3,461,160 *nited States Patent C ’ Patented Aug.- 12, 1969

1 2 HNO3 is introduced into the reaction system as an 3,461,160 I aqueous solution. Optionally, an organic solvent (dioxane, PREPARATION OF DICARBOXYLIC ACIDS acetic acid, tetrahydrofuran, Z-nitropropane, or nitrocy Eugene Dennis Wilhoit, Orange, Tex., assignor to E. I. du Pont de Nemours and Company, Wilmington, Del., a clohexane) can be introduced into the reaction system. The corporation of Delaware preferred organic solvents in this process are dioxane and No Drawing. Filed Apr. 28, 1966, Ser. No. 545,833 acetic acid. In the synthesis of higher molecular weight di Int. Cl. C07c 51/20, 51/32 carboxylic acids (those containing 10-18 carbon atoms, US. Cl. 260-533 13 Claims for example) it is preferred, but not necessary, that an or ganic solvent be present to ensure that all materials are '10 maintained in the liquid phase. Usually when lower molec ABSTRACT OF THE DISCLOSURE ular weight ole?ns are employed as the starting material, A process for the oxidation of cyclic ole?ns to dicar organic solvents are not required. boxylic acids such as 1,12-dodecanedioic acid which com The amount of HNO3, H2O, vanadium element, and prises contacting the ole?ns in a liquid phase reaction sys osmium element present is expressed in terms of the rela tem comprising aqueous nitric acid and a catalyst which tive weights of each in the reaction system, based upon is a combination of osmium and vanadium at a tempera 100 parts. Organic starting materials and products, or ture in the range 50 to 150° C. with an oxygen pressure in ganic solvents, and any other material present (such as the a range of 1-7 atmospheres. remainder of the compound in which the catalysts were introduced, if not introduced as the element itself) do not form part of this calculation. The amount of ole?n and This invention relates to dicarboxylic acids, and more solvent employed is expressed as parts per 100 parts of the particularly, to a process for the preparation of dicarbox system mentioned above. ylic acids from cyclic ole?ns. HNO, can comprise 10-70 parts (by weight) of the above-mentioned 100 part system, preferably 25-50 parts Dicarboxylic acids are useful in the manufacture of 25 synthetic resins, plasticizers, and industrial chemicals. The thereof. The amounts of vanadium and osmium, expressed prior art teaches that cyclic ole?ns may be oxidized to di as the amount of the element present, are vanadium, 0.01 carboxylic acids directly in low yield. Since the low yield 07 part, preferably 0.1-0.5 part; and osmium, 0.01-5.0 might have been due to the complexity of the reaction, parts, preferably 0.5-2.5 parts. Thus the relative amount of water is 24-90 parts. Should the presence of an organic the art further teaches that it is desirable to conduct the 30 oxidation in multiple stages so as to afford greater control solvent be desirable, the amount thereof can be varied of the products formed. widely, depending upon the particular reaction system. The process of the present invention provides a simple With the preferred organic solvent, dioxane, generally no one-step high-yield method for the production of dicar more than 100 parts of dioxane are present. It may be de sirable to add to the reaction system dicarboxylic acids, boxylic acids from cyclic ole?ns, which consumes only 35 small amounts of HNO3. The reduction products of HNO3 such as adipic acid, to increase the solubility of the organic formed in this process (nitric oxide and nitrogen dioxide) materials, For example, due to cosolubility effects, cyclo can, by reaction with oxygen in the presence of water, be hexene seems to be more soluble in an aqueous solution regenerated to HNO3. of adipic acid than in water alone. The process of the present invention comprises oxi 40 The relative amount of ole?n present in the process of dizing cyclic mono-, di-, or polyole?ns in a liquid-phase this invention at any given point should be controlled, system comprising HNO3 and osmium-vanadium catalyst. whether a batch or continuous method is employed. In The presence of an organic solvent (for the dicarboxylic either event, slow continuous admission of ole?n is pre acid product) is optional. Such a solvent is desirable when ferred, so that there is never present at any point during the process more ole?n than osmium on a molar basis. the product is of limited solubility in water. This process, 45 for example, can be employed to oxidize substituted or Should an excess of ole?n be present, a reaction with unsubstituted cyclic monoole?ns to the corresponding di HNO3 would probably ensue, with diminution of yield. basic acid. Likewise, cyclic diole?ns can be oxidatively The heat of reaction can be better controlled with a slow ruptured at each ole?nic bond to form two dibasic acids admission of ole?n. of lower molecular weight and can also be ruptured at one 50 The process of this invention can be carried out as a ole?nic bond to form unsaturated diacids. , batch-type operation or in a continuous manner. Illustrative of cyclic ole?ns useful as starting materials A typical continuous process useful in this invention in the process of this invention are those containing up to comprises feeding aqueous HNO3 (and, optionally, an 18 carbon atoms, for example, cyclohexane, cycloheptene, organic solvent) and the ole?n into a stirred, heated re cyclooctene, cyclononene, cyclodecene, cycloundecene, 55 action mixture described above. An aqueous solution com cyclododecene, cyclohexadiene, 1,5-cyclooctadiene, 3 prising mainly HNO3 and dibasic acid(s) is drawn from methylcyclohexene, 4-methylcyclohexene, 4-vinylcyclohex the reactor. If the aqueous solution is sufficiently concen one, B-methylcyclooctene, 3-methylcyclodecene, 3-methyl trated in dicarboxylic acid, the solution can be cooled, if cyclododecene, and cis-4-cyclohexene-l,Z-dicarboxylic necessary, to 50-70" C. to precipitate out the dicarboxylic acid. 60 acid product(s). The solid product is separated by ?ltra The vanadium-osmium system can be supplied to the re tion and the aqueous ?ltrate is recycled. The aqueous ?l action mixture in any one of a number of forms. For ex trate can optionally be concentrated in a still prior to re ample, either osmium or vanadium can be introduced as cycling. the element itself, an oxide of the element, or a salt con When the process of the present invention is conducted taining the element. It is immaterial in which of the above 65 on a batch basis, it is generally preferred that ole?n be forms osmium and vanadium are supplied to the reaction introduced into a stirred aqueous solution of HNO3 and system, since oxidation occurs at once on making up the osmium-vanadium catalyst (and organic solvent, if any), reaction ssytem as described herein. Illustrative of the the solution being held at reaction temperature. Ole?n and chemical forms in which the catalysts can be introduced osmium can optionally be premixed prior to addition of are osmium (as the element), OsO4, vanadium (as the 70 acid. element), V204, V205, and NH4VO3 (ammonium vana The temperature, time, and composition of the reaction date), I<2[OSO4(OH)2]. system are interrelated, and a degree of latitude is avail 3,461,160 3 4 able in selecting these process variables. The temperature and a portion of the solution was analyzed by liquid of the process can be in the range 50—150° C. The pre chromatography (see table for relative weights of reac~ ferred temperature range is 60—120° C. tants and yield of major products based on amount of The process of this invention can optionally be carried ole?n charged). From the remainder of the solution, di out in the presence or absence of oxygen. Pressures of 5 basic acid products were then isolated by crystallization oxygen of up to several hundred p.s.i. can be employed in and identi?ed. this process. Conveniently maintained oxygen pressures The amount of gaseous product (N2 and N20) not use are in the range from about 1-7 atmospheres, i.e., up to ful in regeneration of HNO3 corresponded to the consump about 100 psi. Air can be employed as the source of tion of 0.15 gram of HNO3 per mole of adipic acid pro oxygen in this process. In this event the oxygen pressure 10 duced. referred to herein is the partial pressure of oxygen in air. Examples II-X The presence of oxygen (as the element or as air) over the ole?n oxidation process incorporates the advantage of The procedure of these examples was that of Example regenerating HNO3 in situ simultaneously with the ole?n I, except for modi?cation as noted in the Table. The total volume of the aqueous solution of HNO3, osmium and oxidation. By applying oxygen pressure to the oxidation 15 system, NO is very rapidly converted to N02, which sub vanadium varied between 20 and 40 ml. Note that in Ex sequently reacts with H2O to form HNO3. Since the major amples II, V, and VI dioxane was present, in Example off-gases from the ole?n oxidation of this process are NO IX 2-nitropropane was employed, and in Example X ace tic acid was present. and N02, applying oxygen to the system thus sharply re Example XI duces the amount of off-gas from the reactor. This meth 20 od of operation, therefore, has the advantage of requiring Dioxane (10 ml.) and 2 ml. of cis,trans,trans-cyclodo the handling of less off-gas. This effect reduces the equip decatriene were mixed at room temperature. A solution ment cost. This ‘mode of operation is applicable to either of one gram of OsO4 in 10 ml. dioxane was added slowly batch or continuous oxidations. with stirring to the former solution. Then 3 ml. of water The duration of the reaction can be varied widely, but 25 and 0.2 gram of platinum black were added. The mixture with the normal process conditions of this invention is was heated to 90° C. At that temperature 45 p.s.i.g. of generally of the order of a few minutes to several hours. hydrogen was applied over the solution and hydrogen was When a cyclic ole?n with two or more ole?nic bonds maintained there until no decrease in hydrogen pressure is employed as the starting material, and it is desired to was noted for a period of an hour. rupture less than all of the ole?nic bonds therein, the 30 The solution of the hydrogenated product was then order of addition of reactants and catalyst to the reaction slowly injected into an oxidation medium, 25 ml. of a system is important. For example, just one of the ole?nic solution of 50 parts of HNO3, 50 parts of water, and 0.3 bonds of cyclododecatriene can be ruptured as follows. An part of vanadium, which was held at 85° C. The tempera equimolar amount of cyclododecatriene and CS0, is dis ture was held at 80—90° ‘C. for an hour. The product was solved in dioxane and then hydrogenated in the presence 35 found to comprise a molar yield of 1,12-dodecanedioic of the osmium by conventional means (for example, as acid of about 70% based on the ole?n. in Example IX). The resulting mixture is then introduced Example XII into the oxidation system of aqueous HNO3 and vanadium, and 1,12-dodecanedioic acid is recovered by ?ltration. This experiment illustrates the use of a pressure of oxy In order that the invention may be better understood, 40 gen substantially higher than atmospheric. the following detailed examples are given in addition to Into a 500-ml. glass bottle there was introduced 80 ml. the examples already given above. All parts and percent (‘94.4 grams) of a solution of the following composition: ages herein are expressed by weight unless otherwise 30 parts HNO3, 68.5 parts H2O, 0.18 part vanadium, and stated. 1.3 parts osmium. Vanadium had been introduced into ‘Example I 45 the solution as V205 and osmium as 0504. Cyclohexene (0.850 part) was introduced to this solution at room tem The composition of the reaction mixture is noted in the perature. Then 49 p.s.i. of oxygen was applied to the sys table. Osmium was introduced as OsO4, vanadium as tem. The temperature of the reaction system was raised V205. About 40 ml. of the mixture was placed in a ?ask to 80° C. and held at that temperature for 20 minutes. and heated to 70° C. with stirring. Cyclohexene (0.735 50 The product comprised 88 mole percent adipicacid.

TABLE.—ONE-STEP OXIDATION OF CYOLIC OLEFINS TO DIOARBOXYLIO ACIDS Reaction medium Org. Solv., 1 parts _ Temp., Time, Example Ole?n, parts by wt. HNOs E20 by wt. Vanadium Osmium ° . hr. Molar yield of acids, percent

I . . _ _ _ _ _. Cyclohexene (1.60) ______25 0.5 1. 5 70 11/5 89 adipic, 3.7 glutaric, 3.0 sueciruc. II ______Cyclododecene (1.81) ______49 0.3 1.3 75 1 70 1,12rdodecanedi0ic, 4 unde— canedioic, 6 deeanedioic. III ______-_ Cyclododecene (2.35) ______50 0.3 (3) 75 1 86 1,.12-dodecanedi0ic. IV ______Cyclohepteno (2.40)______40 0.4 0.9 80 1% 65 pirnelic. Cyclooctene (3.05) ______30 0.4 1. 0 80 1 82 suberic. 3>methylcyclohexene (6.05)- 32 0.5 3 90 1 81 2~methyladipic. li-methylcyclohexene (2.40) 52 0. 2 1 70 1 80 3-methyladipic. 1,5-cyclooctadiene (2.18)__ _ 4O 58 ___ 0.3 2 55 1 30 succinic. __ Cyclohexene (2.51) ______39 59 77N 0.2 2. 3 75 1 83 adipie, 9 glutaric, 6 succinie. X ______Cyclododecene (0.852) ______60 48 100A 0.3 1.6 75 1 70 dodeeanedioic. 1 D ls dioxane, N is 2-nitropropane, and A is acetic acid. 1 Reaction mixture also contained 33 parts of adipic acid. a In this example equimolar amounts of 0504 and ole?n were premixed in dioxane at 25° 0; gram) was injected continuously at that temperature below 70 The data found in the examples demonstrate that the surface of the agitated mixture over a period 11/2 the process of this invention can be employed to oxidize hours. The temperature of the solution was then raised to cyclic 'ole?ns to dicarboxylic acids in high yield, often 105° C. for 10 minutes to complete the reaction and over 80%. This improvement in yield over the prior art volatize out of the system any unreacted ole?n. After the processes is accomplished in a one-step process. Fur product was cooled to room temperature, water was added 75 thermore, the process consumes very little nitric acid. 3,461,160 5 6 The low yields reported in the art for the HNOH oxida 4. The process according to claim 1 in which the re tion of cyclic ole?ns to dibasic acids are due, at least action system comprises aqueous HNO3, an osmium in part, to the reaction of the ole?n with N02 to give vanadium catalyst, ‘and acetic acid. mono- and dinitro compounds. The latter compounds 5. The process according to claim 1 in which the re are only slowly oxidized in low yield to the correspond action system comprises aqueous HNO3, an osmium ing dibasic acid. vanadium catalyst, and 2Pnitropropane. In contrast, with the vanadium-osmium catalyst sys 6. The process according to claim 1 wherein said oxida tem of this invention, the predominant role of HNO3 is tion is carried out at a temperature in the range 50‘-l50° the secondary one of regenerating the osmium-vanadium C. and an oxygen pressure of about l-7 atmospheres. catalyst. The rate of reaction of the catalyst with ole?n 10 7. The process according to claim 6 wherein the tem and intermediates is much vfaster than the rate of reac , perature of said oxidation is in the range 60-120‘7 C. tion of HNO3/NO2 with the ole?n and subsequent inter 8. The process according to claim 7 wherein said mediates. ‘Due to this difference in reaction rates, the ‘ole?n is introduced into a reaction system comprising oxidation of ole?n to acid is largely effected by the osmi 10-70 parts by weight of HNO‘3, 0.0‘l-0L7 part of vana um-vanadium system. 15 dium, 0.01-5.0 parts of osmium, and 24-90 parts of Since relatively little of the oxidation of the cyclic . water. ole?n is due to the action of HNOB/NOZ, the consump 9. The process according to claim 8 wherein the re tion of HNOa (with formation of N2 and N20‘) is very action system comprises 25-50 parts of HNO'g, 0.1-0.5 low also. The major gaseous products arising from the part of vanadium, 0.5-2.5 parts of osmium, and 47-74 regeneration of osmium and vanadium by HNO3 are 20 parts of water. NO and N02. These latter products can be used to re 10. The process according to claim 8 wherein cyclo generate HNO3, whereas, N20 and N2 produced in sig hexene is oxidized to adipic acid. ni?cant amounts according to the prior art processes, are 11. The process according to claim 8 wherein cyclo considered to be “spent” and are discarded. dodecene is oxidized to 1,12~dodecanedioic acid. It is within the contemplation of this invention that 25 12. The process accordingto claim 1 wherein said the dicarboxylic acids might not always remain in solu cyclic ole?n has at least two ole?ni-c bonds and said tion, but the product may be removed from the reaction ole?n is oxidized to a saturated dicarboxylic acid of the vessel as a heterogeneous mixture. same number of carbon atoms as said ole?n, said process The foregoing detailed description has given for clear including the steps of ness of understanding only, and no unnecessary limita 30 (a) hydrogenating a solution of osmium and said tions are to be understood therefrom. The invention is ole?n in dioxane until the consumption of hydrogen not limited to the exact details shown and described has ended, and since obvious modi?cations will occur to those skilled (b) oxidizing the resulting solution with an aqueous in the art. solution of HNOS and vanadium. I claim: 35 13. The process according to claim 12 wherein said 1. A process ‘for the oxidation of cyclic ole?ns to di ole?n is cyclododecatriene and said saturated dicarboxylic carboxylic acids in which the oxidation is effected by acid is 1,12-d0decanedioic acid. contacting said ole?ns with a liquid-phase reaction sys tern comprising aqueous HNOZ and an osmium-vanadium References Cited catalyst. 40 UNITED STATES PATENTS 2. The process according to claim 1 wherein said oxidation is carried out under a pressure of oxygen of 3,306,932 2/1967 Davis ______. ______260-533 about 1-7 atmospheres, whereby HNO3 is regenerated 2,323,861 7/1943 Zellner ______:__ 260-533 from reduction products thereof. 3,317,592 5/1967 Machean et al. ______260-533 3. The process according to claim 1 in which the reac LORRAINE A. WEINBERGER, Primary Examiner tion system comprises aqueous HNO3, an osmium-vana dium catalyst, and dioxane. . D. STENZEL, Assistant Examiner $3230 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION

Patent NQ.____3,_I+61,16Q Dated August 12, 1969

Invent0r(8) EUGENE DENNIS WILHOI‘I'

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

"- Column 5, line 39, CLAIM 1, " EH02 " should be -- mm3 --.

SIGNED AND SEALLZS AUG 4 -1970

ésE-AL) Atteat: mun E. sum. JR Edwm'd M‘ Hacker’ Ir‘ Oonmissionar of ‘Patents Attesting Officer