Abstract:
The invention relates to a process for hydroxylating phenolic substrates such as phenols or phenol ethers. The process comprises reacting the phenolic substrate and hydrogen peroxide in the presence of a catalyst in a reaction mixture; and simultaneously removing water from the reaction mixture. The process improves the reaction rate, yield, and product selectivities.
Abstract:
The present invention relates to the use of a preferably transition metal-free carbonitride as a catalyst, and to a supported catalyst comprising the said carbonitride. The carbonitride catalysts proved effective in the cyclization of organic compounds, in particular in the cyclodimerization and cyclotrimerization of alkynes and nitriles to yield aromatic products. Moreover, the catalyst was shown to be effective in the direct conversion of aromatic compounds with carbon dioxide or a carbonyl compound to the corresponding phenolic compound. Finally, the invention is concerned with the use of the catalyst for the preparation of certain disubstituted organic carbonates. Since the catalysts of the invention do not require the presence of e.g. transition or noble metals, they are environment- friendly and inexpensive while allowing the above types of reactions to be carried out at high conversion rates, and with high regioselectivity.
Abstract:
Process for the hydroxylation of aromatic compounds containing a dioxa-heterocyclic system which comprises directly hydroxylating said compounds with hydrogen peroxide in; the presence of a zeolitic catalyst having the general formula: xTi0 2 '(1 -x)Si0 2 wherein x is i a number ranging from 0.0001 to 0.04.
Abstract:
A process is described for preparing hydroxylated aromatic compounds by means of the direct oxidation of an aromatic substrate with hydrogen peroxide in a triphasic reaction system, in the presence of a TS-1 zeolitic catalyst.
Abstract:
A process for hydroxylating benzene under catalytic distillation conditions to produce hydroxylated products such as phenol is provided. The process provides for direct hydroxylation of liquid phase benzene with an oxidant and a zeolite catalyst under conditions effective to prevent coke formation on the catalyst.
Abstract:
A process for hydroxylating an aromatic compound comprises the steps of: a) contacting an aromatic compound with a catalyst having an average concentration of alpha -sites of at least about 1.10 per gram of catalyst, the catalyst having alpha -oxygen loaded thereon, whereby a hydroxylated derivative of the aromatic compound is produced; and b) regenerating the catalyst when the concentration of alpha -sites falls below a predetermined value. The predetermined value will depend on the process design, but can suitably be about 1.10 per gram of catalyst or higher. Another embodiment of the process comprises: a) contacting an aromatic compound with a catalyst having an average concentration of alpha -sites of at least about 1.10 per gram of catalyst, the catalyst having alpha -oxygen loaded thereon, whereby a hydroxylated derivative of the aromatic compound is produced; and b) reloading the catalyst with alpha -oxygen by contacting the catalyst with a free oxidant activator. The progress of the reloading of the catalyst can be determined by: a) passing an input gas stream over the catalyst, the input gas stream comprising an inert gas; b) collecting an output gas stream that has passed over the catalyst; c) introducing a plurality of nitrous oxide impulses into the input gas stream, each impulse being separated by a period in which the input gas stream contains no nitrous oxide; d) measuring the concentrations of nitrous oxide and nitrogen gas in the output gas stream after an impulse of nitrous oxide is introduced; and e) comparing the concentrations of nitrogen gas and nitrous oxide in the output gas stream.
Abstract:
La présente invention concerne un procédé d'hydroxylation d'un composé de formule (I) par réaction du composé de formule (I) avec un agent oxydant, en présence d'une zéolite titano-silicalite préparée par cristallisation précédée d'une étape de mûrissement. La présente invention concerne également une zéolite titano-silicalite et son procédé de préparation.
Abstract:
La présente invention a pour objet un procédé d'hydroxylation du phénol par le peroxyde d'hydrogène. Le procédé de l'invention d'hydroxylation du phénol en pyrocatéchol et hydroquinone dans un ratio pyrocatéchol/hydroquinone compris entre 1,7 et 2,3, par réaction du phénol avec le peroxyde d'hydrogène, en présence d'un catalyseur, est caractérisé par le fait que la réaction est conduite en présence d'une quantité efficace d'un acide hydroxyaromatique sulfonique.