Chitin-Derived Nanocatalysts for Reductive Amination Reactions

Chitin, the second most abundant biopolymer in the planet after cellulose, represents a renewable carbon and nitrogen source. A thrilling opportunity for the valorization of chitin is focused on the preparation of biomass-derived N-doped carbonaceous materials. In this contribution, chitin-derived N-doped carbons were successfully prepared and functionalized with palladium metal nanoparticles. The physicochemical properties of these nanocomposites were investigated following a multi-technique strategy and their catalytic activity in reductive amination reactions was explored. In particular, a biomass-derived platform molecule, namely furfural, was upgraded to valuable bi-cyclic compounds under continuous flow condition

Green Protocols for Catalytic Sustainable Processes in Organic Synthesis

The present PhD work has been mainly carried out at the department of Molecular Sciences and Nanosystems of the Università Ca’ Foscari Venezia, in the laboratories of the Green Organic Synthesis Team (GOST) led by Professor Maurizio Selva. During his three-years program, the candidate also spent a research semester at the departamento de Quimica Organica of the Universidad de Cordoba (Spain) in the Nanoval Group led by Professor Rafael Luque. Sustainable processes and the use of renewable feedstocks, continuous flow chemistry and microwave-assisted syntheses, the development of multi-phase systems and new chitin-derived nitrogen-doped carbon catalysts have been the leitmotiv of the Thesis. Particularly, the research program has been aimed to the following activities: 1. The conceptualization and development of multiphase systems (MPs) for i) the reduction of sugars and sugars-like substrates, ii) the tunable oxidation of 5-HMF and iii) the synthesis of HHD via hydrogenation/hydrolysis of 5-HMF. 2. The conceptualization and the preparation of chitin-derived nitrogen-doped carbon catalysts for i) the solvent-less CO2 fixation reactions into epoxides, ii) the controlled alcohols oxidation to aldehydes and ketones and iii) the reductive amination reactions. 3. The catalytic upgrading of lignin-derived compounds through i) the microwave-assisted catalytic transfer hydrogenolysis of aromatic ethers and ii) the continuous flow hydrogenation of aromatic ethers. 4. The CO2-assisted hydrolytic hydrogenation of cellulose and cellulose-based waste into sorbitol. 5. The synthesis and catalytic activity/application of biomass-derived metal-free carbon catalysts (review paper). This Ph.D. Research Work represents a comprehensive exploration of sustainable processes and the development of novel catalysts for various chemical transformations. The work has addressed key challenges in the field of green organic synthesis, with a focus on utilizing renewable feedstocks, continuous flow chemistry, and microwave-assisted syntheses. In the future, this research can pave the way for more sustainable and efficient chemical processes, contributing to the broader goals of green chemistry and sustainable development. Further investigations may involve scaling up these processes for industrial applications, exploring new catalyst materials, and continuing to innovate in the field of sustainable chemistry. The Ph.D. Work serves as a strong foundation for these future endeavours, and the insights gained from this work have the potential to make a significant impact on the field of green organic synthesis.The present PhD work has been mainly carried out at the department of Molecular Sciences and Nanosystems of the Università Ca’ Foscari Venezia, in the laboratories of the Green Organic Synthesis Team (GOST) led by Professor Maurizio Selva. During his three-years program, the candidate also spent a research semester at the departamento de Quimica Organica of the Universidad de Cordoba (Spain) in the Nanoval Group led by Professor Rafael Luque. Sustainable processes and the use of renewable feedstocks, continuous flow chemistry and microwave-assisted syntheses, the development of multi-phase systems and new chitin-derived nitrogen-doped carbon catalysts have been the leitmotiv of the Thesis. Particularly, the research program has been aimed to the following activities: 1. The conceptualization and development of multiphase systems (MPs) for i) the reduction of sugars and sugars-like substrates, ii) the tunable oxidation of 5-HMF and iii) the synthesis of HHD via hydrogenation/hydrolysis of 5-HMF. 2. The conceptualization and the preparation of chitin-derived nitrogen-doped carbon catalysts for i) the solvent-less CO2 fixation reactions into epoxides, ii) the controlled alcohols oxidation to aldehydes and ketones and iii) the reductive amination reactions. 3. The catalytic upgrading of lignin-derived compounds through i) the microwave-assisted catalytic transfer hydrogenolysis of aromatic ethers and ii) the continuous flow hydrogenation of aromatic ethers. 4. The CO2-assisted hydrolytic hydrogenation of cellulose and cellulose-based waste into sorbitol. 5. The synthesis and catalytic activity/application of biomass-derived metal-free carbon catalysts (review paper). This Ph.D. Research Work represents a comprehensive exploration of sustainable processes and the development of novel catalysts for various chemical transformations. The work has addressed key challenges in the field of green organic synthesis, with a focus on utilizing renewable feedstocks, continuous flow chemistry, and microwave-assisted syntheses. In the future, this research can pave the way for more sustainable and efficient chemical processes, contributing to the broader goals of green chemistry and sustainable development. Further investigations may involve scaling up these processes for industrial applications, exploring new catalyst materials, and continuing to innovate in the field of sustainable chemistry. The Ph.D. Work serves as a strong foundation for these future endeavours, and the insights gained from this work have the potential to make a significant impact on the field of green organic synthesis

Tunable Multi-Phase System for Highly Chemo-Selective Oxidation of Hydroxymethyl-Furfural

Three different multiphase systems (MP 1-3) comprised of two immiscible liquids, with or without an ionic liquid (IL: methyltrioctyl ammonium chloride), were investigated for the oxidation of 5-hydroxymethyl-furfural (HMF) over 5 % Ru/C as a catalyst and air (8 bar) as an oxidant. These conditions proved versatile for an excellent control of the reaction selectivity to 4 distinct products derived from full or partial oxidation of the carbonyl and alcohol functions of HMF, and each one achieved in 87-96 % isolated yield at complete conversion. MP1 based on water and isooctane, yielded 2,5-furandicarboxylic acid (FDCA, 91 % yield). In MP2, obtained by adding the IL to MP1, the oxidation proceeded towards the formation of 5-formyl-2-furancarboxylic acid (FFCA, 87-89 % yield). MP2 also proved successful in the design of a one pot-two step oxidation/reduction sequence to prepare 5-hydroxymethyl-2-furancarboxylic acid (HMFCA, 85 % yield). In MP3, the use of an acetonitrile/cyclooctane biphase yielded 2,5-diformylfuran (DFF, 96 % yield). All the multiphase systems MP 1-3 allowed a perfect segregation of the catalyst in a single phase (either the hydrocarbon or the IL) distinct from the one containing HMF and its oxidation products. This was crucial not only for the catalyst/product separation but also for the recycle of Ru/C that was possible under all the tested conditions. Accordingly, MP-reaction were run in a semicontinuous mode without removing the catalyst from the reactor nor resorting to conventional separation and activation techniques. Negligible Ru leaching, less than 0.96 ppb, was measured in all cases

Continuous Flow Hydrogenation of Lignin-model Aromatic Compounds over Carbon-supported Noble Metals

An efficient continuous-flow (CF) protocol was designed for the hydrogenation of lignin-derived aromatics to the corresponding cycloalkanes derivatives. A parametric analysis of the reaction was carried out by tuning the temperature, the H-2 pressure and the flow rate, and using diphenyl ether (DPE) as a model substrate, commercial Ru/C as a catalyst, and isopropanol as a solvent: at 25 degrees C, 50 bar H-2, and a flow rate of 0.1 mL min(-1), dicyclohexyl ether was achieved in an 86 % selectivity, at quantitative conversion. By-products from the competitive C-O bond cleavage of DPE, cyclohexanol and cyclohexane, did not exceed 14 % in total. Remarkably, prolonged experiments demonstrated an excellent stability of the catalyst whose performance was unaltered for up to 420 min of time-of-stream. A substrate scope evaluation proved that under the same conditions used for DPE, a variety of substrates including alkoxy-, allyl-, and carbonyl-functionalized phenols, biphenyl, aryl benzyl- and phenethyl ethers (10 examples) yielded the ring-hydrogenated products with selectivity up to 99 % at complete conversion

Diversified upgrading of HMF via green acetylation, aldol condensation, carboxymethylation, vinylation and reductive amination reactions

Multiple sustainable methodologies were developed for the chemical upgrading of HMF: i) at 30-90 degrees C, highly selective base-catalyzed acetylation and carboxymethylation reactions of HMF with nontoxic reagents as isopropenyl acetate (iPAc) and dimethyl carbonate (DMC) were achieved to prepare the corresponding ester and carbonate products, (5-formylfuran-2-yl)methyl acetate (5-formylfuran-2-yl) methyl carbonate, respectively; ii) based on the combined use of iPAc/DMC with acetone, a tandem protocol of acetylation/transcarbonation and aldol condensation was designed to synthesize a variety of HMF-derived alpha,beta-unsaturated carbonyl compounds; iii) in water as a solvent, a chemoselective Pd-catalysed reductive amination of HMF with amino-alcohols also including glycerol derivatives, was developed using H-2 at atmospheric pressure; iv) finally, both HMF and its ester and carbonate products successfully underwent Wittig vinylation reactions promoted by a methyl carbonate phosphonium salt ([Ph3PCH3] [CH3OCO2]), to obtain the corresponding olefins. The vinylation reagent (the salt) was a DMC derivative. In all cases i-iv), not only processes occurred under mild conditions, but post-reaction procedures (work-up and purification) were optimized to isolate final products in high yields of 85-98%

Churg-Strauss syndrome associated with antiphospholipid antibodies in a patient with recurrent myocardial and cerebral ischemia

We report on a case of Churg-Strauss syndrome (CSS) associated with the presence of antiphospholipid antibodies. The patient had a history of recurrent myocardial infarction and presented with acute ischemic cerebral disease. Eosinophilia with typical lung and skin lesions led us to diagnose the patient with CCS. We hypothesize that the presence of antiphospholipid antibodies significantly contributed to the ischemic events. We suggest that the search for antiphospholipid antibodies should be included in the laboratory work-up in CSS patients and patients affected by primary systemic vasculitides in general. Moreover, anticoagulant treatment appears to be warranted in all CSS patients and antiphospholipid antibodies to counteract this thrombosis-favoring association. © 2012 Paroli et al, publisher and licensee Dove Medical Press Ltd

Isopropenyl Acetate for the Continuous-Flow Synthesis of Triacetin, Solketal Acetate, and Allyl Acetate from Pure or Crude Glycerol

Publisher Copyright: © 2023 The Authors. Published by American Chemical Society.Isopropenyl acetate (iPAc) proved to be an effective green reagent for the chemical upgrading of refined and crude glycerol (CG) into valuable products, such as allyl acetate, triacetin (TA), and acetal acetates, under continuous-flow (CF) conditions. Two unprecedented tandem catalytic protocols of deoxydehydration (DODH)/acetylation and acetylation/acetalization were implemented to convert glycerol into allyl acetate and acetal acetates. These products were achieved in 95 and 78% yields, respectively, by combining a pool of innocuous compounds that acted with different roles: iPAc as an acetylating agent, triethylorthoformate as a DODH agent, acetone as an acetalization agent, and acetic acid and Amberlyst-15 as the homogeneous and heterogeneous catalysts, respectively. The parametric analysis of the process variables allowed us to reach the productivity (P) of 10.6 mmol·h-1 mL-1 at 300 °C and 110 bar and 37 mmol·gcat-1 h-1 at 30 °C and ambient pressure for the (DODH)/acetylation sequence and the acetylation/acetalization cascade reaction, respectively. Acetal acetates were obtained as a mixture of (2,2-dimethyl-1,3-dioxolan-4-yl)methyl acetate (solketal acetate) and 2,2-dimethyl-1,3-dioxan-5-yl acetate in a 97:3 ratio. A third protocol was designed for the peracetylation of CG as an industrial waste with iPAc: in the absence of any catalyst, TA (glycerol triacetate) was isolated in 92% yield with the productivity improved by more than 60 times compared to previous literature results. The performance of two of the target products (acetal acetates and TA) as biofuel additives was also investigated.Peer reviewe

Geometric Methods in PDE’s

The analysis of PDEs is a prominent discipline in mathematics research, both in terms of its theoretical aspects and its relevance in applications. In recent years, the geometric properties of linear and nonlinear second order PDEs of elliptic and parabolic type have been extensively studied by many outstanding researchers. This book collects contributions from a selected group of leading experts who took part in the INdAM meeting "Geometric methods in PDEs", on the occasion of the 70th birthday of Ermanno Lanconelli. They describe a number of new achievements and/or the state of the art in their discipline of research, providing readers an overview of recent progress and future research trends in PDEs. In particular, the volume collects significant results for sub-elliptic equations, potential theory and diffusion equations, with an emphasis on comparing different methodologies and on their implications for theory and applications

Point-of-care ultrasound for non-vascular invasive procedures in critically ill neonates and children: current status and future perspectives

point-of-care ultrasound (POCUS) has been established as an essential bedside tool for real-time image guidance of invasive procedures in critically ill neonates and children. while procedural guidance using POCUS has become the standard of care across many adult medicine subspecialties, its use has more recently gained popularity in neonatal and pediatric medicine due in part to improvement in technology and integration of POCUS into physician training programs. with increasing use, emerging data have supported its adoption and shown improvement in pediatric outcomes. procedures that have traditionally relied on physical landmarks, such as thoracentesis and lumbar puncture, can now be performed under direct visualization using POCUS, increasing success, and reducing complications in our most vulnerable patients. In this review, we describe a global and comprehensive use of POCUS to assist all steps of different non-vascular invasive procedures and the evidence base to support such approach.conclusion: there has been a recent growth of supportive evidence for using point-of-care ultrasound to guide neonatal and pediatric percutaneous procedural interventions. a global and comprehensive approach for the use of point-of-care ultrasound allows to assist all steps of different, non-vascular, invasive procedures.What is Known:center dot Point-of-care ultrasound has been established as a powerful tool providing for real-time image guidance of invasive procedures in critically ill neonates and children and allowing to increase both safety and success.what is new:center dot a global and comprehensive use of point-of-care ultrasound allows to assist all steps of different, non-vascular, invasive procedures: from diagnosis to semi-quantitative assessment, and from real-time puncture to follow-up

Multiphase Hydrogenation of -Glucosamine Hydrochloride, N-Acetyl- -Glucosamine, -Glucose, and -Maltose over Ru/C with Integrated Catalyst Recovery

A multiphase (MP) system composed of two immiscible liquids, water and isooctane, and commercial 5% Ru/C as a catalyst, both with and without an additional organic liquid (OL: tetrahydrofuran (THF), 2-methyl-THF, methyl isobutyl carbinol, and cyclopentyl methyl ether) was designed and investigated for the chemoselective catalytic hydrogenation of four model examples of biobased sugars and amino/amido-sugars. At 110 degrees C and 40 bar of H-2, D-glucosamine hydrochloride and N-acetyl-D-glucosamine were converted selectively into their corresponding hydrogenated derivatives, 2-amino-D-sorbitol and 2-acetamide-D-sorbitol, respectively, isolated in >99% yields. Both the reagents and the products were converted and formed in the aqueous phase, respectively, while, by tuning the relative proportions of water, isooctane, and the third added liquid (particularly THF), the catalyst (Ru/C) was perfectly segregated in the organic layer, where it could be recycled and reused up to nine times without any loss of activity and selectivity, in a semicontinuous mode. Under such conditions, the reaction was implemented on a gram scale with a productivity up to 0.89 mmol 2-amino-D-sorbitol/(g(cat) h). The same hydrogenation efficiency and reagent/product/catalyst separation were achieved during the MP reactions of D-glucose and D-maltose. In this case, however, results were independent of the MP composition: at 120 degrees C and 20-40 bar of H-2, using either H2O/isooctane or H2O/isooctane/OL systems, a quantitative conversion of D-glucose and D-maltose was reached with a selectivity up to 78 and >99% toward sorbitol and maltitol, respectively. Ru/C was perfectly separated out of the aqueous phase in both MP mixtures, with a negligible metal leaching, below 0.01 wt %. The multiphase approach for all the tested substrates proved not only to be an original and robust protocol to improve the product isolation and catalyst recycling, but also effective in preventing metal contamination in the synthesis of final derivatives