Patented Feb. 14, 1950 ’ 2,491,304

UNITED STATES PATENT OFFICE 2,497,304 PREPARATION OF OARBOXYLIC ACID ANHYDRIDES William F. Gresham and Richard E. Brooks, Wil mington, DeL, assignors to E. I. do ' Pont de Nemours & Company, Wilmington, Del., poration of Delaware No Drawing. Application November 23, 1945, Serial No. 630,540 , 10 Claims. (01. 260-546)

This invention relates to the synthesis of or- ‘ propionic acid to form propionic anhydride in ganic compounds and particularly to the prepara substantially the following manner: tion of organic carboxylic acid anhydrides by the interaction of ole?nic substances, carbon monoxide, and carboxylic acids. 5 propylene and butylene ‘similarly react with Various processes have been proposed hereto propionic acid to form the corresponding mixed fore for the preparation of organic carboxylic anhydrides. respectively. By utilizing other all acid anhydrides. For example, acetic anhydride phatic carboxylic acids than propionic acid, nu has been prepared by pyrolysis of ethylldene merous organic carboxylic acid anhydrides can be diacetate, or by the direct high temperature de 10 prepared, such, for example, as the following: hydration of acetic acid. Other anhydrides have carbon monoxide reacting with formic acid and been prepared by reaction between acetic anhy ethylene to give formic propionic anhydride; car dride and the corresponding organic carboxylic bon monoxide reacting with acetic acid and acid. ‘ ethylene to give a mixed acetic propionic anhy An object of the present invention is to provide 15 dride; carbon monoxide reacting with propylene a novel process for the synthesis of organic car and butyric acid to give butyric anhydride; car boxylic acid anhydrides from relatively inexpen bon monoxide reacting with isobutylene and sive starting materials. A further object of the isovaleric acid to give isovalericanhydride, etc. invention is to provide a commercially feasible Other 'carboxylic acids such as adipic, benzoic, process for the synthesis of organic carboxylic 2,0 oleic, etc., may be employed in a similar manner. acid anhydrides employing ole?ns and carbon Raw materials suitable for use in the process monoxide as starting materials. Other objects are readily available from a number of sources. and advantages of the invention will appear here Thus, ethylene and various homologs thereof are inafter. found in the gases evolved in cracking petroleum ' It has been discovered, in accordance with the and may be separated therefrom, for example, invention, that organic carboxylic acid anhy by fractional liquefaction. It is preferable, for drides, and, in particular embodiments, car the sake of avoiding undesirable by-products, boxylic acid anhydrides of aliphatic acids can that the hydrocarbon which it is desired to con be prepared by reaction between unsaturated vert be employed in a relatively high degree of compounds containing the non-aromatic ole?nic 30 purity. However, hydrocarbon mixtures. con grouping >C=C<, carbon monoxide and car taining saturated hydrocarbons as well as oletlnes, boxylic acids. The unsaturated compounds ' such as may be obtained by cracking and/or de which may be employed in the practice of ‘the hydrogenation, may be used if desired. ,Di'ole invention include the ole?nic hydrocarbons, such ?nes, cyclo-olefines, and substituted ole?nes are as, for example,‘ ethylene, propylene. the but 35 also generally applicable in the practice of the ylenes, etc. These hydrocarbons may be repre invention. sented by the formula: It is, in general, desirable that neither the car boxylic acid, nor the ole?nic reactant contain substituent groups (such as alcoholic hydroxyls) in which R, Ram and R3 represent hydrogen 40 which react secondarily with the anhydride or an alkyl, aryl, or aralkyl radical. The reaction produced, for this results in a loss of anhydride. also takes place with compounds containing aro Other substituent groups may, of course, be matic unsaturation, such as naphthalene. present without causing such a lose in yield. The following equation illustrates a reaction The highest yields are generally obtained under which takes place when a carboxylic acid an 45 anhydrous conditions. hydride is produced from an oleiine, carbon mon The carbon monoxide required for the synthe oxide, and a carboxylic acid of the formula, sis may be conveniently derived from various . RACOOH, R4 representing alkyl, aryl, or aralkyl commercial sources, such as, for example, water groups: . gas, producer gas, etc., by liquefaction, or by 50 other methods, and should, likewise, for the best RRlc=CR2R3+CO+R4COOH= results, be relatively pure. . CHRR1CRaRaCOOCORi Inert gases, such as nitrogen, methane, etc., The isomeric anhydride, CHRzRaCRRrCOOCOR4 may be included with the reactants, this being also would be produced. In a speci?c embodi advantageous in some cases from the standpoint ment, ethylene reacts with carbon monoxide and of controlling the temperature of the exothermic 9,497,804 4 reaction and limiting the extent thereof, for it , and essentially quantitative yield at the mixed may be desired to restrict the overall conversion anhydride of propionic and acetic acid. of the reaction for the sake of enhancing the rela Example 4.-~A mixture of 74 grams of propionic tive yield of the desired carboxylic acid anhy acid, 28 grams ethylene, and 10 grams nickel drides. formate was processed with carbon monoxide at The relative proportions of‘ the reactants can a temperature of 285° to 303° C. under a pres be varied. ' sure of 500 to 850 atmospheres for 1 hour. The The use 01’ pressure in excess of atmospheric, liquid product was distilled and found to contain say from 25 to 2000 atmospheres, is preferred, propionic anhydride representing 20% conver although somewhat higher pressures may, it de 10 sion based on propionic acid charged. sired, be used. It is preferred to operate at pres Example 5.—A mixture containing 32 grams of sures of about 300 to 1500 atmospheres, in order naphthalene, 20 grams of nickel carbonyl, 74 to obtain a suitable reaction rate. grams of propionic acid processed with carbon Generally, the desired reaction can be ob monoxide at a temperature of 290° to 300° C. tained at temperatures of about 200° to 500° C. 15 under a pressure of 750 to 800 atmospheres for From the standpoint of practical operation, the 30 minutes. The resulting product containing temperature should not be so low that the re considerable unreacted naphthalene was dis action rate is not economical, nor so high as solved in ether and the ether solution extracted to result in undesirable by-products by decom with dilute sodium hydroxide solution. Acidi?ca position and/or polymerization of the raw ma 20 terial. From this point of view, the process has tion of this alkaline solution caused precipitation been found to operate very satisfactorily at 275° of a small amount of an acid M..P. 177-178°, neutral equivalent 179. This acid is regarded as to 400° C. having the following structure (neutral equiva The invention is preferably practiced by heat lent, 174): ing the reactants in the presence of a suitable 25 catalyst under the aforesaid conditions of tem OOOH perature and pressure. v Numerous materials have been found to be e?ective as catalysts, particu O H] larly various salts, oxides, hydroxides, metals and metal carbonyls. However, outstanding results 30 are obtained with catalysts containing nickel car bonyl, or substances which give rise to nickel The isolation of this acid indicated that the re-. carbonyl under the conditions of the reaction. action mixture had contained the mixed anhy Excellent results have been obtained, for example, dride of this acid with propionic acid. in the synthesis'of propionic anhydride by heat 35 Example 6.--A mixture containing 74 grams or ing propionic acid with ethylene and carbon mon propionic acid, 10 grams of nickel propionate and oxide in the presence of nickel propionate. Pro 28 grams of ethylene was heated for 15' minutes pionic anhydride has been obtained in somewhat at a temperature of 275° to 295° C., under a car lower yields by heating ethylene with carbon bon monoxide pressure'of 590 to 810 atmospheres. monoxide and propionic acid in the presence of 40 Distillation of the resulting product gave 52 such catalysts as copper, cobalt, or manganese grams, B. P. 124° to 142° C.; 11 grams, B. P. 142° compounds, or mixtures thereof. Inert supports to 160° 0.; and, 23 grams, B. P. 160° to 167° C. for these catalysts may be used if desired. Analysis of the second and third fractions showed When nickel carbonyl is used as the catalyst the presence of propionic anhydride, correspond in the practice oi’ the invention, it may be re ing to 22.5% conversion and 97% yield, based on covered by distillation under a blanket of carbon the amount of propionic acid initially employed. monoxide. The recovered catalyst, may, of Example 7.—A mixture containing 74 grams of course, be reused. propionic acid, 28 grams of ethylene and 5 grams The following examples will illustrate methods of nickel carbonyl was heated at a temperature of practicing the invention, although the inven 50 of 275° to 290° C. for 20 minutes in a copper-lined tion is not limited thereto: shaker tube, under. a carbon monoxide pressure Example 1.-A mixture containing 74 grams of - of 700 to 820 atmospheres. Distillation of the re propionic acid, 10 grams of nickel carbonyl and sulting product gave a propionic anhydride frac 28 grams of ethylene was heated in a copper tion which corresponded to 28.4% conversion, lined pressure resistant vessel with carbon mon 55 and 92.5% yield, based on the amount of pro oxide at a temperature of 272° to 293° C., under pionic acid employed. _ . a pressure of 600 to 810 atmospheres for 15 Example 8.--Example 1 was repeated using; minutes.‘ Distillation of the resulting product propylene as the ole?nic hydrocarbon in place of showed 39% conversion to propionic anhydride, ethylene. A comparatively low yield of mixed and 93% yield, based on the weight of propionic butyric, isobutyric and propionic anhydrides was acid initially present. obtained, in place of propionic anhydride. Example 2.—A mixture containing 74 grams or In the copending applications S. N. 629,699 and propionic acid, 5 grams of cobalt propionate and S. N. 625,951, now Patents Nos. 2,448,368 and 28 grams of ethylene was processed with CO at 2,448,375, respectively, it is disclosed that organic a temperature of 261° to 280° C. under a pressure ' acids may be obtained by reaction between ole of 525 to 845 atmospheres. The liquid product ?n hydrocarbons, carbon monoxide and water in contained 7 grams of propionic anhydride (5.3% _ the presence of a nickel carbonyl catalyst, under conversion). suitable conditions of temperature and pressure. In the practice of the present invention, it is Example 3.--A mixture of 60 grams of acetic 70 possible to employ, as a starting material, the acid, 28 grams of ethylene and 20 grams of nickel reaction product obtained in accordance with carbonyl was processed with carbon monoxide at the aforesaid processes, provided the amount of 445 to 805 atmospheres pressure at 250° to 275° water present in the said product is not su?lcient C. - Liquid product was distilled and found to con to destroy the organic carboxylic acid anhydride tain a quantity representing 43.8% conversion 76 produced in accordance with the present inven 9,497,304 V - 5' > 6 tion. Moreover, it is entirely possible to prepare alkyl radicals, said ole?nic‘h'ydrocarbon having anhydrides directly from H20, CO, and ole?nes, ‘ from two to four carbon atoms per molecule, with under the temperature and pressure conditions carbon monoxide and an aliphatic carboxylic acid disclosed herein, but no anhydride would be re of the formula RQCOOH, R4 representing an alkyl covered until all of- the water was converted to radical, .at a temperature of from 275° to 400° C_. acid. ‘under superatmospheric pressure in the presence The apparatus which may be employed in the of a nickel carbonyl catalyst, and thereafter sepa- . practice of the present invention may be of any rating organic carboxylic acid anhydride of the conventional type and, preferably, is one in which vformula RR1CHCRzRaC0OCOR4~from the result the temperature of exothermic reactions can be 10 ing product. 1 readily controlled at the desired value. The proc 4. The process of producing organic carboxylic‘ es of the invention may be conducted either acid anhydrides which comprises heating an ole batchwise or continuously. At elevated tempera ?nic hydrocarbon of the formula: tures, and ‘especially when a large excess of car bon monoxide is employed, the reaction evidently 15 takes place in the vapor phase. Under such con in which R, R1, R2 and R: each represents a > ditions, it is frequently desirable to have present member of the class consisting of hydrogen and in the reaction vessel a suitable absorptive ma alkyl radicals, said ole?nic hydrocarbon having terial, such as silica gel or charcoal. from two to four carbon atoms per molecule, with The apparatus employed in the practice of the 20 carbon monoxide and an aliphatic carboxylic acid invention may be made of or lined with any suit of the formula R4COOH, R4 representing an alkyl able'inert material, such as glass, inert metals, radical, at a temperature of from 200° to 500° 0., copper, silver, silver-platinum alloys, and the like. at a pressure of from 25 to 2000 atmospheres in In carrying out the process of the invention in a the presence of a nickel carbonyl catalyst, and ' continuous manner tubular converters may be 25 thereafter separating organic carboxylic acid an employed. hydride of the formula RR1CHCR2R3COOCOR4 Various changes may be made in the method from the resulting product. . hereinbefore described without departing from 5. The process of producing organic carboxylic this invention or sacri?cing any of the advan acid anhydrides which comprises heating an ole tages that may be derived therefrom. , ?nic hydrocarbon of the formula: It is to be understood that the expression . "carboxylic acid” employed in the following claims refers to any organic compound having a in which R, R1, R2 and Ra each represents a —COOH group attached to carbon or hydrogen.‘ member of'the class consisting of hydrogenand We claim: ' 35 alkyl radicals, said ole?nic hydrocarbon having 1. A process for the synthesis of carboxylic from two to four carbon atoms per molecule, with acid anhydrides which comprises reacting under carbon monoxide and an aliphatic carboxylic acid anhydrous conditions a carboxylic acid of the of the formula R4COOH, R4 representing an alkyl formula RCOOH, R being an alkyl group, with a radical, at a temperature of from 200° to 500° 0., hydrocarbon containing non-aromatic monoole 40 at a pressure of from 300 to 1500 atmospheres in ?nic unsaturation, and carbon monoxide, at a the presence of a nickel carbonyl catalyst and temperature within the range of 200° to 500° C., thereafter separating organic carboxylic acid an under a pressure of 25 to 2000 atmospheres, in hydride of the formula RR1CHCR2R2COOCOR¢ ,the presence of a nickel-containing catalyst of from the resulting product. the class consisting of nickel carbonyl and sub 45 6. A process for the synthesis, of propionic stances which produce nickel carbonyl under the anhydride which comprises heating propionic acid conditions of the reaction, whereby a reaction with ethylene and carbon monoxide, at a tem product containing organic carboxylic acid an perature within the range of 200° to 500° 0., hydride is produced and thereafter separating the under a pressure of 25 to 2000 atmospheres, in said organic carboxylic acid anhydride from the 60 the presence of nickel carbonyl, whereby pro resulting mixture. pionic anhydride is produced, and thereafter sep 2. The process of producing organic carboxylic arating the said propionic anhydride from the acid anhydrides which comprises heating an ole resultant reaction product. finic hydrocarbon of the formula: 7. A process for the synthesis of propionic 65 anhydride which comprises heating propionic acid with ethylene and carbon monoxide, at a tem in which R, R1, R2 and R3 each represents a mem perature within the range of 200° to 500° C., under ber of the class consisting of hydrogen and alkyl a pressure of 300 to 1500 atmospheres, in the pres radicals, said ole?nic hydrocarbon having from ence of nickel carbonyl whereby propionic anhy two to four carbon atoms per molecule, with car 60 dride is produced and thereafter separating the bon monoxide and an aliphatic carboxylic acid said propionic anhydride from the resultant reac of the formula RiCOOH, R4 representing an alkyl tion product. radical, at a temperature of from 200° to 500° C. 8. A process for the synthesis of propionic an under superatmospheric pressurein the presence hydride which comprises heating propionic acid of a nickel carbonyl catalyst and thereafter sepae 65 with ethylene and carbon monoxide, at a tem rating organic ‘carboxylic acid anhydride of the perature within the range of 275° to 400° 0., under formula RR1CHCR2RaCOOCOR4 from the result a pressure of 300 to 1500 atmospheres, in the ing product. presence of nickel carbonyl whereby propionic 3. The process of producing organic carboxylic anhydride is produced and thereafter separating acid anhydrides which comprises heating an ole 70 the said propionic anhydride from the resultant ?nic hydrocarbon of the fomula: reaction product. 9. A process for the synthesis of propionic an hydride which comprises heating propionic acid in which R, R1, R2 and R: each represents a with ethylene and carbon monoxide, at a temp member of the class consisting of hydrogen and 75 erature within the range of 200° to 500° 0.. under 2,497,204 8 a pressure of 25 to 2000 atmospheres, in the pres ence of nickel propionate, whereby propionic an UNITED STATES PATENTS hydride is produced, and thereafter separating Number Name Date the said propionic anhydride from the resultant 1,884,626 Dreyfus ...... Oct. 25, 1932 reaction product. 1,884,627 Dreyfus ______-- Oct. 25, 1932 10. The process for the synthesis or propionic 1,973,662 Bchalch ______Sept. 11, 1934 anhydride which comprises heating about 74 parts 2,007,642 deSinio ______July 9, 1935 by weight of propionic acid. about 10 parts of 2,015,065 Carpenter ______.. Sept. 24, 1935 nickel carbonyl, and 28 parts of ethylene, under a 2,079,216 Larson ______-_ May 4, 1937 carbon monoxide pressure of about 600 to 810 ‘ 2,089,903 'Larson ______Aug. 10, 1937 atmospheres, at a temperature of about 272° to 293° 0., whereby a reaction product containing FOREIGN PATENTS propionic anhydride is produced. Number Country Date 316,898 Great Britain ______-_ of 1928 WILLIAM F. GRESHAM. 'I OTHER REFERENCES RICHARD E. BROOKS. "Advances in Acetylene Chemistry as Developed by Walter Reppe” Intelligence Division Report REFERENCES CITED No. 4,149, dated 24 March 1945, p. 26. The ‘following references are of record in the 20 Peck et al., Fiat Final Report No. 273, “Inter file of this patent: view with Dr. W. J. Reppe" dated 2 October 1945, p. 10.