Cobalt(II) naphthenate is a mixture of

cobalt Cobalt is a chemical element with the symbol Co and atomic number 27. As with nickel, cobalt is found in the Earth's crust only in a chemically combined form, save for small deposits found in alloys of natural meteoric iron. The free element, pr ...

(II) derivatives of

naphthenic acid Naphthenic acids (NAs) are a 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. McKee et ...

s. These

coordination complex A coordination complex consists of a central atom or ion, which is usually metallic and is called the ''coordination centre'', and a surrounding array of bound molecules or ions, that are in turn known as ''ligands'' or complexing agents. Many ...

es are widely used as

oil drying agent An oil drying agent, also known as siccative, is a coordination compound that accelerates ( catalyzes) the hardening of drying oils, often as they are used in oil-based paints. This so-called "drying" (actually a chemical reaction that produces an ...

s for the autoxidative crosslinking of

drying oil A drying oil is an oil that hardens to a tough, solid film after a period of exposure to air, at room temperature. The oil hardens through a chemical reaction in which the components crosslink (and hence, polymerize) by the action of oxygen (not ...

s. Metal naphthenates are not well defined in conventional chemical sense that they are mixtures. They are widely employed

catalyst Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recyc ...

s because they are soluble in the nonpolar substrates, such as the

alkyd An alkyd is a polyester resin modified by the addition of fatty acids and other components. Alkyds are derived from polyols and organic acids including dicarboxylic acids or carboxylic acid anhydride and triglyceride oils. The term ''alkyd'' is a m ...

resins or

linseed oil Linseed oil, also known as flaxseed oil or flax oil (in its edible form), is a colourless to yellowish oil obtained from the dried, ripened seeds of the flax plant (''Linum usitatissimum''). The oil is obtained by pressing, sometimes followed by ...

. 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 is the organic compound with the formula CH3(CH2)3CH(C2H5)CO2H. It is a carboxylic acid that is widely used to prepare lipophilic metal derivatives that are soluble in nonpolar organic solvents. 2-Ethylhexanoic acid is a colo ...

. 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 is a salt with the formula Zn(CH3CO2)2, which commonly occurs as the dihydrate Zn(CH3CO2)2·2H2O. Both the hydrate and the anhydrous forms are colorless solids that are used as dietary supplements. When used as a food additive, it ...

. The catalytic properties of cobalt(II) naphthenates are similar to those of related compounds containing

manganese Manganese is a chemical element with the symbol Mn and atomic number 25. It is a hard, brittle, silvery metal, often found in minerals in combination with iron. Manganese is a transition metal with a multifaceted array of industrial alloy use ...

and

iron Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in f ...

. 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.

Toxicity and safety

Cobalt Naphthenate is a moderately toxic substance which can cause a range of acute and chronic conditions, and it is also a carcinogen. It is most commonly used diluted in mineral spirit or mineral oil. Safety equipment must be used to avoid eye and skin contact. The pure compound has a high vapor density of 3.9 (air = 1), and a low vapor pressure of 1 mm Hg at 25 °C (77 °F).https://nj.gov/health/eoh/rtkweb/documents/fs/0523.pdf

References

{{reflist Salts of carboxylic acids Cobalt(II) compounds