92-69-3Relevant articles and documents
SYNTHESIS OF DIARYLS FROM PHENYLBORIC ACID AND ARYL IODIDES IN AN AQUEOUS MEDIUM
Bumagin, N. A.,Bykov, V. V.,Beletskaya, I. P.
, p. 2206 (1989)
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Selective heating of pd-modified ordered mesoporous carbon CMK-3 by microwave irradiation
Inagaki, Satoshi,Onodera, Kenzo,Tani, Kensaku,Kubota, Yoshihiro
, p. 1136 - 1143 (2011)
Various microwave-heated heterogeneous catalytic reactions can be accelerated by choice of the catalyst supports and solvents. In this work, heterogeneous Pd catalysts supported on ordered mesoporous carbon CMK-3 and related catalysts were prepared. In the presence of these catalysts, the effect of microwave heating on Pd-catalyzed SuzukiMiyaura coupling as a probe reaction was investigated. The CMK-3 worked efficiently as a "carbon nanoflask" under microwave irradiation, especially in nonpolar solvents such as toluene and o-xylene with a lower ratio of dielectric constant (δ′) to dielectric loss (δ″) (=tan δ).
One-pot hydrothermal synthesis of Pd/Fe3O4 nanocomposite in HEPES buffer solution and catalytic activity for Suzuki reaction
Li, Shaozhong,Zhang, Wei,Chen, Fengxi,Chen, Rong
, p. 186 - 191 (2015)
The Pd/Fe3O4 nanocomposite integrates versatile Pd nanocatalysts with magnetic separation, and has great potential in fine chemical and pharmaceutical synthesis. Its preparation usually involves multi-steps. Herein it was prepared via a facile one-pot hydrothermal synthesis in 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) buffer solution with the assistant of polyvinylpyrrolidone (PVP). HEPES plays multi-functions, particularly as a ligand to enhance the oxidation of Fe2+ to Fe3+ and as a buffer to control the pH value at slightly basic conditions (ca. 7.4) for the formation of crystalline Fe3O4 phase via Fe2+/Fe3+ co-precipitation. PVP works as a dispersant to prevent the particle from aggregation. The obtained Pd/Fe3O4 nanocomposite comprised uniform Pd nanoparticles (ca. 5 nm) deposited on Fe3O4 nanocrystals (ca. 15 nm). It exhibited excellent catalytic activity and stability for various Suzuki coupling reactions, and could be efficiently recovered with a magnet and recycled for at least 10 cycles without losing catalytic activity.
Kharasch,Sharma
, p. 106 (1966)
Anchoring of palladium(II) in chemically modified mesoporous silica: An efficient heterogeneous catalyst for Suzuki cross-coupling reaction
Bhunia, Susmita,Sen, Rupam,Koner, Subratanath
, p. 3993 - 3999 (2010)
The synthesis and characterization of a highly efficient and reusable catalyst, Pd(II) immobilized in mesoporous silica MCM-41, are described. Pd(II) Schiff-base moiety has been anchored onto mesoporous silica surface via silicon alkoxide chemistry. The catalyst has been characterized by small-angle X-ray diffraction (SAX), FTIR and electronic spectroscopy as well as elemental analysis. The catalyst is used in Suzuki cross-coupling reaction of various aryl halides, including less reactive chlorobenzene, and phenylboronic acid to give biaryls in excellent yields without any additive or ligand. High selectivity for the bi-aryl products containing both electron-donating and electron-withdrawing substituents, mild reaction conditions and possibility of easy recycle makes the catalyst highly desirable to address the industrial needs and environmental concerns.
Pd-sepiolite catalyst for Suzuki coupling reaction in water: Structural and catalytic investigations
Shimizu, Ken-Ichi,Maruyama, Rei,Komai, Shin-Ichi,Kodama, Tatsuya,Kitayama, Yoshie
, p. 202 - 209 (2004)
[Pd(NH3)4]2+-exchanged sepiolite clay (Pd-sepiolite) has been applied to the catalytic Suzuki-type carbon-carbon coupling reactions of 4-bromophenol with phenylboronic acid or sodium tetraphenylborate in water. The Pd-sepiolite effectively catalyzed the reaction under mild reaction conditions (at room temperature in air). The Pd-sepiolite system exhibits higher yield than unsupported Pd(II) salts, [Pd(NH 3)4]Cl2-impregnated SiO2 (Pd-SiO2), and a commercially available Pd/C consisting of Pd metal particles. The structure of Pd species in the catalysts before and after the reaction was well characterized by a combination of XRD, TEM, UV-Vis, Pd K-edge XANES/EXAFS, and Pd LIII-edge XANES. XAFS and TEM results confirmed the formation of metal particles after the reaction by unsupported Pd(II) salt and Pd-SiO2. In contrast, for Pd-sepiolite the change in the structure of Pd species after the reaction was not significant; the highly dispersed Pd(II) complex, present before the reaction, was still the main Pd species together with the small Pd clusters (2-7 nm) as minor species. As a result of the high stability, Pd-sepiolite was reused without losing its activity. Significantly high turnover numbers (TON=940,000) were also attained at reflux temperature. It is suggested that Pd metal precipitation during the reaction is inhibited by a strong electrostatic interaction of sepiolite with Pd(II) species.
Chitosan as a support for heterogeneous Pd catalysts in liquid phase catalysis
Leonhardt, Silke E.S.,Stolle, Achim,Ondruschka, Bernd,Cravotto, Giancarlo,Leo, Cristina De,Jandt, Klaus D.,Keller, Thomas F.
, p. 30 - 37 (2010)
Four different chitosan-supported palladium catalysts were prepared, whereby two of them were modified as Schiff base by reaction with salicylaldehyde and 2-pyridinecarboxaldehyde before complexation with palladium. The remaining differ in their preparation method: co-precipitation or adsorption. The properties of the catalysts were characterized by FTIR, XPS, ICP-MS, and TGA. Comparison of the catalysts activity was assessed in microwave-assisted Suzuki reactions in aqueous media, resulting in good yields and excellent selectivities concerning cross-coupling product. Additionally, the catalysts prove their activity under conductive heating conditions. The study was extended to microwave-assisted Heck and Sonogashira reactions in DMF, confirming the efficiency of chitosan-supported palladium derivatives as catalysts for C-C couplings. Experiments revealed that catalysts prepared by co-precipitation furnished inferior yields concerning the employed C-C coupling reactions. Modification of chitosan with 2-pyridinecarboxaldehyde and subsequent palladium deposition resulted in highly active catalysts affording high product selectivities and yields.
Imidazolium-urea low transition temperature mixtures for the UHP-promoted oxidation of boron compounds
Martos, Mario,Pastor, Isidro M.
, (2022/01/03)
Different carboxy-functionalized imidazolium salts have been considered as components of low transition temperature mixtures (LTTMs) in combination with urea. Among them, a novel LTTM based on 1-(methoxycarbonyl)methyl-3-methylimidazolium chloride and urea has been prepared and characterized by differential scanning calorimetry throughout its entire composition range. This LTTM has been employed for the oxidation of boron reagents using urea-hydrogen peroxide adduct (UHP) as the oxidizer, thus avoiding the use of aqueous H2O2, which is dangerous to handle. This metal-free protocol affords the corresponding alcohols in good to quantitative yields in up to 5 mmol scale without the need of further purification. The broad composition range of the LTTM allows for the reaction to be carried out up to three consecutive times with a single imidazolium salt loading offering remarkable sustainability with an E-factor of 7.9, which can be reduced to 3.2 by the threefold reuse of the system.
Synthesis of Fluorenes and Dibenzo[ g,p]chrysenes through an Oxidative Cascade
Dickinson, Cody F.,Tius, Marcus A.,Yap, Glenn P. A.
supporting information, p. 1559 - 1563 (2022/02/07)
We have developed robust, operationally simple syntheses of fluorenes and of dibenzo[g,p]chrysenes through oxidative cascade processes. These structures that are commonly encountered in optoelectronic materials, dyes, and pharmaceutical products are acces
