The mechanism of cobalt drier action

Abstract

The influence of cobalt driers on the initial stages of the drying of polyunsaturated esters has been studied. Cobalt (II) appears to form an unstable complex of variable composition with the polyunsaturated ester. This complex catalyzes the uptake of oxygen and increases the rate of oxygen absorption by the ester. The energy of activation for oxygen uptake by the ester in the presence of cobalt is only ].3 kcal/mole, while in the absence of cobalt, the activation energy is 10.8 keal/mole. The absorption of oxygen by the ester is followed by the formation of hydroxy and/or hydroperoxy groups, the loss of alkene groups, an increase in conjugation and conversion from the cis to the trans isomer. Polymerization occurs during these latter changes.

Synthesis and characterization of iron carbonyl‐modified hydroxyl‐terminated polybutadiene: A catalyst‐bound propellant binder for burn‐rate augmentation

“…The second sharp exotherm was followed by the usual broad exotherms attributed13, 35, 36 to major oxidative degradations of HTPB involving chain unzipping. The catalytic action of Fe on the thermooxidative degradation of HTPB is ascribed to the various faster electron‐transfer reactions between HTPB and the bound Fe, as reported in the literature30–32, 37–40 for simple organic compounds. Even though Fe in HTPB→[Fe (CO) 3 ] x is expected to have a zero‐valence state, it appears that some of the Fe is also in the oxidized state, as the resin showed the characteristic color reaction13 with the phenolic derivative added as a stabilizer.…”

The influence of lead ions on the drying of oils

“…Driers may act in different ways to alter the drying behavior of oils and they may either increase the oxygen uptake through catalytic action or they may reduce the time when oxygen uptake begins (the induction period) through precipitation or deactivation of antioxidants [14,15]. Beginning in the 1950s, studies have revealed that in some cases the metal driers may form complexes that lower the activation energy for oxygen uptake [14,16], while calcium, zinc and zirconium as well as transition metals can act as secondary or auxiliary catalysts and promote the decomposition of hydroperoxides into…”

“…Beginning in the 1950s, studies have revealed that in some cases the metal driers may form complexes that lower the activation energy for oxygen uptake [14,16], while calcium, zinc and zirconium as well as transition metals can act as secondary or auxiliary catalysts and promote the decomposition of hydroperoxides into…”

Synthesis and characterization of poly(vinyl ferrocene) grafted hydroxyl-terminated poly(butadiene): A propellant binder with a built-in burn-rate catalyst

“…2) of HTPB was attributed to oxygen uptake via hydroperoxidation and peroxidation reactions [21][22][23][24][25][26][27] as depicted in Scheme 1. However, this temperature decreased to 156°C in HTPB-g-PVF (Fig.…”