862. ------. [GREESHAM, W. F., AND BROOKS, R. E.] (E. I. du Pont de Nemours & Co.). Carboxylic Acids From Olefins, Carbon Monoxide, and Water. United States Patent 2,448,368. Aug. 31. 1948. Chem. Abs., vol. 43, 1949. p. 669.

Patent Abstracts

Organic carboxylic acids are prepared by treating 0.1-10 (preferably 0.8-2) mols. unsaturated compounds containing at least 1 nonaromatic C:C bond with 0.1-20 (preferably 0.8-5) mol. CO and 1 mol. H₂O in the presence of 0.05-30% (based on the total weight of the reactants) Ni or Co carbonyl at 150º-500º (preferably 175º-375º) under 50-3,000 (Preferably 500-1,500) atm. in the absence of inorganic acidic substances. Any inert liquid, for example, carboxylic acids, ketones, cyclohexane, or C₆H₆, may be used as reaction medium: however, the reaction may be conducted in the absence of any added medium, using CO₂ as a diluent to suppress the water-gas reaction. The carbonyl catalyst may be introduced as such or formed in situ under conditions of the reaction. The synthesis eliminates excessive corrosion of equipment and utilizes cheap, available raw materials and may be conducted in liquid or vapor phase, operating either batchwise or continuously, using a fixed-bed, solid, or fluidized catalyst. Recovery of the catalyst (75-80%) is effected by direct distillation of the reaction product under a blanket of CO and separation of the acid from the product. For example, 9 cc. distilled H₂O, 10 gm. Ni carbonyl, 44 gm. CO₂ (to suppress the water-gas reaction), and 28 gm. C₂H₄ are heated 30 min. at 300º-375º under 450-740 atm. of CO and the product distilled to yield 30.3 gm. (80%-90%) crude EtCO₂H. Employing Co propionate in place of the Ni carbonyl and omitting the CO₂ diluent in the above example, 46% EtCO₂H and 14.5% Et₂CO are obtained at 234º-250º and 660-830 atm. of CO. Similarly 18 cc. H₂O, 10 gm. Ni carbonyl, 44 gm. CO₂, and 42.1 gm. propene are heated 1 hr. at 314º-334º under 595-765 atm. of CO to yield 67 gm. pale brown liquid, chiefly 2 parts PrCO₂H and 1 part iso-PrCO₂H. Likewise, 56 gm. Me₂C: CH₂, 10 gm. Co. and 9 cc. H₂O were heated 2.2 hr. at 318º-322º under 450-700 atm. of CO: distillation yielded a fraction, b_23-460º-130º, which was a mixture of Me₂C : CH₂ polymers and O₂-containing organic compounds.