UNITED STATES PATENT OFFICE 2,497,304 PRE PARATION of CARBOXYLCAC) ANY ORDES William F

Patented Feb. 14, 1950 2497,304 UNITED STATES PATENT OFFICE 2,497,304 PRE PARATION OF CARBOXYLCAC) ANY ORDES William F. Gresham and Richard E. Brooks, Will mington, Dell, assignors to E. I. duPont de Nemours & Company, Wilmington, Del, a coa poration of Delaware No Drawing, Application November 23, 1945, Serial No. 630,540 10 Claims. (CL 260-546) 2 This invention relates to the synthesis of or propionic acid to form proponic anhydride in ganic compounds and particularly to the prepara substantially the following manner: tion of organic carboxylic acid anhydrides by the interaction of olefinic 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 ali acid anhydrides. For example, acetic anhydride phatic carboxylic acids than propionic acid, nu has been prepared by pyrolysis of ethylidene merous organic carboxylic acid anhydrides can be diacetate, or by the direct high temperature de O 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 5 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 isovaleric anhydride, etc. invention is to provide a commercially feasible Other carboxylic acids Such as adipic, benzoic, process for the synthesis of organic carboxylic 20 oleic, etc., may be employed in a similar manner. acid anhydrides employing olefins 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 olefinic 30 purity. However, hydrocarbon mixtures, Con grouping >C=CC, carbon monoxide and car taining saturated hydrocarbons as well as olefines, 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. Diole invention include the olefinic hydrocarbons, such fines, cyclo-olefines, and substituted olefines are as, for example, ethylene, propylene, the but 35 also generally applicable in the practice of the yenes, etc. These hydrocarbons may be repre invention. sented by the formula: It is, in general, desirable that neither the car boxylic acid, nor the olefinic reactant contain substituent groups (such as alcoholic hydroxyls) in which R, Ri, Ra 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 olefine, carbon mon The carbon monoxide required for the synthe oxide, and a carboxylic acid of the formula, sis may be conveniently derived from various RCOOH, 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 RRC=CRR3--CO--RACOOH= results, be relatively pure. CHRR1CR2R3COOCOR Inert gases, such as nitrogen, methane, etc., The isomeric anhydride, CHR2R3CRR1COOCOR4 may be included with the reactants, this being also would be produced. In a specific embodi advantageous in Some cases from the standpoint ment, ethylene reacts with carbon monoxide and of controlling the temperature of the exothermic 2,497,804 3 4. reaction and limiting the extent thereof, for it and essentially quantitative yield of 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 Eacample 4-A mixture of 74 grams of proponic 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 of 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, if de 0 sired, be used. It is preferred to operate at pres sion based on propionic acid charged. sures of about 300 to 1500 atmospheres, in order Eacample 5-A mixture containing 32 grams of to obtain a suitable reaction rate. naphthalene, 20 grams of nickel carbonyl, 74 Generally, the desired reaction can be obs grams of propionic acid processed with carbon tained at temperatures of about 200 to 500 C. monoxide at a temperature of 290° to 300° C. From the standpoint of practical operation, the 5 under a pressure of 750 to 800 atmospheres for temperature should not be so low that the re 30 minutes. The resulting product containing action rate is not economical, nor so high as considerable unreacted naphthalene was dis to result in undesirable by-products by decom Solved in ether and the ether solution extracted position and/or polymerization of the raw ma with dilute sodium hydroxide solution. Acidifica terial. From this point of view, the process has 20 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°, to 400 C. neutral equivalent 179. This acid is regarded as The invention is preferably practiced by heat having the following structure (neutral equiva ing the reactants in the presence of a suitable lent, 174): catalyst under the aforesaid conditions of tem 25 COO perature and pressure. Numerous materials have been found to be effective as catalysts, particul O larly various salts, oxides, hydroxides, metals and metal carbonyls. However, Outstanding results are obtained with catalysts containing nickel car 30 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 proponic anhydride by heat 35 Eacample 6-A mixture containing 74 grams of 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 C.; 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 of 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 Eacample 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 Eacample 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 non 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 Eacample 8-Example 1 was repeated using minutes. Distillation of the resulting product propylene as the olefinic hydrocarbon in place of showed 39% conversion to propionic anhydride, ethylene.

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