Long-chain polyesters and polyamides from biochemically derived fatty acids Nicolai Kolb a , Matthias Winkler a , Christoph Syldatk b , Michael A.R. Meier a,⇑ a Karlsruhe Institute of Technology, Institute of Organic Chemistry, Fritz-Haber-Weg-6, Building 30.42, 76131 Karlsruhe, Germany b Karlsruhe Institute of Technology, Institute of Bio- and Food Technology, Technical Biology, Engler-Bunte-Ring 1, Building 40.11, 76131 Karlsruhe, Germany article info Article history: Received 17 August 2013 Received in revised form 1 November 2013 Accepted 9 November 2013 Available online 21 November 2013 Keywords: Fatty acids Renewable polyester and polyamides Long-chain monomers Renewable resources Sophorose lipids abstract Here, we describe the use of biochemically derived fatty acid derivatives (x- and x-1 hydroxy fatty acid methyl esters) as starting materials for renewable polyesters and polya- mides. The required long-chain monomers were obtained by chemical derivatization of biochemically derived fatty acids. Thus, a long chain diester and a x-amino fatty acid methyl ester were synthesized and used to prepare polyester PE 32–34:32–34 and polyam- ide PA 16. The polyester was prepared by transesterification using 5 mol% of the catalyst tin(II) 2-ethylhexanoate (Sn(Oct) 2 ), leading to an average molecular weight of M n = 7.4 kDa and a melting point of 109 °C. PA 16 was prepared by amidation using TBD as catalyst and resulting in an average molecular weight of M n = 20.3 kDa and a melting point of 166 °C. Ó 2013 Elsevier Ltd. All rights reserved. 1. Introduction With the ongoing decrease of fossil resources, it is one of the biggest challenges of science in general, and chemis- try in particular, to develop and establish sustainable alter- natives. Within this context, fatty acids have been proven as an ideal renewable starting material for the synthesis of monomers and polymers [1,2]. Many derivatization reactions of fatty acids for the synthesis of valuable mono- mers are reported, for instance using thiol-ene addition reactions [3–13] or ruthenium-catalyzed olefin (cross)- metathesis [14–22]. However, for these derivatizations the double bond of unsaturated fatty acids at a specific po- sition within the aliphatic chain is usually used as reactive site, which limits the scope of the obtained monomers. Thus, the longest yet produced diesters using self-metath- esis reactions have 20 (from undecenoic acid) [21,23] or 26 (from erucic acid) [24] carbon units. A very promising ap- proach was presented by Mecking and coworkers, who isomerized the double bond of methyl oleate using a palla- dium catalyst; the subsequent methoxycarbonylation reaction then occurs only at the terminal position of the fatty acid chain. The resulting C 19 a,x-diester [25,26] can be used to prepare long-chain polyesters that are close to polyethylene in terms of their thermal properties. More- over, Mecking and coworkers showed that the melting point of long-chain polyesters increases with longer ali- phatic chains [27]. Long-chain linear polyamides are also of high interest since, due to reduced hydrogen bonding in relation to the carbon chain length, such long chain polyamides profit from reduced water vapor uptake and molded parts show no or only little dimensional changes with variation of the atmospheric humidity. Additionally, the lower melting point caused by a reduced hydrogen bond frequency can lead to an easier processing of such polyamides. A com- mercially available long-chain linear polyamide is PA 12, which has a melting point of 180 °C. PA 12 is prepared on industrial scale via ring-opening polymerization of lau- ryl lactam, which can be prepared in a multiple step syn- thesis starting from butadiene [28]. In principle, PA 12 could also be prepared from the x-aminoundecanoic acid. 0014-3057/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.eurpolymj.2013.11.007 ⇑ Corresponding author. E-mail address: m.a.r.meier@kit.edu (M.A.R. Meier). URL: http://www.meier-michael.com (M.A.R. Meier). European Polymer Journal 51 (2014) 159–166 Contents lists available at ScienceDirect European Polymer Journal journal homepage: www.elsevier.com/locate/europolj