18358-53-7Relevant academic research and scientific papers
The thermolysis of α-pinene and verbenone epoxides in supercritical solvents
Anikeev,Il'Ina,Volcho,Ermakova,Salakhutdinov
, p. 1112 - 1117 (2010)
Thermal transformations of α-pinene and verbenone epoxides were studied in supercritical solvents with complex compositions, including CO 2, lower alcohols (ethanol and isopropanol), and water, over the temperature and pressure ranges 387-575 K and 135-215 atm. The main product from α-pinene epoxide in a supercritical solvent containing water was campholenic aldehyde and pinocamphone; the total content of these products in the reaction mixture was 80%. Suggestions concerning the mechanism of the thermal isomerization of α-pinene epoxide depending on the acidity of supercritical solvents were made. The direction of verbenone epoxide transformations was independent of the presence of water in the mixture. The main identified products were ketoalcohols with para-menthane and camphane frameworks.
Engineering a Highly Defective Stable UiO-66 with Tunable Lewis-Br?nsted Acidity: The Role of the Hemilabile Linker
De Geyter, Nathalie,De Vos, Dirk E.,Feng, Xiao,Hajek, Julianna,Hoffman, Alexander E. J.,Jena, Himanshu Sekhar,Leus, Karen,Leyssens, Karen,Marquez, Carlos,Meynen, Vera,Morent, Rino,Van Der Voort, Pascal,Van Speybroeck, Veronique,Veerapandian, Savita K. P.,Wang, Guangbo
, p. 3174 - 3183 (2020/03/10)
The stability of metal-organic frameworks (MOFs) typically decreases with an increasing number of defects, limiting the number of defects that can be created and limiting catalytic and other applications. Herein, we use a hemilabile (Hl) linker to create up to a maximum of six defects per cluster in UiO-66. We synthesized hemilabile UiO-66 (Hl-UiO-66) using benzene dicarboxylate (BDC) as linker and 4-sulfonatobenzoate (PSBA) as the hemilabile linker. The PSBA acts not only as a modulator to create defects but also as a coligand that enhances the stability of the resulting defective framework. Furthermore, upon a postsynthetic treatment in H2SO4, the average number of defects increases to the optimum of six missing BDC linkers per cluster (three per formula unit), leaving the Zr-nodes on average sixfold coordinated. Remarkably, the thermal stability of the materials further increases upon this treatment. Periodic density functional theory calculations confirm that the hemilabile ligands strengthen this highly defective structure by several stabilizing interactions. Finally, the catalytic activity of the obtained materials is evaluated in the acid-catalyzed isomerization of α-pinene oxide. This reaction is particularly sensitive to the Br?nsted or Lewis acid sites in the catalyst. In comparison to the pristine UiO-66, which mainly possesses Br?nsted acid sites, the Hl-UiO-66 and the postsynthetically treated Hl-UiO-66 structures exhibited a higher Lewis acidity and an enhanced activity and selectivity. This is further explored by CD3CN spectroscopic sorption experiments. We have shown that by tuning the number of defects in UiO-66 using PSBA as the hemilabile linker, one can achieve highly defective and stable MOFs and easily control the Br?nsted to Lewis acid ratio in the materials and thus their catalytic activity and selectivity.
Synthesis of bimetallic Zr(Ti)-naphthalendicarboxylate MOFs and their properties as Lewis acid catalysis
Rasero-Almansa, Antonia M.,Iglesias, Marta,Sánchez, Félix
, p. 106790 - 106797 (2016/11/23)
Bimetallic Zr(Ti)-NDC based metal-organic frameworks (MOFs) have been prepared by incorporation of titanium(iv) into zirconium(iv)-NDC-MOFs (UiO family). The resulting materials maintain thermal (up to 500 °C), chemical and structural stability with respect to parent Zr-MOFs as can be deduced from XRD, N2 adsorption, FTIR and thermal analysis. The materials have been studied in Lewis acid catalyzed reactions, such as, domino Meerwein-Ponndorf-Verley (MPV) reduction-etherification of p-methoxybenzaldehyde with butanol, isomerization of α-pinene oxide and cyclization of citronellal.
Ring-opening of epoxides promoted by organomolybdenum complexes of the type [(η5-C5H4R)Mo(CO)2(η3-C3H5)] and [(η5-C5H5)Mo(CO)3(CH2R)]
Bruno, Sofia M.,Gomes, Ana C.,Abrantes, Marta,Valente, Anabela A.,Pillinger, Martyn,Gon?alves, Isabel S.
, p. 179 - 183 (2015/10/19)
The cyclopentadienyl molybdenum carbonyl complexes [(η5-C5H4R)Mo(CO)2(η3-C3H5)] and [(η5-C5H5)Mo(CO)3(CH2R)] (R = H, COOH) have been shown to promote acid-catalysed reactions in liquid phase, under moderate conditions. The catalytic alcoholysis of styrene oxide with ethanol at 35 °C gave 2-ethoxy-2-phenylethanol in 100% yield within 30 min for the dicarbonyl complexes and 3-6 h for the tricarbonyl complexes. Steady catalytic performances were observed in consecutive runs with the same catalytic solution, suggesting fairly good catalytic stability. In the second acid-catalysed reaction studied, the isomerization of α-pinene oxide at 55 °C gave campholenic aldehyde and trans-carveol in a total yield of up to 86% at 100% conversion. Chemoselectivity is shown to be solvent dependent.
Infrared Matrix Isolation and Theoretical Studies of Reactions of Ozone with Bicyclic Alkenes: α-Pinene, Norbornene, and Norbornadiene
Kugel, Roger W.,Ault, Bruce S.
, p. 312 - 322 (2015/04/22)
The reactions of ozone with three bicyclic alkenes, α-pinene, norbornene, and norbornadiene, were studied by low-temperature (14 K), argon matrix isolation infrared spectroscopy including 18O isotope-labeling studies. Theoretical calculations of some of the proposed reaction intermediates and products were carried out using the Gaussian 09 suite of programs, applying density functional theory (DFT), the B3LYP functional, and the 6-311G++(d,2p) basis set. In the α-pinene/ozone system, the thermal reaction between α-pinene and ozone was too slow to observe under the twin-jet or merged-jet deposition conditions of these experiments. However, red light (λ ≥ 600 nm) irradiation of the argon matrixes containing α-pinene and ozone caused new infrared peaks to appear that could be readily assigned to reaction products of α-pinene with O(3P) resulting from ozone photolysis: α-pinene oxide (with an epoxide ring) and two isomeric ketones. Norbornene and norbornadiene were both found to react with ozone in the gas phase during twin-jet or merged-jet deposition of these mixtures with argon. New peaks observed in the infrared spectra were assigned to the primary ozonides, Criegee intermediates, and secondary ozonides of norbornene and norbornadiene, indicating that the bulk of these reactions proceeded via the "classic" Criegee mechanism for ozonolysis of alkenes. Calculated infrared frequencies and molecular energies support these conclusions. Ultraviolet irradiation of these mixtures resulted in complete decomposition of the early intermediates and the formation of acids, aldehydes, alcohols, carbon dioxide, and carbon monoxide. In any case, no evidence for "unusual" chemistry, prompted by the bicyclic nature of the reactants, was observed. (Figure Presented).
H- and Fe-modified zeolite beta catalysts for preparation of trans-carveol from α-pinene oxide
Stekrova,Kumar,Daz,M?ki-Arvela,Murzin
, p. 237 - 245 (2015/03/14)
The isomerisation of a-pinene oxide has been intensively investigated for selective preparation of campholenic aldehyde, a compound used in the synthesis of fragrances. Selective preparation of another product of α-pinene oxide rearrangement, trans-carveol, still remains a challenging task. Trans-carveol is a highly valuable compound used in perfume bases, food flavour compositions and as an active pharmaceutical substance in chemoprevention of mammary carcinogenesis. In the present work zeolite beta with different SiO2/Al2O3 molar ratios was modified by iron, characterised and tested per se and in the modified form for trans-carveol preparation from a-pinene oxide. The isomerisation reaction was carried out in a polar basic solvent N, N-dimethylacetamide at 140 °C. The activities and selectivities of the catalysts were correlated with their acid properties and with the iron content.
Isomerization of α-pinene oxide using Fe-supported catalysts: Selective synthesis of campholenic aldehyde
Stekrova, Martina,Kumar, Narendra,Aho, Atte,Sinev, Ilia,Grünert, Wolfgang,Dahl, Johnny,Roine, Jorma,Arzumanov, Sergey S.,M?ki-Arvela, P?ivi,Murzin, Dmitry Yu.
, p. 162 - 176 (2014/01/06)
α-Pinene oxide, an oxygenated derivative of α-pinene, can be converted into various valuable substances useful as flavour, fragrance and pharmaceutical compounds. Campholenic aldehyde is one of the most desired products of α-pinene oxide isomerization being a valuable intermediate for the production of sandalwood-like fragrances. Iron modified zeolites Beta-75 and ZSM-5, mesoporous material MCM-41, silica and alumina were prepared by two methods (impregnation and solid-state ion exchange) and tested for selective preparation of campholenic aldehyde by isomerization of α-pinene oxide. The characterization of tested catalyst was carried out using scanning electron microscope analysis, nitrogen adsorption measurements, pyridine adsorption-desorption with FTIR, X-ray absorption spectroscopy measurements, XPS-analysis, 29Si MAS NMR and 27Al MAS NMR and X-ray diffraction. The isomerization of α-pinene oxide was carried out in toluene as a solvent at 70 C. The main properties influencing the activity and the selectivity are the acidic and structural properties of the tested catalysts. The highest selectivity of 66% was achieved at complete conversion of α-pinene oxide with Fe-MCM-41.
Use of immobilized transition metal complexes as recyclable catalysts for oxidation reactions with hydrogen peroxide as oxidant
Islam, Sk Manirul,Mobarok, Manir,Mondal, Paramita,Roy, Anupam Singha,Salam, Noor,Hossain, Dildar,Mondal, Sanchita
experimental part, p. 97 - 107 (2012/09/22)
A tetradentate Schiff base (teta), obtained from triethylenetetramine and salicylaldehyde, has been covalently bonded to divinylbenzene cross-linked chloromethylated polystyrene. This chelating ligand, abbreviated as PS-teta (PS = polymeric support), reacts with metal chlorides (Cu2+, Co 2+, and Ni2+) in methanol to give polymerbound transition metal complexes, PS-Cu(II)teta/(Cat-1), PS-Ni(II)teta/(Cat-2), and PS-Co(II)teta/(Cat-3), formation of which has been established by various physiochemical methods and spectroscopic techniques. The catalytic potential of these materials has been tested for the oxidation of various alkenes, alkanes, alcohols, and thioethers in the presence of 30% H2O2 as an oxidant. At the same time, these catalysts are very stable and could be reused in oxidation reactions for more than five times without noticeable loss of their catalytic activity. Springer Science+Business Media B.V. 2011.
Acid/vanadium-containing saponite for the conversion of propene into coke: Potential flame-retardant filler for nanocomposite materials
Ostinelli, Luca,Recchia, Sandro,Bisio, Chiara,Carniato, Fabio,Marchese, Leonardo,Guidotti, Matteo,Psaro, Rinaldo
, p. 2394 - 2402,9 (2020/08/24)
Vanadium-containing saponite samples were synthesized in a one-pot synthetic procedure with the aim of preparing samples for potential application as fillers for polymeric composites. These vanadium-modified materials were prepared from an acid support by adopting a synthetic strategy that allowed us to introduce isolated structural V species (H/V-SAP). The physicochemical properties of these materials were investigated by XRD analysis and by DR-UV/Vis and FTIR spectroscopy of CO that was adsorbed at 100 K; these data were compared to those of a V-modified saponite material that did not contain any Bronsted acid sites (Na/V-SAP). The surface-acid properties of both samples (together with the fully acidic H-SAP material and the Na-SAP solid) were studied in the catalytic isomerization of α-pinene oxide. The V-containing solids were tested in the oxidative dehydrogenation reaction of propene to evaluate their potential use as flame-retardant fillers for polymer composites. The effect of tuning the presence of Lewis/Bronsted acid sites was carefully studied. The V-containing saponite sample that contained a marked presence of Bronsted acid sites showed the most interesting performance in the oxidative dehydrogenation (ODH) reactions because they produced coke, even at 773 K. The catalytic data presented herein indicate that the H/V-SAP material is potentially active as a flame-retardant filler. In questo lavoro e stato sintetizzata tramite metodologia one-pot una saponite contenente in struttura vanadio, di interesse come additivo per compositi polimerici. La metodologia di sintesi adottata ha permesso di ottenere un solido acido contenente siti di vanadio strutturale isolati (H/V-SAP). Le proprieta chimico-fisiche di tale materiale sono state studiate tramite XRD, DR-UV-Vis e FT-IR di CO adsorbito a 100 K e confrontate con quelle di una V-saponite priva di acidita di Bronsted (Na/V-SAP). Le proprieta acide di entrambi i materiali (e di saponiti acidi H-SAP e sodica Na-SAP) sono state investigate sottoponendo i campioni ad un test catalitico di isomerizzazione dell' ossido di α-pinene. I campioni contenenti vanadio sono stati infine testati come catalizzatori per la reazione di deidrogenazione ossidativa del propene, con l'obiettivo di valutarne i loro potenziale uso come additivi ritardanti di fiamma per compositi polimerici. La saponite contenente vanadio strutturale e caratterizzata da una marcata acidita di Bronsted ha mostrato le migliori prestazioni catalitiche, producendo prodotti carboniosi anche ad alte temperature di esercizio (773 K). I dati catalitici qui mostrati indicano che il campione H/V-SAP e potenzialmente attivo come ritardante di fiamma per compositi polimerici. A hard day's saponite: An acid/vanadium-containing saponite (H/V-SAP) was synthesized and its physicochemical properties were compared to those of a V-modified saponite material that did not contain acid sites. Both samples were tested in the oxidative dehydrogenation (ODH) reaction of propene to study the capability of the samples to form coke species. H/V-SAP was the most interesting catalyst for the production of coke. Copyright
Influence of the Br?nsted and Lewis acid sites on the catalytic activity and selectivity of Fe/MCM-41 system
Fellenz,Bengoa,Marchetti,Gervasini
scheme or table, p. 187 - 196 (2012/10/08)
The system Fe2O3/MCM-41, with high iron dispersion, was synthesized in order to introduce Lewis acid sites into the MCM-41 structure. Two calcination atmospheres (inert and oxidant) were used to produce iron nanoclusters with different structural properties. Besides, a silylation treatment was realized on both solids with the aim of neutralizing the Br?nsted acidity associated with the MCM-41 silanol groups. The samples were characterized by atomic absorption spectroscopy, X-ray diffraction at low angles, N2 adsorption, temperature-programmed reduction, Fourier transform infrared spectroscopy, nuclear magnetic resonance of 29Si, and M?ssbauer spectroscopy. The influence of the structural changes of the nanoclusters and the effect of the simultaneous presence of Lewis and Br?nsted acid sites were evaluated studying the product distribution from the α-pinene oxide isomerization reaction. It was determined that the Br?nsted acidity of the Fe/MCM-41 system has not the sufficient acid strength to modify the product distribution which is mainly governed by the Lewis sites.
