The reaction of phenylacetylene carbonylation to phenyl maleate, phenyl fumarate, and dimethoxylactone in the homogeneous catalytic system PdI 2 -KI-O 2 -NaOAc in methanol solution was found to exhibit oscillations in the redox potential, pH, and rate of gaseous CO-O 2 mixture consumption. This is the first example of an oscillating chemical reaction in typical metal-complex catalysis where a complex organic molecule is formed from simple reactants in solutions of metal complexes. Oscillations were observed for 3.5 h up to 95% conversion of alkyne. The oxidation of CO to CO 2 occurs in parallel with carbonylation. The products were analyzed by NMR spectroscopy and GLC coupled with mass spectrometry. The compositions of the gas and liquid phases were controlled by GC and GLC, respectively. The range of NaOAc concentrations within which oscillations were observed was found to be very narrow: from 0 to 0.01 mol/L. It was shown that oxygen transfer through the phase boundary is not a cause of oscillations. The run where PdI 2 was replaced by K 2 Pd 2 I 4 exhibited oscillations similar in shape and amplitude. A reaction scheme was proposed, which includes the processes of Pd(II) reduction to the active catalysts of carbonylation, Pd(I) complexes, followed by the oxidation of palladium(I) complexes by iodine.Nearly all homogeneous oscillating reactions, like the Belousov-Zhabotinsky or Briggs-Rauscher systems, are facile oxidations of organic or inorganic substrates (malonic, citric, and oxalic acids, acetone, phenols, benzaldehyde, NADH, Br -, I -, SO 3 2-, S 2 O 3 2-, Sn(II), and HS -) by strong oxidants (KBrO 3 , KIO 3 , H 2 O 2 , and O 2 ) catalyzed by metal ions (Ce(IV)/Ce(III), Mn(III)/Mn(II), Fe(III)/Fe(II), Co(III)/Co(II)). 1 In these reactions, metal ions play the role of one-electron oxidants. Until recently, no oscillations were reported for typical reactions catalyzed by metal complexes (e.g., hydrogenation, cyclization, hydroformylation, carbonylation, polymerization, metathesis, etc.) where an organic molecule is built from simpler blocks (reactants) in solutions of metal complexes. 2Here we show that chemical oscillations in such reactions are possible. We report a new homogeneous oscillating reaction of alkyne carbonylation in the presence of palladium complexes and propose the mechanistic scheme that accounts for the complex dynamic behavior of this system.Our study of oxidative alkyne carbonylation in the catalytic system PdI 2 -KI-O 2 -MeOH, which was described earlier by other researchers, 3 revealed the oscillating behavior of the system with PhCtCH in the presence of small amounts of NaOAc. The reaction occurs in a well-stirred batch reactor at 40°C under atmospheric pressure of the CO-O 2 mixture (1: 1).In a typical run, PdI 2 (0.1 mmol), KI (4 mmol), and NaOAc (0.024 mmol) were dissolved in 8 mL of MeOH with vigorous stirring for 15 min. In due course of the reaction, the reactor was purged with the CO-O 2 mixture. Then, phenylacetylene dissolved in 2 mL of MeOH was added into the solution. The ...
