2808.     REPPE, -----.  New Synthesis of Acrylic Acid.  Modern Plastics, vol. 23, No. 3, 1945, pp. 162-165, 210; Chem. Abs., vol. 40, 1946, p. 1449.

        Translation of a captured German report by the above author, obtained under auspices of U. S. War Department.  Metal carbonyls promote reaction between C₂H₂ or olefins, CO and H₂O, alcohols, or other compounds containing labile H.  Cyclopropenones or cyclopropanones probably form as intermediates by interaction between C₂H₂ or olefin and CO.  These intermediates hydrolyze or alcoholyze to the corresponding acids or esters.  Acrylic esters or amides are obtained from C₂H₂, CO, and alcohol or amine with Ni and NiI₂ catalyst at 150°.  Similarly, olefins with CO and alcohols give almost quantitative yields of saturated carboxylic acid esters, a-olefins yield a mixture of straight chain and a-Me substituted acid esters.  The Oxo synthesis of aldehydes also is explained as owing to hydrogenolysis of a cyclopropanone intermediate.  Ni(CO)₄ (0.25 mol.) added dropwise to a mixture of EtOH (1 mol.) and concentrated HCl (0.5 mol.) saturated with C₂H₂ gives CH₂:CHCO₂Et virtually quantitatively.  Similarly other alcohols give the corresponding acrylate esters, mercaptans give acrylic thio esters, amines give acrylic amides, and H₂O gives CH₂:CHCO₂H, all yields being substantially quantitative.  Co carbonyl, but not Fe carbonyl, may replace Ni(CO)₄ in this reaction.  NiCl₂ solution resulting from the process is reclaimed by adding NH₃ in slight excess over the requirement to form NiCl₂ hexamine and treating with CO at 80° and 50-100 atm. to form Ni(CO)₄.

           RESCORLA, A. R.  See abs. 3082.