GB2129800A - Process for hydroxylating olefins using an osmium oxide catalyst and sodium hydroxide co-catalyst - Google Patents

Abstract

A process for hydroxylating olefins, such as ethylene or propylene, using an organic hydroperoxide oxidant and a catalyst composition comprising at least one osmium oxide catalyst, such as OsO4 and NaOH as a co-catalyst, is characterised by a molar ratio of Na:Os of 0.1:1 to 20:1 in the catalyst, and is conducted in the presence of an inert polar organic solvent sufficient to maintain the reaction mixture at least 50% organic.

Description

SPECIFICATION Process for hydroxylating olefins using an osmium oxide catalyst and sodium hydroxide co-catalyst The present invention relates to processes for hydroxylating olefins in the presence of an osmium oxide catalyst, and a co-catalyst comprising sodium hydroxide.

Processes for the production of glycols such as ethylene glycol, from olefins are well known in the art.

For example, it is well known from the technical literature and patents that olefins can be effectively oxidized to their corresponding diols with a strong oxidizing agent in the presence of catalytic amounts of specific osmium containing compounds, particularly osmium tetroxide.

The patent literature directed to osmium containing hydroxylation catalysts described various osmium oxides used in a variety of reaction systems in conjunction with specific oxidants. The primary oxide catalyst employed in these patents is OsO4. However, the activity and/or selectivity associated with Os04, by itself, as a hydroxylation catalyst is insufficient from a commercial standpoint. Consequently, a variety of promoters have been used to enhance the activity and/or selectivity of the Os04 catalyst for such hydroxylation reactions. The identity of these promoters is dependent on the particular oxidant employed in conjunction with the Os04.

For example, Sharpless et al disclose, in the article, "Osmium Catalyzed Vicinal Hydroxylation of Olefins byTert-Butyl Hydroperoxide Under Alkaline Conditions", J. Amer. Chem. Soc., Vol.98, pp. 1986-87(1976), the use of tetra ethyl ammonium hydroxide as a promoter for the hydroxylation of olefins when employed in conjunction with t-butyl hydroperoxide oxidant and 0504. The (Et)4NOH is employed in a substantial molar excess (e.g. about 50x) relative to the molar amount of Os04 present. The highest disclosed yield of diol is 73%. In addition, it is indicated at footnote 7 of this article that the "use of sodium or potassium hydroxides resulted in a heterogeneous reaction mixture and lower yields". No other details on the use of NaOH as a promoter are provided.However, in view of the large molar excess of (Et)4NOH employed, it appears likely that a similar large molar excess of NaOH would also have been employed in substituting either NaOH or KOH for (Et4)NOH as a promoter, and that this molar excess is responsible for the heterogeneous nature of the system due to insolubility of the NaOH.

While (Et)4NOH exhibits a good promoting effect, in the Sharpless et al system this material is very expensive, and in the large amounts employed to produce the promoting effect, it is undesirable for use in commercial applications.

Sheng et al, U.S. Patent No. 4,049,724 is directed to an aqueous process for hydroxylating olefins using an organic hydroperoxide oxidant, and a water soluble osmium catalyst compound (e.g. Os04). The hydroxylation reaction is conducted in an aqueous solution (i.e. at least about 50% by weight water, based on the combined weight of water and reagents (Col. 2, Line 62). It is critical to this process that the initial pH of the aqueous solution be above 8, e.g. 8 to 12 (Col. 12, Lines 64 et seq). This critical initial pH is obtained and maintained by the use of buffering agents (Col. 2, Lines 65 et seq). To achieve an initial pH well above 8 (e.g. 11.9) strong base (e.g. NaOH) can be employed (Col. 4, Lines 1 et seq).A strong base is also employed to solubilize the 0504 in water due to its low solubility in predominantly aqueous systems. The examples illustrate the use of a molar ratio of NaOH: OsO4 of 2:1 for this latter purpose. One characteristic of the Sheng et al process is the use of excess amounts of water in the reaction mixture, e.g. the examples illustrate the use of about 80-90% water, by weight based on the weight of the reaction mixture exclusive of olefin. Excess water is employed to solubilize the buffering agents and to act as the primary reaction medium. The use of excess water is commercially disadvantageous because it requires eventual separation of the products therefrom, thereby increasing the cost of product recovery.Other disadvantages of employing aqueous based systems for the hydroxylation of olefins include limitations in the solubility of the olefin and organic hydroperoxide in the water of the reaction mixture. Thus, Sheng et al is an aqueous based system which can employ any strong base to control pH and solubilize the osmium catalyst. Sodium hydroxide is not disclosed as a promoter for an Os04 catalyzed organic based system.

Wu et al, U.S. Patent No. 4,229,601 is directed to a heterogeneous process for hydroxylating olefins in the presence of an organic-aqueous two phase system containing an organic polar solvent, an aqueous solution of cesium, rubidium or potassium hydroxide, Os04 catalyst, and organic hydroperoxide. The aforenoted hydroxides exhibit a promoting effect in conjunction with Os04 and enhance the selectivity to the gicyol product. However, at Col 2, Lines 1 et seq and Col 3, Lines 16 et seq it is disclosed that sodium hydroxide is practically or essentially ineffective as a promoter in this process. Thus, Example 5 of this patent illustrates the use of NaOH for comparative purposes.The mole ratio of Os04: NaOH in Example 5 is 1:180 and the reaction temperature is 0 C for 6 hours followed by room temperature for about 18 hours. Glycol yield was only 13.7%. Note further, that the reaction temperatures disclosed in this patent (Col. 4, Lines 20 et seq) vary from - 10 to 50"C (e.g. 00C. At higher temperatures it is disclosed that the selectivity to glycol is reduced substantially. This is a distinct disadvantage because the osmium catalyzed hydroxylation reaction is characterized by thigh heat of reaction. Consequently, the low operable reaction temperatures necessitate expensive refrigeration cooling apparatus to dissipate the heat of reaction.

The process of the present invention was developed in response to the search to identify new and inexpensive promoters active for OSO4 catalyzed organic based systems employing organic hydroperoxide oxidants.

The following is a summary of related commonly assigned osmium catalyzed olefin hydroxylation U.S.

Patent applications.

Commonly assigned U.S. Patent No.4,314,088 and a continuation-in-partthereof, namely, U.S. Patent No.

4,393,253 by R. Austin and R. Michaelson collectively, disclose the use of various halide containing co-catalysts in conjunction with osmium tetroxide catalyst and organq-hydoperoxide oxidantsto hydroxylate olefins. The halide containing co-catalysts include alkali and alkaline earth metal halides, hydrogenhalides, quaternary hydrocarbyl phosphonium halides, halogens, and transition metal halides.

Commonly assigned U.S. Patent No. 4,390,379 by R. Austin and R. Michaelson is directed to the hydroxylation of olefins using oxygen as an oxidant, a catalytically active metal oxide catalyst such as Os04, and at least one transition metal salt co-catalyst.

The following patents are discussed to provide a general background of the prior art.

U.S. Patent No. 2,414,385 discloses the use of hydrogen peroxide and a catalytically active oxide, such as osmium tetroxide, dissolved in an essentially anhydrous non-alkaline, inert, preferably organic, solvent, to convert, by oxidation, unsaturated organic compounds to useful oxygenated products such as glycols, phenols, aldehydes, ketones, quinones and organic acids. The formation of glycols is achieved by conducting the reaction at temperatures of between several degrees below 0 and 21"C. Such low reaction temperatures drastically, and disadvantageously, reduce the reaction rate to commercially unacceptable levels. At temperatures greater than 21 "C, the formation of aldehydes, ketones and acids is favored.

U.S. Patent No. 2,773,101 discloses a method for recovering an osmium containing catalyst such as osmium tetroxide, by converting it to the non-volatile osmium dioxide form, distilling the hydroxylation product, reoxidizing the osmium dioxide to the volatile osmium tetroxide, and then recovering the same by distillation. Suitable oxidizing agents used to oxidize olefins, and re-oxidize the osmium dioxide, include inorganic peroxides such as hydrogen peroxide, sodium peroxide, barium peroxide; organic peroxides, such as t-butyl peroxide or hydroperoxide, benzoyl peroxide; as well as other oxidizing agents such as oxygen, perchlorates, nitric acid, chlorine water and the like. As with other methods of the prior art, the above process yields undesirable by-products (see Col. 1, Line 55) thus reducing the selectivity of the process.

British Patent Specification No. 1,028,940 is directed to a process for regenerating osmium tetroxide from reduced osmium tetroxide by treatment of the latter with molecular oxygen in an aqueous alkaline solution.

More specifically, it is disclosed that when osmium tetroxide is used by itself as an oxidizing agent, or as a catalyst in conjunction with other oxidizing agents, to oxidize hydrocarbons, the osmium tetroxide becomes reduced, and in its reduced form is less active than osmium tetroxide itself. Consequently, by conducting the oxidation reaction in the presence of an alkaline medium and supplying oxygen to the medium throughout the process, the osmium tetroxide is maintained in a high state of activity. The oxidation products disclosed include not only ethylene glycol from ethylene but also organic acids from such compounds as vicinal glycols, olefins, ketones and alcohols.

U.S. Patent No. 4,255,596 is directed to a process for preparing ethylene glycol in a homogeneous single-phase reaction medium using ethylbenzene hydroperoxide as the oxidizing agent dissolved in ethylbenzene and osmium tetroxide as the catalyst The pH of the reaction medium is maintained at about 14 by the presence of tetraalkyl ammonium hydroxide. A small amount of water can dissolve beneficially in the medium to reduce by-product formation and improve selectivity to the glycol.

Japanese Patent Application No. Sho 54-145604, published November 14, 1979 is directed to a process for hydroxylating olefins in the presence of 0504, a quaternary ammonium salt such as tetraethyl ammonium bromide, and a peroxide including organoperoxides and H202 as the oxidant.

U.S. Patent No.3,335,174 is directed to the use of water hydrolyzable Group Vb, Vl-b and VII metal halides and oxyhalides (e.g., OsCI3) as hydroxylation and esterification catalysts in conjunction with aqueous H202 as an oxidant.

See also: U.S. Patent No.3,317,592 (discloses production of acids and glycols using oxygen as oxidant, 0s04 as catalyst at pH 8 to 10); U.S. Patent No. 3,488,394 (discloses hydroxylation of olefins by reacting olefin and hypochlorite in the presence of Os04); U.S. Patent No. 3,846,478 (discloses reaction of hypochlorite and olefin in an aqueous medium and in the presence of Os04 catalyst to hydroxylate the olefin); U.S. Patent No. 3,928,473 (discloses hydroxylation of olefins to glycols with 2 oxidant, octavalent osmium catalyst (e.g. Os04), and borates as promoter);; U.S.Patent No. 3,931,342 (discloses a process for recovering glycolsfrom an aqueous solution containing alkali metal borate and osmium compounds (e.g., Ops04)); U.S. Patent No. 3,953,305 (discloses use of 0504 catalyst for hydroxylating olefins which is regenerated by oxidizing hexavalent osmium with hexavalent chromium and electro-chemically regenerating hexavalent chromium); U.S. Patent No. 4,203,926 (discloses ethylbenzene hydroperoxide as oxidant used in two-phase system to hydroxylate olefins in presence of 0s04 and cesium, rubidium and potassium hydroxides); U.S. Patent No.4,217,291 (discloses the oxidation of Osmium (III) to (IV) in an ionic complex with oxygen and an alkali metal, ammonium, on terra (-lower) alkyl ammonium cation to a valency of greater than +5 + organohydroperoxides); and U.S. Patent No.4,280,924 (discloses a process for regenerating perosmate catalyst, e.g., cesium, rubidium and potassium perosmate).

Summary of the invention In one aspect of the present invention there is provided a- process for hydroxylating olefins which comprises reacting in admixture water, at least one olefinic compound having at least one ethylenic unsaturation, and at least one organic hydroperoxide oxidant, in the presence of (i) a catalyst composition comprising at least one unsupported inorganic osmium oxide and sodium hydroxide wherein said catalyst composition the molar ratio of the sodium hydroxide to osmium in said osmium oxide is from about 0.1:1 to about 20:1; and (ii) at least one liquid inert polar organic solvent in an amount sufficient to control the liquid contents of said reaction admixture to be greater than 70% organic, by weight, based on the total weight of liquid in said admixture; said reaction being conducted in a manner and under conditions sufficient to hydroxylate at least one of said ethylenically unsaturated groups to its corresponding diol.

It has been found that sodium hydroxide is a very effective and inexpensive promoter for the hydroxyl'ation of olefins catalyzed by an osmium oxide, e.g. 0504, in conjunction with an organic hydroperoxide oxidant and a predominantly organic reaction medium. The promoting effect is obtained in such systems by controlling and limiting the amount of NaOH present during reaction relative to the osmium oxide. Efficient elevated reaction temperatures are also made possible by such a reaction system. The need for buffers and excess water in the reaction mixture is eliminated, and the use of an organic based solvent system avoids the disadvantages associated with aqueous based systems wherein excessive amounts of water are employed, for example, to dissolve 0s04 and buffers.The organic based solvent system also enhances the promoting effect of the NaOH.

Description ofpreferred embodiments In accordance with the present invention, at least one olefin containing at least one ethylenic unsaturation is reacted with at least one organic hydroperoxide oxidant, and water in a predominantly liquid organic medium and in the presence of a specifically defined catalyst composition, under conditions and in a manner sufficient to hydroxylate at least one of said ethylenically unsaturated groups to its corresponding diol group.

The catalyst composition comprises at least one inorganic osmium oxide and sodium hydroxide as a co-catalyst. The most preferred osmium oxide is OSO4. Other suitable inorganic osmium oxides include osmium compounds which are converted to osmium tetroxide during the course of reaction such as salts thereof including K, Na, and Li, osmates as well as other osmium oxides such as OsO2, and 0503. The inorganic osmium oxide is employed in the absence of a support and is dissolved in the inert organic solvent described hereinafter.

The osmium oxide catalyst is employed in amounts effective to catalyze the hydroxylation reaction. Thus, while any effective amount of catalyst will suffice, it is preferred that such effective amounts constitute typically from about 1 x 10-6to about 1 mole, preferablyfrom about 1 x 10-5to about 1 x 10-1 mole, and most preferably from about 1 x 10-4 to about 1 x 10-2 mole, of osmium in the osmium catalyst per mole of olefin ethylenic unsaturation to be hydroxylated.

Alternatively, such amounts may be expressed as varying from about 10,000 to about 1, preferably from about 1000 to about 10, and most preferably from about 500 to about 50ppm, based on the total weight of liquid reaction medium.

The osmium oxide catalyst is soluble in the organic polar solvent systems described hereinafter and can be dissolved in said systems for addition to the reaction mixture.

The aforedescribed osmium oxide catalysts are employed in conjunction with NaOH as a promoter (also referred to herein as co-catalyst) which increases the rate and/or selectivity of the hydroxylation reaction.

The NaOH can also be employed in conjunction with additional promoters or co-catalysts such as those co-catalysts disclosed in the commonly assigned U.S. patent applications discussed above.

To exert the appropriate promoting effect, it is critical that the amount of NaOH be controlled in conjunction with the molar amount of osmium in the osmium oxide. Accordingly, the amount of NaOH present in the reaction mixture is controlled in a manner sufficient to achieve a molar ratio of sodium hydroxide to osmium in the osmium catalyst not greater than about 20:1, preferably not greater than about 10:1, and most preferably not greater than about 5:1, and typically from about 0.1:1 to about 20:1, preferably from about 0.1:1 to about 10:1, and most preferably from about 0.1:1 to about 5:1.

If the amount of NaOH exceeds a molar ratio as described above of about 20:1, the pH of the reaction mixture can undesirably drift to 8 or above, and the selectivity to glycol product is reduced. Thus, by limiting the amount of NaOH below that illustrated in U.S. Patent No.4,229,601 in conjunction with the other process conditions described herein, the yield of glycol is substantially improved.

The oxidant which is employed to oxidize the olefin comprises at least one organic hydroperoxide.

Conventional organohydroperoxides include those having the formula: R"OOH (I) wherein R" is a substituted or unsubstituted alkyl, typically about C3 to about C20, preferably about C3 to about C10, most preferably about C3 to C6 alkyl; aryl, typically C6 to C14, preferably C6 to Cic, most preferably C6 aryl; aralkyl and alkaryl wherein the aryl and alkyl groups thereof are as defined immediately above; cycloalkyl typically about C4to about C20, preferably about C4to about Cr0, most preferably about C4to about C8 cycloalkyl; as well as oxacyclic having 1 to about 5 oxygens and preferably 3 to about 20 carbons, and azacyclic having 1 to about 5 nitrogens and preferably about 3 to about 20 carbons; and wherein the substituents of said R" group include halogen, hydroxyl, ester and ether groups.

Representative examples of suitable organohydroperoxides include ethylbenzene hydroperoxide, t-butyl hydroperoxide, t-amyl hydroperoxide, cumene hydroperoxide, methyl 2-hydroperoxy-2-methyl-propionate, 2-methyl-2-hydroperoxy propanoic acid, pyrrolehydroperoxide, furan hydroperoxide, 2-butylhydroperoxide, cyclohexyl hydroperoxide, and 1-phenyl-ethylhydroperoxide.

The most preferred organic hydroperoxides include t-butyl hydroperoxide, ethylbenzenehyd roperoxide and t-amyl hydroperoxide. Frequently these hydroperoxides are made by the molecular oxygen oxidation of the corresponding hydrocarbon which also produces an alcohol as a by-product. For example, when isobutane is oxidized with molecular oxygen there is produced tertiary butyl hydroperoxide and tertiary butyl alcohol. It is not necessary to separate the alcohol from the hydroperoxide since the alcohol can function as a diluent or solvent.

The amount of organohydroperoxide employed is not critical and can vary widely. Generally, the organohydroperoxide is employed in less than stoichiometric requirements (i.e., less than 1:1 molar ratio of organohydroperoxide per mole of ethylenic unsaturation in the olefin to be hydroxylated). Thus, while any amount of hydroperoxide effective to hydroxylate the olefin can be employed, it is contemplated that such effective amount constitute a ratio of moles of ethylenic unsaturation in the olefin to moles of organohydroperoxide of from about 0.5:1 to about 100:1, preferably from about 1.1 to about 20:1 and most preferably from about 2.1 to about 10:1.

While the organohydroperoxide can be added to the reaction mixture in anhydrous form, it may also be added as an aqueous solution comprising from about 1 to about 99%, preferablyfrom about 10 to about 90%. and most preferably from about 20 to about 70%, by weight hydroperoxide, based on the weight of the aqueous hydroperoxide solution. The amount of water employed in such aqueous solutions is subject to the constraints described hereinbelow.

The hydroxylation reaction is conducted in the presence of a liquid reaction mixture, preferably provided as a homogeneous or substantially homogeneous medium using a liquid inert organic solvent to dissolve catalyst and reactants.

Partial immiscibility of the solvent with water is acceptable although not preferred. By an inert solvent is meant one which does not undergo oxidation during the course of the reaction.

Suitable inert organic solvents preferably possess polar functional groups and include aliphatic or aromatic alcohols having from 1 to about 10 carbon atoms, preferably tertiary alcohols, aliphatic or aromatic ketones having from 3 to about 10 carbon atoms, aliphatic or alicyclic ethers having from 2 to about 10 carbon atoms, glycols having from 2 to about 10 carbon atoms, N,N-dialkyl amides having from 3 to about 10 carbon atoms, nitriles having from about 2 to about 10 carbons, aliphatic or aromatic sulfoxides having from 2 to about 14 carbon atoms, aliphatic or aromatic sulfones having from 2 to about 14 carbon atoms, and the like.Examples of suitable solvents include methanol, ethanol, propanol, butanol, hexanol, decanol,t-butyl alcohol, t-amyl alcohol, benzyl alcohol, acetone, methylethyl ketone, methyibutyl ketone, acetophenone, ethylene glycol, propylene glycol, diethylene glycol, tetraethylene glycol, dimethyl formamide, diethyl formamide, dim ethyl acetamide, dimethyl sulfoxide, diethyl sulfoxide, di-n-butyl sulfoxide, diphenyl sulfoxide, dibenzyl sulfoxide, dimethyl sulfone, diethyl sulfone, tetramethylene sulfone, diphenyl sulfone, acetonitrile, pyridine, dioxane, tetrahydrofuran, tetrahydropyran, dioxolane, and mixtures thereof.

The preferred solvents include those which are substantially or completely miscible with water such as t-butyl alcohol, methanol, acetonitrile, acetone, and ethylene glycol.

The most preferred solvent(s) is the product alcohol derived from the organic hydroperoxide or mixtures of the product glycol and the organohydroperoxide derived product alcohol.

For example, when ethylene is hydroxlyated using t-butyl hydroperoxide, the preferred solvent is t-butyl alcohol or a mixture of ethylene glycol and t-butyl alcohol, the latter being formed in-situ from t-butyl hydroperoxide.

The inert solvent is preferably employed in amounts sufficiently to achieve a homogeneous solution with respect to at least the olefin, catalyst, and cxidant. The amount of inert organic solvent is also controlled to insure that greater than 50%, preferably g n3ater than 70%, and most preferably greater than 90%, by weight, of the total liquid contents of the reaction admixture is organic, inclusive of the weight of solvent, organohydroperoxide, olefin and water. Thus, the liquid contents of the reaction mixture are predominantly non-aqueous. Accordingly the amount of inert organic solvent employed in the reaction mixture can vary from about 50 to about 99, preferably from about 70 to about 97, and most preferably from about 80 to about 95%, by weight, based on the total weight of the liquid in the reaction mixture.

It is also critical to have water present during the hydroxylation reaction since the water is believed to contribute one of the oxygen molecules constituting one of the hydroxyl groups in the resulting glycol. The source of this water is not critical. Thus, water can be added separately, or preferably as the solvent for the organohydroperoxide. Consequently, water is provided to, and/or is present in at least a stoichiometric molar ratio with the molar amount of ethylenic unsaturation of the olefin to be hydroxylated. Such ratios preferably also are present in the reaction mixture at any given time after start up. Accordingly, water is present in the reaction mixture at molar ratios of water to olefin ethylenic unsaturation to be hydroxylated in the reaction mixture of from about 1:1 to about 100:1, preferably from about 1:1 to about 50:1, and most preferably from about 1:1 to about 20:1 (e.g. 1:1 to 5:1). Such molar ratios typically can be achieved by controlling the amount of water in the reaction mixture to be from about 1 to about 30, preferably from about 1 to about 20, and most preferably from about 1 to about 10 (i.e. 1 to 5)%, by weight, based on the total weight of the reaction mixture. Preferably the amount of water employed is less than that which will cause separation of the reaction mixture into an aqueous phase and organic phase although this is not a critical condition.Furthermore, it is preferred to maintain the water content of the liquid reaction mixture as close to the aforedescribed minimum stoichiometric requirements as possible, to reduce the cost and difficulty of product-water separation procedures.

The initial pH of the reaction mixture during the hydroxylation reaction is preferably controlled to be less than 8 and typically will not be allowed to drop below about 4. Preferably, the pH of the reaction mixture is maintained at less than 8 for the duration of the hydroxylation reaction. Accordingly, the pH of the reaction mixture typically will be maintained between 4 and 7.9, preferably about 4 and about 7, and most preferably between about 4 and about 6. The pH of the reaction mixture is preferably controlled by controlling the amount of NaOH co-catalyst in the reaction mixture although other suitable materials, such as buffers may be employed. The use of buffers, however, is undesirable because of the possible need to solubilize those buffers with excess water.

Olefins which can be hydroxylated in accordance with the present invention contain at least one ethylenic unsaturation and comprise any of the unsaturated aliphatic or alicyclic compounds well known in the art for undergoing such hydroxylation reactions. Typically, such compounds will contain from 2 to about 20 carbons, preferably from about 2 to about 10 carbons, and most preferably from about 2 to about 5 carbons.

Such compounds may be straight or branched-chain, mono-olefinic, di-olefinic, or poly-olefinic, conjugated or non-conjugated. They may be substituted with such groups as aryl, preferably aryl of from 6 to about 14 carbons, alkyl, preferably alkyl of from 1 to 10 carbons, or aralkyl and alkaryl wherein the alkyl and aryl portions thereof are as described above, as well as with functional groups such as hydroxy, carboxyl and anhydride.

Typical of such olefins are those represented by the structural formula:

wherein R8, R7, R8, and R9, which may be the same or different, are selected from the group consisting of hydrogen; substituted or unsubstituted: alkyl, aryl, alkaryl, and aralkyl hydrocarbyl groups, said hydrocarbyl groups being preferably as defined immediately above; or any two of said R69 groups together can constitute a cycloalkyl group typically of from about 4 to about 12, preferably from about 5 to about 8 carbons.

Representative olefins which can be hydroxylated and contain at least one ethylenic unsaturation include: ethylene, propylene, butene-1, butene-2, isobutene, butadiene, pentene-1, pentene-2, hexene, isohexene, heptene, 3-methyihexene, octene-1, isooctene, nonene, decene, dodecene, tridecene, petadecene, octadecene, eicosene, docosene, tricosene, tetracosene, pentacosene, butadiene, pentadiene, hexadiene, octadiene, decadiene, tridecadiene, eicosadiene, tetracosadiene, cyclopentene, cyclohexene, cycloheptene, methylcyclohexene, isopropylcyclohexene, butylcyclohexene, octylcyclohexene, dodecylohexene, acrolein, acrylic acid, 1 ,2,3,4-tetrahydrophthalic an hydride, methyl methacrylate, styrene, cholesterol and mixtures thereof.

The preferred olefins are ethylene, propylene, isobutylene, butadiene, styrene, allyl alcohol and allyl chloride.

The most preferrred olefins are ethylene and propylene.

In carrying out a preferred embodiment of the invention, olefin, water, oxidant, osmium catalyst, NaOH co-catalyst, and inert solvent are contacted by admixing to form a liquid reaction mixture in a manner and under conditions sufficient to hydroxylate the olefin, i.e., to convert at least one of the ethylenic unsaturations possessed thereby to its corresponding diol. The manner and order of addition of each of the individual components of the liquid reaction mixture to the reaction vessel is not critical. However, it is preferred to mix the osmium catalyst, and NaOH co-catalyst with an aqueous solution, containing solvent, additional additives such as buffers, where needed, olefin, and finally organic hydroperoxide.

For the production of ethylene glycol, propylene glycol or any other product derived from any unsaturated gaseous olefin, the latter may be bubbled through the reaction mixture containing the components described herein or it may be introduced under pressure. However, it is preferred that the reaction takes place in the liquid phase. Consequently, sufficient pressure is preferably employed to maintain the reactants in the liquid phase. Otherwise, the reaction pressure is not critical and can be atmospheric, sub-atmospheric, or super-atomospheric.

When the olefin reactant is a liquid or is dissolved in the reaction mixture under pressure, its concentration in the reaction mixture typically will vary from about 1 to about 98 percent, preferably from about 10 to about 80 percent, and most preferably from about 30 to about 60 percent, by weight, based on the total weight of the reactant mixture inclusive of the weight of components (a) through (d) described above.

The hydroxylation reaction is typically conducted at temperatures which can vary over wide limits although it is preferred to maintain the reaction mixture in the liquid phase. Accordingly, typical reaction temperatures can vary from about 0 to about 250"C, preferably from about 60 to about 150"C, and most preferably from about 60 to about 100 C.

At temperatures greater than the aforenoted ranges, the reaction rate may increase substantially but this usually occurs at the expense of a significant reduction in selectivity. At very low reaction temperatures, e.g., below about 0 C the reaction rate decreases to a commercially undesirable degree. Accordingly, while the reaction temperature is not critical and can vary over a wide range, one normally would not operate at temperature extremes outside the aforenoted ranges.

The hydroxylation reaction can be performed as a batch reaction, as a continuous reaction or as a semi-continuous reaction.

In the batch reaction, a reaction mixture containing the above described components is charged into the reaction vessel along with olefin if in liquid form. Alternatively, the reaction vessel is then pressurized with olefin if in gaseous form. It may be desirable to heat the liquid reaction mixture to reaction temperature prior to pressurizing with the reactant gases. The reaction is allowed to proceed to completion, typically for a period of from about 0.5 to about 5 hours, preferably from about 0.5 to about 3 hours, and most preferably from about 0.5 to about 2 hours.

In the continuous process, the components can be introduced into the inlet of an elongated reactor at a rate such that substantially complete reaction will have taken place by the time the reaction mixture reaches the reactor outlet. The reaction can be carried out in a semicontinuous manner by metering the reactant mixture components into a series of two or more tank reactors at the appropriate rate to maintain the reactor liquid level.

Additionally, the process may be run in either of the aforementioned modes by altering the reaction conditions and/or, the reactant, solvent, catalyst, co-catalyst, during the course of the reaction. Thus, the process may be run by changing the temperature, pressure, catalyst concentration, oxidant concentration, and/or olefin concentration.

The spent reaction mixture after removal of unreacted olefin is a solution of product glycol, by-products if any, solvent, minor amounts of water, catalyst and co-catalyst. The volatile components are distilled out of the reaction mixture into various fractions leaving non-volatile catalyst components in the still. The product glycol is then separated from the high boiling distillate.

The following examples are given as specific illustrations of the claimed invention. It should be understood, however, that the invention is not limited to the specific details set forth in the examples. All parts and percentages in the examples as well as in the remainder of the specification are by weight unless otherwise specified. Furthermore, and unless otherwise specified, while the following examples may be written in the present tense, they represent work actually performed.

Unless otherwise specified, in the following examples, selectivity, conversion and yield are calculated as follows: moles of glycol formed %selectivity = x 100 moles of oxidant consumed moles of oxidant consumed %conversion = x 100 moles of oxidant charged % conversion x % selectivity % yield 100 Examples 1 to 4 For each of Examples 1 to 4, 300ml titanium autoclave was charged with the quantities of 2.5 wt.% osmium tetroxide in t-butanol (TBA), 0.8 wt.% sodium hydroxide in water, and water as shown at Table 1, using t-butanol to wash in the last traces of materials from the bottles used for weighing. The autoclave contents were brought to 70"C and ethylene was added to the pressure shown at Table 1. A solution of 90 wt.% t-butylhydroperoxide (TBHP) in 5 wt.% H20 and 5 wt.% TBA was then added followed by the addition of an internal standard 3-ethyl-3-pentanol in TBA. The quantities of the TBHP solution and the pentanol were as shown in Table 1. The quantity of TBA shown in Table 1 indicates the total amount added to the autoclave and was such that the total liquid reaction mixture weighed about 60 grams. After the time specified at Table 1, the autoclave was cooled, the excess ethylene vented, and the contents discharged into a serum capped bottle. Analysis by gas liquid chromatography showed the yield % of ethylene glycol for each example reported in Table 1.

TABLE 1 Example No. 1 2 3 4 TBA(g) 50.12 39.38 39.36 39.38 2.5% 0sO4/TBA(g) 0.20 1.00 1.00 1.00 0.8% NaOH/H20(g) 0.50 2.50 5.00 2.52 H20(g) 6.60 4.21 1.79 4.20 90% TBHP/5% H20/ 5%TBA(g) 2.00 10.00 10.00 10.00 Et3COH(g) 0.63 2.90 2.92 2.90 Ethylene (psig) 400 400 400 600 Reaction Time (Min) 60 64 77 68 Reaction Temp.

( C) 70 70 70 70 Yield (%) 90 65 83 87 Selectivity (%) 90 65 83 87 NaOH:0sO4 (mole ratio) 5:1 5:1 10:1 5:1 Et3COH = wt. of 3-ethyl-3-pentanol internal standard employed TBA = t-butylalcohol TBHP = t-butyl hydroperoxide Example 5 A solution was prepared containing TBA (40.9g), water (7.2g), Oslo4(0.04 mmole), NaOH (0.04 mmole) and 3-ethyl-3-pentanol internal standard (2.32g). The pH of the solution was then measured and found to be about 5.6. The solution was then charged to the autoclave reactor of Example 1, warmed to 700C, and the reactor pressurized with ethylene (700 psig) and then charged with TBHP 9.0g (100.0 mmole). The solution was stirred at 70"C for 1 hour and the resulting reaction mixture analyzed by gas liquid chromatography.

After completion of the run, the pH of the reaction mixture was measured and found to be 5.0. Conversion of the TBHP was found to be 100% and selectivity to ethylene glycol was 67%.

Comparative Example 1 To provide a basis for comparison, a run was conducted at 700C in general accordance with Example 5 of U.S. Patent No. 4,229,601. Accordingly, the reactor of Example 1 was charged with 100 ml TBA, 7.5ml of 10 wt.% aqueous NaOH, 12g of 70 wt.% TBHP (93 mmole) and the solution warmed to 70"C. Ethylene was pressured into the reactor to about 200 psig followed by Os04 (0.10 mmole) in TBA. The reaction was stirred at 70"C for two hours. Complete conversion of the TBHP was obtained. The selectivity to ethylene glycol based on TBHP charged to the reactor was 3.7%.

Comparative Example 2 Comparative Example 1 was repeated with the exception that the reaction pressure was 700 psig. The selectivity to ethylene glycol based on TBHP charged was 14.4%.

Discussion of Results Examples 1 to 5 illustrate that ethylene glycol yields between 65 and 90% are obtainable from a substantially organic reaction mixture, having limited low amounts of NaOH as a promoter. When the amount of NaOH is increased as per Comparative Examples 1 and 2 (Os04:NaOH mole ratio of 1:180) the glycol yield drops substantially. Furthermore, the high yields of the present invention are obtained at a temperature of 70"C. In contrast, the low preferred (e.g. to 25"C) reaction temperatures employed in U.S.

Patent No.4,229,601 would require costly refrigeration cooling equipment to maintain the reaction temperature at such low temperatures due to the high heats of the hydroxylation reaction. The process of the present invention, however, is not dependent on very low reaction temperatures for enhanced selectivity.

The principles, preferred embodiments and modes of operation of the present invention have been described in the foregoing specification. The invention which is intended to be protected herein, however, is not to be construed as limited to the particular forms disclosed, since these are to be regarded as illustrative rather than restrictive. Variations and changes may be made by those skilled in the art without departing from the spirit of the invention.

Claims (14)

1. A process for hydroxylating olefins which comprises reacting in admixture water, at least one olefinic compound having at least one ethylenic unsaturation, and at least one organic hydroperoxide oxidant, in the presence of (i) a catalyst composition comprising at least one unsupported inorganic osmium oxide and sodium hydroxide wherein said catalyst composition the molar ratio of the sodium hydroxide to osmium in said osmium oxide is from about 0.1:1 to about 20:1; and (ii) at least one liquid inert polar organic solvent in an amount sufficient to control the liquid contents of said reaction admixture to be greater than 50% organic, by weight, based on the total weight of liquid in said admixture; said reaction being conducted in a manner and under conditions sufficient to hydroxylate at least one of said ethylenically unsaturated groups to its corresponding diol.

2. The process of Claim 1 wherein the inorganic osmium oxide is Os04, and the initial pH of the reaction admixture is less than 8.

3. The process of Claim 1 or 2 wherein the molar ratio of sodium hydroxide to osmium in the reaction admixture is from 0.1:1 to 10:1.

4. The process of Claim 1,2 or 3 wherein the mole ratio of water to olefin ethylenic unsaturation to be hydroxylated in the reaction admixture is from 1:1 to 20:1.

5. The process of any of claims 1 to 4 wherein the organic hydroperoxide is selected from the group consisting of t-butyl hydroperoxide, ethyl benzene hydroperoxide, t-amyl hydroperoxide and 2-butyl hydroperoxide.

6. The process of Claim 1 wherein the oxidant is t-butyl hydroperoxide, the olefin is selected from the group consisting of ethylene, propylene, and mixtures thereof, and the inert organic solvent is selected from the group consisting of t-butyl alcohol, ethylene glycol, propylene glycol and mixtures thereof.

7. The process of any preceding claim wherein the liquid inert organic solvent present in the reaction admixture comprises from 70 to 97%, by weight, thereof, based on the total weight of the liquid in the reaction admixture.

8. The process of any preceding claim wherein the hydroxylation reaction is conducted at a temperature of from 60 to 1 50"C.

9. The process of Claim 8 wherein the hydroxylation reaction is conducted at a reaction temperature of from 60 to 1000C.

10. The process of any preceding claim wherein the hydroxylation reaction is conducted in the absence of a buffer.

11. The process of any preceding claim wherein the pH of the reaction admixture is maintained at from 4 to7.9.

12. The process of Claim 1 wherein the inorganic osmium oxide is 0s04; the organic hydroperoxide is t-butyl hydroperoxide; the liquid inert organic solvent is selected from the group consisting of t-butyl alcohol, ethylene glycol, propylene glycol and mixtures thereof present in said reaction admixture in an amount of from 80 to 95%, by weight, thereof, based on the total weight of the liquid contents of said admixture; the molar ratio in said admixture of sodium hydroxide to osmium in the OsO4is from 0.1:1 to 5:1; and the initial pH of said reaction admixture is less than 8.

13. The process of Claim 12 wherein the hydroxylation reaction is conducted at a temperature of from 60 to 1000C.

14. The process of Claim 13 wherein the olefin is selected from the group consisting of ethylene, propylene, and mixtures thereof.