Method for the preparation of a phenol
AssigneeDsm N.V.
InventorsWim Buijs, Leon H. B. Frijns, Matthias R. J. Offermanns
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Abstract
The invention relates to a process for the preparation of a phenol by oxidative decarboxylation of a corresponding arylcarboxylic acid in the presence of a Cu-containing catalyst, the phenol being obtained through a hydrolysis step. The characteristic part of the process is oxidation of a Cu(I)-containing catalyst and reduction and hydrolysis in the absence of oxygen. The process can be carried out under liquid phase or gas phase conditions in a one-step or multi-step process and nucleation agents can be added for crystallization during catalyst oxidation. In a preferred embodiment, at least 0.04 wt.% copper remains present as Cu(I) after oxidation.
Claims39
A process for the preparation of phenol in high yield and selectivity with substantially no tar formation by an oxidative decarboxylation of a corresponding arylcarboxylic acid having the formula ##STR3## wherein R.sub.1 through R.sub.5 can be hydrogen, C.sub.1 -C.sub.6 alkyl, cycloalkyl, aryl, aryalkyl, amino, halogen and nitro acid and wherein at least R.sub.1 or R.sub.5 is hydrogen in the presence of a Cu-containing catalyst in which the Cu concentration as a metal and relative to the reaction mixture amounts to 0.5-15 wt.% and in which the degree of oxidation of the copper can be 1.sup.+ and 2.sup.+ which comprises
- (a) oxidizing the catalyst at a temperature above the melting point of the arylcarboxylic acid with the temperature, retention time, oxidation agent, arylcarboxylic acid concentration and Cu(I) concentration being controlled so that virtually no tar is formed,
- (b) reacting the oxidized catalyst in the presence of water, but in the absence of oxygen, to form a phenol, and
- (c) separating the phenol formed.
A process for the preparation of a phenol by an oxidative decarboxylation in a liquid phase of a corresponding arylcarboxylic acid ##STR4## wherein R.sub.1 through R.sub.5 can be hydrogen, C.sub.1 -C.sub.6 alkyl, cycloalkyl, aryl, aryalkyl, amino, halogen and nitro acid and wherein at least R.sub.1 or R.sub.2 is hydrogen in the presence of a Cu-containing catalyst in which the degree of oxidation of the copper can be 1.sup.+ and 2.sup.+, wherein the oxidative decarboxylation is carried out (i) in the presence of water, (ii) with an amount of oxygen being added such that an amount of copper remains present as Cu(I) so that a selectivity to phenol of more than 92% measured at 1 bar is obtained, and (iii) phenol is separated off.
Dependencies are inferred from the claim text.