{{Short description|Class of chemical compounds}} [[File:Dimerfettsäure Strukturformel.svg|thumb|360px|Simplified structural formula of a dimer fatty acid. The structure may vary depending on the raw materials used. Characteristic is the cyclohexene ring formed by the Diels-Alder reaction.]] '''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.<ref>[http://www.kodia.com.cn/DIMER_ACID.htm] {{webarchive |url=https://web.archive.org/web/20081204062424/http://www.kodia.com.cn/DIMER_ACID.htm |date=December 4, 2008 }}</ref> 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'''.<ref>[http://www.chemicalbook.com/ChemicalProductProperty_EN_CB51011196.htm C36 Dimer acid | 61788-89-4<!-- Bot generated title -->]</ref>
'''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 == Dimer 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.<ref>{{citation|surname1=Walter Krauß|title=Bindemittel für lösemittelhaltige und lösemittelfreie Systeme|edition=2., erw. und neubearb.|publisher=Hirzel|location=Stuttgart u. a.|at=p. 186|isbn=3-7776-0886-6|date=1998|language=German }}</ref> Besides the dimer, trimers as well as (unreacted) monomers of the fatty acids may be present in the mixture.
==References== {{Reflist}}
Category:Fatty acids Category:Dicarboxylic acids Category:Monomers
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