1988-11-0Relevant articles and documents
Synthesis and characterization of titanium-containing mesoporous silica by a non-hydrothermal microwave method
Belhekar,Agashe,Soni,Sathaye,Jacob,Thundimadathil
, p. 2605 - 2608 (2000)
We report on a new method for preparing mesoporous silica and titanium-containing mesoporous silica using microwave (MW) synthesis under non-hydrothermal conditions. The materials were characterized by XRD, nitrogen adsorption, UV-vis and FTIR techniques, and compared with a sample prepared by the conventional method. A single peak at 2θ = 2.4°in the XRD pattern showed the formation of mesoporous silica. A typical isotherm, characteristic of a mesoporous material where pore filling occurred at p/p0 in the range of 0.2 - 0.3 was obtained for nitrogen sorption. UV-vis diffused reflectance spectra showed bands at 210 - 220 nm and a shoulder at 270 nm, indicating the presence of Si-O-Ti bonds for titanium-containing mesoporous silica. This new method has been observed to have inherent advantages over reported methods, such as instant start up, a short heating time and low cost. These mesoporous titanosilicates prepared using a microwave heat energy source are active in the oxidation of 2,6-diisopropylphenol (DIPP) and 2,6-di-t-butylphenol (DTBP) with hydrogen peroxide as an oxidant.
Oxidative coupling of some 2,6-disubstituted phenol derivatives in perchloric acid mediated by cerium(IV) ions
Domagala, Slawomir,Steglinska, Violetta,Dziegiec, Jozef
, p. 761 - 768 (1998)
2,6-Disubstituted phenol derivatives have been oxidized by cerium(IV) perchlorate in aqueous or aqueous-acetonitrile solutions of perchloric acid as well as in two-phase systems to the corresponding 1,4-benzoquinones, 4,4′-diphenoquinones, and oligomeric
Selective synthesis of benzoquinones over Cu(ii)-containing propylsalicylaldimine functionalized mesoporous solid catalysts
Selvaraj, Manickam,Assiri, Mohammed A.
, p. 3291 - 3299 (2019)
The major product, 2,3,5-trimethyl-1,4-benzophenone (TMBO), was synthesised by an eco-friendly liquid-phase oxidation of 2,3,6-trimethylphenol (TMP-OH) over Cu(ii)-containing propylsalicylaldimine (CSA) functionalized mesoporous solid catalysts, namely, CSASBA-15(0.2), CSASBA-15(0.1) and CSAMCM-41(0.2), synthesized using various amounts of copper in a simple post-grafting method using different mesoporous silica materials, e.g., thick-silica walled SBA-15 and thin-silica walled MCM-41. The benzoquinones, i.e., 2,6-disubstituted p-benzoquinones (DSBQs), were also synthesised by the slurry-phase oxidation of di/tri-substituted phenols using the prepared catalysts. A promising chemical treatment was used for the removal of extra-framework copper species from the active surface of CSASBA-15(0.2), and the catalytic activity of the recovered catalyst, i.e. green mesoporous CSASBA-15(0.2) or W-CSASBA-15(0.2), was evaluated. Various reaction parameters, oxidants and solvents were used in this catalytic oxidation. To confirm the catalytic stability, recyclability and hot-catalytic filtration experiments were performed. On the basis of all catalytic results, it is worth noting that the mesoporous CSASBA-15(0.2) is an outstanding and a promising heterogeneous catalyst for the selective synthesis of TMBO and DSBQs, and produces 98% TMBO selectivity with 100% TMP-OH conversion at 353 K for 40 min and 97-99% DSBQ selectivity with 98-100% di/tri-substituted phenols conversion at 330 K for 1-3 h. The green mesoporous catalyst has unprecedented catalytic activity compared with that of other CSA functionalized mesoporous solid catalysts.
Selective activation of C–H bond into C[dbnd]O bond of phenols in para-position via aerobic oxidation
Yang, Shilei,Xu, Guoqiang,Shi, Song,Xin, Hongchuan,Gao, Jin,An, Zengjian
, p. 105 - 108 (2019/02/25)
An efficient method for the oxidation of phenols to 1,4-benzoquinones catalyzed by cuprous(I) chloride was achieved in a solution of acetonitrile and water using molecular dioxygen as an oxidant. Particularly, the inert phenols, such as phenol and mono-alkyl substituted phenols, were effectively oxidized to 1,4-benzoquinones via the selective activation of C–H bond in para-position into C[dbnd]O bond under mild conditions. The catalyst shows high activity for unsubstituted or alkyl substituted phenols, but no effect on substituted phenols with electron-withdrawing groups. This study offers an aerobic method for the selective oxidation of aromatic phenols to 1,4-benzoquinones.
COMPOUND FOR THE PROPHYLAXIS OR TREATMENT OF ORGAN DAMAGE
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Page/Page column 10; 11; 14, (2016/12/22)
The present invention relates to compounds for prophylaxis or treatment of organ damage by restoring endothelial function and/or inhibiting reactive oxygen species production and especially to compounds for prophylaxis or treatment of diabetic kidney dama
