US3061626A - Oxidation of organoboron compounds - Google Patents

Description

United States Patent Ofiice 3,061,626 Patented Oct. 30, 1962 3,061,626 QXlDATlGN F ORGANOBORON COMPOUNDS Tillmon H. Pearson and Kenneth Presswood, Baton Rouge, La., assignors to Ethyl Corporation, New York, N.Y., a corporation of Delaware No Drawing. Filed Mar. 30, 1960, Ser. No. 18,494 9 Claims. (Cl. 260-462) The present invention is concerned with a method for the controlled oxidation of organoboron compounds, particularly to form boric acid esters, alcohols, or phenols directly.

It has long been known that organoboron compounds, for example, t-rialkylboraues, can be oxidized by various techniques to form the corresponding boron esters which in turn can be hydrolyzed to result in the alcohols. For example, it is known that the trialkylboranes can be reacted with various peroxides, such as hydrogen peroxide, in the presence of bases to produce the esters. These procedures are of limited utility because of the cost involved and consequently they have not been employed on a commercial scale. Accordingly, there is a need for a more economical method for oxidizing organoborane compounds and others have attempted with little or no success to fulfill this need.

In order to obviate the above disadvantages of the prior art methods for oxidizing organoboron compounds, there have been attempts to accomplish the oxidation by the controlled reaction of the organoboron compounds with air or oxygen. This, of course, is highly desirable because of the high economies possible using either air or oxygen. However, there are inherent disadvantages in the known prior art techniques of controlled oxidation either with air or oxygen. For example, when moist air is employed for oxidizing a trialkylborane, only one alkyl group is oxidized resulting in only one mole of alcohol after hydrolysis per mole of trialkyl borane. The employment of dry air on the other hand results in the oxidation of two of the alkyl groups which is, of course, more advantageous than the moist air technique but more costly in that the air must be dried. In only one instance is there any report of oxidizing the so-called last alkyl group with air or oxygen and this has been when employing dry air. However, the amount of oxidation of the last carbon to boron linkage was very slow requiring many days in order to obtain appreciable controlled oxidation. Further, the process requires stringent control in order to eliminate the presence of any water since when the same reaction Was attempted using moist air, no oxidation was obtained even after maintaining the system under pressure for 18 months. The literature is abundant in pointing out the problem that with air or oxygen it has been impossible to oxidize more than two alkyl groups and if there were only one alkyl group present in the initial organoborane reactant, e.g. RL-(OR) there is no convenient or practical technique known for oxidizing this so-called last carbon to boron linkage. We have made many attempts employing the presently known techniques to effect a complete controlled oxidation of compounds having carbon to boron linkages with air or oxygen and consistent with the prior art were not able to achieve the controlled oxidation of the last carbon to boron linkage even in dry air. Therefore, it is highly desirable to provide the art with a method for oxidizing organoboranes by which all boron to carbon linkages are reacted in order to effect complete oxidation to ROB moieties and result in the most efficient utilization of this intermediate for forming boron esters or ultimately the more desirable alcohol product.

Accordingly, an object of this invention is to provide a novel process for the controlled oxidation of organoboron compounds, that is, compounds having carbon linked Cir directly to boron. Another object of this invention is to provide a more efficient and economical method for the controlled oxidation of the organoboron compounds in higher yield and purity. A particular object is to provide a method whereby all carbon to boron linkages in an organoboron compound are selectively oxidized to ROB moieties. A still more specific object is to provide a meth od whereby in addition to oxidizing all the carbon to boron linkages in an organoboron compound, an alcohol is directly produced in the reaction mixture in high yield and readily recoverable therefrom.

The above and other objects of this invention are accomplished by reacting an organoboron compound having at least one carbon to boron linkage with oxygen in the presence of an amine or ammonia to efiect controlled oxidation of the carbon to boron linkages. The trialkylboranes in which the alkyl groups are straight chain hydrocarbon groups having up to about 40 carbon atoms comprise preferred organoboron compounds. Likewise, the tertiary amines, particularly the trialkyl amines, having up to about 8 carbon atoms in each alkyl group have been found most advantageous. While the temperature and pressure at which the reaction is conducted are subject to considerable latitude, so long as the reaction is carried out in a temperature insufficient to cause ignition or combustion of the organoboron compound, best results are obtained at a temperature of 0 to C. with the pressure above atmospheric but below 1,000 pounds per square inch (p.s.i.). Thus, one embodiment of this invention comprises reacting a trialkylborane with oxy gen, whether essentially pure or in air, at a temperature between about 0 to 150 C., a pressure above atmospheric but below about 1,000 psi. in the presence of a minor amount of a tertiary amine, particularly a trialkyl amine. The direct product of the process is a boron compound having one or more ester linkages, i.e., ROB, formed by the controlled reaction of the oxygen with the carbon to'boron linkage(s). However, an alternative and preferable embodiment of the invention is to conduct the above-described reaction in the further presence of water. By so doing, an immediate and direct hydrolysis is accomplished so that rather than obtaining the ester, the corresponding alcohol is directly produced which is readily recovered by conventional techniques, usually being immiscible in the reaction mixture. Thus, a particularly preferred embodiment of this invention comprises the reaction of a t-rialkylborane, especially one in which each alkyl group contains up to about 40 carbon atoms, with oxygen or air at the aforementioned temperature and pressure conditions in the presence of at least a minor amount of a tertiary amine, particularly a trialkyl amine, and in the further presence of at least sufficient water to hydrolyze the ester moieties (ROB), in the reaction mixture. These and other embodiments of the invention will be brought forth in greater detail in the discussion which follows.

The process of this invention is of particular advantage in that the controlled oxidation of organoboron compounds is accomplished in an eflicient and practical manner. A specific advantage of the process is the fact that complete oxidation takes place whereby all carbon to boron linkages are oxidized. Until the present invention, no convenient, practical and economical procedure for the oxidation of the so-ca-lled last carbon-boron linkage in an organoboron compound has been possible.

Indeed, so far as we are aware, this has never been accomplished by an air or oxygen oxidation method in a practical manner. Additionally, the process provides a method whereby moist air or oxygen can be used to oxidize the so-called last carbon to boron linkage. Still further, the present process is of advantage in that when conducting the reaction in the further presence of water,

the alcohols are directly produced in a manner readily adaptable to continuous operation. Still further advantages will be evident as the discussion proceeds.

I The process involves the employment of organoboron compounds, particularly hydrocarbon boron compounds, which have at least one carbon to boron linkage. The carbon to boron linkage is the primary requisite of this reactant since this linkage is what is oxidized and desired to be reacted in the process. The remaining valences of the boron can be other ligands including those which are reactive to oxygen provided that they do not destroy the reactivity of the oxygen with the carbon to boron linkages. Thus, such other ligands can be, for example, molities such as the hydrocarbon radicals, alcohol residues (OR), hydrogen, halogens, hydroxyl groups, inorganic acid anions, organic acid anions, particularly of the alkanoic acids, salt structures, (-OM), particularly where M is an metal, and the like. It is preferable, however, that such other ligands can be selected from thesame or different hydrocarbon radicals, and hydroxyl groups. Thus, included among the organoboron reactants employed in the process of this invention are the trialkylboranes as, for example, trimethylborane, triethylborane, tributylborane, tri-S-methylbutylborane, tri- A-methylpentylborane, trihexylborane, trioctylborane, tridecylborane, triundecylborane, tridodecylborane, trioctadecylborane, trieiscosylborane, tri-triacontylborane, tritetracontylborane, and the like; trialkenylboranes as, for example, trivinylborane, tri-l-butenylborane, tri-Z-octenylhorane, trioctadecenylborane, tri-triacontenylborane, and the like; alkynylboron compounds as, for example, tri-lhexynylborane, tri-Z-octynylborane, and the like; cycloalkyland cycloalkenylboron compounds as, for example, tricyclobutylborane, tricyclohexylborane, tricyclooctylborane, tricyclobutenylborane, tricyclohexadienylborane, and the like; arylboron compounds as, for example, triphenylborane, trinaphthylborane, tri (2 phenylethyl)- boraue, tribenzylborane, tritolylborane, and the like; mixed organoboranes as, for example, methyl-diethylborane, octyl-dihexylborane, phenyldioctadecylborane, and the like; cyclic or polymeric hydrocarbon boron compounds as, for example, butane-'1,4-bis( l-boracyclopentane) O (CHM-BO pentane-1,5-bis( l-boracyclohexane); l-n butylboracyclohexane; 1-n-butylboracyclopentane; compounds having the moiety l CHa-OHa- GHr-CHzn where n is at least 2; and the like; hydrocarbonboron acids as, for example, 'benzyl boronic acid, ethyl boronic acid, phenyl boronic acid, dioctadecyl boronous acid, and the like, and their corresponding salts of metals, particularly the alkali metals, as for example, sodium, lithium, potassium, and cesium; hydrocarbonboron halides as, for example, dihexylboron chloride, dioctadecylboron fluoride, dioctylboron bromide or iodide, and the like; hydrocarbon borines as, for example dihexylboron hydride, tetradecyl diborane, and the like; and hydrocarbon boron compounds also containing inorganic and organic acid anions as, for example, dihexylboron sulfate, dihexylboron nitrate, dihexylboron acetate, dihexylboron octadecanoate, and the like. Another type of cyclic organoboron compound also employable are those illustrated by, for example, trimethyl boroxine (MeB) trihexyl boroxine, trioctadecyl boroxine, and the like. The above compounds are presented by way of illustration and it is not intended to be limited thereto. in general, the hydrocarbon moieties contained in such compounds will have up to and including-about 40 carbon atoms. It is to be understood that the hydrocarbon groups can be further substituted to result in branch chains and isomers thereof as well as being substituted by other functional groups which are essentially inert in the reaction or do not defeat the oxidation of the carbon-boron linkages desired. It is preferable, however, to employ the trialkylboranes in which the alkyl groups are preferably straight chain hydrocarbon groups having up to and including about 40 carbon atoms. These reactants are more easily prepared, more stable and economical and result in the greatest practical production of alcohol or boron ester, as the case may be.

The process of this invention involves a controlled oxidation of the carbon to boron linkages. For this purpose either oxygen or air is employed. Thus, the oxygen can be that as commercially available or air itself can be efiectively used. Depending upon the economies to be effected, oxygen is sometimes preferable since minimum reactor space is necessary to obtain the requisite amount of oxygen in contact with the organoboron compound. However, air is generally preferred because of its economy. Wet or dry air or oxygen are equally suitable, with wet air or oxygen being preferred.

The process of this invention is conducted in the presence of amines or ammonia since, by virtue thereof, it has been found that the oxidation proceeds rapidly and etficiently to effect complete and controlled oxidation of all boron-carbon linkages. -While, in general, any amine is employable, it is preferable to employ those which are either liquid under the reaction conditions or dissolve in the reaction mixture. Therefore, in general, the primary, secondary, tertiary, and heterocyclic amines are applicable including those wherein the hydrocarbon portions are aliphatic, cycloaliphatic, or aromatic moieties such as the alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, aryl, alkaryl, aralkyl, and the like. Typical examples of the primary amines include methyl amine, ethyl amine, butyl amine, decyl amine, octadecyl amine, vinyl amine, hexenyl amine, l-hexynyl amine, cyclohexyl amine, phenyl amine, benzyl amine, tolyl amine, and the like. Typical examples of the secondary amines include diethyl amine, didecyl amine, dioctadecyl amine, dihexenyl amine, diheptynyl amine, methylcyclohexyl amine, dicyclohexyl amine, diphenyl amine, and the like. Typical examples of the tertiary amines include trimethyl amine, triethyl amine, tributyl amine, trioctyl amine, tri- Dctadecyl amine, tributenyl amine, myristyl dimethyl amine, .trihexenyl amine, tricyclohexyl amine, tri-hexynyl amine, triphenyl amine, tritolyl amine, dimethylaniline, and the like. Among the heterocyclic amines are included, for example, pyridine, p-methy-l pyridine, 3- benzyl pyridine, 2-propyl pyridine and the like. It is to be understood that the hydrocarbon moieties of the aforementioned amines can be further substituted to result in branch chains or further substituted with functional groups which are essentially inert in the reaction. In general, the hydrocarbon moieties will contain up to and including about 18 carbon atoms although longer chain moieties are employable. It is preferable to employ the tertiary amines, particularly the trialkyl amines in which the alkyl groups are hydrocarbon containing up to about 10 carbon atoms. The trialkyl amines are preferred be cause of their greater availability and practical use in the process. 7

While it is not necessary, it is preferable to conduct the reaction in the presence of water in order that the more useful alcohol products be directly obtained in the reaction mixture; Likewise, although not essential, inert diluents can also be incorporated in the reaction system as an additional means for controlling the reaction temperature or to provide greater solubility of the reactants. The only criteria of such diluents are that they be essentially inert to the reaction, that is not react with the reactants or products. For this purpose the aforementioned amines are employable and the hydrocarbons, particularly the liquid hydrocarbons having up to about 18 carbon atoms as, for example, hexane, decane, cyclohexane, toluene, benzene, and the like including mixtures such as mineral oil, gasoline, and the like.

The proportions of the reactants and diluents are not critical and are limited only by the extent of reaction desired and the reaction conditions. For example, only sufiicient oxygen, either pure or in air, is required to oxidize the carbon to boron linkages. It is preferable to employ at least enough oxygen to oxidize all of the carbon to boron linkages. An eilicient way to accomplish this is to maintain a constant pressure of the oxygen or air in the reaction system. While such results in the employment of excessive amounts of the oxygen or air, this is not deleterious since it is readily recoverable and reused as well as being an economical reactant. The ammonia or amine can be present in minor amounts, e.g. as little as 0.01 mole thereof per mole of carbon to boron linkages, thus, even such small amounts of this catalytic material have some efiect on the rate of oxidation and the ability to accomplish the oxidation of the carbon-boron linkages including the so-called last carbon to boron linkage. In order to achieve best results, it is preferable to employ at least one sixth of a mole of the amine or ammonia per mole of carbon to boron linkage. There is essentially no upper limit to the amount of the amine or ammonia employed since excessive quantities as, for example, solvent quantities, are readily recoverable and reused. The effect of the ammonia or amine is apparent whether or not the system is acid or basic. In those embodiments wherein water is employed in the reaction system resulting directly in the alcohol being produced, generally at least enough water is maintained to hydrolyze the ROB moieties to the alcohol. Thus, for practical reasons, at least one mole of water per carbon to boron linkage or (ROB) linkage contained in the boron reactant is employed with considerable excess also being applicable but not necessary. In those instances wherein an additional diluent is employed as, for example, the hydrocarbons, they can be present in varying amounts but usually only sufficient to provide a fluid reaction system with the attendant amount of heat control desired.

The manipulative operations of the process of this invention are subject to considerable latitude. In general, however, the hydrocarbon boron compound and ammonia or amine are admitted to a reactor along with water and/or hydrocarbon diluent, if so desired, in any order of addition and oxygen or air is bubbled through the reaction mixture and/or pr ssuriz d in the y t with heating where necessary to the desired temperature. The oxidation takes place rapidly and the products and diluents are readily recoverable by conventional techniques. 'In those instances wherein water is employed and the alcohol is formed directly, generally the alcohol is insoluble in the water and can be continuously withdrawn from the reaction system. It will be evident that other conventional techniques of reaction sequences and systems Will be applicable.

The present invention will be more completely understood from a consideration of the following examples wherein all parts are by weight unless otherwise indicated.

Example I Employing a reactor equipped with internal agitation, a means for introducing and discharging reactants and a means for maintaining pressure, there is added thereto 7 parts of tri-n-hexyl-borane. Then, 1 part of triethylarnine is added thereto and the reaction mixture pressurized to 200 p.s.i. of essentially pure and dry oxygen. Reaction immediately takes place and these conditions are maintained for /2 hour while constantly maintaining the aforementioned pressure of oxygen. Then, the temperature is slowly raised to 120 C. and the pressure and temperature maintained for an additional /2 hour. In this manner, tri-n-hexylborate is produced in high yield which is readily separated from the reaction mixture by distilling off the triethylamine and can be converted to n-hexyl alcohol by adding water to the tri-n-hexylborate.

Example II The reactor of Example I was again employed. In the reactor, tri-n-hexylborane in trimethylamine was prepared in situ by reacting 1.83 parts of trimethylamine borane (Me N-BH with 6.3 parts of l-hexene at 150 C. for 1 /2 hours. The reaction mixture was then cooled to room temperature and 20 parts of a 5 percent sodium hydroxide solution was added thereto. The reactor was then pressurized gradually over a 2-hour period to 200 p.s.i. of oxygen maintaining room temperature. Then, the reactor was heated to 150 C. with the pressure of oxygen being gradually increased to 800 p.s.i. over a period of about 1 /2 hours and these conditions maintained for 11 hours, at which time the reactor was cooled to room temperature and vented. The reaction mixture was washed into a separator with water and the hexyl alcohol product was extracted with chloroform and filtered. Analysis showed that 6.3 parts of n-hexyl alcohol were obtained representing a yield of 82 /2 percent.

Example III In this run, 5 parts of tri-n-hexylborane were added to the reactor'along with 20 parts of water and 1 part of triethylamine. The reactor was pressurized at room temperature gradually over a 2-hour period to 200 p.s.i. with oxygen. At the end of this period, the temperature was then raised to C. and the pressure maintained between 500 and 800 p.s.i. for an additional 18-hour period. Very little oxygen was taken up by the reaction during the last 15 hours of reaction which showed that the controlled oxidation was essentially complete after 3 hours. At the end of this period, the reaction mixture was cooled to room temperature and vented and the product worked up as in Example II. The yield of n-hexyl alcohol was 83 percent.

When this example is repeated with exception that 20 parts of ammonia are bubbled into the water in place of the amine, forming ammonium hydroxide with an excess of ammonia present, similar satisfactory results are obtained.

Example IV The procedure of Example III was repeated essentially as described with the exception that after reacting for essentially 1 hour and 20 minutes at room temperature while gradually increasing the oxygen pressure to 200 p.s.i., the reactor was heated to 95 C. and the pressure maintained at 600 p.s.i. for an additional 11 /2 hours. Analysis by vapor phase chromatography showed a 70 percent yield of n-hexyl alcohol.

In contrast to the above results, when 5 parts of tri-nhexylborane in admixture with 20 parts of a' 5 percent sodium hydroxide solution was reacted with oxygen at 400 p.s.i. with the maximum temperature at C. over a period of 13 hours in the absence of any amine, only a 60 percent yield of n-hexyl alcohol was obtained. Likewise, when 13 parts of tri-n-hexylborane was oxidized in the absence of water or amine with the maximum dry oxygen pressure at 500 p.s.i. and the maximum temperature at 150 C. over a period of 12 hours, only a 36' percent yield of n-hexyl alcohol was obtained after hydrolysis of the boron esters formed. Thus, it is evident that in the latter runs, no more than two of the carbon to boron linkages reacted. Further, these comparison illustrate the marked effect achieved by the presence of the amine whereby all of the carbon to boron linkages in the starting reactant are oxidized. v p

The following examples will illustrate additional embodiments of the present invention.

7 Example V A mixture of organoboranes obtained by reacting diborane with a mixture of C through C primary olefins is reacted with oxygen in the presence of parts of triethylamine and 20 parts of water at a temperature of 100 C. with the oxygen pressure maintained at 1000 p.s.i. over a period of hours. At the end of this period, the mixture is cooled to room temperature and an alcohol layer comprising C through C alcohols is readily separated in high yield.

Example VI When 10 parts of tri-n-octylborane is reacted with oxygen in the presence of 2 parts of pyridine and 5 parts of water at 150 C. and 500 p.s.i. for 4 hours after first reacting the mixture at room temperature and 500 psi for 2 hours, n-octyl alcohol is obtained in high yield.

Example VII To an autoclave is added 10 parts of tricyclohexylborane, 10 parts of dimethyl aniline and 10 parts of water. Then oxygen is pressurized to 150 p.s.i. into the system at room temperature and theseconditions maintained for 1% hours with agitation. The reactor is then heated to 125 C. and the oxygen pressure increased to 750 p.s.i. These conditions are maintained for 8 hours. At the end of this period, the reaction mixture is cooled and the cyclohexanol layer is separated. Cyclohexanol is recovered in high yield.

Similar results are obtained when tricyclopentylborane, tricyclobutylborane, tricycloheptylborane, and tricyclehexenylborane are substituted for tricyclohexylborane in the above example.

Example VIII When 5 parts of tri-Z-hexenylborane in 1 part of aniline and 2 parts of water are oxidized employing air at a constant pressure of 1000 p.s.i. at 160 C. for 6 hours, 2- hexenyl alcohol is obtained in high yield.

Similar results are obtained when other olefinic boron compounds are substituted for tri-2-hexenylborane in the above example as, for example, tri-l-octenylborane, tri- 3-octadecenylborane, tri-2-dodecenylborane, and the like.

Example IX Phenol is obtained in high yield and purity when 10 parts of phenyl boronic acid in 4 parts of tri-n-butyl amine and 20 parts of water are oxidized at 100 C. and 800 p.s.i. oxygen pressure for 10 hours.

Equally satisfactory results are obtained when ethyl boronic acid, propyl boronic acid, diphenyl boronous acid, triphenyl boroxine, and the like are substituted for phenyl boronic acid in the above example.

Example X Sec-butyl alcohol is obtained in high yield and purity when tri-sec-butyl borane is oxidized with air when in admixture with cyclohexylamine and water at 135 C. and 100 psi. for 18 hours.

Example XI When trioctadecylborane is oxidized with air at 65 C. and 1000 p.s.i. in the presence of .10 parts of myristyl dimethyl amine and 5 parts of water per part of the borane for hours, octadecyl alcohol is obtained in high yield with essentially all of the carbon to boron linkages being oxidized.

Example XII When the procedure of Example X is repeated substituting triisoamylborane for tri-sec-butylborane and triethyl amine for cyclohexyl amine, isoamyl alcohol is obtained in high yield and purity.

Example XIII S-hexynyl alcohol is produced when tri-S-hexynylborane is reacted with oxygen at 75 C. and 300 p.s.i. in the presence of trimethyl amine and water for 7 hours.

Equally satisfactory results are obtained when tri-3- heptynylborane, tripropynylborane, and the like acetylenic boranes are substituted for tri-S-hexynylborane in the above example.

Example XIV When 15 parts of p-tolylboron dichloride are reacted with oxygen in the presence of 10 parts of ethylene diamine and 12 parts of water at C. and 500 psi. for 12 hours, p-tolyl alcohol is obtained in high yield.

Similar results are obtained when other organoboron halides are substituted for p-tolyl boron dichloride in the above example, as for example, diphenyl boron chloride, dimethyl boron fluoride, phenyl boron dibromide, hexyl boron diiodide, and the like. While generally the hydrocarbon boron halides tend to hydrolyze in water systems and thus are less preferred, the resulting product of the hydrolysis is the corresponding hydrocarbon boron acid which as indicated previously is well suited to the process of this invention.

Example XV When triethylboroxine (EtBO) is reacted with oxygen in the presence of cyclohexylamine and water at 100 C. and 200 p.s.i. for 10 hours, ethyl alcohol is obtained in high yield.

Similar results are obtained when other boroxines are substituted in the above example, as for example, trimethylboroxine, trioctylboroxine, trioctadecylboroxine, and the like.

Example XVI When Example III is repeated substituting other amines as, for example, ethylamine, diamyl amine, vinyl amine, dicyclohexyl amine, benzyl amine, diphenyl amine, and the like for triethylamine in varying proportions, similar results are obtained.

Example X VII When Example IH is repeated substituting butane-1,4- bis-( l-boracyclopentane) for the tri-n-hexylborane, tetramethylene glycol is obtained in high yield.

Similar results are obtained when other cyclic or polymeric hydrocarbon boron compounds are substituted in the above example as, for instance, pentane-l,5-bis-( lboracyclohexane) to produce 1,5-pentanediol, 1-n-butylboracyclopentane to produce a mixture of n-butyl alcohol and 1,4-butanediol which canbe separated, if desired, the reaction product of diborane with acetylene in a molar ratio of 1 to 3 respectively to produce ethylene glycol, and the like. a

The above examples are presented by way of illustration and the invention is not to be limited thereto. It is evident that similar results are readily obtainable when substituting other organoboron compounds, amines, and conditions described hereinbefore.

The temperature at which the reaction is conducted is subject to considerable latitude, the only limitation being that it is generally below the degradation temperature of the organoboron reactant, Generally, however, the reaction is conducted at a temperature between about 0 to C. Temperatures much above 150 C. are not required and are less preferable since some degradation begins to take place. Likewise, temperatures much below 0 C. are not employed since at these conditions, the reaction proceeds more slowly. As indicated by some of the above examples, it is frequently desirable to employ a two-step heating operation. This is particularly the case where a trialkylboron is the organoboron compound being oxidized. For example, in such instances, it is usually advantageous to conduct the oxidation at temperatures between about to 40 C. until essentially the first two boron to carbon linkages have been oxidized and then to conduct the remainder of the oxidation at temperatures between about 40 to 150 C. It has been found that these conditions are admirably suited when reacting the trihydrocarbon boron compounds since better control as well as complete controlled oxidation is obtained.

Similarly, while the reaction can be conducted at atmospheric pressure, pressures above atmospheric are preferably employed for more eflicient operation. The maximum pressure used is limited primarily only by the practicalities involved and for this reason generally the pressure is up to about 5000 p.s.i. More eflicient operation is obtained when the oxygen or air pressure is not higher than about 1000 p.s.i. The reaction time employed is dependent somewhat upon the reactants involved and the reaction conditions but can also be widely varied. Ordinarily, complete oxidation is obtained at reaction times up to about 20 hours and longer reaction times are not required or desirable. Generally reaction times up to 10 hours are suitable and preferred.

In those embodiments wherein the reaction is conducted in the absence of water, the boron ester which is produced is generally soluble in the reaction mixture but is readily recoverable by simple separation techniques. Whether it is soluble or insolube, or in those instances wherein Water is employed to result in the direct formation of an alcohol, fractional distillation techniques can be employed to effect efiicient separation. Generally, however, in those instances where the alcohol that is formed is of a long chain length, that is, above about carbon atoms, it will be insoluble in the reaction mixture and can be recovered by simple decantation. In those instances wherein the alcohol produced is soluble in the reaction mixture, it can also be extracted with suitable solvents therefor which are insoluble in the reaction mixture or a presaturated solution of the alcohol, water and amine can be employed which will automatically result in a phase separation of the alcohol which is produced. Similar tech niques. can be used where the ester is produced rather than the alcohol. Salting out techniques are also available as, for example, adding alkali metal carbonates to the reaction mixture. -The alcohol or ester likewise is generally easily separable from the amine catalyst. In any event, the amine can be washed out with water or acid or it can be distilled from the alcohol or ester. When required, the amine is generally distilled under conditions which are not destructive of the amine. Other methods of recovery of the principal product will be evident to those skilled in the art. It is to be understood that the reaction mixture can be employed as obtained, if desired, without any separation.

The boron esters and alcohols produced according to the respective embodiments of this invention are of considerable and well known utility. For example, the esters, such as triethylborate, can be reacted with sodium hydride to produce sodium borohydride or they can be employed as additives to motor fuels. They likewise can be readily converted to the corresponding alcohols by simple hydrolysis techniques. In the embodiments of the invention wherein the alcohol is directly produced, the alcohols are of particular utility as intermediates for the formation of various detergents. For example, any of the products produced according to the Examples II through XVII, particularly those with 6 carbon atoms or more, can be reacted with sulfuric acid to form the corresponding sulfate esters from which the corresponding alkali metal salts are obtainable by conventional techniques. The resulting sulfates are efiicient detergents and cleansing agents of known utility. Many other diverse uses of alcohols are well known in the art. I

Having thus described the process of this invention, it is not intended that it be limited except as set forth in the following claims.

We claim:

1. The process for the manufacture of a boron ester which comprises oxidizing a hydrocarbon boron compound having at least one carbon to boron linkage with oxygen in the presence of a nitrogen-containing compound selected from the group consisting of a hydrocarbon amine and ammonia.

2. The process of claim 1 further characterized in that the reaction is conducted at a temperature between 0 to C. in the further presence of water.

3. A process for the manufacture of alkanols which comprises reacting a trialkylborane with oxygen at a temperature between about 0 to 150 C. and a pressure between about atmospheric and 5000 p.s.i. in the presence of a hydrocarbon amine and Water.

4. A process for the manufacture of n-hexyl alcohol which comprises reacting tri-n-hexylborane with oxygen at a temperature between about 0 to 150 C. and a pressure between about atmospheric and 1000 p.s.i. in the presence of a trihydrocarbon amine and water.

5. The process of claim 4 further characterized in that said amine is present in amount of at least 0.01 mole per mole of the carbon to boron linkages in said tri-n-hexylborane and said water is present in amount at least sufficient to hydrolyze the oxidized product to the corresponding alcohol.

6. The process of claim 5 wherein said amine is triethylamine.

7. The process of claim 3 wherein said hydrocarbon amine is a trialkylamine.

8. The process of claim 1 further characterized in that said hydrocarbon boron compound is a trialkylborane, in that the reaction is conducted at a temperature between about 0 to 150 C. and at a pressure above atmospheric but below about 1000 p.s.i., and in that said nitrogencontaining compound is a trialkylarnine.

9. The process of claim 8 further characterized in that it is conducted in the further presence of water.

References Cited in the file of this patent UNITED STATES PATENTS 2,542,746 Banus et al Feb. 20, 1951 2,862,951 Stafiej Dec. 2, 1958 2,875,236 Levens et al Feb. 24, 1959

Claims (1)

1. THE PROCESS FOR THE MANFACTURE OF A BORON ESTER WHICH COMPRISES OXIDIZING A HYDROCARBON BORON COMPOUND HAVING AT LEAST ONE CARBON TO BORON LINKAGE WITH OXYGEN IN THE PRESENCE OF A NITROGEN-CONTAINING COMPOUND SELECTED FROM THE GROUP CONSISTING OF A HYDROCARBON AMINE AND AMMONIA.