Synthesis of heterocycles compounds from condensation of limonene with aldehydes using heteropolyacids supported on metal oxides

In this contribution, heterogeneous materials based on heteropolyacids (HPA, H3PW12040 hydrate) supported over several metal oxides (TiO2, SiO2, SBA-15, Al2O3) were prepared using wetness impregnation, characterized by XRD, FTIR, SEM, acidity by TPD, nitrogen physisorption, RAMAN spectroscopy, 31P NMR and then evaluated in the catalytic condensation of limonene with benzaldehyde. After incorporation of HPA over each support, no structural changes were observed as it was suggest by FTIR, RAMAN and XRD. Acidity analysis by TPD-NH3 showed that increasing the HPA amount increases the acidity of the catalyst until it is constant (20–30%). HPA over alumina, silica and SBA-15 also showed high values of acidity but less than typical HPA/P25 catalyst (HPA over commercial Degussa P25). This last was one of the most selective materials (surface area of 39 m2/g and acidity of 187 µmol NH3. gcat−1) for the synthesis of 3-oxabyciclo[3.3.1]nonane (up to 80%) with a low selectivity to the limonene isomers by-products. The use of water as a solvent decreased considerably the catalytic activity. The same observation was found when the volume of the solvent increased to 30 mL. Besides, catalytic condensation can be performed at free solvent conditions and at room temperature; however, when decrease temperature, a higher number of isomers was observed rather than the desired product. In addition, catalytic condensation was also evaluated in biomass of essential oils and mixtures with sesquiterpenes showing good to excellent results. Typical LHHW mechanism was evident after kinetic analysis. HPA/P25 was shown to be a robust material since can be reused up to two times with a possible decrease in its catalytic activity.Funding for open access charge: CRUE-Universitat Jaume

Brønsted acid catalyzed Prins-Ritter reaction for selective synthesis of terpenoid-derived 4-amidotetrahydropyran compounds

A number of SO3H-functionalized solids (biochar, montmorillonites, carbon and halloysite nanotubes) has been studied as catalysts in the cascade Prins-Ritter reaction of (-)-isopulegol with benzaldehyde and acetonitrile for synthesis of octahydro-2H-chromene amides (as 4R- and 4S-isomers). A high selectivity to these products at 30 °C in the presence of H2O was observed on catalysts modified with chlorosulfonic acid (CSA) reaching 84% (4R/4S of 5.7) in the case of biochar, while a relatively large amount of octahydro-2H-chromenols (up to 31%), products of Prins condensation, was formed on the materials functionalized by 2-(4-chlorosulfonylphenyl)ethyltrimethoxysilane (CSP). Although Prins condensation proceeds efficiently on weak acid sites, the Prins-Ritter reaction requires sulfated materials with strong (0.33 – 5.8 mmol/g) Brønsted acidity. Catalysts functionalized by CSP were stable, while for the materials modified with chlorosulfonic acid, leaching of -SO3H groups was observed. Nonetheless, on resistant Bioсhar-CSP, selectivity to the amides at 30 °C (67%) was higher than that with the commercial Amberlyst-15 (47%), and triflic acid at − 25 °C (62%). Similar selectivity to the desired products on Biochar-CSA (-SO3H groups) and H2SO4 (81–84%) as well as on Biochar-CSP (-PhSO3H) and with p-toluenesulfonic acid (67–70%) was observed. DFT calculations and experimental results showed that at 30 °C formation of 4S-amide thermodynamically is more beneficial than of alcohols and dehydration products. However, addition of water results in a sharp increase in the reaction rate and 4R-amide selectivity due to a change to the kinetic control, leading eventually to both high yields and stereoselectivity. The proposed reaction pathways also were confirmed by kinetic modelling.This work is part of the scientific activity of the Institute of Chemistry of New Materials, funded by the National Academy of Sciences of Belarus. Julián E. Sánchez thanks to Pontificia Universidad Javeriana for providing computational powder and to Universidad Jaume I (Pla de Promoció de la Investigació de la Universitat Jaume I) for the Post Doctoral Fellowship. Part of this work (synthesis and charaterization of sulfonic-acid catalysts presented in Fig. 2) was funded by the Portuguese funds through Fundação para a Ciência e a Tecnologia (FCT/MCTES) in the framework of the projects UIDB/50006/2020, UIDP/50006/2020. A.F.P. is also grateful to FCT for funding through the Individual Call to Scientific Employment Stimulus 2020.01614.CEECIND/CP1596/CT0007

Synthesis of Florol via Prins cyclization over heterogeneous catalysts

In this work, several heterogeneous micro- and mesoporous, acidic catalysts were tested for the selective synthesis of Florol (R), an industrial product formed via condensation and rehydration starting from isoprenol and isovaleraldehyde in dimethylcarbonate as a solvent. The results showed that a mildly acidic, microporous H-Beta-300 with SiO2/Al2O3 ratio of 300 was the best catalyst, giving 72% selectivity with 99% conversion at 40 degrees C when using the molar ratio isoprenol to isovaleraldehyde of 1:5. More acidic zeolites gave slightly lower selectivity, while the lowest selectivity (up to 52%) was obtained with mesoporous catalysts exhibiting mild acidity and no strong Bronsted acid sites. Selectivity to pyranols was nearly constant when changing temperature, while a larger excess of isovaleraldehyde promoted formation of tetrahydropyranol. H-Beta-300 catalyst was successfully after calcination at 400 degrees C. DFT calculations pointed out on the parallel formation of tetrahydro pyranols and dihydropyrans, which are the corresponding dehydration products. (C) 2021 Elsevier Inc. All rights reserved

Documento en extenso que incluye los resultados de la revisión de información secundaria y la obtenida en el taller con actores regionales, con la identificación de vacíos de información y prioridades de investigación y monitoreo en la cuenca del rió claro

En el marco del convenio de cooperación técnica y científica No. 19-100, celebrado entre la Fundación Grupo Argos y el Instituto de Investigación de Recursos Biológicos Alexander von Humboldt, con el objeto de aunar esfuerzos administrativos, técnicos, financieros y de gestión para la generación de conocimiento útil en escenarios de evaluación y manejo integral de impactos sobre la biodiversidad, desde una mirada ecosistémica integral del territorio de la cuenca del río Claro (Antioquia) en los múltiples contextos socioecológicos, se ha comprometido la construcción de la línea base de información secundaria disponible sobre biodiversidad para la cuenca del río Claro, Antioquia, que incluya, entre otros, datos sobre ecología, genética, uso, conservación, distribución, uso de hábitat, impactos e información espacial, procesos ecológicos.BogotáCiencias Básicas de la Biodiversida

Synthesis of trans-pinocarveol from oxidation of β-pinene using multifunctional heterogeneous catalysts

In this contribution, several multifunctional heterogeneous catalysts comprising an acid and a metal function were synthesized by wetness impregnation and tested in the allylic oxidation (with hydrogen peroxide as an oxidizing agent) of β-pinene, a monoterpene which is present in several plants being one of the main constituents of the turpentine oil. Among the tested catalysts, the material containing Pd with a heteropolyacid supported on SBA-15 (Pd/HPA-300/SBA-15) was the best catalyst achieving the most promising results (up to 65% of yield to trans-pinocarveol). Independent on the Pd loading (0.5 wt% or 1.0 wt%) and calcination temperature of the heteropolyacid supported on SBA-15 (200°C-300°C), selectivity to trans-pinocarveol remained the same. At the same time the calcination temperature affected conversion, Pd dispersion, acidity, and the surface area. When the support changed to amorphous SiO2 (with a lower surface area < 200 m2/g) both selectivity and conversion decreased dramatically to values lower than 20%. Weak Brønsted acid sited together with a typical particles shape favors formation and selectivity to the desired product. Laboratory scaling up of β-pinene oxidation was performed (up to 10 mL) achieving the same results in terms of activity and selectivity thereby showing a possibility of a practical implementation of the proposed catalytic system. Kinetic modelling of the reaction was performed to elucidate the determining steps involving in the allylic oxidation of β-pinene. The catalysts showed to be robust since it can be used up to 3 times without apparent changes in both selectivity and conversion but with a slight presence of lixiviation

Synthesis of Florol via Prins cyclization over heterogeneous catalysts

In this work, several heterogeneous micro- and mesoporous, acidic catalysts were tested for the selective synthesis of Florol®, an industrial product formed via condensation and rehydration starting from isoprenol and isovaleraldehyde in dimethylcarbonate as a solvent. The results showed that a mildly acidic, microporous H-Beta-300 with SiO2/Al2O3 ratio of 300 was the best catalyst, giving 72% selectivity with 99% conversion at 40 °C when using the molar ratio isoprenol to isovaleraldehyde of 1:5. More acidic zeolites gave slightly lower selectivity, while the lowest selectivity (up to 52%) was obtained with mesoporous catalysts exhibiting mild acidity and no strong Brønsted acid sites. Selectivity to pyranols was nearly constant when changing temperature, while a larger excess of isovaleraldehyde promoted formation of tetrahydropyranol. H-Beta-300 catalyst was successfully after calcination at 400 °C. DFT calculations pointed out on the parallel formation of tetrahydro pyranols and dihydropyrans, which are the corresponding dehydration products.ISSN:0021-9517ISSN:1090-269

Beyond 2,5-furandicarboxylic acid: status quo, environmental assessment, and blind spots of furanic monomers for bio-based polymers

Green Metrics related to the article "Beyond 2,5-furandicarboxylic acid: status quo, environmental assessment, and blind spots of furanic monomers for bio-based polymers