620-23-5Relevant academic research and scientific papers
Silica-embedded tert-butyldimethylsilyltrifluoromethanesulfonate catalysts as new solid acid catalysts
Parvulescu,Gagea,Alifanti,Parvulescu,Parvulescu,Nae,Razus,Poncelet,Grange
, p. 319 - 323 (2001)
Silica-embedded tert-butyldimethylsilyltrifluoromethanesulfonate catalysts were synthesized by a sol-gel method in acidified CCl4, using hexadecyltrimethyl-ammonium bromide as a surfactant. The catalysts were characterized by nitrogen adsorption-desorption isotherms at 77 K; TG-DTA; 1H, 13C, and 29Si solid state MAS/NMR; XRD; XPS; Raman spectroscopy; and FTIR after adsorption of NH3. The characterization data indicated mesoporous solids in which most of the silyl-triflate derivative keeps its integrity. The catalytic tests performed with the methyl ester of 1-cyclopentenylacetic acid in various solvents showed that the reaction selectively leads to 3-methylbenzaldehyde and is sensitive to the solvent accepting ability.
The decomposition of methyl hemiacetals of benzaldehyde in aqueous solution: A study of the effect of aromatic substitution
Engell, Karen M.,McClelland, Robert A.,Sorensen, Poul E.
, p. 978 - 989 (1999)
The acid-base catalysed decomposition of hydrates and hemiacetals of carbonyl compounds are classical examples of reactions where (slow) proton transfer is coupled with heavy atom reorganization, i.e., C - O bond breaking and solvent reorganization. We have studied the influence of m- and p-substitution in the carbonyl electrophile on the kinetics of the acid and base catalysis of the decomposition of methyl hemiacetals of benzaldehyde. The experimental data are well described by three-dimensional More O'Ferrall - Jencks energy contour diagrams according to principles developed by Jencks (the BEMA HAPOTHLE). Thus, for acid catalysis, a Cordes cross-interaction coefficient pxy′ = ?ρ/?pKa = 0.15 indicates the coupled nature of the rate-limiting step in a class e mechanism, similar to conclusions reached from systematic substitution in the nucleophile. Our more extensive set of data for base catalysis permits a more rigorous analysis according to the BEMA HAPOTHLE. The data are consistent with a class n mechanism as also suggested earlier on the basis of substitution in the nucleophile. A slight upward curvature observed in the Hammett plots for the various catalysts is described by the direct correlation parameter py = ?ρ/?σ = -0.11. This second derivative demonstrates the concerted nature of the C - O bond cleavage and O-H formation in the transition state, which changes with changing substituent. A class n mechanism for base catalysis is also supported by the observation of a Cordes cross-interaction parameter pxy = ?ρ/?pKa = -?β/?σ = 0.03, which describes the experimentally observed decrease in Hammett ρ with increasing pKa of the catalyst. This change may be rationalized by the movement of a saddle point on a diagonal reaction coordinate in the energy contour diagram, as a resultant of shifts parallel and perpendicular to the coordinate, when the energy along one side of the diagram is changed. It is concluded that observed rate changes as a result of substitution in the electrophile are consistent with and present further confirmation of earlier suggested mechanisms of hemiacetal decomposition reactions.
A novel and active catalyst Ag/ZnO for oxidant-free dehydrogenation of alcohols
Hosseini-Sarvari, Mona,Ataee-Kachouei, Tahereh,Moeini, Fatemeh
, p. 98 - 105 (2015)
Nano Ag/ZnO catalysts were prepared by varying load of Ag on ZnO supports using a new and very simple method. The structure of nano Ag/ZnO has been confirmed by various techniques. The Ag/ZnO with 7.4 × 10-5 mol% of Ag has pore size distribution about 2.74 nm and this nano Ag/ZnO is found to be the best catalyst for oxidation of primary and secondary benzyl alcohols into corresponding aldehydes and ketones in oxidant-free at the atmospheric pressure. The influence of various parameters such as: solvent, base, temperature, time of reaction, etc. has been systematically studied on nano Ag/ZnO catalyst.
Selective Encapsulation and Unusual Stabilization of cis-Isomers by a Spherical Polyaromatic Cavity
Yuasa, Mana,Sumida, Ryuki,Tanaka, Yuya,Yoshizawa, Michito
supporting information, (2022/02/02)
To explore new cavity functions, we herein employed cis-trans stereoisomers with a N=N, C=C, or C=N unit as guest indicators for a polyaromatic capsule. Thanks to the rigid, spherical cavity with a diameter of ～1 nm, azobenzene and stilbene derivatives ar
A TEMPO-Functionalized Ordered Mesoporous Polymer as a Highly Active and Reusable Organocatalyst
Guo, Ying,Wang, Wei David,Li, Shengyu,Zhu, Yin,Wang, Xiaoyu,Liu, Xiao,Zhang, Yuan
supporting information, p. 3689 - 3694 (2021/09/29)
The properties of high stability, periodic porosity, and tunable nature of ordered mesoporous polymers make these materials ideal catalytic nanoreactors. However, their application in organocatalysis has been rarely explored. We report herein for the first time the incorporation of a versatile organocatalyst, 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO), into the pores of an FDU-type mesoporous polymer via a pore surface engineering strategy. The resulting FDU-15-TEMPO possesses a highly ordered mesoporous organic framework and enhanced stability, and shows excellent catalytic activity in the selective oxidation of alcohols and aerobic oxidative synthesis of 2-substituted benzoxazoles, benzimidazoles and benzothiazoles. Moreover, the catalyst can be easily recovered and reused for up to 7 consecutive cycles.
A new porous Co(ii)-metal-organic framework for high sorption selectivity and affinity to CO2and efficient catalytic oxidation of benzyl alcohols to benzaldehydes
Wu, Yun-Long,Yang, Rong-Rong,Yang, Guo-Ping,Yan, Yang-Tian,Su, Xiao-Lei,He, Xin-Hai,Song, Yan-Yan,Ma, Zheng-Sheng,Wang, Yao-Yu
, p. 3717 - 3723 (2021/05/31)
Herein, we report a new 3D porous Co(ii)-based metal-organic framework catalyst (Me2NH2)2[Co3(L)2(H2O)2]·2DMF (MOF I), which has been successfully prepared by using Co(ii) ions and rigid V-shaped 3,5-di(2,4-dicarboxylphenyl)pyridine (H4L) via the solvothermal reaction. Structural analysis reveals that I displays a porous structure with the pore size of 16.2 × 7.2 ?2 based on the trinuclear [Co3(COO)4(H2O)2N2] secondary building units (SBUs). Gas sorption experiments on the guest free sample I′ reveals a high capacity and selectivity to CO2 over CH4. And further, the catalytic explorations of the I′-catalyzed system (I′: 3 mol%; proline: 40 mol%; CH3CN: 2 mL) reveal that benzyl alcohols with different structures can be efficiently transformed into benzyl alcohols without by-products under mild conditions.
Magneto-structural properties and reliability of (Mn/Ni/Zn) substituted cobalt-copper ferrite heterogeneous catalyst for selective and efficient oxidation of aryl alcohols
Dhabbe, Rohant,Gaikwad, Pratapsingh,Kakade, Bhalchandra,Kamble, Prakash,Kurane, Rajnikant,Parase, Haridas,Sabale, Sandip
, (2021/09/28)
Herein, M2+ substituted CoCuFe2O4 (M2+ = Mn, Zn, Ni) ferrites have been synthesized using the sol-gel auto combustion method. The structural, morphological and magnetic studies confirm the phase formation of pure magnetic cubic spinel MCoCuFe2O4 (M2+ = Mn, Zn, Ni) ferrites. The substitution with Mn, Ni and Zn does not show large variation in binding energies obtained from XPS of Cu (2p) that specifies identical copper concentration (Cu0.5) and substitution of only cobalt (Co2+) in Mn-F, Ni-F and Zn-F catalysts. Interestingly, MCoCuFe2O4 magnetic catalysts were explored for selective oxidation of a series of substituted benzyl alcohols. Catalyst Mn-F showed 93% conversion of benzyl alcohol while, Ni-F showed 95% conversion of 4-nitrobenzyl alcohol. Whereas, the catalyst Zn-F was showed 96% conversion for 4-methoxybenzyl alcohol. Additionally the results also indicate an efficient separation and recovery of the magnetic catalysts after four successive reuses without any considerable loss in its catalytic activity.
Synthesis, characterization, reactivity, and catalytic studies of heterobimetallic vanadium(V) complexes containing hydrazone ligands
Borthakur, Rosmita,Dhanpat, Shobha A.,Kumar, Arvind,Kurbah, Sunshine D.,Lal, Ram A.,Syiemlieh, Ibanphylla
, (2020/10/21)
Six heterobimetallic alkali metal dioxidovanadium(V) coordination polymer complexes {[M6{VO(μ-O)}2(μ-OH)4(μ4-slox/nph)].n DMF}∞ where M = Na, K, and Cs; n = 1 for (1), 0 for (2)-(6) of two dihydrazone ligands, disalicylaldehydeoxaloyldihydrazone (H4slox) and bis(2-hydroxy-1-naphthaldehyde)oxaloyldihydrazone (H4nph) are reported. All the complexes have been characterized by various physicochemical techniques such as elemental analyses, molar conductance, IR, NMR, UV–vis, and cyclic voltammetry. The IR, 1HNMR, and 13CNMR spectral data suggest that the dihydrazones are coordinated through phenolate/naphtholate oxygen, enolate oxygen, and azine nitrogen atoms to the metal centres. The structure of complex {[Na6{VO(μ-O)}2(μ-OH)4(μ4-slox)].DMF}∞ (1) is also determined by single-crystal X-ray data, which revealed that the H4slox coordinated via all possible dative sites to metal centres as tetrabasic octadentate ligand. The vanadium metal centres adopted distorted square-pyramidal coordination geometries, and the sodium atoms are also in five coordination atmospheres. The electronic spectra of the complexes showed LMCT bands in addition to intra-ligand π → π* and n → π* transitions. As evident from the cyclic voltammetry, the complexes showed two metal-centred electron transfer reactions {[(VVVV(slox)2?/VVVIV(slox)3?] and [(VVVIV(slox)3?/VVVIV(slox)4?]}, in addition to the ligand centred electron transfer reactions. Further, bovine serum albumin (BSA interaction studies of the complexes {[Na6{VO(μ-O)}2(μ-OH)4(μ4-slox)].DMF}∞ (1) and [Na6{VO(μ-O)}2(μ-OH)4(μ4-nph)]∞ (4) revealed strong binding affinity. Moreover, the catalytic studies of the complexes (1) and (4) were found to be effective for the oxidation of alcohols into their corresponding aldehydes and ketones and bromination of some organic substrates in the presence of H2O2 as an oxidizing agent.
Dioxido-vanadium(V) complex catalyzed oxidation of alcohols and tandem synthesis of oximes: a simple catalytic protocol for C–N bond formation
Kurbah, Sunshine Dominic
, p. 905 - 918 (2021/02/03)
We report the synthesis of a vanadium(V) complex characterized by FT-IR and 1H NMR spectroscopy. The structure of the complex was established by single crystal X-ray crystallography. We also carried out the catalytic oxidation of benzyl alcohol, hetero-aryl alcohols and propargylic alcohols. Tandem synthesis of oximes from alcohols were also carried out using our vanadium(V) complex. The newly synthesized complex acts as a catalyst for oxidation reactions and tandem synthesis of oxime from alcohols.
La(OH)3nanoparticles immobilized on Fe3O4@chitosan composites as novel magnetic nanocatalysts for sonochemical oxidation of benzyl alcohol to benzaldehyde
Fadaeian, Manoochehr,Ghomi, Javad Safaei,Javidfar, Fereshteh
, p. 35988 - 35993 (2021/12/02)
This work introduces an eco-friendly method for immobilization of La(OH)3 nanoparticles on modified Fe3O4 nanoparticles. The structural and morphological characteristics of the nanocatalyst were determined by various analytical techniques including, FT-IR, EDS, FESEM, VSM and XRD. The catalytic efficiency of the Fe3O4@Cs/La(OH)3 composite as a heterogeneous nanocatalyst was evaluated by selective oxidation of benzylic alcohols to aldehydes. The optimum reaction conditions including time, temperature, nanocatalyst dosage, and solvent were investigated for ultrasound-assisted oxidation processes. Furthermore, the magnetic nanocatalyst was recovered up to seven times without considerable activity loss. Furthermore, the proposed nanocomposite had a remarkable effect on reducing the reaction time and enhancing the yield. This journal is
