Name: designed for molecular recycling: a lignin-derived semi-aromatic biobased polymer
Uploaded: 2020-11-30T14:00:00
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Os autores agradecem o apoio financeiro da Organização Holandesa de Pesquisa Científica (NWO) (bolsa 023.007.020 concedida a Jack van Schijndel).

1. Condensação de knoevenagel verde de seringadeído em direção ao ácido sinapinaico com 5 mol% de bicarbonato de amônio
<ol><li>Adicione ácido malônico (20,81 g, 200,0 mmol) juntamente com seringaldeído (36,4 g, 200,0 mmol) a um frasco de fundo redondo de 250 mL. Dissolva ambos os constituintes em 20,0 mL de acetato de etila e adicione bicarbonato de amônio (790 mgs, 10,0 mmol) ao frasco. NOTA: Para garantir a conclusão completa da reação de condensação, o evaporador rotativo pode ser usado para dest...

<ol>
	<li>Rahimi, A., Garc&#237;a, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chemical+recycling+of+waste+plastics+for+new+materials+production.">Chemical recycling of waste plastics for new materials production.</a> Nature Reviews Chemistry. 1 (6), 41570 (2017).</li><li>Sardon, H., Dove, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Plastics+recycling+with+a+difference.">Plastics recycling with a difference.</a> Science. 360 (6387), 380-381 (2018).</li><li>Jones, G. O., Yuen, A., Wojtecki, R. J., Hedrick, J. L., Garc&#237;a, J. 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R., Stukenbrock, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=New+polymer+syntheses,+92.+Biodegradable,+thermotropic+copolyesters+derived+from+&#946;-(4-hydroxyphenyl)propionic+acid.">New polymer syntheses, 92. Biodegradable, thermotropic copolyesters derived from &#946;-(4-hydroxyphenyl)propionic acid.</a> Macromolecular Chemistry and Physics. 198 (11), 3753-3767 (1997).</li><li>Kreye, O., Oelmann, S., Meier, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Renewable+Aromatic-Aliphatic+Copolyesters+Derived+from+Rapeseed.">Renewable Aromatic-Aliphatic Copolyesters Derived from Rapeseed.</a> Macromolecular Chemistry and Physics. 214 (13), 1452-1464 (2013).</li><li>Mialon, L., Pemba, A. G., 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=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. F., Hay, J. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isothermal+crystallization+kinetics+and+melting+behaviour+of+poly(ethylene+terephthalate).">Isothermal crystallization kinetics and melting behaviour of poly(ethylene terephthalate).</a> Polymer. 42 (23), 9423-9431 (2001).</li><li>S&#225;nchez, M. E., Mor&#225;n, A., Escapa, A., Calvo, L. F., Mart&#237;nez, O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Simultaneous+thermogravimetric+and+mass+spectrometric+analysis+of+the+pyrolysis+of+municipal+solid+wastes+and+polyethylene+terephthalate.">Simultaneous thermogravimetric and mass spectrometric analysis of the pyrolysis of municipal solid wastes and polyethylene terephthalate.</a> Journal of Thermal Analysis and Calorimetry. 90 (1), 209-215 (2007).</li></ol>

Quando o ácido dihidrosinóptico foi aquecido em um vaso de reação, a sublimação do material inicial ocorreu, e esse efeito foi aumentado quando um vácuo foi aplicado. A acetilação foi realizada em ácido dihidrosinapinapílico para evitar sublimação. Kricheldorf et al.12,27 reconheceram que não só ocorreu acetilação, mas igualmente di-e oligomerização. No entanto, esses monômeros e oligômeros esterificados não são mais sublimes e são adequad...

Em contraste com a incineração de resíduos poliméricos, a reciclagem química oferece a possibilidade de recuperar os monômeros. A reciclagem química é uma escolha lógica no final da vida técnica dos materiais poliméricos, uma vez que esses materiais poliméricos são produzidosquimicamente 1. Existem duas maneiras de reciclar o material polimérico quimicamente, a pirólise e a reciclagem molecular2. Com a pirólise, o material polimérico é transformado em produtos de maior valor utilizando condições extremas3,4. A reciclagem molecular é um método eficiente para recuperar os materiais iniciais usando a despolimerização. Após a despomerização, as unidades monoméricas podem ser repolammerizadas em materiais poliméricos virgens5. A disponibilidade de monômeros adequados para aplicar reciclagem molecular em maior escala é desejada. O problema atual do plástico dita que a sociedade exige materiais polimédicos robustos e robustos. Ao mesmo tempo, também é preferível que os mesmos materiais poliméricos sejam facilmente recicláveis e não resistam ao ambiente. Materiais poliméicos atuais com boas propriedades térmicas e mecânicas não despomerizamfacilmente 6.
A lignina, comumente encontrada em plantas vasculares, é responsável por 30% do teor de carbono natural do mundo e é o segundo biopolímero mais abundante depois da celulose. A lignina tem uma estrutura amorfa complexa e parece ser uma alternativa adequada para substituir os aromáticos extraídos de materiais fósseis. A estrutura tridimensional da lignina fornece força e rigidez à madeira, bem como resistência à degradação. Quimicamente falando, a lignina é um termoset polifenólico muito complexo. Consiste em uma composição variada de três estruturas diferentes de fenilpropano metoxilatado. Seringila, guaiacyl e p-hidroxifenil (muitas vezes abreviados como S, G e H, respectivamente) são derivados dos monolignols sinapyl álcool, álcool coniferyl e p-coumaryl7. A distribuição dessas unidades difere por tipo de biomassa, com madeira macia, por exemplo, consistindo principalmente de unidades guaiacicl e madeira de guaiacyl e seringilunidades 8,9. Fontes naturais renováveis, como árvores e plantas, são desejáveis para a produção de monômeros redesenhados para materiais poliméricos inovadores10. Esses monômeros, isolados e sintetizados a partir de fontes naturais, são polimerizados aos chamados polímeros biobásicos11.
Os ácidos carboxílicos aromáticos são várias ordens de magnitude menos eletrofílica do que os ácidos carboxílicos alifáticos equivalentes por razões eletrônicas12. Vários poliésteres comerciais usam ácidos carboxílicos aromáticos em vez de ácidos carboxílicos alifáticos. Como resultado, as fibras em tecidos de poliéster feitos de fibras poli (etileno tereftalato) (PET) são quase insensíveis à hidrólise durante a lavagem ou, por exemplo, chuva13. Quando a reciclagem molecular de poliésteres é desejada, é aconselhável usar ésteres alifáticos no acúmulo do polímero.
Pelas razões mencionadas, investigamos as possibilidades de fabricação de poliésteres a partir de ácidos 4-hidroxi-3,5-dimetiloxy-dihidrocinâmica14. Estudos anteriores de Kricheldorf15, Meier16e Miller17,18 mostram que é desafiador construir polímeros usando ácido 4-hidroxi-3,5-dimetiloxy-dihidrocinnâmico. A descarboxing e o crosslinking dificultaram as polimerizações, limitando assim o sucesso dessas sínteses. Além disso, o mecanismo da policondensação permaneceu incerto. O artigo apresentado descreve as condições em que o poliéster (ácido dihidrosinapina), pode ser sintetizado regularmente e em alto rendimento, abrindo assim o caminho para o uso de polísteres semi-aromáticos que são molecularmente recicláveis.
Desenvolvemos uma maneira verde e eficiente de sintetizar o ácido sinapinaico usando uma reação de condensação entre seringaldeído e ácido malônico19,20. Depois deste Knoevenagel Verde, a hidrogenação produz ácido dihidrosinapinapílico, que é adequado para policondensação reversível. Esta publicação visualiza os passos sintéticos para o polimer de polímero molecularmente reciclável (ácido dihidrosinapinapínico), referindo-se às unidades base da lignina, chamada poli-S. Depois de analisar o material polimérico, o poli-S é despolimerizado ao ácido dihidrosinapínico monômero em condições relativamente favoráveis e repolammerizado repetidamente.

<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

O desenvolvimento de biopolímeros quimicamente recicláveis oferece oportunidades dentro da busca de uma economia circular. Biopolímeros quimicamente recicláveis fazem um esforço positivo para resolver a questão dos materiais polímeros na fase de descarte após a fase de uso. Neste artigo, a produção de poliésteres semi-aromáticos biobasados, que podem ser extraídos inteiramente da biomassa, como a lignina, é descrita e visualizada. O polímero poli-S descrito neste papel tem propriedades térmicas semelhantes a certos plásticos comumente usados, como o PET. Desenvolvemos uma reação green knoevenagel, que pode produzir eficientemente monômeros a partir de aldeídos aromáticos e ácido malônico. Esta reação tem sido comprovadamente escalável e tem um fator E notavelmente baixo calculado. Estes poliésteres com ligno-fitoquímicos como ponto de partida mostram uma reciclagem molecular eficiente com perdas mínimas. O poliéster (ácido dihidrosinapina), (poli-S) é apresentado como um exemplo desses polísteres semi-aromáticos, e a polimerização, despomerização e repolimerização são descritas.

O ácido sinapúnico foi sintetizado em alta pureza e alto rendimento (> 95%) de seringa por meio da condensação de Knoevenagel Verde. (Informações de suporte: Figura S1) O fator E é uma indicação de produção de resíduos onde um número maior indica mais desperdícios. O fator E é calculado tomando a entrada total do material, subtraindo a quantidade do produto final desejado e dividindo o todo pela quantidade do produto final. Esta condensação green knoevenagel tem um fator E de 1.0, que po...

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

Um exemplo de uma abordagem de circuito fechado em direção a uma economia de materiais circulares é descrito aqui. Um ciclo sustentável é apresentado onde poliésteres semi-aromáticos biobálticos são projetados por polimerização, despomerização e, em seguida, repolimerizados com apenas pequenas alterações em seus rendimentos ou propriedades finais.

Projetado para reciclagem molecular: um polímero semi-aromático derivado da lignina

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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&alpha;-Carbon Chemistry: Enols, Enolates, and Enamines

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