Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Patent
1998-08-13
2000-03-21
Killos, Paul J.
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
568771, 568716, 568744, C07C 3760
Patent
active
060404841
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a process for the hydroxylation of phenolic compounds and, more particularly, to a process for the hydroxylation of phenols and phenolic ethers with hydrogen peroxide.
Numerous processes for the hydroxylation of phenols are described in the state of the art. The patent FR-A 2 071 464 which relates to a very important industrial process for the hydroxylation of phenols and phenolic ethers may be mentioned amongst others.
The said process consists in carrying out hydroxylation with hydrogen peroxide in the presence of a strong acid. The strong acids most commonly used are sulfuric acid, paratoluene sulfonic acid, and perchloric acid.
The hydroxylation of phenol carried out under the conditions described leads to a mixture of hydroquinone and pyrocatechol, with a predominance of the latter since the hydroquinone/pyrocatechol ratio most often ranges between 0.3 and 0.7.
FR-A 2 266 683 proposed an improvement to this process which consists in carrying out hydroxylation in the presence of a ketone. This results in an improvement in the hydroquinone and pyrocatechol yield of the reaction. However, all the examples described lead to a greater quantity of pyrocatechol compared with that of hydroquinone.
The known processes lead, therefore, mainly to pyrocatechol.
It is apparent that, in order to meet market demand which fluctuates, it is important to have an industrial process which makes it possible either to increase the production of hydroquinone formed with respect to pyrocatechol, or to promote the quantity of pyrocatechol formed.
The applicant proposed, in FR-A 2 667 598, a process which makes it possible to increase the quantity of hydroquinone formed with respect to the quantity of pyrocatechol and to obtain, in its preferential variant, more hydroquinone than pyrocatechol.
The said process consists in carrying out the hydroxylation of phenol in the presence of an effective quantity of a strong acid, said process being characterised in that the reaction is conducted in the presence of a ketone compound chosen from benzophenone and the benzophenones of which the hydrogen atoms of the aromatic nucleus may be substituted by an electro-donor group.
According to the process described in FR-A 2 667 598, the presence of the ketone compound as selected during the hydroxylation of phenol affects the regioselectivity of the reaction, and hydroquinone/pyrocatechol ratios ranging between 1.0 and 1.13 are advantageously obtained.
Pursuing his research, the applicant found another process involving an original catalysis and making it possible to obtain good diphenol yields and to control the selectivity of the reaction.
More specifically, the present invention relates to a process for the hydroxylation of a phenolic compound with hydrogen peroxide, said process being characterised in that the reaction is conducted in the presence of an effective quantity of at least one triflate of rare earth or of bismuth.
A first variant of the process of the invention is to conduct the reaction in the presence of an organic solvent.
A second variant of the process of the invention consists in using a ketone compound as co-catalyst.
A third variant of the process of the invention is to use, at the same time, the co-catalyst and the organic solvent.
In accordance with the process of the invention, hydroxylation of a phenolic compound is carried out in the presence of a catalyst chosen from the triflates of rare earths or of bismuth.
The term "triflate of rare earth or of bismuth" means a rare earth or bismuth salt of trifluoromethane sulfonic acid.
The term "rare earth" means the lanthanides having an atomic number of 57 to 71 and yttrium and also scandium.
The present invention relates to the phenolic compounds having the general formula: ##STR1## in which formula (1): R.sub.1, R.sub.2, R.sub.3 and R.sub.4, identical or different, represent a hydrogen atom or any substituent, vicinal carbon atoms may, together and with the carbon atoms bearing them, form a ring, carbon atoms, which may be a saturated or
REFERENCES:
patent: 3615169 (1971-10-01), Thom
patent: 4301307 (1981-11-01), Jouffret
patent: 4547474 (1985-10-01), Olah
patent: 5434317 (1995-07-01), Costantini
patent: 5714641 (1998-02-01), Costantini
Costantini Michel
Gilbert Laurent
Spagnol Michel
Killos Paul J.
Rhodia Chimie
Vollano Jean F
Wood John Daniel
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