In the last years, a growing interest in using biochar as catalyst or catalyst support has arisen due to its relatively low cost and easy functionalization. Even though pristine biochar does not have a well-developed specific surface area and pore size distribution, which are essential features for a catalyst, they can be easily improved by means of further procedures. Among all the biochar upgrading procedures, CO₂ controlled gasification is one of the most promising since it is possible to obtain activated carbons with high surface area and expanded pore size distribution. One of the most interesting field of application of the biochar-based catalysts is the upgrading of pyrolysis vapors through the conversion of the condensable products (bio-oil) into permanent gases via catalytic steam reforming. The specific aim of this work is to produce biochar-based catalyst for pyrolysis vapors upgrading starting from binder-free wheat straw pellets. For this purpose, the selected biomass was first pyrolyzed under N₂ atmosphere and then activated with CO2 at 700°C and 1.0 MPa. These activated biochars were then loaded with different percentages of Fe, Co, Ce and Ni in order to produce mono and bi-metallic catalysts to be tested for mid-temperature (400–600 °C) steam reforming of a pyrolysis bio-oil model compound. The samples which showed the most promising results in terms of selectivity, conversion and stability were finally tested for steam reforming of the aqueous phase of a real bio-oil.

The non-degradability which earlier had been thought to be a good advantage of using plastic now has been reconsidered the main source of environmental issues, especially the heaps of solid plastics in the ocean. The degradation of plastic can be done using chemical process or by using biodegradation which is safer. Recently, a new bacterial species, Ideonella sakaiensis, was found and isolated that was exposed to use PET(Poly Ethylene Terephthalate) as a carbon source[1-4] and it can degrade PET polymer into monomers of monohydroxyethyl tereph-thalate (MHET), by means of two enzymes PETase and MHETase respectively. The catalytic site is consisting of three amino acids (S131, H208, D177) which form the catalytic triad. the catalytic triad has studied in detail during the simulation of 150 ns and found that these amino acids were quite stable even in the presence of PET. Here we attempt to understand the effect of aqueous ionic liquid on the stability and catalytic activity of PETase since ionic liquids are environment friendly, enhance the stability and catalytic activity of certain enzymes[5-6]. The ligand present is having 2 terephthalate units connected with one ester bond. Three different ionic liquids are [C2mim] [CH3COO], [C4mm] [CH3COO], and [Ch]₃[PO₄] simulated at three different concentration of 40 %, 30%, and 20% in the presence of enzyme PETase docked with the ligand. The structure seems to be quite stable after 150ns simulation in the presence of ionic liquids. The stability of the enzyme is relatively high in cholonium phosphate ionic liquid.

The Frustrated Lewis Pairs (FLP) concept recently demonstrated to be a powerful way to activate small molecules and promote a plethora of organic reactions without the help of transition metals. This strategy is based on simple combinations of Lewis acids and bases that are sterically or electronically hindered from forming classical Lewis acid-base adducts. Generally, the Lewis acid is a fluorinated compound of boron or aluminum, and the Lewis base is based in most cases on phosphorous, nitrogen or, seldom, oxygen. To the best of our knowledge, no attempt has been made to isolate, characterize and test in catalysis selenium-based FLP. In the present contribution, the interaction between sterically encumbered organoselenium compounds, as selenides and selones, and standard Lewis acids, as B(C₆F₅)₃ and less-fluorinated boranes, will be studied by DFT calculations and compared to the interaction present in already known P-based FLPs. Attempts will be made to find bench-stable FLPs, with the aim to simplify the experimental studies and encourage the possible applications to real systems. Energy Decomposition Analysis results are shown and discussed, showing that selenium-based FLPs are theoretically possible. For the most promising candidates, the products of the activation of small molecules (H₂ or CO₂) will be theoretically optimized, in order to check if the reaction would be thermodynamically favored.

Abstract:

Heterocyclic chemistry has undergone considerable development due to the pharmacological importance of the majority of heterocyclic compounds, particularly nitrogen heterocycles. Pyrazolo-enaminones are versatile synthons due to their rapidity of both electrophilic and nucleophilic attack, in addition to reducing reaction time and increasing yield and process efficiency. Pyrazolo-enaminones are attractive intermediates for the synthesis of therapeutically active heterocycles such as quinolines, dibenzodiazepines, pyridinones, oxazoles and tetrahydrobenzoxazines. In this context, we were interested in the synthesis of antibacterial, anti-inflammatory agents from pyrazolo-enaminones which are the starting compounds for this synthesis and which are obtained by condensation of pyrazolo diketone with aromatic primary amines with the use of double lamellar hydroxides (LDH) as catalyst.

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3-Aminobenzoic acid is a molecule of interest, widely considered as promising platform chemicals for the production of dyes, antioxidants, pharmaceuticals and agricultural chemicals. The conventional catalytic hydrogenation processes for the production of 3-aminobenzoic acid and derivatives was conducted with transition metals, such as platinum, nickel, or palladium in organic solvent. There are three main drawbacks: (i) metal catalysts can pose some concerns such as high cost, recycling from the system, as well as some environmental concerns; (ii) organic solvents requires high-energy consumption for the recovery of aromatic amines and (iii) dihydrogen H2 causes security risks. In this present work, newoxydo-reduction process for the production of 3-aminobenzoic acid starting from 3-nitrobenzaldehyde in a single step called "one pot" catalyzed by carbonaceous bio-based materials in subcritical water without added metal and H₂ has been developed. In another word, the reaction permits to have the reduction of the nitro group to the amino group and the oxidation of the formyl group to the carboxylic acid. The optimized experimental conditions (3-nitrobenzaldehyde (10 mmol), Norit Gac 12-40 (6 g), 55 mL H₂O at 300 °C for 6 h) furnished the target 3-aminobenzoic acid in 60% yield using dihydrogen free and metal free process. The scope of the reaction using different starting materials will be developed.

Organoselenium compounds have promising antioxidant activity, anxiolytic-like, and antidepressant-like proprieties. Additionally, some pharmacokinetics propriety of drugs are increased when phosphorus is added to their structure. Thus, this study hypothesized to test the antioxidant activity of compounds using selenium and phosphorus on its structures using five phosphoroselenoates: O,O-Dimethyl Se-phenyl phosphoroselenoate (3a), O,O-Dibutyl Se-phenyl phosphoroselenoate (3c), O,O-Dibenzyl Se-phenyl phosphoroselenoate (3d), O,O-Dimethyl Se-(p-tolyl) phosphoroselenoate (3f), Se-(4-Methoxyphenyl) O,O-dimethyl phosphoroselenoate (3g), that may act against oxidative stress in biological systems. Antioxidant evaluation of phosphoroselenoates was investigated in the concentration of 10, 50, 100 and 500 µM using dimethyl sulfoxide as a solvent and were performed on five in vitro assays: 2‐azinobis‐3‐ethylbenzothiazoline‐6‐sulfonic acid (ABTS), 2,2‐diphenyl‐1‐picrylhydrazyl radical (DPPH), ferric ion reducing antioxidant power (FRAP), inhibition of reactive species formation and thiobarbituric acid reactive species (TBARS) on cerebral tissue of mice. All procedures were approved by the guidelines of the Committee on Care and Use of Experimental Animal Resources of Federal University of Pelotas (13008-2020). The results were expressed as mean ± standard error of the mean and the data was performed using one-way analysis of variance followed by Tukey test. Phosphoroselenoates showed antioxidant activity by being able to scavenging ABTS and DPPH radicals, ferric-reducing ability, prevented lipidic peroxidation and formation of reactive species on different levels. From these compounds, 3g presented the most promising activity. In conclusion, phosphoroselenoates presented antioxidant effect in different assays, which could be beneficial in the treatment of diseases that have oxidative stress on their physiopathology.

In this work, the stability of Pt-Ni and Ru-Ni catalysts supported on a CeO₂-SiO₂ oxide was investigated for oxidative steam reforming of ethanol in a fluidized bed reactor at 500°C, H₂O/C₂H₅OH ratio of 4 and O₂/C₂H₅OH of 0.5. The time-on-stream behaviour of the catalysts was studied for 25 hours at 500°C; very stressful conditions were selected in terms of contact time (50 ms), which was considerably lower than the values commonly selected for ethanol reforming. As expected, due to the high space velocity selected, all the catalysts underwent deactivation with time-on-stream and a decreasing trend in ethanol conversion was observed. The highest activity was obtained over the 2Pt10Ni sample, which reached 95% of ethanol conversion after 25 hours of time-on-stream. The worst results in terms of ethanol conversion and hydrogen yield were obtained over the low-loaded samples: despite the 0.5Ru10Ni and 0.5Pt10Ni catalysts assured high activity in the interval 300-600°C, as previously reported, the small noble metal content resulted in poor stability. The most stable sample was also tested under a real bioethanol stream, containing methanol, sulphur compounds and higher saturated alcohols. Despite the more pronounced extent of deactivation compared to the tests carried out under the pure water/ethanol mixture, the 2Pt10Ni catalyst reached a steady state condition after almost 30 h, with no more activity loss. In fact, the net rate of carbon deposition became equal to zero and the change in coke accumulation was negligible.

Organoselenium compounds find many applications in biology, medicine and material science. One of the important features of selenium influencing the biological application is its redox state, which in turn is affected by its interactions with nearby heteroatoms. To modulate the biological action of selenium, researchers have designed new structural motifs and also developed new formulations using inorganic nanoparticles. Metal nanoparticles like gold nanoparticles (GNP) have been extensively studied for conjugation with many heteroatoms (sulphur, nitrogen, oxygen) containing ligands. Selenium being more polarisable than sulphur can induce significant surface passivation thereby providing easy modulations in physico-chemical properties. With this aim, we investigated the physico-chemical properties of a few selenium compounds conjugated to GNP and iron oxide (Fe₃O₄) based magnetic nanoparticles (MNP) Two water soluble selenium compounds (an aliphatic selenide and a selenolane ) were conjugated with GNP and characterised by spectroscopic and microscopic tools like optical absorption, Raman spectroscopy, DLS, Zeta potential and TEM. The results confirmed that the selenium atom was covalently conjugated to GNP and this conjugation has not only increased their electron transfer ability but also their antioxidant ability. In another study two asymmetric phenyl selenides were conjugated with MNP and characterised by XRD, TEM, DLS and zeta-potential. The radical scavenging ability of the selenium compound improved on conjugation with the MNPs. Thus, the above studies confirmed that the redox activities of selenium compounds can be modulated on conjugating with inorganic nanoparticles like GNP and MNP, which in turn provide new avenues for delivering organoselenium compounds.

Designing a highly active and selective Se-therapeutic, that mimics the activity of the antioxidant enzyme glutathione peroxidase (GPx), still remains a challenge. Since the discovery of ebselen (N-phenyl-1,2-benzisoselenazol-3(2H)-one) and its ability to act as a GPx mimetic, the search for more effective peroxide scavengers has become a ‘hot topic’ in this field of research. Herein, we present several modifications of the benzisoselenazolone core that enable to improve the antioxidant and anticancer potential of the basic ebselen structure. These transformations include: (a) installation of chiral terpene skeletons, from p-menthane, pinane and carane systems, on the nitrogen atom; (b) exchange of the carbonyl oxygen atom for sulphur to obtain thiocarbonyl derivatives; (c) oxidation of the selenium moiety resulting in a series of benzenoselenenic acids and their further transformation to corresponding water-soluble potassium salts; (d) attachment of an additional phenyl group leading to variously N-substituted unsymmetrical phenylselenides with an o-amido function. All of the synthetized compounds were tested as antioxidants and antiproliferative agents. Conclusions concerning the structure-activity correlation, including the difference in reactivity of specific Se-moieties (-Se-N-, -SeOOH, -SeOOK, -SePh), N-substituents (the influence of bulky aliphatic moiety and the 3-dimensional orientation of atoms), and incorporated heteroatoms (-C=O, -C=S), are presented.

Nowadays, the transformation of lignocellulosic biomass into added-value products, such as bio-based platform chemicals, biofuels and biofuel additives, is attracting great attention. In this research, the acid-catalyzed hydrolysis of waste residues of grape pomace and Cynara Cardunculus L. (cardoon), remained after wine and oil exploitation respectively, to levulinic acid was investigated. The grape pomace residue was employed as received, whereas the cardoon one was used both as received and after a steam explosion treatment, being the obtained feedstock enriched in cellulose. Since both these types of waste biomasses are low value materials, this investigation was performed adopting the High Gravity approach, using biomass loadings as higher as possible to achieve the maximum levulinic acid concentration in the hydrolyzates, at the same time maintaining an appreciable yield. Moreover, the effect of the main reaction parameters was assessed. Under the optimized reaction conditions, starting from grape pomace residue, the levulinic acid yield and concentration of 49.5 mol% and 8.5 g/L were reached respectively, whereas, from cardoon residue, levulinic acid yields and concentrations up to 53 mol% and 62 g/L were attained, highlighting the cardoon biomass as the most promising feedstock. On this basis, preliminary studies on the one-pot alcoholysis of cardoon in n-butanol to n-butyl levulinate were performed and the achieved results demonstrate the possibility of its direct production. In summary, this work proves that the cardoon waste biomass is a promising feedstock for the sustainable production of both levulinic acid and alkyl levulinates, paving the way towards a real circular economy.