Synthesis of Novel Renewable Polyesters and Polyamides with Olefin Metathesis

Abstract

Unsaturated and hydroxyl-functionalized C6-dicarboxylic acids were successfully synthesized via olefin metathesis from methyl vinyl glycolate (MVG), a renewable α-hydroxy C4-ester product from Lewisacid carbohydrate conversion. Addition of a second-generation Hoveyda-Grubbs catalyst to neat MVG leads to a near quantitative yield of dimethyl-2,5-dihydroxy-3-hexenedioate (DMDHHD). Additional hydrolysis and hydrogenation steps form interesting polymer building blocks like 2,5-dihydroxy-3hexenedioic acid (DHHDA) and 2,5-dihydroxyadipic acid (DHAA). Their use in polyester and polyamide synthesis is demonstrated after determination of their physical and spectroscopic characteristics. Copolymerization of DHHDA with L-lactic acid for instance produces a crosslinked poly(L-lactic acid-co-DHHDA) polyester. Proof of crosslinks is ascertained by NMR and FT-IR. Substantial impact on the melting, thermal and polar properties of PLA are observed already at low amounts of DHHDA (0.1 mol%) in accord with the presence of crosslinks in the polymer. Bio-based polyamides were also synthesized by equimolar reaction of DHHDA with hexamethylenediamine, producing a renewable polyamide analogue of the petroleum-based nylon 6,6. Interestingly, the assynthesized polyamide (α-bishydroxylated unsaturated polyamide, HUPA) possesses similar thermal stability as nylon 6,6 but shows different chemical properties as a result of the double bond and αhydroxy functionality.

Synthesis of a novel polyester building block from pentoses by tin-containing silicates

“…23 Additionally, it has recently been reported that MVG can be converted into dimethyl (E)-2,5-dihydroxyhex-3-enedioate, via a metathesis reaction. 57,58 This new product has also been successfully co-polymerised with lactic acid. 57 In contrast to MVG, DPM contains both a secondary and a primary alcohol, which prevents the use of classical polymerisation catalysts due to poor selectivity control.…”

“…57,58 This new product has also been successfully co-polymerised with lactic acid. 57 In contrast to MVG, DPM contains both a secondary and a primary alcohol, which prevents the use of classical polymerisation catalysts due to poor selectivity control. However, enzymatic polymerisation methods permit polymerisation of such highly functional monomers.…”

Active Site Hydration Governs the Stability of Sn-Beta during Continuous Glucose Conversion

“…Of particular interest is the conversion of highly functionalised molecules such as glucose and fructose, which can be obtained following depolymerisation of cellulose. In this respect, the heterogeneous catalyst Sn-Beta (Sn- is of prime interest, having been shown to be highly active and selective for a range of processes such as i) fructose production via glucose-fructose isomerisation; [6][7][8][9][10] ii) the generation of renewable monomers such as alkyl lactates, 11,12 furanics 13,14 and methyl vinyl glycolate; [15][16] iii) the H2free reduction of carbonyl compounds via catalytic transfer hydrogenation; 17 and the Baeyer-Villiger oxidation of (renewable) ketones with H2O2 as oxidant. [18][19][20] Possessing an ability to operate continuously, without exhibiting excessive levels of deactivation, is one of the most important properties a promising heterogeneous catalyst must exhibit, in order to be suitable for industrialization.…”

Overcoming catalyst deactivation during the continuous conversion of sugars to chemicals: maximising the performance of Sn-Beta with a little drop of water

“…16,17 Additionally, methyl lactate (ML) is a very attractive bio-monomer for the production of renewable plastics, and other co-products formed during ML production, such as methyl vinyl glycolate (MVG), also have potential for application in the bio-polymers industry. 18,19 Each of these processes are best catalysed by a Sn-modified Beta zeolite (Sn-Beta), 20 widely accepted to be the state of the art heterogeneous catalyst for sustainable chemical processing, and are typically performed in polar solvents such as methanol or water. Scheme 1.…”