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Dive into the research topics where Simona M. Coman is active.

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Featured researches published by Simona M. Coman.


Green Chemistry | 2013

Ru-based magnetic nanoparticles (MNP) for succinic acid synthesis from levulinic acid

Iunia Podolean; Victor Kuncser; Nicoleta G. Gheorghe; Dan Macovei; Vasile I. Parvulescu; Simona M. Coman

Ru(III)/functionalized silica-coated magnetic nanoparticles (Ru(III)-MNP) were proven to be a highly active, selective and easily recoverable catalyst for the oxidation of levulinic acid to succinic acid under green conditions.


Applied Surface Science | 1999

Reducibility of ruthenium in relation with zeolite structure

Vasile I. Parvulescu; Simona M. Coman; P Palade; Dan Macovei; Cristian M. Teodorescu; G Filoti; R. Molina; Georges Poncelet; Fe Wagner

Ru-zeolites prepared via deposition of aqueous solution of ruthenium chloride on X, L, ZSM-5 and APO-54 were investigated. The impregnated solids were characterized by the following techniques: N-2 sorption, H-2 chemisorption, TPR, XRD, XPS, EXAFS and Mossbauer spectroscopy. It was found that deposition of Ru is influenced by the pore structure and the chemical composition of the supports, in particular the concentration and strength of the protonic sites, with the formation of the different species. The packing of Ru as well as the degree of the reduction and the metal particle size are different according to the penetration depth of the metal and the nature of the zeolite. The amount of chlorine possibly remaining as adatoms of Ru is very low or inexistent. In calcined and reduced catalysts no chloride peak could be evidenced by XPS. The experiments confirmed that the use of large amounts of Ru chloride precursor leads to rather large metal particles


Nature Communications | 2015

High catalytic activity of oriented 2.0.0 copper(I) oxide grown on graphene film

Ana Primo; Iván Esteve-Adell; Juan F. Blandez; Amarajothi Dhakshinamoorthy; Mercedes Alvaro; Natalia Candu; Simona M. Coman; Vasile I. Parvulescu; Hermenegildo García

Metal oxide nanoparticles supported on graphene exhibit high catalytic activity for oxidation, reduction and coupling reactions. Here we show that pyrolysis at 900 °C under inert atmosphere of copper(II) nitrate embedded in chitosan films affords 1.1.1 facet-oriented copper nanoplatelets supported on few-layered graphene. Oriented (1.1.1) copper nanoplatelets on graphene undergo spontaneous oxidation to render oriented (2.0.0) copper(I) oxide nanoplatelets on few-layered graphene. These films containing oriented copper(I) oxide exhibit as catalyst turnover numbers that can be three orders of magnitude higher for the Ullmann-type coupling, dehydrogenative coupling of dimethylphenylsilane with n-butanol and C–N cross-coupling than those of analogous unoriented graphene-supported copper(I) oxide nanoplatelets.


Chemical Communications | 2004

Ir-Beta zeolite as a heterogeneous catalyst for the one-pot transformation of citronellal to menthol

F Iosif; Simona M. Coman; Parvulescu; Paul Grange; Stéphanie Delsarte; Dirk E. De Vos; Pascale Jacobs

Beta zeolites, impregnated with Ir, catalyze the one-pot full conversion of citronellal to menthol by consecutive acid-catalyzed cyclization and Ir-catalyzed hydrogenation, with 95% selectivity for the menthol isomers, of which 75% is the desired (-)-menthol.


Chemsuschem | 2012

Sn‐Doped Hydroxylated MgF2 Catalysts for the Fast and Selective Saccharification of Cellulose to Glucose

Stefan Wuttke; Alina Negoi; Nicoleta Gheorghe; Victor Kuncser; Erhard Kemnitz; Vasile I. Parvulescu; Simona M. Coman

TIN, TAILORED, NOT SOLDER, BUT CAT: Doped hydroxylated fluorides, prepared by a modified sol-gel method, offer enhanced acidity and improved stability against water, and efficiency in the degradation of cellulose. These materials extend the portfolio of acid catalysts for fast and selective hydrolysis of biomass to glucose, which offers a feedstock for bioethanol production.


Chemcatchem | 2010

Synthesis of Vitamin K-1 and K-1-Chromanol by Friedel-Crafts Alkylation in Heterogeneous Catalysis

Simona M. Coman; Vasile I. Parvulescu; Stefan Wuttke; Erhard Kemnitz

The partly hydroxylated MgF2 and AlF3 materials are efficient and selective catalysts for the preparation of two important members of the vitamin K class: vitamin K1 and vitamin K1‐chromanol. The high activity in combination with high selectivity in one of the target products is due to both the acidic strength and the synergistic effect of the presence of both, optimized Brønsted and Lewis sites. Therefore, the best catalyst for a target product can be obtained through a very simple tuning of the acidic properties of the material. Moreover, the results obtained in the present study (Yvitamin K1=57.8 % and Yvitamin K1‐chromanol=71.4 %) are also very encouraging from the environmental standpoint as green elements are introduced by using solid catalysts and a biphasic solvent system.


Chemsuschem | 2013

Direct synthesis of sorbitol and glycerol from cellulose over ionic Ru/magnetite nanoparticles in the absence of external hydrogen.

Alina Negoi; Ioan Teodor Trotus; Olimpia Mamula Steiner; Madalina Tudorache; Victor Kuncser; Dan Macovei; Vasile I. Parvulescu; Simona M. Coman

A sweet catalyst: A catalyst formed of Ru/functionalized silica-coated magnetite nanoparticles is highly efficient in the one-pot production of sorbitol and glycerol, starting from cellulose and in the absence of an external hydrogen source. The ease of recoverability of the catalyst from the solid residues, and its reuse without loss of activity or selectivity for several runs, is an important green element of the process.


Journal of Molecular Catalysis A-chemical | 1999

Stereocontrolled hydrogenation of prostaglandin intermediates over Ru–MCM-41 catalysts

Simona M. Coman; V.I Pârvulescu; B. Tesche; H Bönnemann; J.F. Roux; P.A. Jacobs

Ru–MCM-41 catalysts were investigated in the diastereoselective hydrogenation of class F prostaglandin intermediates. The catalysts were prepared by deposition of Ru from different precursors (ruthenium acetylacetonate, ruthenium chloride or ruthenium hexaamine chloride). These catalysts were characterized using several techniques: atomic emission spectroscopy with inductively coupled plasma, N2 adsorption–desorption curves at 77 K, H2-chemisorption, temperature-programmed oxidation, temperature-programmed reduction, XPS, XRD and transmission electron microscopy (TEM). The measurements indicated that Ru is homogeneously distributed on the surface of MCM-41 and that using the hexamine chloride complex allows a better penetration of Ru inside the mesoporous tubes then the other two precursors. Hydrogenation of a prostaglandin F intermediate, namely the one with R=H and –R′=CH2–O–C6H4 (m) Cl, showed that the catalysts prepared using ruthenium acetylacetonate and ruthenium chloride exhibit a higher selectivity to allylic alcohol than that prepared using ruthenium hexaamine chloride. In all the investigated catalysts the diastereomeric excess was in the (11R,15S) allyl alcohol and it varied in the same order as the chemoselectivity. A positive effect of pressure was found.


Catalysis Science & Technology | 2015

Direct oxidation of amines to nitriles in the presence of ruthenium-terpyridyl complex immobilized on ILs/SILP

Octavian Dumitru Pavel; Peter Goodrich; Liliana Cristian; Simona M. Coman; Vasile I. Pârvulescu; Christopher Hardacre

The immobilization of a ruthenium complex (Ru2Cl4(az-tpy)2) within a range of supported ionic liquids ([C4C1im]Cl, [C4C1im][NTf2], [C6C1im]Cl, [C4C1pyrr]Br, [C4C1im]Br, [C4C1pyrr]Cl) dispersed silica (SILP) operates as an efficient heterogeneous catalyst in oxidation of long chain linear primary amines to corresponding nitriles. This reaction follows a “green” route using a cheap and easy to handles oxidant (oxygen or air). The conversion was found to be strongly influenced by the alkyl chain length of the amine substrate and the choice of oxidant. No condensation reaction was observed between the starting amines and the selectivity to nitrile is 100%. Moving from a composition of 20 atm N2/5 atm O2 to 5 atm N2/20 atm O2 led to enhancements in the conversion (n-alkylamines) and selectivity (benzonitrile) which have been correlated with an increase of the solubilized oxygen. This was further supported by using different inert gas (nitrogen, helium, argon)/oxygen mixtures indicating that the O2 solubility in the SILP system, has an important effect on conversions and TON in this reaction using SILP catalysts. Experiments performed in the presence of CO2 led to a different behaviour due to the formation of amine-CO2 adducts. The application of the Weisz–Prater criterion confirmed the absence of any diffusional constraints.


Catalysis Science & Technology | 2015

Efficient magnetic and recyclable SBILC (supported basic ionic liquid catalyst)-based heterogeneous organocatalysts for the asymmetric epoxidation of trans-methylcinnamate

Natalia Candu; Cristina Rizescu; Iunia Podolean; Madalina Tudorache; Vasile I. Parvulescu; Simona M. Coman

A green alternative, based on the use of an efficient and recyclable chiral ketone@SBILC@MWCNT@Fe3O4 catalytic system (Y = 35%, S = 100% and ee = 100%), was developed for the asymmetric epoxidation of trans-methylcinnamate to (2R,3S)-phenyl glycidate.

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Erhard Kemnitz

Humboldt University of Berlin

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Hermenegildo García

Polytechnic University of Valencia

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Alina Negoi

University of Bucharest

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