal compound in the oxidation step. An important object of the present invention is the provision of a process which overcomes the disadvantages of the prior methods of operation. A more particular object of the invention is to provide a commercially more attractive method for the oxidation of hydrocarbon compounds of aluminum, boron, lead, silicon, and tin to hydrocarboxy compounds of these metals. Still another object is the provision of an improved method for producing alcohols and/or phenols via such oxidation. Still other objects and advantages of the new process will be apparent from the following description of the invention.

In accordance with the invention, hy-drocarboxy compounds of aluminum, boron, lead, silicon and/or tin are produced by oxidizing hydrocarbyl compounds of these metals in the presence of a hydrocarboxy compound of cadmium or zinc.

The mechanism whereby the cadmium or zinc hydrocarboxy compounds alfects the improved oxidation of the hydrocarbyl compound of the Group III-B and/or Group IVB metal is not a feature of the invention nor essential to an understanding of the new process. However, the improved results which are achieved can be explained on the basis that the oxidation promoters used in accordance with the invention are cadmium and/or zinc compounds which can form hydrocarbyl compounds having a hydrocarbyl group which, under the oxidation conditions employed, is more readily oxidized than the most difiicultly oxidized hydrocarbon radical of the Group III-B and/or Group IVB metal compounds which is to be converted to a hydrocarbyloxy group. The relative ease of oxidation here referred to is readily determined by measuring the maximum percentage conversion of hydrocarbon radical to hydrocarboxy radical of the metal compounds being compared, using comparable oxida tion conditions. These oxidation promoters may function via some kind of radical interchange during the course of the oxidation. Such interchange is thought to result in transfer of a diflicultly oxidizable hydrocarbon radical of the Group III-B or Group IVB metal compound to the cadmium or zinc atom of the oxidation promoter. The hydrocarboxy radical from the promoter presumably is transferred to the Group III-B or Group IVB metal atom. On becoming attached to the cadmium or zinc atom, the previously diflicultly oxidizable hydrocarbon radical becomes more easily oxidizable to a hydrocarboxy radical which is then available for further radical interchange with hydrocarbon radicals of the Group III-B or IVB metal. Typical of the changes which take place in such a series of reactions when starting with a trior tetrahydrocarbyl metal compound MR are those shown in the following equations:

Here M is the metal of Group III-B or IVB, particularly aluminum, boron, lead, silicon, or tin, whose valence n is 3 or 4. R and R are hydrocarbon radicals. R" is a hydrocarbon R or hydrocarboxy radical --OR, and X is an atom of cadmium or zinc. For the sake of simplicity, only the replacement of two hydrocarbon radicals of the compound MR by hydrocarboxy radicals have been shown in the equations. It will be apparent, however, that through further oxidation of the cadmium or zinc compound R'-XR and exchange of radicals in the same way, all the hydrocarbon radicals on the Group IIIB or IVB metal can be converted to hydrocarboxy radicals. The final oxidation product will then be a mixture of hydrocarbyloxy compounds of the starting cadmium or zinc and Group IIIB and/or Group IVB metals. These on hydrolysis will yield alcohols and/or phenols R-OH and R'OH which may be the same if the hydrocarbon radicals R and R are identical, or may be mixtures of up to 5 or 6 different hydroxy products where the hydrocarbon groups of compound MR are not all the same and/ or the hydrocarbon groups R of the cadmium or zinc hydrocarboxy compound R"XOR are different. Complex products will of course also be produced when using mixtures of different starting compounds instead of the single compounds MR and R"XOR indicated in the foregoing equations.

The cadmium or zinc hydrocarboxy compound which must be present in the oxidation mixture according to the invention, can be added as such or can be formed in the mixture from a suitable added precursor. Because of their ready oxidation to the corresponding hydrocarboxy compounds, hydrocarbyl compounds of cadmium and zinc are especially suitable as precursors for the formation of the oxidation promoters in situ. Applicants have found that other cad-mium and zinc compounds can also be added to the oxidation reaction mixture to promote the formation of higher yields of desired oxidation products of the starting Group IIIB and Group IVB metal compounds. These can be any of the cadmium and zinc compounds which react under the oxidation conditions used with the Group III-B and Group IVB metal compound being oxidized or with some other component of the mixture to form a hydrocarbyl or hydrocarboxy compound of cadmium or zinc. The invention is therefore not limited as to the manner in which the cadmium and/or zinc hydrocarboxy compound which functions as the oxidation promoter is introduced into the oxidation mixture.

The results of applicants investigations in connection with the present invention show that other variations can be made in the manner in which the oxidation promoter is made available in the oxidation mixture. For example, in the oxidation of a Group IIIB and/ or Group IV-B metal hydrocarbyl (MR starting material, the promoter can be added thereto before oxidation commences or it can be added to the reaction mixture during oxidation at any time not later than the stage at which a substantial conversion of MR to M(OR) R has occurred. One can also of course utilize a compound M(OR) R as the initial starting material, though such procedure may not be as economically advantageous. It is the final stages of the oxidation in which complete conversion of the starting Group III-B and/ or IVB metal compound to hydrocarboxy compound is effected that are most difficult to carry out, and it is in these stages of the process that the oxidation promoter is most advantageous.

As previously pointed out, the cadmium or zinc compound added as oxidation promoter can with advantage be a hydrocarbyl (e.g. an alkyl) compound or a hydrocarboxide (e.g. an alkoxide) and since the required amount of added promoter can be small relative to the total amount of Group IIIB and/or IV-B metal compound starting materials to be oxidized, it matters little whether the cadmium or zinc compound contains -R or OR' radicals of the same kind as are present in the starting Group III-B and/or IV-B metal compound or its oxidation product(s). For example, a lower alkyl (or alkoxy) compound of cadmium or zinc, e.g. zinc diethyl, can be added as the oxidation promoter irrespective of the kind of starting material to be oxidized; although on a plant scale, the promoter can with advantage be a cadmium or zinc hydrocarboxy (e.g. alkoxy) compound corresponding to the hydrocarboxy oxidation product to be produced. As indicated, only a small amount of oxidation promoter is usually necessary, although the amount actually used in any particular case may depend on the nature of the starting material to be oxidized and also on the nature of the cadmium or zinc compound added. As a rule, about 1 mole percent to about 12 mol percent of cadmium and/or zinc compound, based on the amount of Group IIIB and/ or Group IV-B metal hydrocarbon compound being oxidized will be sufficient in the reaction mixture although large amounts can be employed if desired, although usually Without compensating advantage. For example, when using a zinc compound (e.g. an alkoxide or alkyl) as a promoter in the oxidation of an aluminum trialkyl containing to carbon atoms in each alkyl radical an amount of promoter (expressed for convenience in terms of zinc metal) within the range 0.1 to 1.0% by weight of the starting material is usually sufficient, although larger amounts, e.g., up to 1.5 to 2.0% by weight thereof may be used if desired.

It is advantageous to use as oxidation promoter a cadmium or zinc organo-compound which is readily soluble in the reaction mixture comprising the starting material to be oxidized. It will be understood that if desired, an inert solvent, e.g., an alkane may also be present in the reaction mixture. Suitable promoters are cadmium and zinc compounds which contain a hydrocarboxy group (OR' where R is hydrocarbon) which is capable of interchanging under the oxidation conditions with a hydrocarbon group of the Group III-B or IV-B metal compound being oxidized. Cadmium and zinc compounds having alkoxy and/or aralkoxy or cycloalkoxy or like groups which contain up to carbon atoms in their hydrocarboxy group or groups are especially useful oxidation promoters. More preferably, such compounds having 2 to 20 carbon atoms per hydrocarboxy group and having only aromatic double bonds as multiple bonds between carbon atoms are used. Particularly advantageous additives are the lower alkyls and alkoxides of cadmium and zinc, lower here signifying less than 10 carbon atoms. Specific examples of suitable additives are zinc di-normal-propyl; zinc ethyl-n-propyl; zinc didecyl; zinc dibenzyl; zinc di(ethyl-/3-cyclohexyl); zinc di-n-propoxide;

zinc n-propyl-ethoxide; zinc ethoxide-n-propoxide; zinc decyl-n-decoxide; and zinc di-lauryloxide; zinc stearate; zinc di-isopropyl salicylate; and the like; and corresponding compounds of cadmium.

The oxidation can be carried out in any suitable manner. The methods of the previously referred to U.S. patents, for example, are suitable.

Molecular oxygen is the preferred oxidizing medium. It can be used in pure or diluted form, for instance, as air. Ozone or ozonated air is another oxidizing medium. In some cases it may be advantageous to carry out the oxidation initially with air or even more dilute oxygen and increase the oxygen content of the oxidizing gas at at a later stage of reaction, using pure oxygen for the final oxidation.

Temperatures of the order of about 20 C. to about 150 C. are generally satisfactory although about 40 to about C. is usually preferable. It may be advantageous to use a lower temperature in this range for the initial oxidation and complete the oxidation at a higher temperature also preferably in the indicated operating range. Either atmosphere or higher or lower pressure can be used for the oxidation which can be carried out batch-wise, intermittently or continuously.

It is a feature of the invention that the new method of oxidizing hydrocarbon compounds of metals of Groups IIIB to IVB of the Periodic Table can be combined with hydrolysis of the resulting oxidation mixture to produce alcohols and/or phenols of low solubility in water in an especially advantageous way. This is because the cadmium or zinc hydrocarboxy compound present as oxidation promoter in the first step not only improves the oxidation but also has a beneficial effect in the subsequent production of these alcohols and/or phenols. In the hydrolysis step, the metal corresponding to the Group IIIB or Group IV-B metal Whose hydrocarbon compound is being oxidized is converted to the metal oxide in a finely divided suspended form. These oxides accumulate at the interface between the aqueous layer of the hydrolysis product and the organic layer thereof which contains the water-insoluble alcohols and/or phenols. Separation of the organic layer and recovery of the alcohol and/or phenol product is made difficult by this contamination of the interface. For example, the recovery of higher alcohols from oxidation of C or higher trialkyl aluminums and hydrolysis of the resulting aluminum trialkoxide is interferred with by the by-product alumina which collects at the interface between the two liquid phases present after the hydrolysis mixture is allowed to settle. The hydrolysis product in the case of the present invention can have the advantage of a clearer interface between the organic and aqueous layers since there is less tendency for alumina to collect at this interface. This improvement in the interface is an appreciable improvement processwise, and it is believed that the improvement may be due to the fact that oxidation in accordance with the present invention may be more specific from the point of view of giving rise to fewer and/ or less deleterious (from the interface aspect) by-products than in the case of oxidation in the absence of the cadmium or zinc compounds used as oxidation promoter in the oxidation step of the process.

Any of the prior art methods of hydrolyzing metal hydrocarboxy compounds can be used in the hydrolysis step of the new combination process for producing alcohols and/or phenols, the mode of hydrolysis not being a feature of the invention. The previously mentioned patents, for example, disclose methods of hydrolysis which are suitable and which are made a part of the present disclosure by reference as is the disclosure in copending application, Ser. No. 113,599, filed Mar. 31, 1961, by Shimmin and Wright, now abandoned, and corresponding Canadian Patent 667,017, of a more advantageous method of hydrolyzing hydrocarboxy compounds of metals of Groups II and III such as zinc and aluminum (a) A C C aluminum trialkyl starting material was obtained by heating aluminum tri-isobutyl with a C C cracked wax olefin at 145 C. for 1 hour under which conditions isobutyl radicals were displaced by the longer chain radicals derived from the C C olefins. The resulting aluminum trialkyl displacement product was then analyzed to determine the C C alkyl radical content thereof, and the amount of aluminum C C trialkyl present was calculated from the analytical figures.

(b) The aluminum Cpl-C1 trialkyl (in the form of the displacement product containing unreacted cracked wax olefin) was then oxidized in accordance with the present invention using various zinc hydrocarboxy compounds as oxidation promoter additives. In each oxidation the reaction mixture was maintained at 60 to 90 C. during oxidation, which was effected by first passing air and then substantially pure oxygen through the reaction mixture at the rate of 26 and 20 liters per hour respectively. Each oxidation product was hydrolyzed by refluxing with water for one hour, after which time the organic component was readily removed as the result of the clear organic-aqueous interface and an alcohol-hydrocarbon fraction distilled therefrom. This fraction was then analyzed to determine its alcohol content and from this, the percentage conversion of alkyl to alkoxide was calculated.

(c) By way of comparison oxidation of the C -C trialkyl aluminum was carried out in the absence of oxidation promoter but under otherwise identical conditions.

The conditions employed and the results obtained in all those oxidations are indicated in the following table where the additives were:

AZinc di-iso-octoxide B-Zinc di-phenoxide CZinc di-isopropoxide DA complex: 2NaCl/Zn(OEt) EZinc dicetoxide Example II The C -C trialkyl aluminum mixture prepared as in Example I was oxidized in the same way but using as the oxidation promoters zinc dialkoxide formed in situ from zinc dialkyls added at the start of the oxidation. The oxidation products were hydrolyzed and the alcohols produced were determined as in Example I with the following results for zinc diethyl and zinc di-isobutyl as additives identified as F and G respectively.

the manner described in Example I, and the following results were obtained:

Amount of C alkyl grams 505 Amount of Cd(OEt) d0 5.7 Al:Cd ratio- Molar :5 Air flow time minutes 252 Oxygen flow time do 54 Amount of C1448 alkoxy formed grams 286 Conversion of alkyl to alkoxy percen-t 87 Example IV In this example n-hexanol was prepared by oxidation of boron tri-n-hexyl followed by hydrolysis and in part (a) of this example the boron trihexyl was oxidized in the absence of an oxidation promoter so as to give comparative data, while in part (b) the boron trihexyl was oxidized in the presence of added zinc di-isobuntyl as an oxidation promoter in accordance with the present invention.

(a) Air was blown into a reaction mixture comprising a solution of grams of boron tri-n-hexyl in grams of toluene at 60 C. for 222 minutes at the rate of 26 liters per hour, after which oxygen was blown into the reaction mixture at the rate of 33.4 liters per hour for 180 minutes. The resulting reaction mixture was then subjected to hydrolysis by refluxing with water for 1 hour and the hydrolysis product distilled to give a distillate containing 81 .grams of n-hexanol. The conversion of boron alkyl to boron alkoxide was calculated to be 54%.

(b) A reaction mixture comprising 114.7 grams of boron tri-n-hexyl dissolved in 106.9 grams of toluene to which had been added 2.20 grams of zinc di-isobutyl was oxidized under similar conditions to those employed in part (a) of this example. Air blowing was for 285 minutes at 26 liters per hour and oxygen blowing was for minutes at 33.4 liters per hour, the reaction being maintained at 60 C. Following hydrolysis and distillation a distillate containing 86 grams of n-hexanol was obtained. The conversion of boron alkyl to boron alkoxide when operating under the conditions of the present invention was calculated to be 72%. The boron:zinc molar ratio in the reaction mixture was 98:2, the w./w. ratio being 88:12.

Example V l Oxidation of tin tetra-n-hexyl with air and oxygen under the conditions used in Example IV but employing zinc di-n-hexyl as the additive for in situ formation. of zinc di-n-hexoxide as oxidation promoter, and hydrolysis of the tin n-hexoxide gives n-hexanol in the same way.

O "-11; alkyl (grams) I 313 163 252 23s 99 142 172 174 176 152 140 126 Additive None None A A A B C D E F G G Additive amount rams) 868.2 1 4,2 0. 4 13 3 5 3.2 3. 9 898317 1. 3 1 .1 2.

:1 :2 1: 88: 2 8 :1 8 :11 :1 {94. 6:5. 4 s9=11 91:9 94:6 94:6 95:5 9515 94:6 97:3 94:6 Air flow (mins.) 173 267 186 72 125 132 138 168 196 174 150 Oxygen flow (mins.) 152 73 98 125 150 213 172 168 126 47 165 16!) Amount of 014-18 alko deformed (gram 245 128 249 230 31 136 166 156 161 144 131 120 Conversion of alkyl to alkoxide, perce11t t 73 73 92 90 82 90 90 83 85 88 86 89 Other additives used to produce the oxld-ation promoter 65 Example VI in situ in oxidation tests carried out in the same way were zinc chloride and colloidal zinc oxide which were found to also result in increased yields of aluminum (DH-C18 trialkoxides.

Example III The aluminum Cpl-C13 trialkyl displacement product referred to in Example I was also oxidized in accordance with the present invention using cadmium ethoxide as the oxidation promoter additive. Oxidation, hydrolysis and working up of the alcohol product was carried out in As previously indicated, the present invention is in no way limited to the production of aliphatic monohydric alcohols by oxidation of e.g. aluminum alkyls, followed by 70 hydrolysis of the alkoxide intermediate, and this example nate from the selective solvent extraction of heavy catalytically cracked cycle oil, the selective solvent (e.g., liquid sulfur dioxide or furfural) extracting aromatics therefrom. Both cracked wax olefins and cracked rafiinate olefins are olefin mixtures, the olefins of which commonly contain six to twenty-five carbon atoms per molecule and the olefin mixtures commonly contain a large proportion of straight chain alpha olefins. However, aluminum trialkyl starting materials for use in the present invention can be prepared from other olefins or olefin mixtures, e.g., individual C to C olefins or mixtures thereof or olefins Citronellene (AlfiBu):

Yield of citro- Oxidation Promoter ncllol in mole Grams Moles o1 Grams Moles t 9 1 w./\v. of Al Zn percent based on DMO Active D 0 Air rate: 26 liters/hour. Oxygen rate: 30 liters/hour.

The improvement obtained by the use of cadmium and zinc hydrocarboxy compounds as oxidation promoters according to the invention contrasts markedly with the results obtained in the oxidation of Group III-B and IVB metal hydrocarbon compounds in the presence of other metal compounds which do not give a substantial improvement in the oxidation.

While, as previously pointed out, the invention can be applied successfully in the oxidation of any compound of a metal of Group III-B or IV-B having a hydrocarbon group directly linked to the metal atom, the best results are obtained with compounds of these metals having hydrocarbon groups of up to 30 carbon atoms each. Most preferably the starting material is a compound of this kind having only hydrocarbyl or hydrocarbyl and hy-drocarboxy groups linked to the metal atom. Especially preferred are the compounds having as hydrocarbyl groups, allyl, aryl, alkaryl, aralkyl, and/or cycloalkyl groups of 4 to 30 carbon atoms each and containing as the only multiple bonds ethylenic and aromatic double bonds between carbon atoms. The hydrocarbon radicals (R) may contain substituen-t atoms or groups which do not interfere with the oxidation of such radicals to the corresponding oxy radicals OR, but generally it is preferred to use starting compounds containing only, carbon and hydrogen in the hydrocarbon and hydrocarboxy linked to the metal atoms.

Particularly advantageous results have been obtained in the oxidation of compounds of the formula MR where M denotes a metal of Group I'II B, and each R denotes a hydrocarbon radical, which can be the same or different radicals selected from the group consisting of the unsubstituted alkyl, aryl, alkaryl, aralkyl, and cycloalkyl radicals having 4 to carbon atoms and the corresponding compounds of the formula M(OR),,R where a is 1, 2, or 3 and b is 3-a. The aluminum and boron compounds of this type are especially preferred because of the good results which have been obtained with them. For example, particularly suitable aluminum trialkyl starting compounds can be derived from an olefin or olefin mixture obtained by the thermal or catalytic cracking of hydrocarbon streams such as are produced from crude petroleum feedstocks. For example, olefins may be produced by cracking paraffin wax fractions and the olefin mixtures (e.g., C C olefin mixtures) produced in this way are referred to herein as cracked wax olefins. Other olefins which may be used for the preparation of suitable aluminum trialkyl starting materials are the socalled cracked ratfinate olefins obtained by cracking raffiderived from a Fischer-Tropsch synthesis or obtained, for example, by the dimerization or trimerization of lower olefins such as ethylene, propylene or l-butene or by the tetramerization of propylene. The aluminum trialkyls may contain straightor branched-chain alkyl radicals or both.

As will be realized, aliphatic monohydric alcohols are obtained from aluminum trialkyls in accordance with the present invention, but the invention is not limited to the production of such alcohols but also includes the preparation of aromatic monohydric alcohols and phenols, cycloaliphatic alcohols, for example, citronel-lol and other hydroxy compounds depending on the choice of starting material.

Suitable aluminum trialkyl starting materials can be prepared by many processes. For example, UK. patent specification No. 770,707 describes a process for preparing, e.g., aluminum tri-isobutyl, and the latter can be reacted with other olefins to form aluminum trialkyls containing alkyl radicals of various carbon chain lengths. For example, the process described in UK. patent specification No. 794,359 enables the preparation of many different aluminum trialkyl starting materials: for example, cracked wax or cracked rafiinate olefins can be used to prepare long-chain aluminum alkyls from aluminum tri-isobutyl. Other processes for preparing aluminum trihydrocarbyls are described in U.K. patent specifications Nos. 763,824 and 763,081.

In some circumstances, it may be convenient to prepare a long-chain aluminum alkyl starting material for the process of the present invention from the corresponding long-chain olefin under conditions in which the alkyl product is in admixture with unreacted olefin, and it is to be understood that such a mixture can be used as such as the starting material without prior separation of the olefin.

A special feature of the present invention in one of its modifications is the provision of a particularly advantageous method for producing starting material for oxidation by the new process. In this modification, aluminum trialkyls are prepared by reacting an aluminum tri (lower alkyl) with an olefin or mixture of olefins to effect displacement of one or more, preferably all three, of the lower alkyl groups of the aluminum tri (lower alkyl) by higher alkyl groups. The lower alkyl groups here referred to will usually be groups of l to 4 carbon atoms but may contain more carbon atoms. The displacement can be carried out by any of the known methods.

Other tri-hydrocarbyl aluminum and boron compounds useful as starting materials for the method of oxidation of the invention can be prepared in other known Ways as can suitable tetra-hydrocarbyl lead, silicon, and tin compounds for use in the new process. Examples of the latter compounds are, for instance, tetra-octyl lead, tetrahexyl silicon, tetra-dodecyl tin, diphenyl-didecyl lead, tetraphenyl silicon, tetra-allyl lead, tetra-cyclohexyl silicon, and the like.

It will thus be seen that the new process is broadly applicable and can be carried out in various ways without departing from the invention. It is, as previously indicated, especially useful for the production of alcohols and/or phenols by hydrolysis of the oxidation products, but the invention is not limited thereto since the hydrocarboxy products of the new oxidation process have other uses. They can, for example, be employed as catalysts for chemical reactions and as intermediates in the synthesis of other compounds. They can, for instance, be used to reduce carbonyl compounds such as ketones and aldehydes, to alcohols. They are also useful additives for lubricating oil. It will be understood, therefore, that the invention is not limited to the examples which have been given by way of illustration only, nor is the invention limited by any theory proposed in explanation of the improved results which are achieved.

We claim as our invention:

1. In a process for oxidizing a compound of the formula MR where M is aluminum or boron and the Rs represent hydrocarbyl or hydrocarbyloxy (-OR) radicals of not more than 30 carbon atoms with the proviso that at least one R is always hydrocarbyl, to produce the corresponding compound in which each of said hydrocarbyl radicals attached to the metal atom M is converted to a hydroca-rbyloxy radical (OR), the improvement of effecting the oxidation in the presence of from about 1 to about 12 molar percent based on the amount of MR present of a compound of the formula R' X-*(OR') where R represents hydrocarbyl of not more than 30 carbon atoms, X represents cadmium or zinc, and a and I) each represent integers from 0 to 2 such that the sum of a and b is always 2.

2. The process in accordance with claim 1 wherein X is cadmium, a is 0, b is 2, and R represents alkyl of from 2 to 20 carbon atoms.

3. The process in accordance with claim 1 wherein X is zinc, a is 0, b is 2, and R represents alkyl of from 2 to 20 carbon atoms.

4. The process in accordance with claim 3 wherein Zn(OR') is formed in the oxidation.

5. The process in accordance with claim 1 wherein MR in which M is aluminum and R is alkyl, is oxidized with molecular oxygen to M(OR) in the presence of Zn(OR') 6. The process in accordance with claim 5 wherein R is al-kyl of 4 to 30 carbon atoms and R is alkyl.

7. The process in accordance with claim 6 wherein Zn(OR') is formed in the mixture by oxidizing Zn(R) 8. The process in accordance with claim 7 wherein the oxidation is conducted at a temperature of from about 40 to about C.

9. The process in accordance with claim 1 wherein M is boron, R is alkyl, X is zinc, a is 2, b is O, and R is alkyl.

References Cited UNITED STATES PATENTS 12/1962 Ramsden 260-429] 12/1962 Flanagan 260 448 OTHER REFERENCES Coates, G. E.: Organometallic Chemistry, second edition 1960, p. 67.

Eaborn, C.: Organosilicon Compounds, 123124.

TOBIAS E. LEVOW, Primary Examiner.

H. M. S. SNEED, Assistant Examiner.

Claims

1. IN A PROCESS FOR OXIDIZING A COMPOUND OF THE FORMULA MR3 WHERE M IS ALUMINUM OR BORON AND THE R''S REPRESENT HYDROCARBYL OR HYDROCARBYLOXY (-OR) RADICALS OF NOT MORE THAN 30 CARBON ATOMS WITH THE PROVISO THAT AT LEAST ONE R IS ALWAYS HYDROCARBYL, TO PRODUCE THE CORRESPONDING COMPOUND IN WHICH EACH OF SAID HYDROCARBYL RADICALS ATTACHED TO THE METAL ATOM M IS CONVERTED TO A HYDROCARBYLOXY RADICAL (-OR), THE IMPROVEMENT OF EFFECTING THE OXIDATION IN THE PRESENCE OF FROM ABOUT 1 TO ABOUT 12 MOLAR PERCENT BASED ON THE AMOUNT OF MR3 PRESENT OF A COMPOUND OF THE FORMULA R''A-X-(OR'')B WHERE R'' REPRESENTS HYDROCARBYL OF NOT MORE THAN 30 CARBON ATOMS, X REPRESENTS CADMIUM OR ZINC, AND A AND B EACH REPRESENT INTEGERS FROM 0 TO 2 SUCH THAT THE SUM OF A AND B IS ALWAYS 2.