Cobalt(II) naphthenate
Encyclopedia
Cobalt naphthenate is a mixture of cobalt
(II) derivatives of naphthenic acid
s. These coordination complexes are widely used as oil drying agent
s for the autoxidative
crosslinking of drying oil
s. Metal naphthenates are not well defined in conventional chemical sense that they are mixtures. They are widely employed catalysts because they are soluble in the nonpolar substrates, such as the alkyd
resins or linseed oil
. The fact that naphthenates are mixtures helps to confer high solubility. A second virtue of these species is their low cost. A well-defined compound that exhibits many of the properties of cobalt naphthenate is the cobalt(II) complex of 2-ethylhexanoic acid
. Often in technical literature, naphthenates are described as salts, but they are probably also non-ionic coordination complexes with structures similar to basic zinc acetate
.
The catalytic properties of cobalt(II) naphthenates are similar to those of related compounds containing manganese
and iron
. Such species are sometimes classified as active driers." Active driers are catalysts that feature redox-active metal centers. Such centers promote redox reactions with hydroperoxide-containing intermediates.
Cobalt
Cobalt is a chemical element with symbol Co and atomic number 27. It is found naturally only in chemically combined form. The free element, produced by reductive smelting, is a hard, lustrous, silver-gray metal....
(II) derivatives of naphthenic acid
Naphthenic acid
Naphthenic acid is the name for an unspecific mixture of several cyclopentyl and cyclohexyl carboxylic acids with molecular weight of 120 to well over 700 atomic mass units. The main fraction are carboxylic acids with a carbon backbone of 9 to 20 carbons. The naphtha fraction of the crude oil...
s. These coordination complexes are widely used as oil drying agent
Oil drying agent
An oil drying agent is a coordination compound that accelerates the hardening of drying oils through chemical crosslinking. The catalysts affect the autoxidation of the oils with air...
s for the autoxidative
Autoxidation
Autoxidation is any oxidation that occurs in open air or in presence of oxygen and/or UV radiation and forms peroxides and hydroperoxides. A classic example of autoxidation is that of simple ethers like diethyl ether, whose peroxides can be dangerously explosive. It can be considered to be a slow,...
crosslinking of drying oil
Drying oil
A drying oil is an oil that hardens to a tough, solid film after a period of exposure to air. The oil hardens through a chemical reaction in which the components crosslink by the action of oxygen . Drying oils are a key component of oil paint and some varnishes...
s. Metal naphthenates are not well defined in conventional chemical sense that they are mixtures. They are widely employed catalysts because they are soluble in the nonpolar substrates, such as the alkyd
Alkyd
An alkyd is a polyester modified by the addition of fatty acids and other components. They are derived from polyols and a dicarboxylic acid or carboxylic acid anhydride. The term alkyd is a modification of the original name "alcid", reflecting the fact that they are derived from alcohol and...
resins or linseed oil
Linseed oil
Linseed oil, also known as flaxseed oil, is a clear to yellowish oil obtained from the dried ripe seeds of the flax plant . The oil is obtained by cold pressing, sometimes followed by solvent extraction...
. The fact that naphthenates are mixtures helps to confer high solubility. A second virtue of these species is their low cost. A well-defined compound that exhibits many of the properties of cobalt naphthenate is the cobalt(II) complex of 2-ethylhexanoic acid
2-Ethylhexanoic acid
2-Ethylhexanoic acid is the organic compound with the formula CH33CHCO2H. This carboxylic acid is widely used to prepare metal derivatives that are soluble in nonpolar organic solvents. These lipophilic metal-containing derivatives are used as catalysts in polymerizations. For example, tin...
. Often in technical literature, naphthenates are described as salts, but they are probably also non-ionic coordination complexes with structures similar to basic zinc acetate
Zinc acetate
Zinc acetate is the chemical compound with the formula Zn2, which commonly occurs as a dihydrate Zn22. Both the hydrate and the anhydrous forms are colorless solids that are commonly used in chemical synthesis and as dietary supplements. Zinc acetates are prepared by the action of acetic acid on...
.
The catalytic properties of cobalt(II) naphthenates are similar to those of related compounds containing manganese
Manganese
Manganese is a chemical element, designated by the symbol Mn. It has the atomic number 25. It is found as a free element in nature , and in many minerals...
and iron
Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...
. Such species are sometimes classified as active driers." Active driers are catalysts that feature redox-active metal centers. Such centers promote redox reactions with hydroperoxide-containing intermediates.