Studies of Polymer-Metal Catalysts. Isotactic and Atactic Polyacrlamidoxime-Co(ll) Chelates as Catalysts for the Oxidative Coupling of 2,6-XYLENQL

Abstract

The catalytic behavior of isotactic (isot) and atactic (at) PAAO-Co(I1) chelates as catalysts for oxidative coupling of 2,6-xylenol has been examined. The experimental results show that these reactions follow the Michaelis-Menten mechanism and may be described by Compound E' is quickly oxidized to E. The second reaction is the ratedetermining step. At 30,35, and 40°C, the rate constant k2 equals 0.274, 0.304, and 0.450 min-' for 2,6-xylenol-isot-PAAO-Co(II) and 0.1 89, 0,284, and 0.335 min-' for 2,6-xylenol-at-PAAO-Co(II), respectively. It is obvious that the isotactic chelate is more catalytically active than the atactic one. The negative values found for AG show that the formation of the catalyst-substrate complexes may take place spontaneously. This may be mainly attributed to the entropy increase. On the other hand, since the main chains of isot-PAAO-Co(I1) are more regularly helicoidal in the reactions, it has lower entropy in the initial 243