Catalytic reduction of benzoate esters and lactones in the presence of PhMeSiH2 and a titanocene-based catalyst

2002 ◽  
Vol 80 (5) ◽  
pp. 489-495 ◽  
Author(s):  
Ronghua Shu ◽  
John F Harrod ◽  
Anne-Marie Lebuis
Keyword(s):  
Catalytic Reduction ◽  
Catalytic Amount ◽  
Ethyl Benzoate ◽  
Ethoxy Group ◽  
Reaction Conditions ◽  
X Ray ◽  
Stoichiometric Amount ◽  
Stoichiometric Reaction

PhMeSiH2 reduces ethyl benzoate in the presence of a Cp2TiMe2 (Cp = η5-cyclopentadienyl) catalyst to give PhMeSi(OEt)(OCH2Ph) (1). Small to moderate amounts of toluene are also produced, depending on the reaction conditions. Under 40 psi of H2 the same reaction gives quantitative reduction of the ester to toluene. PhCHO is reduced, under the same conditions as the ester, to a mixture of PhMeSi(OCH2Ph)2 and toluene in proportions similar to that observed with the ester. A stoichiometric reaction of PhMeSiH2, PhCOOEt, and Cp2TiMe2 resulted in the formation of known [Cp2Ti(OEt)]2 (2) in 75% isolated yield. A mechanism is proposed in which the C=O of the ester inserts into a Ti–H bond. A Ti-mediated transfer of the ethoxy group from the resulting (α-ethoxy)benzyloxytitanium intermediate to silicon produces PhMeSi(OEt)H and PhCHO. 1 is generated via hydrosilation of PhCHO by PhMeSi(OEt)H. Both β- and γ-butyrolactones react with PhMeSiH2 in the presence of a catalytic amount of Cp2TiMe2 to produce copolymers -[O-PhMeSi-O(CH2)3CHR]n- (R = H, 3; R = Me, 4) (Mw [Formula: see text] 1 × 103; Mw/Mn [Formula: see text] 1.3). A mechanism analogous to that proposed for the ethyl benzoate reduction is proposed. A reaction of PhMeSiH2 and γ-butyrolactone with a stoichiometric amount of Cp2TiMe2 in the presence of tetrahydofuran (THF) produces Cp2Ti(µ-H)(µ-η1,η5-C5H4)Ti(OC4H8)Cp(5) (65% isolated yield) whose structure is determined by X-ray crystallography.Key words: hydrosilation, esters, lactones, titanocene, catalysis.

Synthesis of Palladium Chloride Impregnated on Al2O3- Pillared Clay for Reduction of Nitrobenzene

2020 ◽  
Vol 856 ◽  
pp. 218-223
Author(s):  
Piyarat Trikittiwong ◽  
Jedsada Maliwong
Keyword(s):  
Catalytic Amount ◽  
Solvent System ◽  
Pillared Clay ◽  
Palladium Chloride ◽  
X Ray Diffraction ◽  
Reaction Conditions ◽  
X Ray ◽  
Catalytic Activities ◽  
Atomic Spacing ◽  
Desorption Method

Palladium chloride impregnated on Al2O3-pillared clay (Pd/Al-PILC) was synthesized by intercalation of aluminium (III) chloride into clay interlayers and calcined at 500°C for 1 h. Subsequently, impregnated with PdCl2 and calcination at 450°C for 4 h. The modified clay catalyst was characterized by X-ray diffraction (XRD) for investigated atomic spacing of catalysts and N2 adsorption and desorption method (BET) for investigated surface area and pore volume of catalysts. The catalytic activities of Pd/Al-PILC was utilized for the reduction of nitrobenzene for synthesis aniline. The effect of various reaction factors, such as reaction time, reaction temperature, solvent system and the amount of catalyst were studied in order to optimize the reaction conditions. Aniline was prepared conveniently and efficiently via the reduction of nitrobenzene in the presence of a catalytic amount 40%Pd/Al-PILC of substrate in reflux temperature at 70°C for 4 h under extremely mild conditions.

The synthesis of a hexameric expanded hemiporphyrazine

2020 ◽  
Vol 24 (01n03) ◽  
pp. 129-134
Author(s):  
Briana R. Schrage ◽  
Kullapa Chanawanno ◽  
Laura A. Crandall ◽  
Christopher J. Ziegler
Keyword(s):  
Structure Elucidation ◽  
Catalytic Amount ◽  
Protonated Form ◽  
Free Base ◽  
Reaction Conditions ◽  
X Ray ◽  
X Ray Crystallography ◽  
The Third ◽  
Expanded Porphyrins

Although the chemistry of expanded porphyrins is well developed, there has been significantly less work on expanded isoindoline based macrocycles such as hemiporphyrazines. In this report we present the synthesis and characterization of a new hexameric expanded hemiporphyrazine which we refer to as hexahemiporphyrazine. The synthesis incorporated bis(6-amino-2-pyridyl)amine as a starting material, which could be produced from 2,6-diaminopyridine using melt reaction conditions. Bis(6-amino-2-pyridyl)amine can adopt a three different conformations, two of which are observed in the free base and protonated form, and the third in the backbone of hexahemiporphyrazine. Reaction of bis(6-amino-2-pyridyl)amine and diiminoisoindoline in the presence of a catalytic amount of BF3 produces the hexihemiporphyrazine macrocycle, which was characterized spectroscopically and by X-ray crystallography. Structure elucidation reveals two inverted pyridine rings in a configuration reminiscent of that seen in hexaphyrin, however hexahemiporphyrazine lacks cross conjugation across the macrocycle.

Surfactant involved in Copper Sulfide Nanocrystallites Synthesis

2009 ◽  
Vol 59 (12) ◽  
Author(s):  
Claudia Maria Simonescu ◽  
Valentin Serban Teodorescu ◽  
Camelia Capatina
Keyword(s):  
Copper Sulfide ◽  
X Ray Diffraction ◽  
Reaction Parameters ◽  
Reaction Conditions ◽  
X Ray ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Shape Of Nanoparticles ◽  
Tem Transmission Electron Microscopy ◽  
Shape And Size

This paper presents the obtaining of copper sulfide CuS (covelite) from Cu(CH3COO)2.H2O and thioacetamide (TAA) system. The reaction was conducted in presence or absence of sodium-bis(2-ethylhexyl) sulfosuccinate (Na-AOT). The effects of various reaction parameters on the size and on the shape of nanoparticles have been examined. CuS obtained was characterized by X ray diffraction, IR spectroscopy, TEM � transmission electron microscopy and SAED selected area electron diffraction. The influence of surfactant to the shape and size of CuS (covellite) nanocrystals was established. The size of the nanocrystals varied from 10-60 nm depending on the reaction conditions such as quantity of surfactant.

One-pot Synthesis of Pyrazolone Sulfones by Iodine-catalyzed Sulfenylation of Pyrazolones with Aryl Sulfonyl Hydrazides Followed by Oxidation in Water

2018 ◽  
Vol 15 (3) ◽  
pp. 380-387
Author(s):  
Xia Zhao ◽  
Xiaoyu Lu ◽  
Lipeng Zhang ◽  
Tianjiao Li ◽  
Kui Lu
Keyword(s):  
Double Bond ◽  
Efficient Method ◽  
Room Temperature ◽  
Sulfonyl Chloride ◽  
Antibacterial Activities ◽  
Oxidation Reactions ◽  
Reaction Conditions ◽  
One Pot ◽  
X Ray ◽  
Amide Form

Aim and Objective: Pyrazolone sulfones have been reported to exhibit herbicidal and antibacterial activities. In spite of their good bioactivities, only a few methods have been developed to prepare pyrazolone sulfones. However, the substrate scope of these methods is limited. Moreover, the direct sulfonylation of pyrazolone by aryl sulfonyl chloride failed to give pyrazolone sulfones. Thus, developing a more efficient method to synthesize pyrazolone sulfones is very important. Materials and Method: Pyrazolone, aryl sulphonyl hydrazide, iodine, p-toluenesulphonic acid and water were mixed in a sealed tube, which was heated to 100°C for 12 hours. The mixture was cooled to 0°C and m-CPBA was added in batches. The mixture was allowed to stir for 30 min at room temperature. The crude product was purified by silica gel column chromatography to afford sulfuryl pyrazolone. Results: In all cases, the sulfenylation products were formed smoothly under the optimized reaction conditions, and were then oxidized to the corresponding sulfones in good yields by 3-chloroperoxybenzoic acid (m-CPBA) in water. Single crystal X-ray analysis of pyrazolone sulfone 4aa showed that the major tautomer of pyrazolone sulfones was the amide form instead of the enol form observed for pyrazolone thioethers. Moreover, the C=N double bond isomerized to form an α,β-unsaturated C=C double bond. Conclusion: An efficient method to synthesize pyrazolone thioethers by iodine-catalyzed sulfenylation of pyrazolones with aryl sulfonyl hydrazides in water was developed. Moreover, this method was employed to synthesize pyrazolone sulfones in one-pot by subsequent sulfenylation and oxidation reactions.

Solution multinuclear (31P,111Cd,77Se) magnetic resonance studies of cadmium complexes of heterocyclic aromatic thiones and the structure of [tetrakis(2(1H)-pyridinethione)cadmium] nitrate, [Cd(C5H5NS)4](NO3)2

2000 ◽  
Vol 78 (5) ◽  
pp. 590-597 ◽  
Author(s):  
Umarani Rajalingam ◽  
Philip AW Dean ◽  
Hilary A Jenkins
Keyword(s):  
Cadmium Nitrate ◽  
Cadmium Complexes ◽  
Nmr Studies ◽  
X Ray ◽  
X Ray Crystallography ◽  
Stoichiometric Reaction ◽  
Complex Salts ◽  
Reduced Temperature ◽  
Aromatic Heterocyclic ◽  
Phosphine Chalcogenides

The complex salts CdL4(O3SCF3)2 (L = 2(1H)-pyridinethione (Py2SH), 4(1H)-pyridinethione (Py4SH), or 2(1H)-quinolinethione (Q2SH)) have been synthesized by the stoichiometric reaction of Cd(O3SCF3)2 and the appropriate thione. Both ambient-temperature 13C and reduced-temperature 111Cd NMR of CdL4(O3SCF3)2 in solution are consistent with L being bound through sulfur. Reduced-temperature NMR (31P, 77Se, 111Cd, as appropriate) of mixtures of CdL4(O3SCF3)2 and Cd(EPCy3)4(O3SCF3)2 (E = Se, Cy = c-C6H11) and of Cd(EPCy3)4(O3SCF3)2 (E = S, Se) and L in solution provides evidence for various [CdLn(EPCy3)4-n]2+. Similarly, reduced-temperature metal NMR of [CdL4]2+ and [CdL'4]2+ (L, L' = Py2SH, Py4SH, Q2SH; L not equal L') in solution shows the formation of [CdLnL'4-n]2+. Thus it has been demonstrated that at reduced temperature [CdL4]2+ is intact in solution and exchange of L is slow on the timescale of the metal chemical shift differences. From the NMR studies of Cd(EPCy3)4(O3SCF3)2 (E = S, Se):L mixtures, the binding preferences are found to be L > EPCy3 in solution. Similarly, from the reduced temperature metal NMR spectra of mixtures where L and L' compete for Cd(II) in solution, the binding preferences are Py4SH > Py2SH > Q2SH. The structure of Cd(Py2SH)4(NO3)2 (4) has been determined by single crystal X-ray analysis. Colorless crystals of 4 are tetragonal, I4(1)/acd with 8 molecules per unit cell of dimensions a = 18.660(3), c = 15.215(3) Å. The structure is comprised of recognizable NO3- anions and [Cd(Py2SH)4]2+ cations. In the cations, which have S4 symmetry, the ligands are S-bound. A network of NH···O hydrogen bonds links the cations and anions.Key words: aromatic heterocyclic thiones, cadmium complexes, phosphine chalcogenides, 111Cd, 31P, 77Se NMR, X-ray crystallography.

scholarly journals Self-Assembled Bimetallic Aluminum-Salen Catalyst for the Cyclic Carbonates Synthesis

Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 4097
Author(s):  
Wooyong Seong ◽  
Hyungwoo Hahm ◽  
Seyong Kim ◽  
Jongwoo Park ◽  
Khalil A. Abboud ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Self Assembly ◽  
Reaction Pathway ◽  
Kinetic Studies ◽  
Cyclic Carbonate ◽  
Reaction Conditions ◽  
Formation Reaction ◽  
X Ray ◽  
Carbonate Formation ◽  
Salen Aluminum

Bimetallic bis-urea functionalized salen-aluminum catalysts have been developed for cyclic carbonate synthesis from epoxides and CO2. The urea moiety provides a bimetallic scaffold through hydrogen bonding, which expedites the cyclic carbonate formation reaction under mild reaction conditions. The turnover frequency (TOF) of the bis-urea salen Al catalyst is three times higher than that of a μ-oxo-bridged catalyst, and 13 times higher than that of a monomeric salen aluminum catalyst. The bimetallic reaction pathway is suggested based on urea additive studies and kinetic studies. Additionally, the X-ray crystal structure of a bis-urea salen Ni complex supports the self-assembly of the bis-urea salen metal complex through hydrogen bonding.

Selective catalytic reduction of NO by Co-Mn based nanocatalysts

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Vahid Zabihi ◽  
Mohammad Hasan Eikani ◽  
Mehdi Ardjmand ◽  
Seyed Mahdi Latifi ◽  
Alireza Salehirad
Keyword(s):  
Selective Catalytic Reduction ◽  
Catalytic Reduction ◽  
Energy Dispersive ◽  
Diffraction Field ◽  
X Ray Diffraction ◽  
X Ray ◽  
Analysis Techniques ◽  
Acidic Sites ◽  
Temperature Window ◽  
Temperature Programmed

Abstract One of the most significant aspects in selective catalytic reduction (SCR) of nitrogen oxides (NOx) is developing suitable catalysts by which the process occurs in a favorable way. At the present work SCR reaction by ammonia (NH3-SCR) was conducted using Co-Mn spinel and its composite with Fe-Mn spinel, as nanocatalysts. The nanocatalysts were fabricated through liquid routes and then their physicochemical properties such as phase composition, degree of agglomeration, particle size distribution, specific surface area and also surface acidic sites have been investigated by X-ray diffraction, Field Emission Scanning Electron Microscope, Energy-dispersive X-ray spectroscopy, energy dispersive spectroscopy mapping, Brunauer–Emmett–Teller, temperature-programmed reduction (H2-TPR) and temperature-programmed desorption of ammonia (NH3-TPD) analysis techniques. The catalytic activity tests in a temperature window of 150–400 °C and gas hourly space velocities of 10,000, 18,000 and 30,000 h−1 revealed that almost in all studied conditions, CoMn2O4/FeMn2O4 nanocomposite exhibited better performance in SCR reaction than CoMn2O4 spinel.

scholarly journals Effects of thermal treatments on characteristics and morphological variations in the deposits of urea-SCR systems

2021 ◽  
Author(s):  
Sadashiva Prabhu S ◽  
Kapilan Natesan ◽  
Nagaraj Shivappa Nayak
Keyword(s):  
Cyanuric Acid ◽  
Catalytic Reduction ◽  
Morphological Changes ◽  
Water Solution ◽  
Slight Variation ◽  
Gravimetric Analysis ◽  
Oxides Of Nitrogen ◽  
Deposit Formation ◽  
X Ray ◽  
Exhaust Gases

AbstractSelective catalytic reduction (SCR) systems are employed by automobile manufacturers for the abatement of environmental pollutants like oxides of nitrogen (NOx) emitted from exhaust gases of diesel engines. In SCR, the urea-water solution (UWS) is injected to exhaust gases in the form of a spray to generate the reducing agent NH3. Deposit formation at lower temperatures is a major concern with this technology. The deposits not only create backpressure but also leak NH3 to the environment as they deplete. It is very important to know the depletion characteristics of deposits formed at lower temperatures in order to assess the NH3 leakage to the environment when the engine exhaust gases attain higher temperatures. In the present work, deposits formed at a low-temperature range of 150–200°C for continuous run along with UWS injection were investigated. Additionally, they were aged at 300°C in the absence of UWS to check the variation in characteristics with the rise of temperature. By gravimetric analysis, it is inferred that the deposits formed at higher pre-age temperatures are less prone to depletion as the temperature increases. The elemental analysis using energy-dispersive X-ray spectroscopy (EDX) indicates slight variation in carbon, nitrogen and oxygen compositions for all the pre-age conditions. As an extended study, the byproducts at pre-age and post-age conditions were investigated through X-ray diffraction (XRD). The compounds like cyanuric acid (CYA) and biuret were not observed when pre-age samples were aged at 300°C. Instead, the compounds like ammelide, ammeline, triuret and melamine were observed. Scanning electron microscope (SEM) study revealed morphological changes in both pre-age and post-age samples. Further, the crystallinity variations were also observed for the changes in the heating cycles during deposit formation. The gravimetric analysis of deposits in pre-age and post-age conditions helps in predicting the amount of deposits for transient load cycles.

scholarly journals UV-Accelerated Photocatalytic Degradation of Pesticide over Magnetite and Cobalt Ferrite Decorated Graphene Oxide Composite

Plants ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 6
Author(s):  
Asma Tabasum ◽  
Mousa Alghuthaymi ◽  
Umair Yaqub Qazi ◽  
Imran Shahid ◽  
Qamar Abbas ◽  
...  
Keyword(s):  
Spectroscopic Techniques ◽  
Combined Effects ◽  
X Ray Diffraction ◽  
Contributing Factors ◽  
Reaction Conditions ◽  
X Ray ◽  
Oxidant Concentration ◽  
Optimized Conditions ◽  
High Degradation Rate ◽  
Considerable Loss

Pesticides are one of the main organic pollutants as they are highly toxic and extensively used worldwide. The reclamation of wastewater containing pesticides is of utmost importance. For this purpose, GO-doped metal ferrites (GO-Fe3O4 and GO-CoFe2O4) were prepared and characterized using scanning electron microscopy, X-ray diffraction and Fourier transform infrared spectroscopic techniques. Photocatalytic potentials of catalysts were investigated against acetamiprid’s degradation. A detailed review of the parametric study revealed that efficiency of overall Fenton’s process relies on the combined effects of contributing factors, i.e., pH, initial oxidant concentration, catalyst dose, contact time, and acetamiprid load. ~97 and ~90% degradation of the acetamiprid was achieved by GO-CoFe2O4 and GO-Fe3O4, respectively during the first hour under UV radiations at optimized reaction conditions. At optimized conditions (i.e., pH:3, [H2O2]: 14.5 mM (for Fe3O4, GO-Fe3O4, and GO-CoFe2O4) and 21.75 mM (for CoFe2O4), catalysts: 100 mgL−1, time: 60min) the catalysts exhibited excellent performance, with high degradation rate, magnetic power, easy recovery at the end, and efficient reusability (up to 5 cycles without any considerable loss in catalytic activity). A high magnetic character offers its easy separation from aqueous systems using an external magnet. Moreover, the combined effects of experimental variables were assessed simultaneously and justified using response surface methodology (RSM).

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