Name: designed for molecular recycling: a lignin-derived semi-aromatic biobased polymer
Uploaded: 2020-11-30T14:00:00
Description: Watch this Scientific Journal Video about Designed for Molecular Recycling: A Lignin-Derived Semi-aromatic Biobased Polymer at JoVE.com

Författarna är tacksamma för det ekonomiska stödet från Nederländernas organisation för vetenskaplig forskning (NWO) (anslag 023.007.020 tilldelas Jack van Schijndel).

1. Grön Knoevenagelkondensering av syringaldehyd mot sinapinsyra med 5 mol% ammoniumbikarbonat
<ol><li>Tillsätt äppelsyra (20,81 g, 200,0 mmol) tillsammans med syringaldehyd (36,4 g, 200,0 mmol) till en kolv på 250 ml rund botten. Lös upp båda beståndsdelarna i 20,0 ml etylacetat och tillsätt ammoniumbikarbonat (790 mg, 10,0 mmol) till kolven. OBS: För att säkerställa full slutförande av kondensreaktionen kan den roterande förångaren användas för att destillera etylacetatet och koncentrera reaktionsb...

<ol>
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A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biorenewable+polyethylene+terephthalate+mimics+derived+from+lignin+and+acetic+acid.">Biorenewable polyethylene terephthalate mimics derived from lignin and acetic acid.</a> Green Chemistry. 12 (10), 1704 (2010).</li><li>Nguyen, H. T. H., Reis, M. H., Qi, P., Miller, S. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Polyethylene+ferulate+(PEF)+and+congeners:+polystyrene+mimics+derived+from+biorenewable+aromatics.">Polyethylene ferulate (PEF) and congeners: polystyrene mimics derived from biorenewable aromatics.</a> Green Chemistry. 17 (9), 4512-4517 (2015).</li><li>van Schijndel, J., Canalle, L. A., Molendijk, D., Meuldijk, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Green+Knoevenagel+Condensation:+Solvent-free+Condensation+of+Benzaldehydes.">The Green Knoevenagel Condensation: Solvent-free Condensation of Benzaldehydes.</a> Green Chemistry Letters and Reviews. 10 (4), 404-411 (2017).</li><li>van Schijndel, J., Molendijk, D., Spakman, H., Knaven, E., Canalle, L. A., Meuldijk, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanistic+considerations+and+characterization+of+ammonia-based+catalytic+active+intermediates+of+the+Green+Knoevenagel+reaction+of+various+benzaldehydes.">Mechanistic considerations and characterization of ammonia-based catalytic active intermediates of the Green Knoevenagel reaction of various benzaldehydes.</a> Green Chemistry Letters and Reviews. 12 (3), 323-331 (2019).</li><li>Sheldon, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fundamentals+of+green+chemistry:+efficiency+in+reaction+design.">Fundamentals of green chemistry: efficiency in reaction design.</a> Chemical Society Reviews. 41 (4), 1437-1451 (2012).</li><li>van Schijndel, J., Molendijk, D., Canalle, L. A., Rump, E. 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LC-copolyesters of 3-(4-hydroxyphenyl) propionic acid and 4-hydroxy benzoic acids.</a> Journal of Polymer Science Part A: Polymer Chemistry. 25 (2), 489-504 (1987).</li><li>Chen, Y., Tan, L., Chen, L., Yang, Y., Wang, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Study+on+biodegradable+aromatic/aliphatic+copolyesters.">Study on biodegradable aromatic/aliphatic copolyesters.</a> Brazilian Journal of Chemical Engineering. 25 (2), 321-335 (2008).</li><li>Han, X., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Change+in+Mechanism+from+Acidolysis+to+Phenolysis+in+the+Bulk+Copolymerization+of+4-Acetoxybenzoic+Acid+and+6-Acetoxy-2-naphthoic+Acid.">A Change in Mechanism from Acidolysis to Phenolysis in the Bulk Copolymerization of 4-Acetoxybenzoic Acid and 6-Acetoxy-2-naphthoic Acid.</a> Macromolecules. 29 (26), 8313-8320 (1996).</li><li>Lu, X. 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När dihydrosinapinsyra upphettades i ett reaktionskärl inträffade sublimering av utgångsmaterialet, och denna effekt förbättrades när ett vakuum applicerades. Acetylering har utförts på dihydrosinapinsyra för att undvika sublimering. Kricheldorf et al.12,27 erkände att inte bara acetylering men på samma sätt di- och oligomerization inträffade. Dessa föresmälta monomerer och oligomerer sublimerar dock inte längre och är lämpliga som monomerer f?...

I motsats till förbränning av polymeravfall erbjuder kemisk återvinning möjligheten att återvinna monomererna. Kemisk återvinning är ett logiskt val i slutet av det tekniska livet för polymera material eftersom dessa polymera material produceras kemiskt1. Det finns två sätt att återvinna det polymera materialet kemiskt, pyrolys och molekylär återvinning2. Med pyrolys omvandlas det polymera materialet till produkter av högre värde genom att använda extrema förhållanden3,4. Molekylär återvinning är en effektiv metod för återvinning av utgångsmaterial med hjälp av depolymerisering. Efter depolymerisering kan de monomeriska enheterna repolymeriseras till jungfruliga polymera material5. Tillgången på lämpliga monomerer för att applicera molekylär återvinning i större skala är att vilja. Det nuvarande plastproblemet dikterar att samhället kräver robusta och robusta polymera material. Samtidigt föredras det också att samma polymera material är lätt återvinningsbara och inte uthärdar i miljön. Nuvarande polymera material med goda termiska och mekaniska egenskaper avkopplar inte lätt6.
Lignin, som ofta finns i kärlväxter, står för 30% av världens naturliga kolhalt och är den näst vanligaste biopolymeren efter cellulosa. Lignin har en komplex amorf struktur och verkar vara ett lämpligt alternativ för att ersätta aromater extraherade från fossila material. Den tredimensionella strukturen av lignin ger styrka och styvhet mot trä, liksom motståndskraft mot nedbrytning. Kemiskt sett är lignin en mycket komplex polyfenol termosett. Den består av olika sammansättning av tre olika metoxilaterade fenylpropanstrukturer. Syringyl, guaiacyl och p-hydroxyphenyl (ofta förkortat S, G och H) härrör från monolignolerna sinapylalkohol, barralkohol respektive p-coumarylalkohol7. Fördelningen av dessa enheter varierar per biomassatyp, med barrved, till exempel bestående av mestadels guaiacylenheter och lövträ av guaiacyl- och syringylenheter8,9. Förnybara naturkällor, såsom träd och växter, är önskvärda för produktion av omdesignade monomerer för innovativa polymera material10. Dessa monomerer, isolerade och syntetiserade från naturliga källor, polymeriseras till så kallade biobaserade polymerer11.
Aromatiska karboxylsyror är flera storleksordningar mindre elektrofila än motsvarande alifatiska karboxylsyror av elektroniska skäl12. Olika kommersiella polyesterer använder aromatiska karboxylsyror istället för alifatiska karboxylsyror. Som ett resultat är fibrerna i polyestertextilier gjorda av poly (etylentereftalat) (PET) fibrer nästan okänsliga för hydrolys under tvättning eller till exempel regn13. När molekylär återvinning av polyester önskas är det lämpligt att använda alifatiska estrar vid uppbyggnaden av polymeren.
Av de nämnda orsakerna har vi undersökt möjligheterna att göra polyester från 4-hydroxy-3,5-dimethoxy-dihydrocinnamicsyror 14. Tidigare studier av Kricheldorf15, Meier16, och Miller17,18 visar att det är utmanande att bygga polymerer med 4-hydroxy-3,5-dimethoxy-dihydrocinnamic syra. Dekarboxylering och korslänkning hindrade polymerisationerna, och på så sätt begränsa framgången för dessa synteser. Mekanismen för polykondensationen förblev också oklar. Det presenterade dokumentet beskriver de förhållanden under vilka polyesterpoly (dihydrosinapinsyra) kan syntetiseras regelbundet och i högt utbyte, vilket banar väg för att använda semi-aromatiska polyesterer som är molekylärt återvinningsbara.
Vi har utvecklat ett grönt och effektivt sätt att syntetisera sinpinsyra med hjälp av en kondensationsreaktion mellan syringaldehyd och äppelsyra19,20. Efter denna gröna Knoevenagel producerar hydrogenering dihydrosinapinsyra, som är lämplig för reversibel polykondensation. Denna publikation visualiserar de syntetiska stegen till den molekylärt återvinningsbara polymerpoly (dihydrosinapinsyra), med hänvisning till basenheterna av lignin, kallad poly-S. Efter att ha analyserat det polymera materialet depolymeriseras poly-S till monomer dihydrosinapinsyran under relativt gynnsamma förhållanden och repolymeriseras om och om igen.

<table>
	<tbody>
		<tr>
			<td>Reaction 1: Green Knoevenagel condensation</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Ammonium bicarbonate</td>
			<td>Sigma Aldrich</td>
			<td>&#62;99%</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethanol</td>
			<td>Boom</td>
			<td>Technical grade</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethyl acetate</td>
			<td>Macron</td>
			<td>99.8%</td>
			<td></td>
		</tr>
		<tr>
			<td>Hydrochloric acid</td>
			<td>Boom</td>
			<td>37%</td>
			<td></td>
		</tr>
		<tr>
			<td>Malonic acid</td>
			<td>Sigma Aldrich</td>
			<td>99%</td>
			<td>used as received</td>
		</tr>
		<tr>
			<td>Sodium bicarbonate</td>
			<td>Sigma Aldrich</td>
			<td>&#62;99.7%</td>
			<td></td>
		</tr>
		<tr>
			<td>Syringaldehyde</td>
			<td>Sigma Aldrich</td>
			<td>98%</td>
			<td>used as received</td>
		</tr>
		<tr>
			<td>Reaction 2: Hydrogenation</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Magnesium sulfate</td>
			<td>Macron</td>
			<td>99%</td>
			<td>dried</td>
		</tr>
		<tr>
			<td>Raney&#8482; nickel</td>
			<td>Sigma Aldrich</td>
			<td>&#62;89%</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium hydroxide</td>
			<td>Boom</td>
			<td>Technical grade</td>
			<td>dissolved</td>
		</tr>
		<tr>
			<td>Reaction 3: Acetylation</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Acetic anhydride</td>
			<td>Macron</td>
			<td>&#62;98%</td>
			<td></td>
		</tr>
		<tr>
			<td>Acetone</td>
			<td>Macron</td>
			<td>&#62;99.5%</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium acetate</td>
			<td>Sigma Aldrich</td>
			<td>&#62;99%</td>
			<td></td>
		</tr>
		<tr>
			<td>Reaction 4A: Polymerisation</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>1,2-xylene</td>
			<td>Macron</td>
			<td>&#62;98%</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium hydroxide</td>
			<td>Boom</td>
			<td>Technical grade</td>
			<td>finely powdered</td>
		</tr>
		<tr>
			<td>Zinc(II)acetate</td>
			<td>Sigma Aldrich</td>
			<td>99.99%</td>
			<td></td>
		</tr>
		<tr>
			<td>Reaction 4B: Depolymerisation</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium hydroxide</td>
			<td>Boom</td>
			<td>Technical grade</td>
			<td>dissolved</td>
		</tr>
		<tr>
			<td>Sulfuric acid</td>
			<td>Macron</td>
			<td>100%</td>
			<td></td>
		</tr>
		<tr>
			<td>Analysis</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>CDCl3</td>
			<td>Cambride Isotope Laboratories, Inc.</td>
			<td>99.5%</td>
			<td></td>
		</tr>
		<tr>
			<td>CF3COOD</td>
			<td>Cambride Isotope Laboratories, Inc.</td>
			<td>98%</td>
			<td></td>
		</tr>
		<tr>
			<td>Dimethylformamide</td>
			<td>Macron</td>
			<td>&#62;99.9%</td>
			<td></td>
		</tr>
		<tr>
			<td>Hexafluoro-2-propanol</td>
			<td>TCI Chemicals</td>
			<td>&#62;99%</td>
			<td></td>
		</tr>
		<tr>
			<td>Methanol</td>
			<td>Macron</td>
			<td>&#62;99.8%</td>
			<td></td>
		</tr>
		<tr>
			<td>Tetrahydrofuran</td>
			<td>Macron</td>
			<td>&#62;99.9%</td>
			<td></td>
		</tr>
	</tbody>
</table>

designed for molecular recycling: a lignin-derived semi-aromatic biobased polymer

Utvecklingen av kemiskt återvinningsbara biopolymerer erbjuder möjligheter inom strävan efter en cirkulär ekonomi. Kemiskt återvinningsbara biopolymerer gör en positiv ansträngning för att lösa problemet med polymermaterial i bortskaffningsfasen efter användningsfasen. I detta dokument beskrivs och visualiseras produktionen av biobaserade semi-aromatiska polyesterer, som kan extraheras helt från biomassa som lignin. Polymerpoly-S som beskrivs i detta papper har termiska egenskaper som liknar vissa vanliga plaster, såsom PET. Vi utvecklade en grön Knoevenagel reaktion, som effektivt kan producera monomerer från aromatiska aldehyder och äppelsyra. Denna reaktion har visat sig vara skalbar och har en anmärkningsvärt låg beräknad E-faktor. Dessa polyesterer med ligno-fytokemikalier som utgångspunkt visar en effektiv molekylär återvinning med minimala förluster. Polyester poly(dihydrosinapinsyra) (poly-S) presenteras som ett exempel på dessa semi-aromatiska polyesters, och polymerisation, depolymerisering och re-polymerization beskrivs.

Sinapinsyra syntetiserades i hög renhet och högt utbyte (> 95%) från syringaldehyd med hjälp av green knoevenagelkondensationen. (Stöduppgifter: figur S1) E-faktorn är en indikation på avfallsproduktion där ett högre antal indikerar mer avfall. E-faktorn beräknas genom att ta den totala materialinmatningen, subtrahera mängden önskad slutprodukt och dividera helheten med mängden slutprodukt. Denna gröna Knoevenagel kondensation har en E-faktor på 1,0, som kan beräknas: [(((29,81 g äppelsy...

Watch this Scientific Journal Video about Designed for Molecular Recycling: A Lignin-Derived Semi-aromatic Biobased Polymer at JoVE.com

Designed for Molecular Recycling: A Lignin-Derived Semi-aromatic Biobased Polymer

Här beskrivs ett exempel på en sluten strategi för en cirkulär materialekonomi. En hel hållbar cykel presenteras där biobaserade semi-aromatiska polyesterer är utformade genom polymerisation, depolymerisering och sedan återpolymeriseras med endast små förändringar i deras utbyten eller slutliga egenskaper.

Utformad för molekylär återvinning: En Lignin-härledd semi-aromatisk biobaserad polymer

The development of chemically recyclable biopolymers offers opportunities within the pursuit of a circular economy. Chemically recyclable biopolymers make ...

Throughout the synthesis described in this paper provides a way to produce a new polymeric material specifically designed for molecular recycling, which is a way of chemical recycling. The depolarization and repolarization of the foreign material poly-S creates a fully sustainable cycle, which is a proof of concept for the future of polymers. The polymer waste of the world accumulates.For instance in the ocean, as the plastic soup, which could be prevented by introducing molecularly recyclable polymers. The polymer presented is an example of a polymeric material designed for molecular recycling. This in our opinion, should be implemented in other materials to prevent accumulation in nature.Green Knoevenagel reaction and subsequent steps have been designed for and by our undergraduated students. So certain robustness is already implemented in these reaction steps. The COVID-19 pandemic creates a situation where online learning becomes more important than ever.Visualization of these experiments helps us and others to deepen practical chemical education. Begin by adding 20.81 grams of malonic acid and 36.4 grams of syringaldehyde to a 215 milliliter round bottom flask. Dissolve both constituents in 20 milliliters of ethyl acetate and add 719 milligrams of ammonia bicarbonate to the flask.Mix and distill the solvent with a water bath. Keep the reaction mixture at 90 degrees Celsius for two hours in the open flask without stirring for complete conversion to sinapinic acid. In the work-up of the sinapinic acid product, dissolve the residue in 100 milliliters of a saturated aqueous sodium bicarbonate solution, then transfer the solution to a beaker, and acidify it to a pH two.Using six molar hydrogen chloride, separate the resulting residue by vacuum filtration and wash it with demineralized water. Charge a 450 milliliters flask with 33.6 grams sinapinic acid. Dissolve the sinapinic acid in 300 milliliters of two molar sodium hydroxide solution, and add 1.5 grams of nickel slurry before fitting the flask to the operators.Pressurize the reactor with three bar of hydrogen gas and mechanically shake the reaction at 80 degrees Celsius for three hours. Cool the reactor to room temperature and depressurize slowly. Recover most of the nickel catalyst with a magnet, then filter the solution.Acidify the solution with four molar hydrogen chloride solution to a pH of two, then perform an extraction with ethyl acetate. Remove the solvent under reduced pressure after drying over magnesium sulfate and dry the dihydrosinapinic acid at 60 degrees Celsius in a vacuum oven. Add 22.6 grams dihydrosinapinic acid to a 250 milliliter round bottom flask.Followed by 14.2 milliliters of acetic anhydride and 0.82 grams of sodium acetate. Heat the solution to 90 degrees Celsius while stirring for one hour for complete conversion of dihydrosinapinic acid to 4-Acetoxy-dihydrosinapinic acid, and it's acetylated oligomers. Dissolve the solid in 25 milliliters of acetone precipitated into 250 milliliters of 0.1 molar hydrogen chloride, then filtered on the vacuum.Add the monomers 20.8 grams of 4-Acetoxy-dihydrosinapinic acid and prepolymer to a 100 milliliter round bottom flask. Then add 400 milligrams of finely powdered sodium hydroxide, heat the reaction mixture for three hours at a set temperature of 140 degrees Celsius in the open flask while staring at 100 RPM. Set up a solvent assisted polymerization by adding 180 milligrams of zinc two acetate and 25.0 milliliters of 1, 2-xylene to the flask, then raise the set temperature to 160 degrees Celsius.Reflux the mixture at 144 degrees Celsius for three hours with constant water and acetic acid removal using Dean-Stark head. Cool the reaction mixture down and remove the 1, 2-xylene by applying a vacuum. Raise the temperature to 240 degrees Celsius during the final stage of the polymerization and apply a high vacuum for 30 minutes.Cool the polymer poly-S to room temperature and wash it with methanol to eliminate dihydrogen sinapinic acid and prepolymers. The obtained product should be a light brown solid. Finally grind and serve the poly-S into particles smaller than 180 micrometres to measure hydrolytic degradation.Load several test tubes with 20 milligrams of poly-S and add one milliliter of one molar sodium hydroxide solution. Incubate the tubes at three different temperatures with an agitation of 500 RPM. Neutralize the test tubes at regular time intervals with one milliliter of 0.5 molar sulfuric acid, and add two milliliters of methanol after cooling.Filter all samples using 0.45 micro meter PTFE syringe filters and inject 20 microliters into HPLC using an auto sampler. Monitor the absorbance at 254 nanometers and calculate the concentrations from a calibration curve of known dihydrosinapinic acid standard solutions. Sinapinic acid was synthesized in high purity and a greater than 95%yield from syringaldehyde using the Green Knoevenagel Condensation, the proposed mechanism of the step growth polymerization of 4-Acetoxy-dihydrosinapinic acid is shown here.Hydrogen one and MR measurements were taken during the polymerization process. When poly-S was hydrolyzed in sodium hydroxide, the molecularly recyclable polyester yielded the starting material dihydrosinapinic acid in less than 10 minutes. As confirmed by HBLC melting point analysis and hydrogen one and MR.Extended reaction times did not increase the yield.The thermal grams and GPC analysis of poly-S 1.0 and their successive generations poly-S 2.0 and polyester 3.0 after forced amorphicity with a tactic polystyrene are shown here. DSC analysis of poly-S shows a glass transition signal at 113 degrees Celsius and endothermic melting signal at 281 degrees Celsius. The polymers from re-polymerized sinapinic acid three eight poly-S 2.0 up and poly-H 3.0 exhibit similar thermal properties.Poly-S is a semi crystalline polymeric material because glass transition temperatures and melting signals are present in the thermograms of poly-S and their successive generations. GPC analysis after forced amorphicity with a tactic polystyrene displays a constant length of polymeric material throughout the different generations. While attempting the Green Knoevenagel reaction, please keep in mind that a correct temperature is used.A slightly higher temperature can lead to different site reactions. We have explored an example of a molecularly recyclable polymer. Closely related building blocks can follow the same procedure, or while maintaining thermal and mechanical properties.This method can be used in organic catalysis by demonstrating of the catalytic intermediates, as well in the still unexplored area of molecular recycling.

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