chemistry Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science that covers the Chemical element, elements that make up matter to the chemical compound, compounds made of atoms, molecules and ions ...

, a fatty amine is loosely defined as any amine possessing a mostly linear hydrocarbon chain of eight or more carbon atoms. They are typically prepared from the more abundant fatty acids, with vegetable or seed-oils being the ultimate starting material. As such they are often mixtures of chain lengths, ranging up to about C22. They can be classified as oleochemicals. Commercially important members include coco amine, oleylamine, tallow amine, and soya amine. These compounds and their derivatives are used as fabric softeners, froth flotation agents (purification of ores), corrosion inhibitors, lubricants and friction modifiers. They are also the basis for a variety of cosmetic formulations.

Production and reactions

Fatty amines are commonly prepared from fatty acids; which are themselves obtained from natural sources, typically seed-oils. The overall reaction is sometimes referred to as the Nitrile Process and begins with a reaction between the fatty acid and ammonia at high temperature (>250 °C) and in the presence of a metal oxide catalyst (e.g., alumina or zinc oxide) to give the fatty

nitrile In organic chemistry, a nitrile is any organic compound that has a functional group. The prefix ''cyano-'' is used interchangeably with the term ''nitrile'' in industrial literature. Nitriles are found in many useful compounds, including met ...

. : RCOOH + NH₃ → RC≡N + 2 H₂O The fatty amine is obtained from this by hydrogenation with any of a number of reagents, including Raney nickel or cobalt, and copper chromite catalysts. When conducted in the presence of excess ammonia the hydrogenation affords the primary amines. : RCN + 2 H₂ → RCH₂NH₂ In the absence of ammonia, secondary and tertiary amines are produced. :2 RCN + 4 H₂ → (RCH₂)₂NH + NH₃ :3 RCN + 6 H₂ → (RCH₂)₃N + 2 NH₃

Fatty secondary and tertiary amines

Alternatively, secondary and tertiary fatty amines can be generated by the reaction of

fatty alcohol Fatty alcohols (or long-chain alcohols) are usually high-molecular-weight, straight-chain primary alcohols, but can also range from as few as 4–6 carbons to as many as 22–26, derived from natural fats and oils. The precise chain length varies ...

s and fatty alkyl bromides with (di)alkylamines. For example 1-bromododecane reacts with dimethyl amine: :RBr + HNMe₂ → RNMe₂ + HBr By reaction with tertiary amines, long-chain alkyl bromides give quaternary ammonium salts, which are used as phase transfer catalysts. Secondary and tertiary amines may also be produced by the Leuckart reaction. This reaction effects N-methylation using formaldehyde with

formic acid Formic acid (), systematically named methanoic acid, is the simplest carboxylic acid, and has the chemical formula HCOOH and structure . It is an important intermediate in chemical synthesis and occurs naturally, most notably in some ants. Es ...

as the reductant. These tertiary amines are precursors to quaternary ammonium salts used for a variety of applications.

Applications and derivatives

The main application of fatty amines is for the production of the corresponding quaternary ammonium salts, which are used as fabric softeners and

hair conditioner Hair conditioner is a hair care cosmetic product used to improve the feel, texture, appearance, and manageability of hair. Its main purpose is to reduce friction between strands of hair to allow smoother brushing or combing, which might otherwise ...

s (e.g. Behentrimonium chloride). Fatty amines are also used in froth flotation, for the beneficiation of various ores. The amines bind to the surfaces of certain minerals allowing them to be readily separated from those lacking the bound amine. They are also additives in the production of asphalt.

References

{{Reflist Amines