Dimer acids, or dimerized fatty acids, are dicarboxylic acids prepared by dimerizing unsaturated fatty acids obtained from tall oil, usually on clay catalysts. The CAS number of the material is [61788-89-4]. Dimer acids are used primarily for synthesis of polyamide resins and polyamide hot melt adhesives. They are also used in alkyd resins, adhesives, surfactants, as fuel oil additives, lubricants, etc.[1] It is a light yellow or yellow viscous transparent liquid.
Dimer acid usually contains predominantly a dimer of oleic acid. It is also called C36 dimer acid.[2]
Trimer acid is a corresponding material where the resulting molecule consists of three fatty acid molecules. Its CAS number is [68937-90-6].
Dimer acids can be converted to dimer amines by reaction with ammonia and subsequent reduction.
Production
editDimer fatty acids are produced from different fatty acids by heating. Necessary are a fatty acid with conjugated double bonds or other unsaturated fatty acids. Examples of such fatty acids are conjugated linoleic acids. The reaction is carried out via Diels-Alder addition, whereby a partially unsaturated C6 ring is formed.[3] Besides the dimer, trimers as well as (unreacted) monomers of the fatty acids may be present in the mixture.
References
edit- ^ [1] Archived December 4, 2008, at the Wayback Machine
- ^ C36 Dimer acid | 61788-89-4
- ^ Walter Krauß (1998), Bindemittel für lösemittelhaltige und lösemittelfreie Systeme (in German) (2., erw. und neubearb. ed.), Stuttgart u. a.: Hirzel, p. 186, ISBN 3-7776-0886-6
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