4407-36-7Relevant academic research and scientific papers
Microwave-assisted syntheses of 1,2-diketones
Mitra, Alok Kumar,De, Aparna,Karchaudhuri, Nilay
, p. 246 - 247 (1999)
A comparative study of the conversion of a number of α-hydroxyketones into 1,2-diketones by three oxidants under microwave irradiation is reported.
The novel and efficient reduction of graphene oxide using Ocimum sanctum L. leaf extract as an alternative renewable bio-resource
Mahata, Suhasini,Sahu, Anjumala,Shukla, Prashant,Rai, Ankita,Singh, Manorama,Rai, Vijai K.
, p. 19945 - 19952 (2018)
The efficient, rapid, bio-inspired synthesis of reduced graphene oxide (rGO) nanosheets was explored using green leaf extract of Ocimum sanctum L. (Tulsi leaves). This mild biorenewable reducing agent containing eugenol, ascorbic acid, and polyols also acts as a stabilizer for the prepared rGO. Characterization of the synthesized graphene nanosheets was performed using XPS, TEM, SEM, XRD, FT-IR, Raman and UV-vis spectroscopy studies. The catalytic application of the prepared rGO was established through the fruitful reduction of α,β-unsaturated aldehydes to the corresponding allylic alcohols in aqueous media. Excellent yields of pure products (92%) in addition to regioselective reduction were practically observed.
Unique Regio- and Stereoselectivity in Pd-Catalyzed Chlorocarbonylation Reaction of 2-Phenylethynyl Selenides and 2-Alkylethynyl Selenides. Highly Stereoselective Synthesis of 2-Seleno-3-chloroacrylates
Huang, Xian,Sun, Aiming
, p. 6561 - 6565 (2000)
Regio- and stereoselectivity in the chloropalladation carbonylation reaction of different acetylenic selenides in the presence of 0.05 equiv of PdCl2 and 3 equiv of cupric chloride under 1 atm of carbon monoxide affording 2-seleno-3-chloroacrylates were investigated. Opposite stereoselectivities were observed with 2-phenylethynyl selenides and 2-alkylethynyl selenides: the reactions of 2-phenylethynyl selenides afforded (E)-2-seleno-3-chloro-3-phenylacrylates, while the reactions of 2-alkylethynyl selenides gave (Z)-2-seleno-3-chloro-3-alkylacrylates. A chloropalladation carbonylation mechanism for this reaction was proposed. The regio- and stereoselective chloropalladation of the carbon-carbon triple bond in acetylenic selenides affords 1-enylpalladium intermediates, in which the palladium atom connects with the carbon atom bonding with the selenium atom. Carbonylation in the presence of an alcohol affords 2-seleno-3-chloroacrylates.
Accelerated reduction of carbonyl compounds under microwave irradiation
Barbry, Didier,Torchy, Severine
, p. 2959 - 2960 (1997)
Aldehydes and ketones are quickly reduced to alcohols by aluminium isopropoxide under microwave irradiation.
Trimerisation of the cationic fragments [(eta ring)M(Aa)]+ (where eta ring)M=eta 5 pentamethylcyclopentadienyl rhodium, eta 5 pentamethylcyclopentadienyl iridium, or eta 6 4isopropyltolyl ruthenium and Aa = alpha amino acidate) with chiral self-recognition: Synthesis, characterisation, solution studies and catalytic reactions of the trimers tris[eta ring M(Aa)] tris(tetrafluoroborate)
Carmona, Daniel,Lahoz, Fernando J.,Atencio, Reinaldo,Oro, Luis A.,Lamata, M. Pilar,Viguri, Fernando,San Jose, Emilio,Vega, Cristina,Reyes, Josefa,Joo, Ferenc,Katho, Agnes
, p. 1544 - 1564 (1999)
The mononuclear neutral chlorides [(η-ring)M(Aa)Cl] ((η-ring)-M- (η5-C5Me5)Rh, (η5-C5Me5)Ir, (η6-p-MeC6H4iPr)Ru; Aa = α-amino acidate) were treated with AgBF4 to yield the corresponding new chiral trimers [{(η-ring)M(Aa)}3](BF4)3. Compounds [{(η5- C5Me5)Ir(Ala)}3](BF4)3 (1b) and [{(η6-p-MeC6H4iPr)Ru(L- Pro)}3](BF4)3 (6c) were characterised by X-ray diffraction. Trimerisation takes place by chiral self-recognition: the trimers R(M)R(M)R(M) (ρ isomer) or S(M)S(M)S(M) (σ isomer), which have equal configuration at the metal centre, were the only diastereomers detected. In solution, a diastereomerisation process between both isomers occurs, where the equilibrium constant depends on the solvent, amino acidate, and metal. The different localisation of the polar groups (NH or NH2 moieties) on the molecular surface of the two diastereomers (ρ and σ) provides a qualitative explanation for the different diastereomer stability observed in solution. The new chiral trimers catalyse the reduction of unsaturated aldehydes to unsaturated alcohols by hydrogen transfer from aqueous sodium formate and the reduction of acetophenone by hydrogen transfer from 2-propanol with up to 75 % ee.
Selectivity in the electrochemical deprotection of cinnamyl groups from oxygen and nitrogen functionalities: Carbonates versus carbamates
Canka?, Petr,Dubas, Diane,Banfield, Scott C.,Chahma, M'hamed,Hudlicky, Tomas
, p. 6851 - 6854 (2005)
Several cinnamyloxy carbamates and carbonates were subjected to electrochemical reduction, and the reductive fate of the cinnamyl group was investigated. Complete selectivity was observed in the removal of the cinnamyl group from oxygen versus nitrogen.
Differentiation of Pt?Fe and Pt?Ni3 Surface Catalytic Mechanisms towards Contrasting Products in Chemoselective Hydrogenation of α,β-Unsaturated Aldehydes
Ning, Liangmin,Zhang, Mingtao,Liao, Shengyun,Zhang, Yuting,Jia, Dandan,Yan, Yunfang,Gu, Wen,Liu, Xin
, p. 704 - 711 (2020/12/07)
Noble-metal catalysts serve as an irreplaceable role in pharmaceutical, perfume and fine chemicals fields. However, there still remains a grand challenge in controlling chemoselectivity. Herein, we have synthesized a bimetallic nanostructure supported on porous metal-organic frameworks (Pt?Fe/UiO-66, Pt-Ni3/UiO-66), in which Pt nanoparticles was modified with non-noble metal (Fe or Ni) directly. The as-synthesized catalysts can function as a switch for selective hydrogenation of α,β-unsaturated aldehydes to afford the potential products on-demand. In comparison with the conventional Pt-based catalysts, Pt?Fe/UiO-66 and Pt-Ni3/UiO-66 catalysts exhibit excellently catalytic activity, enhanced selectivity and improved stability for selectivity hydrogenation. The partial charge reconfiguration and electronic coupling effect existing in such distinctive bicomponent nanocatalysts was confirmed by some comprehensive characterization and density functional theory (DFT) calculations. The developed method for precisely modification the composition and interaction between the noble metal and non-noble metal provides a feasible avenue to design the advanced catalysts.
Platinum and cobalt intermetallic nanoparticles confined within MIL-101(Cr) for enhanced selective hydrogenation of the carbonyl bond in a,?-unsaturated aldehydes: synergistic effects of electronically modified Pt sites and Lewis acid sites
Zahid, Muhammad,Li, Jiang,Ismail, Ahmed,Zaera, Francisco,Zhu, Yujun
, p. 2433 - 2445 (2021/04/22)
Precious metals have been shown to play a vital role in the selective hydrogenation of a,?-unsaturated aldehydes, but still suffer from challenges to control selectivity. Herein, we have advanced the design of catalysts made out of Pt-Co intermetallic nanoparticles (IMNs) supported on a MIL-101(Cr) MOF (3%Pty%Co/MIL-101(Cr)), prepared by using a polyol reduction method, as an effective approach to enhance selectivity toward the production of a,?-unsaturated alcohol, the desired product. XRD, N2adsorption-desorption, FTIR spectroscopy, SEM, TEM, XPS, CO adsorption, NH3-TPD, XANES and EXAFS measurements were used to investigate the structure and surface properties of our 3%Pty%Co/MIL-101(Cr) catalysts. It was found that the Co-modified 3%Pty%Co/MIL-101(Cr) catalysts can indeed improve the hydrogenation of cinnamaldehyde (CAL) to cinnamyl alcohol (COL), reaching a higher selectivity under mild conditions than the monometallic Pt/MIL-101(Cr) catalysts: 95% conversion of CAL with 91% selectivity to COL can be reached with 3%Pt3%Co/MIL-101(Cr). Additionally, high conversion of furfural (97%) along with high selectivity to furfural alcohol (94%) was also attained with the 3%Pt3%Co/MIL-101(Cr) catalyst. The enhanced activity and selectivity toward the unsaturated alcohols are attributed to the electronic and geometric effects derived from the partial charge transfer between Co and Pt through the formation of uniformly dispersed Pt-Co IMNs. Moreover, various characterization results revealed that the addition of Co to the IMPs can promote the Lewis acid sites that facilitate the polarization of the charge-rich C?O bonds and their adsorptionviatheir oxygen atom, and also generate new interfacial acid sites.
Platinum Nanosheets Intercalated into Natural and Artificial Graphite Powders
Shirai, Masayuki,Kubo, Kohei,Sodeno, Mika,Nanao, Hidetaka
, p. 2035 - 2040 (2021/06/25)
Insertion of sheet-type platinum particles (platinum nanosheets) between graphite layers was achieved by a thermal treatment of a mixture of platinum chloride (IV) and graphite powder (natural graphite or artificial graphite) under 0.3 MPa of chlorine at 723 K, followed by the treatment under 40 kPa of hydrogen pressure. Similar platinum nanosheets, which were 1–3 nm in thickness and 100–500 nm in width and had a number of hexagonal holes and edges with 120° angle, were formed between the layers of both natural graphite or artificial graphite; however, their location in the graphite layers depended on the type of graphite used. A number of platinum nanosheets were observed in the edge region of natural graphite particles which have flat surface. On the other hand, a number of platinum nanosheets were found inside and away from the edge of the artificial graphite particles especially in the vicinity of the cracks. Both the platinum nanosheet-containing artificial and natural graphite samples showed high selectivity to cinnamyl alcohol in cinnamaldehyde hydrogenation under supercritical carbon dioxide conditions, while spherical platinum particles, which were located on the surface of natural and artificial graphite, showed lower selectivity.
Supported silver catalysts prepared via melt infiltration: Synthesis, characterization and performance in selective hydrogenation
Keijzer,Donoeva,de Jong,de Jongh
, p. 393 - 400 (2020/04/01)
Heterogeneous supported catalysts are often synthesized by impregnation or precipitation methods. Recently, melt infiltration has emerged as an alternative method that allows high metal loadings and eliminates the need for a solvent, but challenges arise regarding control over the particle size and distribution. In this work, melt infiltration for the synthesis of supported silver catalysts is explored. The narrow pore size distribution of the chosen ordered mesoporous silica support, SBA-15, allowed in depth in-situ and ex-situ characterization of the infiltration of the precursor, molten silver nitrate, into the support and its subsequent decomposition to form metallic silver nanowires or nanoparticles. The heat treatment parameters during decomposition played a key role in determining whether nanowires or nanoparticles were formed. The supported silver catalysts containing high silver weight loadings were investigated in the selective hydrogenation of cinnamaldehyde, where the silver nanowires showed superior activity and selectivity over the nanoparticles. Hence, melt infiltration shows great promise for the synthesis of supported silver catalysts containing high silver weight loadings, which are applicable in, e.g., selective oxidation or hydrogenation reactions.
