Navegando por Autor "Gusevskaya, Elena Vitalievna"
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Item Cobalt-catalyzed oxidation of terpenes : Co-MCM-41 as an efficient shape-selective heterogeneous catalyst for aerobic oxidation of isolongifolene under solvent-free conditions.(2009) Robles Azocar, Patrícia Alejandra; Rocha, Kelly Alessandra da Silva; Sousa, Edésia Martins Barros de; Gusevskaya, Elena VitalievnaCobalt-containing MCM-41 was used as a heterogeneous catalyst for the liquid-phase aerobic oxidation of isolongifolene, one of the most available sesquiterpenes. The material was prepared by direct incorporation of cobalt into the framework through the hydrothermal method, and was characterized by ICPAES, N2 adsorption–desorption, TEM, XRD, SAXS, XPS, and H2-TPR techniques. Characterizations suggest that cobalt introduced into MCM-41 exists mainly in a single-site Co2+ state, whereas the amounts of the extraframework Co3O4 are relatively low. The oxidation of isolongifolene under mild solvent-free conditions results mainly (90% selectivity) in isolongifolen-9-one, a compound which occupies a vintage place in modern perfume industry. The total concentration of oxygenated products in the final mixtures reaches 90 wt%. The catalyst undergoes no metal leaching, and can be easily recovered and re-used. A silica- included cobalt catalyst prepared through a conventional sol–gel method shows a catalytic activity comparable with that of Co-MCM-41; however, selectivity is much lower.Item Coupling of monoterpenic alkenes and alcohols with benzaldehyde catalyzed by silica-supported tungstophosphoric heteropoly acid.(2017) Cotta, Rafaela Ferreira; Rocha, Kelly Alessandra da Silva; Kozhevnikova, Elena Fedorovna; Kozhevnikov, Ivan V.; Gusevskaya, Elena VitalievnaThe reactions of biomass-based substrates, i.e., limonene, -pinene, -pinene, terpinolene, -terpineol,nerol and linalool, with benzaldehyde in the presence of tungstophosphoric heteropoly acid H3PW12O40(HPW) supported on silica give an oxabicyclo[3.3.1]nonene compound with fragrance characteristics ingood to excellent yields. The reactions apparently involve the formation of -terpenyl carbenium ion bythe protonation of alkene or dehydration of alcohol followed by the nucleophilic attack of benzaldehyde.The subsequent oxonium-ene cyclization of the resulting oxocarbenium ion gives the oxabicyclic product.The process is an environmentally benign and heterogeneous and can be performed under mild conditionswith low catalyst amounts and no significant leaching of active components.Item Coupling of phenylacetaldehyde and styrene oxide with biorenewable alkenes in eco-friendly solvents.(2021) Cotta, Rafaela Ferreira; Martins, Rafael Araújo; Rocha, Kelly Alessandra da Silva; Kozhevnikova, Elena Fedorovna; Kozhevnikov, Ivan V.; Gusevskaya, Elena VitalievnaAcidic cesium salt of tungstophosphoric heteropoly acid, Cs2.5H0.5PW12O40 (CsPW), is an excellent solid acid catalyst for the reaction of phenylacetaldehyde with biorenewable monoterpenic alkenes: limonene, α-terpineol, α-pinene and β-pinene. Simultaneously with a conventional oxonium-ene cyclization to give an oxabicyclo[3.3.1] nonene compound, phenylacetaldehyde undergoes Friedel-Crafts alkylation by the monoterpenes resulting in a new product with an unusual fused tetracyclic structure, obtained in ca. 80 % yield. A combined yield for both products was up to 95 %. Styrene oxide can be also used as a starting material for these reactions to give the same products in up to 85 % combined yield. A novel one-pot tandem process thus developed involves the isomeri- zation of styrene oxide into phenylacetaldehyde and cycloaddition of the latter to the monoterpene, with both steps being catalyzed by CsPW. The reactions were performed in green solvents diethylcarbonate or anisole, which have high sustainability ranks in modern solvent selection guides, comparable to those of ethanol and water.Item Esterification of camphene over heterogeneous heteropoly acid catalysts : synthesis of isobornyl carboxylates.(2011) Meireles, Augusto Luís Pereira de; Rocha, Kelly Alessandra da Silva; Kozhevnikov, Ivan V.; Gusevskaya, Elena VitalievnaSilica supported H3PW12O40 (PW), the strongest heteropoly acid in the Keggin series, is an active and environmentally friendly solid acid catalyst for liquid-phase esterification of camphene, a renewable biomass-based substrate, with C2, C4 and C6 short-chain fatty acids. The reaction provides isobornyl carboxylates, useful as fragrances, in virtually 100% selectivity and 80–90% yield. The reaction is equilibrium-controlled and occurs under mild conditions with a catalyst turnover number of up to 3000. The use of hydrocarbon solvent prevents PW from leaching to allow easy catalyst recovery. The catalyst can be reused several times without loss of activity and selectivity.Item Heteropoly acid catalysis for the isomerization of biomass-derived limonene oxide and kinetic separation of the trans-isomer in green solvents.(2019) Cotta, Rafaela Ferreira; Martins, Rafael; Pereira, Matheus Mello; Rocha, Kelly Alessandra da Silva; Kozhevnikova, Elena Fedorovna; Kozhevnikov, Ivan V.; Gusevskaya, Elena VitalievnaTerpenes are an abundant class of natural products, which is important for flavor and fragrance industry. Many acid catalyzed reactions used for upgrading terpenes still involve mineral acids as homogeneous catalysts and/or toxic solvents. Heteropoly acids represent a well-established eco-friendly alternative to conventional acid catalysts. As these reactions are usually performed in the liquid phase, solvents play a critical role for the process sustainability. In the present work, we developed a catalytic route to valuable fragrance ingredients, dihydrocarvone and carvenone, from limonene oxide by its isomerization using silica-supported tungstophosphoric acid as a heterogeneous catalyst and dialkylcarbonates as green solvents. The reaction pathway can be switched between dihydrocarvone and carvenone (obtained in 90% yield each) simply by changing the reaction temperature. In addition, we developed an efficient method for kinetic separation of trans-limonene oxide from commercial cis/trans-limonene oxide mixture and stereoselective synthesis of trans-dihydrocarvone.Item Heteropoly acid catalysts for the synthesis of fragrance compounds from bio-renewables : acetylation of nopol and terpenic alcohols.(2016) Costa, Vinícius Vieira; Rocha, Kelly Alessandra da Silva; Oliveira, Luiz Carlos Alves de; Kozhevnikova, Elena Fedorovna; Kozhevnikov, Ivan V.; Gusevskaya, Elena VitalievnaThe cesium salt of tungstophosphoric heteropoly acid, Cs2.5H0.5PW12O40, is an active and environmentally friendly heterogeneous catalyst for the liquid-phase acetylation of nopol and several biomass-derived terpenic alcohols (i.e., a-terpineol, nerol, geraniol, linalool, menthol, isoborneol, perillyl alcohol, carveol, isopulegol, carvacrol and nerolidol) with acetic anhydride. The resulting flavor and fragrance acetic esters, which are widely used in perfumery, household and food products, are obtained in good to excellent yields. The reactions occur at room temperature with low catalyst loadings without substantial catalyst leaching and can be performed with stoichiometric amounts of an acetylating agent in solvent free systems.Item Heteropoly acid catalysts for the synthesis of fragrance compounds from biorenewables : isomerization of limonene oxide.(2013) Costa, Vinícius Vieira; Rocha, Kelly Alessandra da Silva; Kozhevnikov, Ivan V.; Kozhevnikova, Elena Fedorovna; Gusevskaya, Elena VitalievnaThe liquid-phase isomerization of limonene oxide was studied in the presence of heteropoly acid catalysts in aprotic solvents in homogeneous and heterogeneous systems. Among the catalysts were bulk and silica-supported tungstophosphoric acid H3PW12O40 and its acidic Cs salt Cs0.5H0.5PW12O40 (CsPW). The reaction gave dihydrocarvone, a valuable fragrance intermediate, as the main product with turnover numbers of up to 8000. The nature of the solvent had a strong effect on reaction rate and selectivity. CsPW (0.1 mol%) was found to be a highly efficient and truly heterogeneous catalyst for this reaction, providing 82% yield of dihydrocarvone in 1,4-dioxane as a solvent under ambient conditions. This simple catalytic method represents economically attractive route to industrially important compounds starting from bio-renewable substrates easily available from essential oils.Item Heteropoly acid catalysts for the synthesis of fragrance compounds from biorenewables : the alkoxylation of monoterpenes.(2014) Meireles, Augusto Luís Pereira de; Costa, Maíra dos Santos; Rocha, Kelly Alessandra da Silva; Gusevskaya, Elena Vitalievna; Kozhevnikov, Ivan V.The cesium salt of tungstophosphoric heteropoly acid, Cs2.5H0.5PW12O40, is an active and environmentally friendly solidacid catalyst for the liquid-phase alkoxylation of widespread monoterpenes, such as camphene, limonene, a-pinene, and bpinene. These reactions provide isobornyl or a-terpenyl ethers, useful as fragrances, in good to excellent yields. The reactions are equilibrium-controlled and occur with high catalyst turnover numbers (TONs) up to 1500–4200 without catalyst leaching. Heteropoly acid H3PW12O40 also efficiently catalyzes the alkoxylation of these monoterpenes under homogeneous conditions with TONs up to 1500–11 300.Item Heteropoly acid catalysts in Prins cyclization for the synthesis of Florol.(2021) Meireles, Augusto Luís Pereira de; Rocha, Kelly Alessandra da Silva; Kozhevnikova, Elena Fedorovna; Kozhevnikov, Ivan V.; Gusevskaya, Elena VitalievnaH3PW12O40 heteropoly acid supported on SiO2 and its bulk acidic cesium salt Cs2.5H0.5PW12O40 are demonstrated to be highly active and recyclable solid catalysts for Prins cyclization allowing for the clean, high-yielding synthesis of Florol® from isoprenol and isovaleraldehyde. Florol®, a valuable floral odorant employed in a vast variety of commercial products, was obtained in ca. 80 % yield under nearly ambient conditions. Dime- thylcarbonate or diethylcarbonate used as green reaction media, low catalyst loadings and moderate conditions are important features that contribute for the sustainability of the method.Item Heteropoly acid catalysts in the valorization of the essential oils : acetoxylation of b-caryophyllene.(2010) Rocha, Kelly Alessandra da Silva; Rodrigues, Nathália V. S.; Kozhevnikov, Ivan V.; Gusevskaya, Elena VitalievnaH3PW12O40 (PW), the strongest heteropoly acid in the Keggin series, is an active and environmentally friendly catalyst for the liquid-phase conversion of b-caryophyllene (1) to b-caryolanyl acetate (2) in homogeneous and heterogeneous systems. An efficient and clean method for the synthesis of 2, providing amixture containing two stereoisomeric b-caryolanyl acetates 2a and 2b, 2a/2b = 80/20 mol/ mol, with 100% GC yield, has been developed using PW as a homogeneous catalyst under mild reaction conditions. The reaction occurs at 25 8C with a catalyst turnover number of 2000. The catalyst can be recovered without neutralization and reused without loss of activity and selectivity.Item Heteropoly acid catalysts in upgrading of biorenewables : cycloaddition of aldehydes to monoterpenes in green solvents.(2017) Cotta, Rafaela Ferreira; Rocha, Kelly Alessandra da Silva; Kozhevnikova, Elena Fedorovna; Kozhevnikov, Ivan V.; Gusevskaya, Elena VitalievnaAcidic Cs salt of tungstophosphoric heteropoly acid, Cs2.5H0.5PW12O40 (CsPW), is excellent solid acid catalyst for liquid-phase cycloaddition reactions of biomass-based and easily available from essential oils monoterpenic compounds, such as limonene, α-terpineol, α-pinene, β-pinene and nerol, with aldehydes, including benzaldehyde, crotonaldehyde as well as biomass-derived cuminaldehyde and trans-cinnamaldehyde. The reactions give oxabicyclo[3.3.1]nonene compounds potentially useful for the fragrance and pharmaceutical industries in good to excellent yields. The process is environmentally benign and can be performed in biomass-derived solvent 2-methyltetrahydrofuran and eco-friendly “green” organic solvents such as dimethylcarbonate and diethylcarbonate under mild conditions at low catalyst loadings without leaching problems. The solid CsPW catalyst can be easily separated from the reaction media and low-boiling solvents can be removed by distillation. Silica-supported H3PW12O40 also demonstrated good performance in these reactions.Item Heteropoly acid catalysts in upgrading of biorenewables : synthesis of para-menthenic fragrance compounds from α-pinene oxide.(2020) Ribeiro, Cláudio Júnior Andrade; Pereira, Matheus Mello; Kozhevnikova, Elena Fedorovna; Kozhevnikov, Ivan V.; Gusevskaya, Elena Vitalievna; Rocha, Kelly Alessandra da SilvaThe isomerization of α-pinene oxide in the presence of Cs2.5H0.5PW12O40 (CsPW) heteropolysalt as solid acid catalyst is reported. The reactions were performed in various solvents, which allowed to obtain trans-carveol, trans-sobrerol and pinol in 60–80% yield each, which exceed the yields reported so far. The CsPW catalyst could be recovered and reused without loss of its activity and selectivity.Item Heteropoly acid catalyzed cyclization of nerolidol and farnesol : synthesis of bisabolol.(2015) Meireles, Augusto Luís Pereira de; Costa, Maíra dos Santos; Rocha, Kelly Alessandra da Silva; Gusevskaya, Elena VitalievnaHeteropoly acid H3PW12O40 is an active and environmentally friendly homogeneous catalyst for the synthesis of _-bisabolol, a high-priced and highly demanded ingredient for the fragrance, cosmetic and pharmaceutical industries, starting from more abundant biomass-based sesquiterpenic alcohols. The solvent nature remarkably affects the reaction pathways and product selectivity. In acetone solutions, _-bisabolol can be obtained in 55–60% GC yields from nerolidol and 60–70% GC yields from farnesol at complete substrate conversions, which are probably the best results ever reported for these reactions. _-Bisabolol synthesized by this method contains no farnesol, which is a potentially allergenic compound and should be avoided in the commercially used _-bisabolol. This advantage is especially important because the distillative separation of _-bisabolol and farnesol is a troublesome task. The catalyst shows high turnover numbers and operates under mild nearly ambient conditions.Item Isomerization of a-pinene oxide over cerium and tin catalysts : selective synthesis of trans-carveol and trans-sobrerol.(2011) Costa, Vinícius Vieira; Rocha, Kelly Alessandra da Silva; Sousa, Líniker Fabrício de; Robles Azocar, Patrícia Alejandra; Gusevskaya, Elena VitalievnaA remarkable effect of the solvent nature on the acid catalyzed transformation of _-pinene oxide allowed direction of the reaction to either trans-carveol or trans-sobrerol. Each of these highly valuable compounds was obtained in nearly 70% yield using an appropriate polar solvent, whose basicity affected strongly the product distribution. In acetone, a weakly basic solvent, the reaction over heterogeneous sol–gel Sn/SiO2 or Ce/SiO2 catalysts gave mainly trans-sobrerol. No leaching of active components occurs under the reaction conditions and the catalysts can be recovered and reused. On the other hand, in more basic solvent, i.e., dimethylacetamide, the reaction was essentially directed to trans-carveol. Due to the leaching problems with Sn/SiO2 and Ce/SiO2 materials, the synthesis of trans-carveol was performed under homogeneous conditions using CeCl3 or SnCl2 as catalysts with a catalyst turnover number up to ca. 1200. The method represents one of the few examples of the synthesis of isomers from _-pinene oxide, other than campholenic aldehyde, with a sufficient for practical usage selectivity.Item Isomerization of styrene oxide to phenylacetaldehyde over supported phosphotungstic heteropoly acid.(2010) Costa, Vinícius Vieira; Rocha, Kelly Alessandra da Silva; Kozhevnikov, Ivan V.; Gusevskaya, Elena VitalievnaSilica-supported H3PW12O40 (PW), the strongest heteropoly acid in the Keggin series, is an efficient, environmentally friendly heterogeneous catalyst for the liquid-phase isomerization of styrene oxide into phenylacetaldehyde, an industrially important intermediate for fine chemical synthesis. The reaction occurs in cyclohexane as a solvent under mild conditions at 25–70 ◦C with low catalyst loadings and without PW leaching in solution. At 60 ◦C, the yield of phenylacetaldehyde reaches 92% at 97% styrene oxide conversion, with a catalyst turnover number of 19 600. The catalyst can be recovered and reused.Item Palladium-catalyzed sabinene oxidation with hydrogen peroxide : smart fragrance production and DFT insights.(2022) Vieira, Camila Grossi; Angnes, Ricardo Almir; Braga, Ataualpa Albert Carmo; Gusevskaya, Elena Vitalievna; Rossi, Liane MarciaFragrance substances derived from natural sources are essential to the fine chemical industry, being an interesting task to pursue. Herein, we present a smart catalytic oxidation route for bio-renewable (1R,5R)-sabinene obtainment in acetonitrile or acetone, just using Pd(OAc)2 as catalyst and hydrogen peroxide as an final oxidant. The products obtained from (1R,5R)-sabinene and their mixtures have a distinct and pleasant smell and therefore are candidates for fragrance and pharmacological applications. Three oxyfunctionalized products were obtained with ca. 80% combined selectivity at high substrate conversions. The major products, two novel isomeric carane-type ketones with a bicyclo[4.1.0] skeleton, were formed by expanding the five-membered ring in the sabinene molecule, while (-)-sabina ketone was produced as a minor product. An uncommon mechanistic route was suggested and supported by density functions theory (DFT), which could suitably explain the formation of these ketones. DFT results supported a proposed concerted mechanism for the Csingle bondC activation, like a semipinacol rearrangement, which includes a heterolysis of the Pd-C bond and synchronous cleavage of the Csingle bondC bond in an intermediate organopalladium peroxo complex. We highly believe that such findings allow a step forward a deep understanding of such organic transformation, helping in future new routes for value-added products.Item Phosphotungstic heteropoly acid as efficient heterogeneous catalyst for solvent-free isomerization of a-pinene and longifolene.(2009) Rocha, Kelly Alessandra da Silva; Robles Azocar, Patrícia Alejandra; Kozhevnikov, Ivan V.; Gusevskaya, Elena VitalievnaSilica-supported H3PW12O40 (PW), the strongest heteropoly acid in the Keggin series, is an efficient, environmentally friendly heterogeneous catalyst for the liquid-phase isomerization of a-pinene and longifolene into their more valuable isomers – camphene and isolongifolene, respectively, which are intermediates in the synthesis of expensive fragrances. The reactions occur under solvent-free conditions in the temperature range of 80–100 8C, with low catalyst loadings (0.15–5 wt%) and high turnover numbers (up to 6000 per proton). The catalyst can be easily recovered and reused. No PW leaching is observed in the reaction system.Item Solvent-free chromium catalyzed aerobic oxidation of biomass-based alkenes as a route to valuable fragrance compounds.(2011) Robles Azocar, Patrícia Alejandra; Brandão, Bruno Bitarães Neto Salgado; Sousa, Líniker Fabrício de; Gusevskaya, Elena VitalievnaChromium containing mesoporous molecular sieves MCM-41 were shown to be an efficient heterogeneous catalyst for the liquid-phase aerobic oxidation of various monoterpenic alkenes under mild solvent-free conditions. The material was prepared through a direct hydrothermal method and characterized by ICP-AES,N2 adsorption–desorption, TEM, XRD, SAXS, andH2-TPR techniques. Characterizations suggest that chromium introduced in MCM-41 is essentially incorporated in the silica framework, with no extraframework chromium oxides being detected. Various oxygenated monoterpenoids important for the flavor and fragrance industry were obtained with high combined selectivities (75–92%) at 30–40% substrate conversions. The oxidation of _-pinene led almost exclusively to allylic mono-oxygenated derivatives, whereas limonene and _-pinene gave both epoxides and allylic oxidation products. The catalyst undergoes no metal leaching and can be easily recovered and re-used. A silica-included chromium catalyst prepared through a conventional sol–gel method showed activity comparable with that of Cr- MCM-41; however, selectivity was much lower.Item Synthesis of fragrance compounds from acyclic monoterpenes : rhodium catalyzed hydroformylation and tandem hydroformylation/acetalization of linalool and B-citronellene.(2013) Vieira, Camila Grossi; Santos, Eduardo Nicolau dos; Gusevskaya, Elena VitalievnaRhodium-catalyzed hydroformylation of acyclic monoterpenic compounds, i.e., linalool and _- citronellene, was studied in toluene and ethanol solutions in the presence of PPh3 or P(O-o-tBuPh)3 ligands. Although both substrates have a monosubstituted terminal double bond, they show different behavior under the hydroformylation conditions. In toluene, linalool gave almost quantitatively a cyclic hemiacetal; whereas the hydroformylation of _-citronellene resulted in two isomeric aldehydes also in a nearly quantitative combined yield. The reactions occurred approximately two times faster in ethanol than in toluene giving the corresponding acetals even in the absence of additional acid co-catalysts. In the absence of phosphorous ligands, linalool (differently from _-citronellene) was very resistant to hydroformylation probably due to the binding with rhodium through both the double bond and the hydroxyl group to form stable chelates. The P(O-o-tBuPh)3 ligand exerted a remarkable effect on the reactivity of both substrates accelerating the reactions by 5–20 times as compared to the system with PPh3. Several fragrance compounds were obtained in high yields through a simple one-pot procedure starting from the substrates easily available from natural bio-renewable resources.Item Synthesis of fragrance compounds from biorenewables : tandem hydroformylation–acetalization of bicyclic monoterpenes.(2013) Freitas, Marina Caneschi de; Vieira, Camila Grossi; Santos, Eduardo Nicolau dos; Gusevskaya, Elena VitalievnaThe Rhodium-catalyzed tandem hydroformylation–acetalization of the terpenes 3-carene, 2-carene, a-pinene, and b-pinene was studied in ethanol solutions in the presence of PPh3 or tris(O-tert-butylphenyl)phosphate, P(O-o-tBuPh)3, ligands. All these terpenes are constituents of turpentine oils obtained commercially from coniferous trees. b-Pinene gave the corresponding aldehyde and acetal in excellent combined yields in both systems. 3-Carene, 2-carene, and a-pinene, which contain sterically encumbered endocyclic double bonds, showed an extremely low reactivity with PPh3. The use of P(O-o-tBuPh)3 not only accelerated the hydroformylation of all four substrates remarkably but also increased the acetalization activity of the catalyst. In the Rh/P(O-o-tBuPh)3 system, various fragrance acetals and aldehydes were obtained from these renewable substrates in nearly quantitative combined yields. The process was performed under mild conditions, in environmentally friendly ethanol as a solvent, and in the absence of acid cocatalysts.