Patented Feb. 14, 1950 2497,303 UNITED STATES PATENT OFFICE 2,497,303 REACT ON BETWEEN OLEFNC COM. POUNDS, CARBON MONOXDE, AND HY DROGEN IN THE PRESENCE OF A META, CARBONY, CATALYST william F. Gresham and Richard E. Brooks, wil mington, Del, assignors to E. I. du Pont de Nemours & Company, Wilmington, Del, a cor poration of Delaware No Drawing. Application May 23, 1945, Serial No. 595,474 . 3 Claims. (C. 260-604) 2 This invention relates to the synthesis of Or While metal carbonyls in general are effective ganic oxygen-containing compounds, and in par in the practice of the invention, outstanding re ticular to the synthesis of organic oxygen-con sults are obtained with carbonyls of metals hav taining compounds by employing a metal car ing atomic numbers of from 26 to 28 inclusive, bonyl catalyst for the reaction between organic namely, Carbonyls of the class consisting of co unsaturated compounds, carbon monoxide, and balt, nickel and iron carbonyls. The amount of compounds capable of adding to organic unSat catalyst is preferably within the range of about urated compounds. 0.1 to 10%, based on the total weight of the re An object of this invention is to provide an action mixture, but it has been observed that the improved method for preparing organic oxygen 10 Cobalt carbonyl catalysts exert an effect even containing compounds from olefinic compounds, when present to the extent of only about 200 carbon monoxide and hydrogen. Another object parts per million or even less. is to provide an improved process for the Syn The formation of oxygen-containing products thesis of propionaldehyde and higher aldehydes from olefinic compounds, carbon monoxide and . from Organic unSaturated compounds containing 5 hydrogen involves competing reactions. As an olefinic unsaturation, carbon monoxide, and hy illustration, in the synthesis of oxygen-contain drogen, in the presence of certain highly active ing compounds from ethylene, carbon monoxide catalysts, e. g., metal carbonyls, as described in and hydrogen, by methods of the prior art, at detail hereinafter. pressures below 300 atmospheres, the following In the copending application Serial No. 598,208, 20 two reactions and various others may occur. filed June 7, 1945, now matured to U. S. Patent (1) CH2=CH2--CO--Ha-9CH2CH2CHO No. 2,437,600, dated March 9, 1948, it is disclosed that propionaldehyde and higher aldehydes may (2) 2CH2=CH2--CO--Ha->CH3CH2COCHCH be prepared in excellent yield by reaction between It was not known heretofore how to control unsaturated compounds containing olefinic un 5 these various reactions So as to produce a pre Saturation, carbon monoxide and hydrogen at dominantly aldehydic product. According to the pressures in excess of 300 atmospheres, in the conventional rules of chemistry, the effect of in presence of hydrogenation catalysts. creased preSSure on. Such competing reactions. It has been discovered in accordance with the normally would be to favor the reaction which is present invention that certain metal carbonyls, 30 accompanied by the greater volume decrease, and which heretofore have been found to be unsatis to suppress the reaction which is accompanied factory as catalysts in ordinary hydrogenation by the lesser volume decrease. However, accord reactions since they themselves are easily de ing to this invention, an anomalous effect is ob composed or hydrogenated, are outstandingly Served at elevated pressures. Instead of sup excellent catalysts for the synthesis of aldehydes 35 pressing Reaction 1, which is accompanied by the by the simultaneous reaction between carbon lesser volume decrease, the effect of pressure is monoxide, hydrogen and compounds containing to suppress Reaction 2, thereby making possible olefinic unsaturation. These catalysts are SO the formation of the aldehyde via Reaction 1 in efficient that they exert a profound effect when high yield. present in relatively minute concentrations. 40 The reaction between the olefinic compound, Moreover, they are effective when employed in the carbon monoxide and hydrogen in the presence liquid phase and are substantially completely re of the aforesaid metal carbonyl compounds as coverable from the reaction mixture. These prop catalysts is generally conducted at a temperature erties make the carbonyls highly valuable as cat of about 75° to 250° C., preferably 100° to 200° C., alysts in continuous processes for the Synthesis of according to the invention. The process may be aldehydes from olefines, carbon monoxide and hy carried out at Ordinary or Superatmospheric pres drogen, especially in processes in which the car Sures, especially at pressures of from 50 atmos bonyl is recovered as such and recycled to the re pheres to 1500 atmospheres. At pressures in ex action mixture. The present invention provides a cess of 300 atmospheres, especially above about process for the preparation of oxygen-containing 50 375 atmospheres, the reaction product is pre organic compounds which comprises reacting an dominantly aldehydic. The maximum pressure organic unsaturated compound containing ole which may be employed is determined by the finic unsaturation simultaneously with carbon strength of the retaining vessel and may be as monoxide and hydrogen in the presence of a cat high as 3000 atmospheres or even higher. alyst consisting of a metal carbonyl. 55 The relative proportions of reactants may be 2,497,803 3 4. the stoichiometrically required quantities, al aldehyde groups attached to carbon atoms other though other proportions may be employed if de than the carbon atoms which are separated by sired. Excellent results are obtained when the the sterically-hindered olefinic bond. molar ratio of CO:H:olefine is within the range If desired, any inert liquid may be employed of about 1:2:1 to about 2:4:1, but such an ex as a reaction medium. When such a medium is cess of hydrogen is not at all indispensable. employed, solvents in which the metal carbonyls In one method of practicing the invention, the are readily soluble and stable are preferred. olefinic compound and a solution of the metal When the metal carbonyl catalyst is to be recov carbonyl are placed in a pressure-resistant vessel, ered by separating the aldehydic product there and a mixture of carbon monoxide and hydrogen 0 from at elevated temperature under high carbon is injected therein under high pressure. Thus, monoxide pressure as above described, it is de the advantages of the invention are gained by sirable that the inert liquid be relatively high employing a reaction mixture which initially boiling, e. g., its boiling point should be above the contains the carbonyl. A polymerization inhibi boiling point of the principal aldehydic product. tor may also be present in the mixture if desired. A suitable inert solvent is xylene or diethyl After the reaction is completed, the resulting re benzene in any of their isomeric forms. Examples action product may be removed from the pressure of other solvents which may be used are cyclo resistant vessel, and the catalyst may be recovered hexane, ethylbenzene, saturated esters and satu by any convenient method. The oxygen-contain rated ethers. ing organic compounds produced by the reac 20 The invention is illustrated further by means tion are likewise separated from the mixture by of the following examples. any suitable method, such as fractional distilla Eacample 1.-A mixture containing 128 cc. of tion. cyclohexane and 10 grams of finely divided re Since the metal carbonyl catalysts are volatile duced, sintered cobalt oxide was placed in a sil compounds which in many instances decompose ver-lined shaker tube and heated for two hours during distillation of the crude reaction prod at a temperature of 140 to 160° C. under a pres ucts, a vexatious problem is encountered in at sure of 650 to 750 atmospheres of carbon monox tempting to separate the carbonyl catalyst from ide. Approximately 2.5 grams of the cobalt went the aldehydic product substantially quantita into solution in the form of cobalt carbonyl. The tively, and without decomposition. According to 30 resulting product was filtered, and diluted until the invention, carbon monoxide under high pres the concentration of cobalt carbonyl corre sure is effective in suppressing the thermal de sponded to 0.01 gram (as Co) per cc. A portion of composition of thermally unstable carbonyls this Solution (58 cc.) was transferred to another (such as cobalt carbonyl), and these carbonyls shaker tube, and a mixture of 70 cc. cyclohexane can be employed conveniently, without decompo 35 and 28 grams of ethylene was introduced. The sition, at elevated temperatures in Catalytic resulting mixture was heated for 45 minutes at processes, or in processes for recovering such car a temperature of 110 to 172° C. under a pressure bonyls from mixtures with other substances, by of 375 to 725 atmospheres of a gas which consisted imposing a high pressure of carbon monoxide of 2 volumes of hydrogen per volume of carbon thereon. Accordingly, a convenient method for 40 monoxide (hereinafter called CO:2H2). The re recovering the carbonyl catalyst, and aldehyde action product was discharged from the shaker (particularly a low-boiling aldehyde such as tube and was distilled, yielding 39.7 grams of propionaldehyde or the butyraldehydes, i. e., the propionaldehyde, and 10 grams of the azeotrope aldehyde derived from monoolefines having not of n-propanol and cyclohexane. more than 3 carbon atoms), from the reaction 5 Eacample 2.-A mixture containing 1.00 grams product obtained in the olefine -CO-H2 reac of cyclohexane, 24.3 grams of iron carbonyl and tion is to conduct carbon monoxide through the 28 grams of ethylene was heated for one hour at liquid reaction product at a temperature of about a temperature of 130 to 200° C. under a pres 100 to 200 C., under a pressure of about 100 to Sure of 440 to 740 atmospheres of CO:2H2.