Process for preparation of hydroxyarylglyoxylic acids and their

Details Process for preparation of hydroxyarylglyoxylic acids and their Process for preparation of hydroxyarylglyoxylic acids and their

1982-04-20

1983-05-17

Killos, Paul J.

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

Organic compounds

Carboxylic acids and salts thereof

C07C 5990, C07C 6540

Patent

active

043841376

DESCRIPTION:

BRIEF SUMMARY
This invention relates to a novel process for preparation of hydroxyarylglyoxylic acids and their alkaline salts, and application thereof to the preparation of sodium parahydroxyphenylglyoxylate crystallized anhydrous or with two molecules of water.
Hydroxyarylglyoxylic acids are precious raw materials to have access among others to hydroxylated aromatic aldehydes by decarboxylating degradation. The easy decarboxylation of arylglyoxylic acids and fragility of arylglycolic acids to the oxidation supplying by decarboxylating degradation the corresponding aromatic aldehyde, has for a long time rendered the preparation of arylglyoxylic acids redhibitory by oxidation of the corresponding arylglycolic acids. For the preparation of such acids, for the last few years, indirect methods have been employed, either by condensation of ethoxalyl chloride on an alkoxy benzene followed by alkaline hydrolysis of the ester and ether functions, according to L. BOUVEAULT, Bull.Soc.chim. France, 1898, (3), 19, 75, or by hydrolysis in an aqueous medium of an oxaloaryldiazonium sulfate obtained by diazotation in a sulfuric medium of an aminoarylglyoxylic acid generally resulting from permanganic oxidation in an aqueous alkaline medium of an aminoacetophenone previously acylated with nitrogen, according to J. Aloy and Ch. Rabaut, Bull.Soc.chim. France, 1911, (4), 9, 763, or by permanganic oxidation in an alkaline medium of a hydroxyacetophenone, according to the Italian patent 475 964 or by alkaline hydrolysis of a benzoylcyanide, according to P. Francis et al., Annalen, 1911 382, 206, or by chromic oxidation of a mandelamide according to M. S. Mashevskaya, Khim,Prom., 1979, 2; 5-7 (C.A. 1979, 91,211037j), or finally, by Hoesch's reaction (K. Hoesch, Ber., 1915, 48, 1122).
Such preparation processes, however, either use toxic, dangerous or expensive reactives or supply the desired acids with a low yield, or finally, require the use of rare raw materials.
Recently, a process for oxidation of arylglycolic acids into arylglyoxylic acids has been described in the European patent application No. 0 005 779. According to such process, the oxidation is effected through oxygen in an aqueous alkaline medium, in the presence of a catalyst deposited on carbon black and constituted by platinum or palladium activated by a lead or bismuth salt.
But this preparation process requires expensive catalysts which, due to unavoidable losses upon the recovery and recycling operations, result in high manufacturing costs.
The Applicant has now discovered a novel economical process for preparation of hydroxyarylglyoxylic acids from hydroxyarylglycolic acids, which eliminates such disadvantages.
This process which is the object of the present invention is a process for catalytic oxidation through oxygen in an aqueous alkaline medium, characterized in that it is carried out at the ambient temperature and in homogeneous catalysis with cupric ions.
Cupric ions are known as capable of oxidizing certain carbonylated structures such as e.g. acyloins. Until now, however, to the Applicant's knowledge, when they had been used for oxidizing alpha-hydroxylated carboxylic acids, they were causing an oxidizing scission into carbonylated derivatives having one carbon atom less than the starting acid and into carbon dioxide.
Thus, on studying novel syntheses of vanillin, A. Guyot and A. Gry, Bull.Soc.chim. France, 1910, (4), 7, 902-913, were not capable to oxidize 4-hydroxy-3-methoxy-phenylglycolic acid into 4-hydroxy-3-methoxy-phenylglyoxylic acid, in spite of the use of varied conditions and more particularly utilization of cupric sulfate; they obtained only vanillin or products derived therefrom by resinification.
The process which is the object of this invention is carried out at the ambient temperature or at a temperature close to the ambient temperature. Since oxidation of a secondary alcohol into carbonyl is exothermic, it is therefore often necessary to cool the reactional medium during oxidation. As a matter of fact, the Applicant has noted that an increase in t

REFERENCES:
patent: 3846470 (1974-11-01), Raabe et al.
patent: 3943169 (1976-03-01), Murcita et al.
L. Bouveault, Bull. Soc. Chim. France 1898 (3) 19, 75.
P. Francis et al., Annalen, 1911, 382, 206.
Guyot, A. et al., Bull. Soc. Chim. France, 1910 (4), 7,902-913.

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