PROCESS FOR HYDROXYLATING OLEFINS USING OSMIUM-HALOGEN COMPOUND CATALYSTS

Abstract: Olefins are hydroxylated by reaction with water and an ox­ idant, particularly an organo-hydroperoxide, in the presence of an osmium-halogen compound hydroxylation catalyst such as OsCl₃ and optionally in the presence of a co-catalyst such as a transition metal halide.

Description: PROCESS FOR HYDROXYLATING OLEFINS USING OSMIUM HALOGEN COMPOUND CATALYSTS The present invention relates to processes for hydroxylating olefins in the presence of a specifically defined osmium-halogen compound catalyst. 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 with a strong oxidizing agent in the presence of catalytic amounts of specific osmium containing compounds, particularly osmium tetroxide, e.g., to their corresponding glycols. The patent literature directed to osmium containing hydroxylation catalysts describes various osmium oxides used in conjunction with specific oxidants. The primary oxide catalyst employed in these patents is Os04, a highly volatile (B.P. 1300C) and toxic substance. Ordinarily, the toxic nature of Os04 alone, while troublesome to some extent, could be dealt with by reasonably economic precautions. However, the combined properties of high volatility and toxicity (human tolerance is 0.002 mg/m3 of air) render this compound extremely dangerous necessitating large capital expenditures in plant safety equipment and design if one attempts to commercialize a process employing this compound as a catalyst. It is for this reason that commercialization of Os04 based plants has infrequently occurred in the past, if at all. If commercialization is attempted, the aforedescribed capital investment in safety equipment must reduce the profit margin on the products made by these processes. Accordingly, it would be of extreme economic significance if alternative osmium catalysts could be identified which possess the property of low volatility and/or low toxicity (in relation to Os04), together with processes for using the same to achieve glycol product selectivity and yield comparable to or better than the conventional OsO4 catalyst. One step in this direction is described in U.S. Patent No. 3,335,174, which is directed to the use of water hydrolyzable Group Vb, VI-b and VIII metal halides and oxyhalides (e.g., OsCl3) as hydroxylation and esterification catalysts in conjunction with aqueous H202 as an oxidant. However, the process for using this catalyst requires the presence of lower aliphatic hydrocarbon acids such as glacial, formic, acetic and propionic acid as solvents. Under these conditions the reaction times vary from 1/2 to-4 hours, but at the shorter reaction times it is disclosed that substantial amounts of epoxide result. The only yield disclosed is obtained in connection with tungsten hexachloride in Example 1. This yield is extremely low, i.e., 22%, and includes both halfacetate and diol. Thus, among the major disadvantages of the process described in this patent are the low selectivities to diol and the corrosiveness of metal halides in the presence of glacial acids such as acetic acid. Aside from the aforenoted disadvantages, the above-described process is also disadvantageous in being limited to the use of H2O2 as the oxidant. This is disadvantageous from an economic standpoint in that this oxidant is expensive and does not form a saleable coproduct. For example, the commercial attractiveness of processes which employ organohydroperoxides to hydroxylate olefins, such as t-butyl hydroperoxide, are dependent on the ability to use or sell the organic alcohol co-product (derived from the hydroperoxide) such as t-butyl alcohol. Thus, provided the market for the co-product alcohol holds up, it is difficult for an H202 oxidant based olefin hydroxylation system to compete successfully with one which employs an organohydroperoxide as the oxidant. Where one wishes to use an osmium catalyst in conjunction with an organohydroperoxide, such catalysts have typically always been osmium oxides such as OsO4. The disadvantages of this catalyst have been discussed above. Consequently, while from a marketing standpoint organohydroperoxide based systems are generally superior to H202 based systems, the economics of the former processes (i.e., organohydroperoxide based) could be improved even further if a suitable non-volatile, preferably non-toxic catalyst could be found to replace Os04. Notwithstanding the above, it is obvious that the demand for organic alcohol co-products obtained in conjunction with the use of organohydroperoxide can fluctuate with changing market conditions. Consequently, during periods of low demand for organic alcohol coproduct, it would be advantageous if one could switch to oxygen as an oxidant in place of organohydroperoxides. Oxygen is abundantly available in the air and is cheaper than H202. However, as with organohydroperoxides, the osmium catalysts known to be useable with oxygen oxidants are predominantly osmium oxides such as Os04. Consequently, the disadvantages of these catalysts are imparted to the processes which employ them. It would, therefore, also be economically advantageous if a relatively non-volatile, relatively non-toxic osmium catalyst could be employed in conjunction with an oxygen gas containing oxidant to hydroxylate olefins. Aside from the aforediscussed U. S. Patent 3,335,174 which is limited to the use of H202 -asanoxidant, it is believed that no prior art discloses the use of osmium halides, or oxy halides as catalysts to be used in conjunction with organohydroperoxide or oxygen gas containing oxidants for the hydroxylation of olefins. However, the following patents are discussed to provide a general background of osmium oxide catalysts for hydroxylating olefins. 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 OOC and 210C. Such low reaction temperatures drastically, and disadvantageously, reduce the reaction rate to commercially unacceptable levels. At temperatures greater than 210C, 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, re-oxidizing 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 pero xide; 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.l 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. U.S. Patent No. 4,049,724 describes the preparation of glycols from alkenes and from unsaturated alcohols in an aqueous system using osmium tetroxide and specifying stable and water-soluble aliphatic hydroperoxides, such as t-butyl hydroperoxide, while a critical pH of 8 to 12 is maintained by a suitable combination of alkali meal buffering compounds. The preparation of propylene glycol utilizing t-butyl hydroperoxide is exemplified in the patent at a selectivity based on the hydroperoxide of 45%. Japanese Patent Application No. Sho 54-145604, published November 14, 1979, is directed to a process for hydroxylating olefins in the presence of OsO4, a quaternary ammonium salt such as tetraethyl ammonium bromide, and a peroxide including organoperoxides and H202 as the oxidant. See also: U.S. Patent No. 3,317,592 (discloses production of acids and glycols using oxygen as oxidant, OsO4 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 OsO4); U.S. Patent No. 3,846,478 (discloses reaction of hypochlorite and olefin in an aqueous medium and in the presence of OsO4 catalyst to hydroxylate the olefin); U.S. Patent No. 3,928,473 thydroxylation of olefins to glycols with 02 oxidant, octavalent osmium catalyst (e.g. OsO4), and borates as promoter); U.S. Patent No. 3,931,342 (discloses a process for recovering glycols from an aqueous solution containing alkali metal borate and osmium compounds (e.g. Oslo4)); U.S. Patent No. 3,953,305 (discloses use of OsO4 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 Os04 and cesium, rubidium and potassium hydroxides), U.S. Patent No. 4,17,291 (discloses the oxidation of Osmium (III) or (IV) in an ionic complex with oxygen and an alkali metal, ammonium, or tetra (-lower) alkyl ammonium cation to a valency of greater than +5 + organohydroperoxides); U.S. Patent No. 4,229,601 (discloses the use of cesium, rubidium and potassium hydroxides as promoters for Os04 catalyst and t-butyl hydroperoxide oxidant for hydroxylating olefins); and U.S. Patent No. 4,280,924 (discloses a process for regenerating perosmate catalyst, e.g., cesium, rubidium and potassium perosmate). As emphasized above, none of the aforenoted patents discloses the use of osmium halides or oxy halides as catalysts for the hydroxylation reaction between olefins, and organohydroperoxide or oxygen oxidants. Accordingly, the search has continued for relatively non-volatile and/or relatively non-toxic osmium compounds capable of catalyzing the hydroxylation reaction between olefins and an oxidant such as organohydroperoxide or oxygen, as well as processes for improving the reaction between olefins and H202 in the presence of osmium halides. According to the present invention there is provided a process for producing an hydroxylated olefinic compound which comprises reacting in admixture at least one olefinic compound having at least one ethylenic unsaturation, water, and an oxidant selected from the group consisting of (I)H202 provided that in this case the reaction medium initially has a pH of from neutral to basic, (II) oxygen, (III) organo hydro peroxidesand (IV) inorganic oxidants selected from the group consisting of Nay04, Na0Cl, NaC104, Na02, KMn04 and mixtures thereof, in the presence of at least one catalyst in a manner and under conditions sufficient to hydroxylate at least one of said ethylenically unsaturated groups, said catalyst (a) being capable of catalyzing said hydroxylation reaction and (b) being initially present as at least one compound represented by a structural formula selected from the group consisting of Os(X)n, Os(OH)X3, OsOX4, OsO3X2, OsONX4, (M)n[OsX6]-2, (M)n[OS02X4]-2, M+1[Os(OH)X5]-1, (M)n[Os04X2]-2, (M)n[OsO2(0H)X2]¯2, (M)nw[OsNXs]¯2, and mixtures thereof, in which formulae: X is at least one halide independently selected from the group consisting of F, C1, Br, and I; n is an integer of from 3 to 5, M is selected from the group consisting of cations of Li, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Ba, Ra, NH4, tetra hydrocarbyl ammonium, and tetra hydrocarbyl phosphonium; and n' is a number selected in conjunction with the valence of cation M to achieve a neutral complex. Thus, one aspect of the invention may be summarized as providing an improvement in a process for reacting in admixture at least one olefinic compound having at least one ethylenic unsaturation with water and an oxidant selected from the group consisting of organohydroperoxides and oxygen, the improvement comprising conducting said reaction in the presence of at least one catalyst in a manner and under conditions sufficient to hydroxylate at least one of said ethylenically unsaturated groups, said catalyst (a) being capable of catalyzing said hydroxylation reaction, and (b) being initially added to said admixture as at least one compound represented by the structural formulae specified above. Another aspect of the present invention may be summarized as providing a process for hydroxylating olefins which comprises reacting in admixture at least one olefinic compound having at least one ethylenic unsaturation with H202 and water in the presence of at least one added osmium halide (osmium-halogen compound) as defined above, said reaction being conducted at a pH of from neutral to basic. In a preferred embodiment at least one olefin is reacted with at least one oxidant, and water in the presence of at least one catalyst optionally. at least one co-catalyst, under conditions and in a manner sufficient to hydroxylate at least one ethylenically unsaturated group to its corresponding diol group. The catalysts employed in the process of the present invention comprise compounds containing osmium and halogen. Such osmium-halogen containing compounds include osmium halides and osmium oxy halides, and complexes thereof, (all of the above being referred to herein collectively as osmium-halides) such as those represented by the structural formulae: Os(X)n (e.g., OsX3, OsX4, and OsX5); Os(OH)X3; OsOX4; OsOX5N; OsO3X2; OsONX4; (M)nl [OsX6]¯2; (M)n'[OsO2X4]-2; M+1[Os(OH)X5]-1; (M)n'[OsO4X2)2; (M)n'[OsO2(OH)X2]-2; (M)n.[OsNXs]¯2; and mixtures thereof: wherein X is halogen independently selected from the group consisting of F, Cl, Br and I; n is an integer which can vary from 3 to 5, M is a cation including cations of alkali (e.g., Li, Na, K, Rb, Cs, Fr) metals, alkaline earth metals (e.g., Be, Mg, Ca, Sr, Ba, Ra), ammonium (i.e. NH4+), tetra hydrocarbyl ammonium (e.g.(R)4N+)and tetra hydrocarbyl phosphonium (e.g.(R)4P+) said tetra hydrocarbyl groups being as defined in connection with Group 5 co-catalysts discussed below; and n' is a number which is selected in conjunction with the valence of cation M to achieve a neutral complex; preferably n' is 1. Representative examples of such compounds include OsF3, OsC13, OsBr3, OsI3, OsF4, OsC14, OsBr4, OsI4, Offs, Os(OH)C13, Os(OH)F3, OsOF4, OsOC14, Os03F2, OsONC14 K2tO5Cl2Br2I2] (NH4)2[OsF6], Ca[OsI6], Li2[OsO2Cl4], (CH3CH2)4N[Os(OH)Cls] , (CH3CH2)4P(Os(OH)Br5], Mg[OsO4F2], Na2[O5(OH)2Cl2], Ba[OsCl5N], K2[OsNCl5], K2[OsNBrs], and mixtures thereof. The preferred catalysts are those having a boiling point at atmospheric pressure of typically greater than about 130 C, preferably greater than about 150 C, and most preferably greater than about 175 C. The most preferred catalysts are those repre sented by the structural formula OsX3 such as OsC13. Since the volatility of these osmium catalysts is reduced, preferably substantially, relative to OsO4, the expensive equipment necessary to deal with the volatile and toxic nature of Os04 can be eliminated or reduced substantially in cost thereby rendering the overall process extremely competitive from an economic standpoint. The catalysts having the formula s(X)n can be prepared by the general methods described in "Advanced Inorganic Chemistry" by Cotton and Wilkinson (hereinafter Cotton and Wilkinson), p.909 (4th ed. 1980). Catalysts having the formula OsOX4 and Os03X2 can be prepared by the method described in the "J. Inorganic Nuclear Chemistry" by Hepworth and Robinson, Vol.4, p.24 (1957). Catalysts having the formula Os(OH)X3 can be prepared byl the method described in "Comprehensive Inorganic Chemistry", Trotman-Dickerson (ed.) vol.3, p.1217 (1973). Catalysts having the formula OsONX4 can be prepared by the method described in "Comprehensive Inorganic Chemistry" described above at vol.3, p,1233. Catalysts having the formula (M)n[OsX6]¯2 can be prepared by the general method described in Cotton and Wilkinson, p.919. Catalysts having the formula (M)n[Oso2x4]-2 can be Prepared by the general method described in Cotton and Wilkinson, p. 917. Catalysts having the formula M+1[Os(OH)X5]1 can.be prepared by the general method described in "Z. Anorg. Allgen. Chem" by Krauss and Wilken (hereinafter Krauss and Wilken) vol.137, p.349 (1924). Catalysts having the formula (M)n'[OsO4X2]-2 can be prepared by the method described in Krauss and Wilken, vol.145, p.151 (1925). Catalysts having the formula (M)n[OsO2(0H)X2]¯2 can be prepared by the method described in Cotton and Wilkinson, p. 914. Catalysts having the formula (M)n.[OsNXs]¯2 can be prepared by the method described in "Inorganic Synthesis", by E.G. Rochow, vol.6, p.204 (1960). The disclosures of all of the above references illustrating the methods of preparation of the aforenoted osmium-halide catalysts are herein incorporated by reference. The osmium-halide catalysts are 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 10-1 to about 1 x 10-8 moles, preferably from about 1 x 10-2 to about 1 x 10-6 moles, and most preferably from about 1 x 10-2 to about 1 x 10-4 moles, of osmium in the osmium-halide catalyst per mole of olefin ethylenic unsaturation to be hydroxylated. Alternatively, such amounts may be expressed as varying from about 1 to about 10,000, preferably from about 50 to about 1,000, and most preferably from about 200 to about 800 ppm, based on the total weight of liquid reaction medium exclusive of the weight of olefin and any other additives (e.g., buffers) solvent, or co-catalysts if present. The osmium-halide catalysts are soluble in aqueous and/or organic polar solvent systems described hereinafter and can be dissolved in said systems for addition to the reaction vessel. For example, the osmium-halide catalysts are preferably added to the reaction vessel as a solution having the catalyst dissolved in a water/organic solvent mixture containing excess organohydroperoxide. The aforedescribed catalysts can be employed alone or with one or more promoters (also referred to herein as co-catalysts) which increase the reaction rate of the hydroxylation reaction. Such promoters or cocatalysts can be those conventionally employed in conjunction with OsO4 as well as those disclosed in commonly assigned U.S. patent applications by the inventors herein. For example, suitable promoters or co-catalysts include alkali (e.g., Li, Na, K, Rb, Cs, and Fr), and alkaline earth metal (e.g., Be, Mg, Ca, Sr, Ba and Ra): halides, hydroxides, carboxylates, aryloates, aryolates and pseudo halides; tetra hydrocarbyl ammonium and tetra hydrocarbvl phosphonium: hydroxides, halides, pseudohalides, carboxylates, aryloates, and aryolates; transition metal: halides, pseudohalides, porphyrins, carboxylates, and aryloates; hydrogen halides; alkyl, aryl,-aralkyl, and alkaryl halides; Group III-b, (i.e., B, A1, Ga, In, T1), IV-b (i.e., Si, Ge, Sn, Pb), V-b (i.e., N, P, As, Sb, Bi) and VI-b (i.e., S, Se, Te, Po) halides; and the halogens F2, C12, I2, Br2. More specifically, suitable alkali and alkaline earth metal halide co-catalysts (referred to herein as Group 1 co-catalysts) include the Li, Na, K, Rb, and Cs lodides, bromides, chlorides and fluorides; and Mg, Ca, Sr, and Ba, iodides, bromides, chlorides, and fluorides and mixtures thereof. Pre-ferred-Group 1 co-catalysts include the Na, K, Rb, Cs, Mg and Ca halides. Suitable alkali and alkaline earth metal hydroxide co-catalysts (referred to herein as Group 2 cocatalysts) include LiOH, NaOH, KOH, RbOH, CsOH, Ca(OH)2, Ba(OH)2, Mg(OH)2 and mixtures thereof. Preferred Group 2 co-catalysts include the Na, K, Rb, Mg, and Ca hydroxides. Suitable alkali and alkaline earth metal: carboxylate aryloate, and aryolate co-cdtalysts (referred to herein as Group 3 co-catalysts) include those which possess as anions respectively: (a) carboxylate anions represented by the structural formula: EMI12.1 wherein R1 can be substituted or unsubstituted: alkyl, typically alkyl of from about 1 to about 10 carbons, preferably about 1 to about 5 carbons and most preferably about 1 to about 3 carbons, or aralkyl, typically aralkyl wherein the aryl group thereof is as defined in connection with Ar of structural formula II below and the alkyl group thereof is as defined immediately above; said R1 substituents including: hydroxyl; halide (i.e., F, C1, Br, and I); ether groups represented by the structural formulae -O-R2 and -R3-O-R2 wherein R2 and R3 are independently selected from the group consisting of alkyl, typically about C1 to about C10 alkyl, preferably about C1 to about C5 alkyl, and most preferably about C1 to about C3 alkyl; and ester groups represented by the structural formulae: EMI13.1 EMI13.2 wherein R4 and R5 which may be the same or different are as defined in connection with R2 and R3; and mixtures thereof; (b) aryloate anions represented by the structural formula: EMI13.3 wherein Ar is selected from the group consisting of substituted and unsubstituted: aryl, typically aryl of from about 6 to about 14 carbons, preferably from about 6 to about 10 carbons (e.g., 6 carbons), and alkaryl, typically alkaryl wherein the alkyl group is from about 1 to about 6 carbons, preferably from about 1 to about 3 carbons, and the aryl group thereof is as defined above, and wherein said substituents on the Ar group are as defined above in connection with R1; and (c) aryolate anions represented by the structural formula: Ar-O' III wherein Ar is as described above in connection with structural formula II, and preferably is aryl. Illustrative examples of such Group 3 co-catalysts include: sodium acetate, potassium acetate, calcium acetate, cesium acetate, magnesium acetate, potassium ethanoate, sodium propanoate, magnesium butanoate, strontium pentanoate, sodium benzoate, potassium benzoate, magnesium benzoate, calcium benzoate, sodium naphthoate, potassium naphthoate, beryllium naphthoate, sodium 4-(6methyl-2-naphthyl) pentanoate, potassium 3-(7-methyl-1naphthyl)-propanoate, magnesium 2- (4-propyl-l-benzyl) ethanoate, calcium phenolate, sodium naphtholate, potas sium naphtholate, sodium 3-(ethoxy) propanoate, potassium 4-(propoxy carbonyl) butanoate, calcium 3-(propyl carbonyl oxy) propanoate, magnesium 2- (methyl carbonyl oxy methyl) acetate, beryllium 4-(ethoxy carbonyl methyl) butanoate, cesium 4-(ethoxy methyl) benzoate, sodium 3-(propoxy) naphthoate, potassium 4-(ethoxy carbonyl) benzoate, barium 2-(hydroxy) acetate, rubidium 2-chioropropanoate, magnesium 4-bromobenzoate, magnesium phenolate, and mixtures thereof. Preferred Group 3 co-catalysts include the Na, K, Rb and Cs acetates. Suitable alkali and alkaline earth metal pseudo halide co-catalysts (referred to herein as Group 4 cocatalysts) include those which possess pseudo halide anions selected from the group consisting of: SCAN', Sect¯, TeCN', OCN-, and COO', and mixtures thereof. Illustrative examples of such Group 4 co-catalysts include NaSCN, NaSeCN, KSeCN, CsSeCN, NaTeCN, KTeCN, NaOCN, NaCNO, KOCN, KCNO, CsOCN, CsCNO, CsTeCN, Mg(SeCN)2, Ca(TeCN)2, Ca(OCN)2, Ca(CNO)2. Preferred Group 4 co-catalysts include the Na, K, Rb and Cs thiocyanates. Tetra hydrocarbyl ammonium or phosphonium salt co-catalysts (referred to herein as Group 5 co-catalysts) possess a cation and an anion. The respective cations can be represented by the respective structural formula (R)4N+ and (R)4P+ wherein R is a hydrocarbyl group independently selected from the group consisting of substituted and unsubstituted: alkyl, typically alkyl having from about 1 to about 30 carbons, preferably from about 1 to about 20 carbons, and most preferably from about 1 to about 10 (e.g. 1-5) carbons, aryl, preferably aryl having from 6 to about 14 carbons, and most preferably from 6 to about 10 carbons,and alkaryl and aralkyl wherein the aryl and alkyl groups thereof are as described immediately above; said R substituents being as defined in connection with the substituents of R1 described above. Accordingly, the term hydrocarbyl is intended to include both substituted and unsubstituted groups, and mixtures thereof. The anion of the Group 5 co-catalysts are selected from the group consisting of hydroxyl, halide, pseudo halide, carboxylate, aryloate and aryolate, said pseudo halide, carboxylate, aryloate, and aryolate anions, being as defined above in connection with the anions of the alkali and alkali metal salt co-catalysts described above. Illustrative examples of such Group 5 co-catalysts include tetra methyl ammonium bromide, tetra ethyl phosphonium chloride, tetra decyl phosphonium bromide, tetra phenyl ammonium chloride, tetra phenyl phosphonium bromide, dimethyl diethyl ammonium iodide, methyl triethyl phosphonium chloride, tetra butyl ammonium chloride, phenyl trimethyl ammonium bromide, phenyl trimethyl phosphonium chloride, phenyl triethyl ammonium iodide, phenyl triethyl phosphonium chloride, tetra ethyl ammonium hydroxide, tetra butyl ammonium hydroxide, tetra ethyl phosphonium hydroxide, phenyl triethyl ammonium hydroxide, phenyl trimethyl phosphonium hydroxide, tetraethyl ammonium acetate, tetra butyl phosphonium acetate, phenyl triethyl ammonium acetate, phenyl trimethyl phosphonium acetate, tetraethyl ammonium benzoate, phenyl trimethyl phosphonium benzoate, phenyl triethyl ammonim naphthoate, tetra ethyl ammonium phenolate, tetra butyl phosphonium naphtholate, tetra 2-(methoxy) ethyl phosphonium chloride, tetra 4 (propoxy methyl) phenyl ammonium bromide, di 3-(methoxy carbonyl) -propyl -diethyl phosphonium iodide, di 4 (ethyl carbonyloxy) butyl-dimethyl ammonium chloride, tetra 5-(ethoxy carbonyl methyl) pentyl phosphonium bromide, tetra 4-hydroxy butyl ammonium acetate, tetra 3chloropropyl phosphonium acetate, tetra-methyl ammonium thiocyanate, tetra ethyl phosphonium selenio cyanate, tetra (4-methyl phenyl) ammonium chloride, tetra (3phenyl-l-propyl) phosphonium bromide. Preferred Group 5 co-catalysts include the unsubstituted tetra lower alkyl (e.g., C1 to C5 alkyl) ammonium hydroxides, iodides, bromides, fluorides, chlorides and acetates. Transition metal containing co-catalysts (referred to herein as Group 6 co-catalysts) include those having a cation and anion wherein the transition metal cation is selected from the group consisting of cations of Fe, Co, Ni, Cu, V, Cr, Mn, Sc, Ti, Mo, Ru, Rh, Pd, and W, preferably Cu, Fe, Ni, Co and Mn, most preferably Cu, and mixtures thereof. Anions of the Group 6 co-catalysts include halide, porphyrin (as defined in the Condensed Chemical Dictionary 9th ed. revised by G. Hawley (1977) including benzoporphyrins), pseudo halide, carboxylate and aryloate; said pseudo halide7 carboxylate and aryloate anions being as defined generally in connection with the alkali and alkaline earth metal containing co-catalysts and as illustrated by specific examples of suitable anions in conjunction with other co-catalysts described herein. Representative examples of Group 6 co-catalysts include FeF3, FeC13, FeBr3, FeF2, FeC12, FeBr2, FeI2, CoC12, CoF3, CoF2, NiF2, NiBr2, NiI2, NiC12, CuF2, CuBr2, CuI2, CuF2, CuI, CuCl, CuBr, VF5, VF4, VF3, VF2, VC14, VC13, VBr4, VBr3, VI3, CrF2, CrF3, CrF4, CrF5, CrF6, CrC13, CrC14, CrBr3, CrBr4, CrI3, MnC12, MnCl3, MnCl4, MnBr3, MnI3, ScC13, ScBr3, ScF3, TiC14, TiBr4, TiF4, MoC13, Mo2C110, MoBr4, Mo2Fg, MoF6 MoF5, RuF5, RuF3, RuF4, RuF6, RuC13, RuC14, RuC16, RuBr6, RhF3, RhF4, RhF6, PdF2, PdC12, PdBr2, PdI2, WC16, Wars, WC13, WBr3, WI3, copper acetate, copper naphthoate, copper benzoate, copper propanoate, iron acetate, iron benzoate, iron naphthoate, copper 4-ethyl benzoate, iron 4-butyl benzoate, nickel acetate, nickel benzoate, nickel naphthoate, copper decanoate, iron hexanoate, iron phthalocyanine, manganese phthalocyanine, copper phthalocyanine, nickel phthalocyanine, and the Fe, Mn, Cu, and Ni porphyrin salts. Preferred Group 6 co-catalysts include copper bromide, chloride, iodide, and acetate; iron bromide, chloride, iodide and acetate; manganese bromide, chloride, and acetate, and mixtures thereof. Suitable hydrogen halides (referred to herein as Group 7 co-catalysts) include HF, HCL, HBr and HI. Preferred Group 7 co-catalysts include HI, HBr, and HCl. Suitable alkyl, aryl, aralkyl and alkaryl halide co-catalysts (referred to herein as Group 8 co-catalysts) include those represented by the respective structural formulae: R'-(X)n" (IV) and (Arl++x)n (V) wherein R' can be substituted or unsubstituted: alkyl, typically alkyl of from about 1 to about 20, preferably from about 1 to about 10, most preferably from about 1 to about 5 carbons, and aralkyl, typically aralkyl wherein the alkyl group thereof is as defined immediately above and the aryl group thereof is as defined in connection with Ar below; Ar' is aryl, typically aryl of from about 6 to about 14, preferably 6 to about 10, most preferably 6 carbons, and alkaryl wherein the alkyl and aryl groups thereof are as defined immediately above; X is at least one halogen independently selected from the group consisting of F, Cl, Br and I, and preferably I and Br; n" is an integer of from about 1 to about 10, preferably from about 2 to about 8, and most preferably from about 2 to about 6; and said R' substituents include hydroxyl. Representative examples of Group 8 co-catalysts include iodomethane, bromomethane, 1-iodoethane, l-bromoethane, 1,2-dibromoethane, l-chloroethane, 1,2-dichloroethane, l-iodopropane, l-bromopropane, l-chloropropane, 2-iodo-1-methylethane, 2-bromo-1-methylethane, 2-chloro1-methylethane, l-iodobutane, 2-bromobutane, l-chlorobutane, l-iodo-1-methylpropane, 1-bromo-l-methylpropane, l-chloro-l-methylpropane, l-iodo-l,l-dimethylethane, 1chloro-l,l-dimethylethane, l-chloro-l,l- imethylethane, phenyliodomethane, phenylchloromethane, phenylbromomethane, 1,2-dichlorobenzene, 2-bromoethanol, 2-chloroethanol, 2iodoethanol, l-phenyl-2-iodoethane, 1-phenyl-4,4-dichlorobutane, 1- (1,2-dichloroethyl) benzene 1- (1-chloropropyl) napthalene t-butyl bromide, t-butyl iodide and mixtures thereof. Preferred Group 8 co-catalysts include bromomethane, l-bromobutane, l-iodobutane, l-bromo-l,l-di methylethane, l-ioso-l,l-âimethylethane, 2-bromoethanol, and 2-chloroethanol. Representative examples of suitable Group IIIb, IV-b, V-b and VI-b element halides (according to the periodic chart of Cotton and Wilkinson "Advanced Inorganic Chemistry" [3rd end.1972)) referred to herein 2s Group 9 co-catalysts include halides of Al, Ga, In, T1, Ge, Sn, Pb, P, Si, As, Sb, Bi, S, Se, Te, and Po. Specific Group 9 element halides include A1C13, GaBr3, Tic13, SiC14, Sir4, PI3, PBr3, SbFg, SbBr3, SbI3, BiC13, BiBr3, AsI3, AsBr3, AsC13, SeF4, Sect4, SeBr4, TeF4, and mixtures thereof. Suitable halogen co-catalysts (referred to herein as Group 10 co-catalysts) include F2, C12, Br2, and 12. One or more co-catalysts described in each of the aforenoted Group 1 to 10 co-catalysts can be employed alone or in conjunction with one or more co-catalysts in the same group and/or with one or more of the co-catalysts in the remainder of said groups in any amounts effective to increase the rate of the hydroxylation reaction relative to the rate observed in their absence. Accordingly, while any effective amount of cocatalysts can be employed, it is contemplated that such effective amounts constitute typically from about 1 to about 10,000 mole percent, preferably from about 50 to about 1,000 mole percent, and most preferably from about 200 to about 500 mole percent, Group 1 co-catalyst based on the total number of moles of osmium in the osmiumhalide catalyst employed; typically from about 1 to about 10,000 mole percent, preferably from about 50 to about 1,000 mole percent, and most preferably from about 200 to about 500 mole percent, Group 2 co-catalyst based on the total number of moles of the osmium in the osmium-halide catalyst employed; typically from about 1 to about 10,000 mole percent, preferably from about 50 to about 1,000 mole percent, most preferably from about 200 to about 500 mole percent, Group 3 co-catalyst, based on the total number of moles of osmium in the osmium-halide catalyst employed; typically from about 1 to about 10,000 mole percent, preferably from about 50 to about 1,000 mole percent, and most preferably from about 200 to about 500 mole percent, Group 4 co-catalyst, based on the total number of moles of the osmium in the osmium-halide catalyst employed; typically from about 1 to about 10,000 mole percent, preferably from about 50 to about 1,000 mole percent, and most preferably from about 200 to about 500 mole percent, Group 5 co-catalyst based on the total number of moles of osmium in the osmium-halide catalyst employed; typically from about 1 to about 10,000 mole percent, preferably from about 50 to about 1,000 mole percent, and most preferably from about 200 to about 500 mole percent, Group 6 co-catalyst based on the total number of moles of the osmium in the osmium-halide catalyst employed; typically from about 1 to about 10,000 mole percent, preferably from about 50 to about 1,000 mole percent, and most preerably from about 200 to about 500 mole percent, Group 7 co-catalyst based on the total number of moles of osmium in the osmium-halide catalyst employed; typically from about 1 to about 10,ode mole percent, preferably from about 50 to about 1,000 mole percent, and most preferably from about 200 to about 500 mole percent, Group 8 co-catalyst based on the total number of moles of osmium in the osmium-halide catalyst employed; typically from about 1 to about 10,000 mole percent, preferably from about 50 to about 1,000 mole percent, and most preferably from about 200 to about 500 mole percent, Group 9 co-catalyst based on the total number of moles of the osmium in the osmium-halide catalyst employed; and typically from about 1 to about 10,000 mole percent, preferably from about 50 to about 1,000 mole percent, and most preferably from about 200 to about 500 mole percent, Group 10 co-catalyst based -on the total number of moles cf the osmium in the osmium-halide catalyst. Preferred combinations of co-catalysts include the use of at least one Group 1 co-catalyst in combination with at least one co-catalyst falling within any one or more co-catalyst Groups 2-9 (e.g., Group 6). Illustrative examples of suitable co-catalyst combinations include CuBr2 and NaC1; CuC12 and NaBr2; FeC13 and NaCl; CuBr2 and tetra ethyl ammonium chloride; FeC12 and KBr; FeBr3 and CsCl; and CuI and NaBr. The oxidant which can be employed to oxidize the olefin may be any of the oxidants employed for hydroxylating olefins in the presence of Os04, including organic hydroperoxides, oxygen (including (molecular) oxygen-containing gases), hydrogen peroxide, and inorganic oxidants such as Nay04, NaOC1, NaC104, NaO2, KMn04, and the like, and mixtures thereof. The preferred class of oxidants is the organohydroperoxides. Conventional organohydroperoxides in clude those having the formula: R"OOH wherein R" is a substituted or unsubstituted: alkyl, typically about C3 to about C2o, preferably about C3 to about Clo, most preferably about C3 to about C6 alkyl; aryl, typically C6 to C14, preferably C6 to ClOr most preferably C6 aryl; aralkyl and alkaryl wherein the aryl and alkyl groups thereof are as defined immediately above; cycloalkyl, typically about C4 to about C20, preferably about C4 to about Clo, most preferably about C4 to 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 ethylbenzyl hydroperoxide, t-butyl hydroperoxide, t-amyl hydroperoxide, cumene hydroperoxide, 2-methyl-2-hydroperoxy-methyl propionate, 2-methyl-2hydroperoxy propanoic acid, pyrrolehydroperoxi e, furan hydroperoxide, 2-butylhydroperoxide, cyclohexyl hydroperoxide, and l-phenyl-ethylhydroperoxide. The most preferred organic hydroperoxides include t-butyl hydroperoxide, ethylbenzylhydroperoxide, 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 preferred that such effective amounts 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 is preferred to add the organohydroperoxide as an aqueous solution comprising from about 1 to about 99%, preferably from 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. If oxygen or an oxygen-containing gaseous mixture (e.g., containing one or more inert gases such as N2 or air) is employed as the oxidant, it is preferred to also employ at least one Group 6 co-catalyst (described above) in conjunction therewith. The molar ratio of oxygen to olefin ethylenic unsaturation also can vary widely but for safety reasons it is preferably maintained outside exPlosive limits, said explosive limits usually being expressed as weight percent ratios. For example, when hydroxylating ethylene or propylene, if oxygen is in excess, the ratio typically will be about 98 weight percent oxygen or more and 2 percent or less of the olefin based on the total weight of these two reactants. Alternatively, if the olefin is in large excess, the oxygen concentration typically will be about 10 weight percent and about 90 weight percent olefin. When¯oxygen is in excess, olefin can be added during the reaction as the reaction proceeds. On the other hand, where the olefin is in excess, oxygen can be added during the reaction as the oxygen is consumed. A suitable, but less preferred oxidant is H202. This oxidant has the disadvantage of being more expensive overall than oxygen or the organohydroperoxides which yield saleable co-products. The amount of H2 2 employed can vary over wide limits and can be any effective amount. Accordingly, effective molar ratios of olefin ethylenic unsaturation to H2O2 can vary from about 0.5:1 to about 100:1, preferably from about 1:1 to about 20:1, most preferably from about 2:1 to about 10:1. Unlike the prior art which employs OsC13 in an initially acid reaction medium in conjunction with H202 oxidant,the initial presence of acid is believed to be detrimental to the progress of the reaction and when using H202 oxidant should be avoided, i.e., the initial pE of the reaction mixture should be neutral to basic. Furthermore, pH control (discussed hereinafter) is advantageous in this instance to avoid an acid medium during the course of the reaction. The H202 can be employed in anhydrous form or as an aqueous solution. Such aqueous solutions typically will contain from about 3 to about 99.9%, preferably from about 20 to about 755, and most preferably from about 20 to about 45% (e.g., 25 to 35%), by weight, H2O2 based on the total weight of the aqueous solution. Other inorganic oxidants, such as NalO4, NaOCl, NaClO4, NaO2, KMnO4, and the like, may also be employed in any effective amount but their cost renders them much less preferred. Typically, such oxidants are used in less than stoichiometric amounts in relation to the moles of olefin ethylenic unsaturation. 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, the water formed in-situ during the reaction between 02 or H 202 with olefin can contribute to the water content for the reaction. Water can also be added separately, preferably as the solvent for the organohydroperoxide. Consequently, water is provided to, and/or is present, in the initial reaction mixture 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. Such molar ratios typically can be achieved by controlling the amount of water in the reaction mixture (including water formed in-situ) to be from about 1 to about 90 percent, preferably from about 15 to about 85 percent, and most preferably from about 20 to about 60 percent, 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. 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 a'bicyclic compounds well known in the art for undergoing such hydroxylation reactions. Typically, such compounds will contain from about 2 to about 20 carbons, preferably from about 2 to about 10 carbpns,and most preferably from about 2 to about 5 carbons. Such compounds may be straight or branched chain, mono-olefinic, di-olefinic, or polyolefinic, conjugated or non-conDugated. They may be substituted with such qroups 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 hydroxyl, carboxyl and anhydride. Typical of such olefins are those represented by the structural formula: EMI24.1 wherein R6, R7, Rg, and Rg, 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 R7-9 groups together can constitute a cycloalkyl group tyically 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-l, butene-2, isobutene, pentene-l, pentene-2, isobutene, butadiene, pentene-l, pentene-2, hexene, isohexene, heptene, 3-methylhexene, octene-l, isooctene, nonene, decene, dodecene, tridecene, pentadecene, octadecene, eicosene, docosene, tricosene, tetracosene, pentacosene, butadiene, pentadiene, hexadiene, octadiene, decadiene, tridecadiene, eicosadiene, tetracosadiene, cyclopentene, cyclohexene, cycloheptene, methyl cyclohexene, isopropylcyclohexene, butylcyclohexene, oxtylcyclohexene, dodecyclohexene, acrolein, acrylic acid, 1,2,3,b-tetrahydrophthalic anhydride, methyl methacrylate, styrene, cholesterol, and mixtures thereof. The preferred olefins are ethylene, propylene, isobutylene, butadiene, styrene, allyl alcohol and allyl chloride. The most preferred olefin is ethylene and/or propylene. The preferred mode for conducting the hydroxylation reaction is in a liquid reaction mixture, preferably provided as a homogeneous or substantially homogeneous medium and preferably but optionally by using an inert organic solvent to dissolve or assist in dissolving the osmium and halide containing catalyst, co-catalysts if any, 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,Ndialkyl 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, methylbutyl ketone, acetophenone, ethylene glycol, propylene glycol, diethylene glycol, tetraethylene glycol, dimethyl formamide, diethyl formamide, dimethyl acetamide, dimethyl sulfoxide, diethyl sulfoxide, di-n-butyl sulfoxide, diphenyl sulfoxide, dibenzyl sulfoxide, dimethyl sulfone, diethyl sulfone, tetra methylene sulfone, diphenyl sulfone, acetonitrile, pyridine, dioxane, tetra hydrofuran, tetra hydropyran, dioxolane, and mixtures thereof. The preferred solvents include those which are substantially or completely miscible with water such as t-butyl alcohol, methanol, and acetonitrile. The most preferred solvent(s) is the hydroxylated olefin which possesses at least one glycol functionality or mixtures of the product glycol and the product alcohol derived from the organohydroperoxide. For example, when ethylene is hydroxylated using t-butyl hydroperoxide, the preferred solvent is ethylene glycol or a mixture of ethylene glycol and tbutyl alcohol the latter being formed in-situ from tbutyl hydroperoxide. The former (product glycol) avoids solvent separation process steps and the latter is economical since the ethylene glycol and t-butyl alcohol are both saleable products which have to be separated anyway. In either instance, an additional solvent separation step is avoided. The inert solvent is preferably employed in amounts sufficient to achieve a homogeneous solution with respect to at least the olefin and catalyst system. Typically, such amounts can vary from about 0 to about 90 percent, preferably from about 20 to about 80 percent, and most preferably from about 20 to about 50 percent, by weight, based on the total weight of the reaction mixture. The pH of the reaction mixture during the hydroxylation reaction mixture using oxidants other than H202 typically will not be allowed to drop below about 4, preferably not below about 6. Likewise, the pH of the reaction mixture using similar oxidants typically will not be allowed to exceed about 12 although the process can still be conducted at a pH below 4 and above 12. Accordingly, the pH of the reaction mixture typically will be maintained between about 4 and 12, preferably between about 6 and about 12, and most preferably between about 7 and about 12. The pH of the reaction mixture can be controlled by the use of conventional buffers or base where needed. Preferably, pH control is achieved by the use of co-catalyst base. For example, one mole of HC1 may form per mole of OsC13 catalyst employed under reaction conditions. To compensate for this effect, suitable phosphate, acetate, carbonate, and pyridine buffers can be employed. In the embodiment wherein H202 is employed as the oxidant, it is essential to maintain the initial pH of the reaction mixture from neutral to basic, e.g., typically from about 7 to 14, preferably from about 7 to about 10, and most preferably from about 7 to about 8. Preferably, the pH is maintained at these levels throughout the reaction. Alternatively, it is critical to conduct the reaction in the initial absence of glacial formic, acetic, propionic acids as well as other strong acids. In carrying out a preferred embodiment of the invention, olefin, water, oxidant, osmium-halide catalyst, optional co-catalyst, and/or buffer, and optional inert solvent are contacted by admixing to form a liquid reaction medium 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 medium to the reaction vessel is not critical. However, when an organohydroperoxide is used as the oxidant, it is preferred to mix the osmium-halide catalyst, and optional co-catalyst if employed, with an aqueous solution of the hydroperoxide and then add solvent, additional additives such as buffers, where needed, and finally olefin. Accordingly, the initial reaction medium prior to introduction of olefin when using an organohydroperoxide oxidant will typically comprise: (a) an organohydroperoxide in an amount of from about 1 to 70 percent, preferably from about 5 to about 60 percent, and most preferably from about 10 to about 50 percent, by weight, based on the weight of the reaction medium exclusive of the weight of olefin, catalyst, and any other additive (e.g. buffers) and/or co-catalysts if present; (b) osmiumhalide catalyst in amounts heretofore specified; (c) water, subject to the molar constraints heretofore specified, in an amount of 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 reaction medium exclusive of the weight of olefin, catalyst, and any other additives (e.g. buffers) and/or co-catalysts if present; and (d) inert organic solvent in an amount of from about 0 to about 99 percent, preferably from about 20 to about 80 percent, and most preferably from about 30 to about 60 percent, by weight, based on the weight of the reaction medium exclusive of the weight of olefin, catalyst, other additives, and/or co-catalyst if present. Co-catalysts if employed are used in effective amounts as described above as are buffers to control pH where desired. When an aqueous H2O2 solution (as defined above) is employed as the oxidant, it preferably will comprise from about 1 to about 70 percent, preferably from about 5 to about 60 percent, and most preferably from about 10 to about 50 percent, by weight, based on the weight of the reaction medium exclusive of olefin, catalyst, other additives, and/or co-catalyst if present. For the production of ethylene glycol, propylene glycol or any 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. Likewise with the oxygen-containing gas if employed as the oxidant. However, it is preferred that the reaction takes place in the liquid phase. Consequently, sufficient pressure is preferably employed to maintain the gaseous reactants in the liquid phase. otherwise, the reaction pressure is not critical and can be atmospheric, sub-atmospheric, or super-atmospheric. 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 2500C, preferably from about 20 to about 1500C, and most preferably from about 30 to about 1300C. 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 OOC 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 semicontinuous reaction. In the batch reaction, a reaction medium 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 and oxygen'if employed. 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 semi-continuous 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, cocatalyst, and pH control additive concentrations 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, byproducts if any, solvent, water, catalyst and optional 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. In the embodiment wherein an organohydroperoxide, such as t-butyl hydroperoxide, is employed as the oxidant, there is usually no significant amount of reacted hydroperoxide in the reaction product, since the reaction is generally carried out under conditions, including a stoichiometric excess of olefin, for complete reaction of the oxidant. If unreacted hydroperoxide is present in the reaction product, it can be removed by the use of a suitable reducing agent in an extra processing step as a safety precaution to avoid possible hazards resulting from the undesired decomposition of the hydroperoxide during product work-up. Therefore, insuring the substantial absence of hydroperoxide in the reaction product represents a safety precaution and avoids substantial processing costs. 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 theremainder of the specification are by weight unless otherwise specified. Unless otherwise specified, in the following examples selectivity, conversion and yield are calculated as follows: % selectivity = moles of glycol formed x 100 moles of oxygenated product % conversion = moles of product x 100 moles of hydroperoxide charged % yield =(% conversion x % selectivity) + 100 EXAMPLE 1 Into a 100 ml 3-neck round bottom flask equipped with a magnetic stirrer, reflux condenser, dropping funnel, and thermometer, is charged 0.77g of a 2.5% aqueous solution of OsC13 (0.1 mmole OsC13), 18.3g t-butyl alcohol, 0.76g (2.9 mmoles) tetra ethylammonium acetate (i.e., ET4NOAC), and 8.Og (71 mmoles) l-octene under continuous agitation. An aqueous solution (4.2g) containing 70% tbutyl hydroperoxide is then added slowly over a period of 45 minutes at 250C to the mixture thereby introducing a total of 32.7 mmoles of hydroperoxide. The total amount of water in the resulting mixture is 3.7g. The reaction is allowed to proceed at 250C and atmDspheric pressure, for a period of 12 hours. The contents of the reaction flask are then analyzed by gas chromatography. The conversion of hydroperoxide is found to be 90 percent. 2.6g of 1,2-octanediol is obtained indicating a selectivity of 60 percent and a yield of 54 percent. EXAMPLE 2 Into a 100 ml 3-neck round bottom flask provided with a magnetic stirrer, reflux condenser, dropping funnel, and thermometer is charged a sufficient amount of a 0.2% aqueous solution of OsC13 to introduce 3mg (0.01 mmole) of OsC13, Prior to introduction of the OsC13 aqueous solution into the flask, this solution is premixed in a separate vessel with 0.2g of t-butyl hydroperoxide added as a 70 percent solution of hydroperoxide in water. Tertiary butyl alcohol (9.6g) and l-octene (1.45g) are then added to the flask and the contents stirred. To this mixture is added slowly, over a period of 10 minutes, a sufficient amount of a 70 percent solution of t-butyl hydroperoxide in water (at 270C) to introduce 0.90g of hydroperoxide into the flask. The contents of the flask are warmed to 350C as a result of the reaction exotherm during the addition of the hydroperoxide solution. The total amount of water present in the flask is 2.0g. The reaction mixture is stirred continuously and the reaction is allowed to proceed at a temperatuare of 33-370C, and atmospheric pressure for a period of 20 minutes measured from completion of the hydroperoxide addition. An additional amount (1.0g) of the 70 percent aqueous hydroperoxide is then added to the reaction mixture over a period of 5 minutes. The reaction mixture is stirred continuously for an additional 25 minutes. The-contents of the flask are then analyzed by gas chromatography. The selectivity to the 1,2-octanediol is found to be 52 percent, the conversion is 45 percent, and the yield is 25 percent. EXAMPLE 3 Into a 100 ml 3-neck round bottom flask is charged 40.0 mg (0.13 mmole) OsC13, 25.0g methanol, and 4.8g (43 mmole) l-octene. To the flask is then added slowly, over a period of 20 minutes, a sufficient amount of a 70 percent solution of t-butyl hydroperoxide in water at 250C to introduce 5.0g of hydroperoxide thereto. The total amount of water in the flask is 1.5g. The flask contents are warmed to 270C by the reaction exotherm after 10 minutes from the start of hydroperoxide addition, and to 450C after 25 minutes from the start of hydroperoxide addition. The reaction is terminated after 25 minutes from the start of hydroperoxide addition. The contents of the flask are analyzed by gas chromatography. Conversion is found to be 100 percent, selectivity to 1,2-octanediol is 47 percent and the yield is 47 percent. EXAMPLE 4 Into a flask as described and equipped in Example 1 is charged, under continuous agitation, t-butyl alcohol (14.0g) l-octene (3.0g) and OsC13 (0.115g in 3.7g H20). Tetra ethylammonium hydroxide (0.03g) is added to the flask as a 25 percent by weight solution thereof in methanol. Tertiary butyl hydroperoxide (2.0g) is added as a 70 percent, by weight, solution thereof in water with stirring over a period of 10 minutes at 250C. The reaction mixture is warmed to about 460C during the addition. An additional amount of tetra ethylammonium hydroxide (0.5g of a 25 percent by weight solution thereof in methanol) is then added to the reaction mixture. The pH of the reaction mixture at this point is about 8. An additional amount of t-butyl hydroperoxide (1.75g) is then added slowly over a period of 10 minutes at 250C, and the reaction mixture stirred for an additional 30 minutes. The reaction mixture is then allowed to cool to ambient temperature and analyzed by gas chromatography. The selectivity to 1,2-octanediol is about 82 percent and the conversion is 100 percent. From the results of the Example 4 it can be seen that the selectivity of the reaction to diol is increased by the presence of base co-catalyst. Comparative Example 1 The following comparative example is intended to illustrate the effect of the presence of glacial acetic acid in the reaction mixture using OsC13 catalyst and H202 oxidant in accordance with the general procedure of Example 2 of U.S. Patent No. 3,335,174. Into a flask, as described and equipped in Example 1, is charged 14.5ml of a 30 percent, by weight, aqueous solution of H202 and 45ml of glacial acetic acid and the mixture heated at 750C for 1 hour. OsC13 (0.3g) is then added to the flask and the solution cooled to 280C. To this solution is added l-octene (10 ml) over 10 minutes and the solution cooled with an ice bath to main- tain the temperature thereof between 20-30 . The pH of the solution is 2. After stirring for an additional 20 minutes, the solution is analyzed by gas chromotography. Conversion of 202 is 10 percent, selectivity to 1,2octanediol is 10 percent, and selectivity to 1,2-octane diacetate is 20 percent. EXAMPLE 5 In a flask, as described and equipped in Example 1, is charged 14.5 ml of a 30 percent H202 aqueous solution, 20.9g, H20 and 0.-3g OsC13. The resulting mixture is stirred for 10 minutes at 250C. To this solution is then added 10 ml of l-octene dropwise over a period of 10 minutes. The reaction mixture is cooled with an ice bath to maintain the temperature between 23 and 27or. The pH of the reaction mixture at the beginning of reaction is 7 and upon completion of the reaction the pE is 5.8. The contents of the flask are then analyzed by gas chromatography. The conversion of 202 is 100 percent, and selectivity to 1,2-octanediol, the major product is about 2 percent. Comparing the results of Example 5 with compara- tive Example 1, it can be seen that the absence of glacial acetic acid substantially improves the selectivity and conversion of the reaction. Even greater improvements can be achieved by maintaining the p!I of the reaction mixture during the course of the reaction from neutral to basic. 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 Eo be construed as limited to the partif-ular 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: Claims 1 A process for producing an hydroxylated olefinic com pound which comprises reacting in admixture at least one olefinic compound having at least one ethylenic unsaturation, water, and an oxidant selected from the group consisting of (I)H202 provided that in this case the reaction medium initially has a pH of from neutral to basic, (II) oxygen, (III) organo hydro peroxidesand (IV) inorganic oxidants selected from the group consisting of NaI04, Na0Cl, NaC104, Na02, KMn04 and mixtures thereof, in the presence of at least one catalyst in a manner and under conditions sufficient to hydroxylate at least one of said ethylenically unsatura ted groups, said catalyst (a) being capable of cataly zing said hydroxylation reaction and (b) being initially present as at least one compound represented by a structural formula selected from the group consisting of OS(X)n, Os(OH)X3, OsOX4, OsO3X2, OsONX4, (M)n[OsX6]¯2, (M)n'[CosO2X4]-2, M+1[Os(OH)X5i1, (M)n'[OsO4X2]-2, (M)n'[O5O2(OH)X232, (M),ICOsNX5]-2I and mixtures thereof, in which formulae: X is at least one halide independently selected from the group consisting of F, C1, Br, and I; n is an integer of from 3 to 5, M is selected from the group consisting of cations of Li, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Ba, Ra, NH4, tetra hydrocarbyl ammonium, and tetra hydrocarbyl phosphonium; and n' is a number selected in conjunction with the valence of cation M to achieve a neutral complex. 2 A process according to Claim 1 wherein said hydro xylation reaction is conducted in the additional presence of at least one co-catalyst capable of increasing the rate of reaction, said co-catalyst being selected from the group consisting of: (1) alkali and alkaline earth metal halides; (2) alkali and alkaline earth metal hydroxides; (3) alkali and alkaline earth metal: carboxylates, aryloates, and aryolates; (4) alkali and alkaline earth metal pseudo halides; (5) tetra hydrocarbyl ammonium and tetra hydro carbyl phosphonium: hydroxides, halides, pseudo halides, carboxylates, aryloates and aryolates. (6) transition metal: halides, porphyrins, pseudo halides, carboxylates, and aryloates said transit ion metals being selected from the group consisting of Fe, Co, Ni, Cu, V, Cr, Mn, Sc, Ti, Mo, Ru, Rh, Pd, and W; (7) hydrogen halides except when the oxidant is H202; (8) alkyl, aryl, aralkyl and alkaryl halides; (9) Group III-b, IV-b, V-b, and VI-b element halides, said elements being selected from the group consisting of Al, Ga, In, T1, Ge, Sn, Pb, P, As, Sb, Bi, S, Se, Te, and Po; and (10) halogens. 3 A process according to claim 2 wherein the co-catalyst is at least one member of the group consisting of transition metal halides, transition metal acetates, and transition metal benzoates. 4 A process according to claim 3 wherein the co-catalyst additionally comprises at least one member of the group consisting of alkali metal hydroxides, alkaline earth metal hydroxides, alkali metal halides, alkaline earth metal halides, alkali metal acetates, alkaline earth metal acetates, tetra alkyl ammounium halides wherein the alkyl group contains from 1 to 3 carbons, and tetra alkyl phosphonium halides wherein the alkyl group contains from 1 to 3 carbons. 5 A process according to claim 2 wherein the oxidant is oxygen and the co-catalyst is at least one member of the group consisting of transition metal: halides, pseudo halides, carboxylates, and aryloates. 6 A process according to claim 1, 2, 3 or 4 wherein the oxidant is at least one organohydroperoxide and the olefin contains from 2 to 20 carbons. 7 A process according to any one of the preceding claims wherein the catalyst is one or more of OsF3, OsC13, OsBr3, and 0513. 8 A process according to claim 7 wherein the catalyst as admixed is OsCl3. 9 A process according to any one of the preceding claims wherein the reaction is carried out in the liquid phase. TO A process according to any one of the preceding claims wherein the olef in is ethylene and/or propylene. 11 A process according to any one of the preceding claims wherein the reaction mixture additionally comprises an inert solvent, 12 A process according to claim 11 wherein the oxidant comprises t-butyl hydroperoxide, the olefin is ethylene, and the inert solvent is selected from the group consisting of t-butyl alcohol, ethylene glycol, and mixtures thereof.

Inventors: AUSTIN, RICHARD GRAHAM, MICHAELSON, ROBERT CHARLES
Applicants: EXXON RESEARCH AND ENGINEERING COMPANY
Application year: 1982
Main classification: C07C29
IPC codes: C07C31, C07C29, B01J27