Catalytic carbonylation of ethylene in the presence of the Pd(acac)2-m-Ph2PC6H4SO3Na(H)-AcOH system

Catalytic systems based on phosphine complexes of palladium have been developed for synthesizing propionic acid (monocarbonylation) and alternating (11) ethylene-carbon monoxide copolymers,i.e., polyketones (polycarbonylation).m-(Diphenylphosphino)benzenesulfonic acid or its sodium salt were used as ligands. Monocarbonylation proceeds at atmospheric pressure in dioxane or acetic acid solvents. Under high pressure, the reaction pathway can change from monocarbonylation, which occurs in the presense of the sodium salt of the ligand, to polycarbonylation when the sodium ion at the sulfo group is completely replaced by a proton. This change in reaction selectivity is observed when the process is performed in acetic acid. When the ligand is present both in the acid and the neutral form, products of di- and oligocarbonylation are formed along with propionic acid and the polyketone. These products were characterized by¹H and¹³C NMR spectra as alternating keto acids C₂H₅(COCH₂CH₂)_nCOOH, wheren=1÷3. Kinetic equations were derived for the selective synthesis of propionic acid and polyketones.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 401–404, March, 1994.The authors are grateful to V. A. Zavel'skii who recorded the 1H NMR spectra on a Bruker CXP-200 spectrometer.