Synthesis of pseudo‐telechelic diols by transesterification and thiol‐ene coupling

Abstract

Transesterification of methyl esters of rapeseed oil with ethylene glycol in excess led to a v-hydroxy fatty ester with a yield of 90%. 2-Mercaptoethanol was grafted onto the double bonds of this v-hydroxy fatty ester by UV initiated thiol-ene coupling under mild conditions. Double bond conversion was found to be quantitative and yielded a polyol with average of two primary hydroxyl functions. This pseudo-diol was characterized by means of NMR spectroscopy, titration and mass spectroscopy (MS) and was used to synthesize polyurethane (PU) by step growth polyaddition with methylene diphenyl-4,4 0 -diisocyanate. The polymer, analyzed by thermogravimetric analysis (TGA) and DSC, showed a glass transition temperature of À38C, close to the one measured (88C) on a PU based on a commercial polyol, Desmophen 1150.Practical application: The products of the chemistry described in this contribution, i.e. polyol from vegetable oils derivatives, provide biobased building blocks for further PUs syntheses by reaction with diisocyanates. The obtained PUs are partially biobased and may be applied as binders and coatings.

Monomers and polymers from plant oils via click chemistry reactions

“…Later, rapeseed oil was also transformed into polyols applying the same approach. 41 A dramatic reduction of the thiol-ene addition reaction time was reported by Cramail and coworkers when carried out the functionalization of similar oleic acid-based structures with 1,5-pentanediol (M27) and polyethyleneglycols of different length (13 and 45 repeating units, M29 and M30) spacers. 39 Using photochemical initiation (225 nm) and a thiol to C@C molar ratio of 6:1, 90% conversion determined by 1 H NMR spectroscopy was achieved at 0 C after 2 h demonstrating a temperature effect in the dissociation rate of the radical generated from addition of thiyl radicals to C@C bonds.…”

Vegetable oils: a source of polyols for polyurethane materials

“…Boutevin and coll. have used a similar strategy to prepare symmetrical diester diols by transesterification of methyl oleate with ethylene glycol followed by a grafting of 2-mercaptoethanol onto the double bonds using thiol-ene click chemistry (Desroches et al, 2012b). The diester diols appeared not pure enough to synthesize TPUs.…”

Synthesis of new polyurethanes from vegetable oil by thiol-ene coupling

“…51 The objective of this study is to functionalize the vegetable oils by thiol-ene coupling; a comprehensive model study of experimental conditions on oleic acid was previously performed to identify all the by-products and determine the fundamental parameters improving the yield of functionalization. 47,52,53 Indeed, the grafting of mercaptoethanol on the internal bonds of the fatty acids leads to side-reactions, such as the formation of disulfides or intermolecular coupling reactions. These side-reactions have no direct impact on the use of the product since they are reproducible and lead to the formation of polyols which take part in the polymer network.…”