Biobased Epoxy Resin by Electrochemical Modification of Tall Oil Fatty Acids

Abstract

A biobased epoxy resin was prepared from tall oil fatty acids (TOFAs), a byproduct of the pulping industry. As free carboxylic acids compromise resin stability, TOFA was subjected to non-Kolbe decarboxylation to give alkenes upon loss of CO2. Thereby, the degree of unsaturation is significantly increased. This electrosynthetic protocol using an undivided cell setup and inexpensive graphite electrodes in a galvanostatic operation mode was scaled to a 1.5 L reactor, making use of electric current as a green and waste-free reagent. Simple, cost-efficient epoxidation using oxone subsequently gives an epoxy resin of low viscosity. Curing with anhydrides yields thermoset materials. Dynamic mechanical analyses and tensile and flexural tests were conducted to determine the effect of different curing agents on the thermomechanical properties. For methyl tetrahydrophthalic anhydride (MTHPA) and methyl-5-norbornene-2,3-dicarboxylic anhydride (MNA), good mechanical properties were observed, whereas dodecenyl succinic anhydride (DDSA) resulted in a brittle material with low T g.

(Non-)Kolbe electrolysis in biomass valorization – a discussion of potential applications

“…However, this has significantly changed; today, a growing number of studies focus on the necessary understanding and applicability in bio-refineries. 18,25,26,[61][62][63] This chapter aims to recapitulate the literature concerning (Non-)Kolbe electrolysis since 2000, devoting special attention to green and economical approaches, in particular the conversion of biogenic acids into fuels, platform chemicals and value-added compounds. The chapter will be organized with respect to general feasibility e.g.…”

“…de Kruijff et al reported a suitable replacement for the harmful bisphenol A resins (bisphenol A diglycidyl ether) through the production of epoxy resins from lignocellulosic biomass. 63 The novel resins could be obtained from tall oil fatty acids via Non-Kolbe electrolysis (81% ethers and olefins) and subsequent epoxidation with oxone (99%). The Non-Kolbe operation mode enabled a scale up of up to three orders of magnitude (5 mL to 1.5 L).…”

“…The obtained epoxy resins exhibited good mechanical properties and storage moduli, particularly if the curing was conducted with MTHPA. 63 When using an aqueous electrolyte in combination with ultrasound, triglycerides were converted into olefins, glycerol, and oleic acid. However, high conversions (>95%) of oleic-and stearic acid could be only achieved when applying four equivalents of Farad charge (20% faradaic efficiency) ( Fig.…”

“…In addition, specifically designed electrolytes could add to reaction performance, enable facilitated product recovery and reduce the environmental foot print of (Non-)Kolbe electrolysis. Novel value chains based on carboxylic acids readily available in the form of plant based fatty acids 63,100,101,105 and via the fermentation of various feedstocks such as biomass, [24][25][26][114][115][116][117][118] CO x and even plastic wastes remain yet to be explored.…”

Recent Advances in Electrochemical Chalcogen (S/Se)‐Functionalization of Organic Molecules

“…Electrosynthesis has contributed to the new generation of organic chemistry procedures, offering elegant synthetic routes with excellent atom economy, without the need for expensive oxidants, catalysts or ligands, thus being framed within the green chemistry principles . Using electric current as a reagent, a clean and efficient alternative is obtained for large transformations, allowing controlled reactions to be carried out via radical cation or radical anion intermediates in organic synthesis.…”