Process for the preparation of hydroxybenzaldehydes

Details Process for the preparation of hydroxybenzaldehydes Process for the preparation of hydroxybenzaldehydes

1982-08-26

1984-11-06

Helfin, Bernard

Organic compounds -- part of the class 532-570 series

Organic compounds

Oxygen containing

562459, 549436, C07C 4538

Patent

active

044813740

DESCRIPTION:

BRIEF SUMMARY
This invention relates to a novel process for the preparation of hydroxybenzaldehydes by the oxidation of primary hydroxybenzylic alcohols through oxygen or oxygen-containing gas in aqueous alkaline mediums.
In the prior art, very many processes either chemical or catalytic, have been proposed for oxidizing a benzylic alcohol to the corresponding benzaldehyde.
It is known particularly to oxidize a hydroxybenzylic alcohol either substituted or not, to the corresponding hydroxybenzaldehyde through catalytic oxidization by oxygen or oxygen-containing gases in aqueous alkaline mediums and in the presence of a metallic catalyst based on a noble metal such as platinum or palladium. To avoid the specific disadvantages of these processes such as the necessity of using large quantities of catalyst, the German patent application DE AS No. 1 188 069 (U.S. Pat. No. 3,321,526) teaches the use of boric acid as an activator of the palladium catalysts; other activators of this type of oxidation have been proposed, such as for example, according to the U.S. Pat. No. 3,673,257, the cadmium, cerium, indium, lanthanum, copper, yttrium, magnesium, uranyl, zinc, cadmium-tetramine ions, or to Japanese patent application No. 55-59128, an inorganic salt of a metal selected from the following metals: lead, bismuth, silver and tin.
Other processes have been described with a view to either reducing consumption of metal from the platinum group, or inhibiting secondary reactions, or finally, to preparing a specific aromatic aldehyde.
Thus, the French patent application No. 77-13941 (2 350 323) teaches the use of a catalyst based on a noble metal of the platinum group associated with lead, silver, tellurium and/or tin and/or their compounds, the French patent application No. 75-09932 (2 305 420) describes a co-catalyst based on a derivative of bismuth, the Japanese patent application No. 55-22615 discloses a process for oxidation of piperonylic alcohol to piperonal in the presence of a catalyst based on a metal of the platinum group associated with an inorganic salt of a metal selected among the following metals: lead, bismuth, silver and tin, and finally, the U.S. Pat. No. 4,190,605 realizes the acceleration of the catalytic oxidation by activation of the palladium based catalyst through preliminary reaction thereof with a hydroxy-benzylic alcohol.
It is to be noted that in all of these processes the influence of the temperature is not negligible and may sometimes be determinant.
Also, it is known to realize catalytic oxidation of a hydroxybenzylic alcohol in the presence of an organic solvent. Thus again, the Japanese patent application No. 55-35003 teaches such an oxidation carried out either in the dimethylsulfoxide or in the dimethylformamide in the presence of a vanadium catalyst. Moreover, the temperature must be in the range of 100.degree. to 180.degree. C.
Thus, the oxidation processes of hydroxybenzylic alcohol to hydroxybenzaldehydes in aqueous alkaline medium through oxygen or oxygen-containing gases are catalytic processes requiring a metallic catalyst constituted either by a derivative of vanadium or by a metal of the platinum group alone or associated with various mineral ions. These expensive catalysts at the end of the reaction require expensive treatments for recovery and/or purification thereof thereby resulting in ineluctable losses, which therefore increase the manufacturing costs. Furthermore, keeping reactional temperatures which are often in excess of 50.degree. C. implies not insignificant thermal energy consumptions which add to such costs.
The Applicant has now discovered in a completely unexpected manner a new process, which is the object of this invention, for the preparation of hydroxybenzaldehydes by oxidation of primary hydroxybenzylic alcohols by means of oxygen or oxygen-containing gas in an aqueous alkaline medium, characterized by effecting such oxidation at a temperature lower than, or equal to, 50.degree. C., on the one hand, and on the other hand, in the absence of any catalyst whatsoever.
Accordin

REFERENCES:
patent: 4306083 (1981-12-01), Ma
patent: 4351962 (1982-09-01), Gradeff et al.
Claus et al., Monatshefte fur Chemie, vol. 103, No. 4, (1972), 1178-1193.

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