Naphthenic acid
Encyclopedia
Naphthenic acid is the name for an unspecific mixture of several cyclopentyl
Cyclopentane
Cyclopentane is a highly flammable alicyclic hydrocarbon with chemical formula 510 and CAS number 287-92-3, consisting of a ring of five carbon atoms each bonded with two hydrogen atoms above and below the plane. It occurs as a colorless liquid with a petrol-like odor. Its melting point is −94 °C...

 and cyclohexyl
Cyclohexane
Cyclohexane is a cycloalkane with the molecular formula C6H12. Cyclohexane is used as a nonpolar solvent for the chemical industry, and also as a raw material for the industrial production of adipic acid and caprolactam, both of which being intermediates used in the production of nylon...

 carboxylic acids with molecular weight of 120 to well over 700 atomic mass unit
Atomic mass unit
The unified atomic mass unit or dalton is a unit that is used for indicating mass on an atomic or molecular scale. It is defined as one twelfth of the rest mass of an unbound neutral atom of carbon-12 in its nuclear and electronic ground state, and has a value of...

s. The main fraction are carboxylic acids with a carbon backbone of 9 to 20 carbons. The naphtha
Naphtha
Naphtha normally refers to a number of different flammable liquid mixtures of hydrocarbons, i.e., a component of natural gas condensate or a distillation product from petroleum, coal tar or peat boiling in a certain range and containing certain hydrocarbons. It is a broad term covering among the...

 fraction of the crude oil refining is oxidized and yields naphthenic acid. The composition differs with the crude oil composition and the conditions during refining and oxidation.
Naphthenic acids are present in crude oil and leads to corrosion problems within the oil refineries
Oil refinery
An oil refinery or petroleum refinery is an industrial process plant where crude oil is processed and refined into more useful petroleum products, such as gasoline, diesel fuel, asphalt base, heating oil, kerosene, and liquefied petroleum gas...

, therefore "naphthenic acid corrosion" phenomena are well researched.
Crude oils with a high content of naphthenic acids are often referred to as high TAN (Total Acid Number) crude oils or high acid crude oil (HAC
HAC
HAC may refer to:* Hackney Downs railway station, London; National Rail station code HAC* Le Havre Athletic Club a professional football club in France.* Hectare* High Acid Crude oil a crude oil with a high concentration of Naphthenic acids...

). There is also a conference called the High TAN Crude Conference which was first organized in 2005.

Mixtures of a flammable substance and naphthenic and palmitic acid
Palmitic acid
Palmitic acid, or hexadecanoic acid in IUPAC nomenclature, is one of the most common saturated fatty acids found in animals and plants. Its molecular formula is CH314CO2H. As its name indicates, it is a major component of the oil from palm trees . Palmitate is a term for the salts and esters of...

 aluminium salts were discovered during World War II to make napalm
Napalm
Napalm is a thickening/gelling agent generally mixed with gasoline or a similar fuel for use in an incendiary device, primarily as an anti-personnel weapon...

. These acids caused flammable hydrocarbons to gel.

Other uses of naphthenic acids depend on the refinement of the material. Naphthenic acids are used as a source material in the manufacture of corrosion inhibitors, wood preservatives, lubricant and fuel additives, driers for paints and inks, and in the production of metal soaps.

Naphthenates

Naphthenates are the salts of naphthenic acids. These salts have industrial applications including synthetic detergent
Detergent
A detergent is a surfactant or a mixture of surfactants with "cleaning properties in dilute solutions." In common usage, "detergent" refers to alkylbenzenesulfonates, a family of compounds that are similar to soap but are less affected by hard water...

s, lubricant
Lubricant
A lubricant is a substance introduced to reduce friction between moving surfaces. It may also have the function of transporting foreign particles and of distributing heat...

s, corrosion inhibitors, fuel and lubricating oil additives, wood preservations, insecticide
Insecticide
An insecticide is a pesticide used against insects. They include ovicides and larvicides used against the eggs and larvae of insects respectively. Insecticides are used in agriculture, medicine, industry and the household. The use of insecticides is believed to be one of the major factors behind...

s, fungicide
Fungicide
Fungicides are chemical compounds or biological organisms used to kill or inhibit fungi or fungal spores. Fungi can cause serious damage in agriculture, resulting in critical losses of yield, quality and profit. Fungicides are used both in agriculture and to fight fungal infections in animals...

s, acaricides, wetting agents, and 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 used in painting and wood surface treatment.

Industrially useful naphthenates include barium naphthenate, calcium naphthenate, cobalt naphthenate, copper naphthenate, lead naphthenate, magnesium naphthenate, manganese naphthenate, nickel naphthenate, sodium naphthenate, vanadyl naphthenate and zinc naphthenate.

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