5306-98-9Relevant articles and documents
Process for the preparation of phenols
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Paragraph 0024, (2017/01/12)
The present invention relates to a process for the preparation of phenols in which an aryldiazonium salt, which is prepared by the diazotization of a corresponding aromatic, primary amine, by heating in a mixture comprising hot water, a mineral acid and an organic solvent, is decomposed, where the organic solvent comprises a ketone of the formula (I) R1C(O)R2, in which R1 and R2, independently of one another, are (C1-C5)-alkyl and R1 and R2 together have at least four carbon atoms, where the aromatic primary amine is aniline or a substituted aniline which comprises at least one further substituent which is selected from: alkyl, alkenyl, alkynyl, halogen, haloalkyl, cycloalkyl, heteroalkyl, carboxyl, cyano, alkoxy and ester, and where essentially no copper salts are present in the mixture.
Oxidation of p-chlorotoluene and cyclohexene catalysed by polymer-anchored oxovanadium(iv) and copper(ii) complexes of amino acid derived tridentate ligands
Maurya, Mannar R.,Kumar, Maneesh,Kumar, Amit,Pessoa, Joao Costa
experimental part, p. 4220 - 4232 (2009/02/03)
3-Formylsalicylic acid (Hfsal), covalently bound to chloromethylated polystyrene (PS) and cross-linked with 5% divinylbenzene reacts with d,l-alanine and l-isoleucine to give the Schiff-base tridentate ligands PS-H 2fsal-d,l-Ala and PS-H2fsal-l-Ile, respectively. These anchored ligands upon reaction with VOSO4 and Cu(CH 3COO)2?H2O form the complexes PS-[VO(fsal-d,l-Ala)(H2O)], PS-[Cu(fsal-d,l-Ala)(H2O)], PS-[VO(fsal-l-Ile)(H2O)] and PS-[Cu(fsal-l-Ile)(H2O)]. The structures of these immobilized complexes have been established on the basis of scanning electron micrographs, spectroscopic (infrared, electronic and EPR), thermogravimetric and elemental analysis studies. The oxidation of p-chlorotoluene and cyclohexene has been investigated using these complexes as the catalysts in the presence of H2O2 as the oxidant. Reaction conditions have been optimised by considering the concentration of the oxidant, the amount of catalyst used and the temperature of the reaction mixture. Under the optimised conditions, p-chlorotoluene gave a maximum of 14% conversion using PS-[VO(fsal-d,l-Ala)(H2O)] as the catalyst, with the main products having a selectivity order of: p-chlorobenzaldehyde >> p-chlorobenzylalcohol > p-chlorobenzoic acid > 2-methyl-5-chlorophenol > 3-methyl-6-chlorophenol. The oxidation of cyclohexene with PS-[VO(fsal-d,l-Ala)(H2O)] proceeds with 79% conversion, which is followed by PS-[VO(fsal-l-Ile)(H2O)] with 77% conversion, and the oxidation of cyclohexene by Cu-based catalysts occurs with considerably lower conversions (29-32%). The selectivity of the products follows the order: 2-cyclohexene-1-ol > cyclohexene oxide > cyclohexane-1,2-diol > 2-cyclohexene-1-one. Recycling studies indicate that these catalysts can be reused at least three times without any significant loss in their catalytic potential. However, EPR studies indicate that while the polymer supported V(iv)O-complexes do not change after being used, the EPR spectra of the Cu-complexes show significant changes. The corresponding non-polymer bound complexes [VO(fsal-d,l-Ala)(H2O)], [Cu(fsal-d,l-Ala)(H 2O)], [VO(fsal-l-Ile)(H2O)] and [Cu(fsal-l-Ile)(H 2O)] have also been prepared in order to compare their spectral properties and catalytic activities. The non-polymer bound complexes exhibit lower conversion, along with lower turn-over frequency as compared to their polymer-bound analogues. Several EPR, 51V NMR and UV-vis studies have been undertaken to detect the intermediate species, and outlines for the mechanisms of the catalytic reactions are proposed.
Single Step Selective Oxidation of para-Chlorotoluene to para-Chlorobenzaldehyde over Vanadium Silicate Molecular Sieves
Selvam, T.,Singh, A. P.
, p. 883 - 884 (2007/10/02)
Selective formation of para-chlorobenzaldehyde (> 65percent) in a single step from para-chlorotoluene is reported for the first time using H2O2 as an oxidant and vanadium silicate molecular sieves as the catalyst.
