1,720,975 research outputs found
Synthesis and derivatization of 2,5-bis(hydroxymethyl)furan (BHMF)
No full textBiomass-derived C6-furanic platform chemicals are regarded as the most promising building blocks in biorefinery exploitation. 5-Hydroxymethylfurfural (HMF) is referred as a “sleeping giant” in consideration of its potential in bridging the gap from a fossil-based chemistry to a more sustainable one. HMF is a versatile substrate with enormous market potential as it can be easily converted into high value chemicals, materials and bio-based polymers.[1] However, there are some limitations in developing an efficient HMF-based chemistry, i.e., its preferred solubility in water rather than in organic solvents, the absence of a cost-efficient scale-up synthesis, and well know HMF stability issue partially solved by the addition of small amount of specific stabilizers.
In our laboratory we have developed a new approach to HMF from D-Fructose using dimethyl carbonate as an extracting solvent in the presence of an acidic heterogenous catalyst. This synthesis is easily scalable up to 20 grams of D-fructose and allows to recover HMF in 70% isolated yield.[2] Quick reduction of HMF to the related 2,5-bis(hydroxymethyl)furan (BHMF) was also carried out using sodium borohydride as reducing agent. This latter approach led to prepare rapidly a rather large amount of BHMF. As a result, BHMF derivatization was also investigated. In particular we have focused on BHMF etherification reaction to achieve 2,5-bis(alkoxymethyl) furans (BAMFs) – well-known biofuel candidates. Several catalysts were investigated; (mild) reaction conditions were optimized and thus employed for the preparation of a library of BAMFs (10 compounds). Products isolation and purification were addressed for each BAMFs.[3] Two examples of etherification reactions were also conducted in gram-scale i.e. for the synthesis of 2,5-bis(methoxymethyl)furan and 2,5-bis(isopropoxymethyl) furan.
Ongoing research on BHMF includes studying its reactivity with dialkyl carbonates. The idea is to develop a library of easy accessible bio-based monomers for polycarbonate, polyurethanes as well as potentially interesting intermediates for surfactants and detergents production.[4
Analoghi carbonati delle ipriti
Full text linkI gas mostarda o ipriti, bis(2-cloroetil)solfuro e la bis(2-cloroetil)etilammina, sono tristemente conosciuti per il loro impiego come armi chimiche durante la Prima Guerra Mondiale.1 La tossicità delle ipriti è strettamente correlata alla loro elevata reattività. Infatti, questi composti sono in grado di eliminare lo ione cloruro attraverso una sostituzione nucleofila intramolecolare grazie all’effetto anchimerico dello zolfo o dell’azoto vicinale, generando uno ione episolfonico o aziridinico ciclico che è – a sua volta - estremamente reattivo.2 Nonostante la loro ben nota tossicità, questi composti trovano largo impiego nella preparazione di farmaci, nonché come reagenti per la sintesi di intermedi di reazione.3
Nello studio qui presentato, i dialchil carbonati (DAC)4 – noti reagenti e solventi Green – sono stati fatti reagire con alcoli/dioli precursori dei gas mostarda portando ad una nuova classe di composti: le mostarde carbonate. La reattività degli analoghi carbonati delle ipriti è stata successivamente investigata dimostrando che questi composti preservano l’effetto anchimerico dei gas mostarda, ma non presentano alcuna tossicità, nè pericolo per l’operatore o l’ambiente.5 Le reazioni di alchilazione favorite dall’effetto anchimerico delle mostarde carbonate sono state condotte impiegando diversi nucleofili e operando sia in autoclave ad alta temperatura (180 °C) che in neat a temperature inferiori (150 °C) e a pressione atmosferica. Inoltre, recentemente sono state studiate reazioni di alchilazione in one-pot dove la mostarda carbonata è sintetizzata in situ e reagisce immediatamente con il nucleofilo scelto.
Riferimenti
1. a) J. C. Dacre, M. Goldman, Pharmacol. Rev. 1996, 48, 289–326; b) J. Liu, K. L. Powell, H. D. Thames, M. C. MacLeod, Chem. Res. Toxicol. 2010, 23, 488–496.
2. E. Block in Reactions of Organosulfur Compounds, Academic Press, New York, 1978, pp. 141–145.
3. M. C. S. Barnes, H. J. Dennison, S. S. Flack, J. A. Lumley, P. S. Pang, K. C. Spencer, WO2011/27156, 2011.
4. a) P. Tundo, M. Selva, Acc. Chem. Res. 2002, 35, 9, 706; b) Fabio Arico,̀ A. S. Aldoshin, and P. Tundo, ACS Sustainable Chem. Eng.2016, 4, 2843−2851
5. F. Aricò, M. Chiurato, J. Peltier, P. Tundo. Eur. J. Org. Chem. 2012, 3223–322
Nitrile Furanics via Copper‐Catalyzed Dehydration of Aldoximes and Knoevenagel Condensation
No full textIn this work two synthetic approaches to introduce nitrile moieties into bio-based derived furanic compounds were
investigated, i. e., dehydration of aldoximes and Knoevenagel condensation. Both methodologies have been first tested and optimized on furfural and thus exploited on 5-hydroxymethyl-2-furfural (HMF) and 5,5’-oxy(bismethylene)-2-furaldehyde (OBMF). The syntheses of furfural, HMF and OBMF aldoximes were efficiently conducted (also in large scale) under mild reaction conditions and short reaction time. The subsequent dehydration to nitrile furanic compounds was carried out in the presence of catalytic amount of copper acetate monohydrate. Furthermore, Knoevenagel condensations were performed on furfural, HMF and OBMF with different Activated Methylene Group compounds, using for the first-time dimethyl carbonate as the reaction media. Most of the resulting products were isolated as pure via simple liquid-liquid extraction in good to
excellent yields. Future applications of these compounds might include aldoxime reduction into amine furanics - herein also preliminary investigated - and hydrolysis of the nitrile derivatives in the related carboxylic acid (or ester) furanics. All these products are interesting monomers for the preparation of biobased polymers
Alkyl Levulinates from Furfuryl Alcohol Using CT151 Purolite as Heterogenous Catalyst: Optimization, Purification, and Recycling
Full text linkCommercially available Purolite CT151 demonstrated to be an efficient acid catalyst for the synthesis of alkyl levulinates via alcoholysis of furfuryl alcohol (FA) at mild temperatures (80–120 °C) and short reaction time (5 h). Reaction conditions were first optimized for the synthesis of ethyl levulinate and then tested for the preparation of methyl-, propyl-, isopropyl-, butyl, sec-butyl- and allyl levulinate. Preliminary scale-up tests were carried out for most of the alkyl levulinates (starting from 5.0 g of FA) and the resulting products were isolated as pure by distillation in good yields (up to 63%). Furthermore, recycling experiments, conducted for the preparation of ethyl levulinate, showed that both the Purolite CT151 and the exceeding ethanol can be recovered and reused for four consecutive runs without any noticeable loss in the catalyst activity
2‐formyl‐5‐(hydroxymethyl)furan (HMF) derivatives as active complexing agent for CO2 insertion reaction
Full text linkRenewable-based furan compounds derived from 2-formyl-5-(hydroxymethyl)furan (5-HMF) were successfully employed as catalysts to synthesize cyclic organic carbonates through the reaction of carbon dioxide with epoxides. The effects of temperature, reaction time, reagent ratios, and carbon dioxide pressure were optimized before evaluating various bio-based complexing agents in combination with different alkali metal halide salts. Among them, 2,5-bis(hydroxymethyl)tetrahydrofuran (BHTHF) showed the highest efficiency as a complexing agent when paired with sodium bromide (NaBr), enabling the production of industrially relevant cyclic carbonates in high yields (12 examples, achieving 94-99% epoxide conversion and 70-99% carbonate selectivity) under mild pressure conditions (carbon dioxide pressure of 1-10 bar, reaction time of 6 hours, and temperature of 120 °C). Additionally, the BHTHF/NaBr catalytic system demonstrated high stability, maintaining its performance over nine consecutive epoxide additions (8 mmol each) without any loss of efficiency
Alkyl carbonate derivatives of furanics: A family of bio-based stable compounds
No full textSeveral alkyl carbonate derivatives of 5-hydroxymethylfurfural (HMF) and 2,5-bis(hydroxymethyl)furan (BHMF) have been synthesized for the first time. In most cases high yields were achieved using mild reaction conditions and compounds were recovered as pure with none or minimal purification. The new HMF and BHMF derived products resulted stable over time and they are suitable monomers for new bio-based polycarbonates and polyurethanes.Fil: Sathicq, Angel Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Ciencias Aplicadas "Dr. Jorge J. Ronco". Universidad Nacional de la Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Ciencias Aplicadas; ArgentinaFil: Annatelli, Mattia. Universita' Ca' Foscari Di Venezia; ItaliaFil: Abdullah, Iskandar. No especifíca;Fil: Romanelli, Gustavo Pablo. Facultad de Ciencias Agrarias y Forestales, Universidad Nacional de la Plata; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Ciencias Aplicadas "Dr. Jorge J. Ronco". Universidad Nacional de la Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Ciencias Aplicadas; ArgentinaFil: Aricò, Fabio. Universita' Ca' Foscari Di Venezia; Itali
Mustard Carbonate Analogues as Sustainable Reagents for the Aminoalkylation of Phenols
Full text linkThe nitrogen mustard gas moiety is present as a basic, amine-containing side chain in numerous pharmacophore scaffolds engaging in crucial interactions with targeted biological macromolecules. Herein, a one-pot synthetic approach for the easy introduction of nitrogen mustard-like moieties through dialkyl carbonate chemistry into different phenolic substrates is reported. The scope and limitations of this reaction as a chlorine-free direct substitution of the phenolic −OH group have been investigated
Multigram Synthesis of Pure HMF and BHMF
Full text link5-Hydroxymethylfurfural (HMF) is a bio-based platform chemical that can be used as a building block to produce several compounds with diverse applications. Even though HMF synthesis holds promise for a greener future, the current state of technology and the high production cost limit its competitiveness on an industrial scale. In this prospect, we have developed a multigram-scale procedure for HMF by reacting D-fructose with Purolite CT275DR-an acidic resin-in a dimethyl carbonate (DMC)/tetraethyl ammonium bromide (TEAB) biphasic system. Reactions performed in an autoclave for 2 h at 110 degrees C using up to 40 gram of D-fructose resulted in an overall HMF yield of 70%. HMF was purified by a custom-made procedure leading to ca 50% of the pure crystalline product; meanwhile, the residual HMF-rich oil was directly reduced to bis(hydroxymethyl)furan (BHMF). Green metrics and the Ecoscale algorithm were used to evaluate the sustainability of the herein-proposed procedure in comparison with works
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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