Process of preparation of racemic hydroxyarylglycolic acids and

Details Process of preparation of racemic hydroxyarylglycolic acids and Process of preparation of racemic hydroxyarylglycolic acids and

1981-02-25

1982-07-13

Killos, Paul J.

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

Organic compounds

Carboxylic acids and salts thereof

562470, C07C 6511, C07C 5950

Patent

active

043396020

DESCRIPTION:

BRIEF SUMMARY
This invention relates to a novel process of preparation of racemic ortho- or parahydroxyarylglycolic acids and novel products resulting therefrom.
Racemic hydroxyarylglycolic acids are raw materials appreciated in organic synthesis, since the works of P. Hebert, Bull. Soc. Chim. France, 1920, 27 (4th series), 45-55, have confirmed their degradation into carbonylated derivative by decarboxylating oxidation.
It is known from the prior art to accede to racemic hydroxyarylglycolic acids from an aromatic phenol derivative in alkaline aqueous medium either by condensation of glyoxylic acid in accordance with U.S. Pat. No. 2,062,205 or by condensation of chloral followed by a hydrolysis of the hydroxyaryltrichloromethylcarbinol, formed according to Austrian Pat. No. 141 159.
It is known that glyoxylic acid in alkaline aqueous medium is little stable and dismutes when hot quantitatively into oxalic and glycolic acids by Cannizzaro's reaction (BOETTINGER, Ber., I880, 13 I931I). For this reason, reactions that involve glyoxylic acid in alkaline aqueous medium are achieved at a temperature lower or equal to the room temperature. Thus, in the process described in French Pat. No. 2,132,364, condensation of glyoxylic acid with phenol in excess dissolved in 10% aqueous sodium hydroxide solution is achieved at 15.degree. to 25.degree. C. in 36 hours. In German Pat. No. 621 567, an alkaline aqueous solution of phenol and glyoxylic acid is held several days at the room temperature to obtain racemic parahydroxymandelic acid. J. GOODMAN et Al. .,Biochem. Biophys. Acta, 1968, 156, 364.67, condense glyoxylic acid with gaiacol in 68 hours at 25.degree. C., and J. KAMLET, U.S. Pat. No. 2,640,083 proceeds in 48 hours at 15.degree.-20.degree. C. to prepare racemic 4-hydroxy 3-methoxy mandelic acid. Recently, Belgian Pat. No. 867 287 has described a process for obtaining an alkaline metal salt of solid monohydrated parahydroxymandelic acid by condensing glyoxylic acid with phenol in excess in alkaline aqueous solution at a temperature slightly higher than room temperature either in 18 hours from 30.degree. to 35.degree. C. (example 1) or 5 hours at 35.degree. C. (example 2), or again 8 hours at 35.degree. C. (example 3).
According to A. I. FATIADI et R. SCHAFFER, J. Research Nat. Bur. Stand., Sect. A, I972, 78A, 411-12, any increase in temperature affects negatively the condensation yield of glyoxylic acid on gaiacol to accede to racemic 4-hydroxy 3-methoxy mandelic acid, and these authors recommend carrying out such condensation by supplying glyoxylic acid in 4 hours into an alkaline aqueous solution of gaiacol, cooled to about 0.degree. C., and then maintaining the reaction medium for 20 hours at 0.degree.-20.degree. C. For the preparation of racemic 3,4-dihydroxy mandelic acid NIPPON SYNTHETIC CHEMICAL INDUSTRY Co. Ltd. in their Japanese patent application No. 75-29522 (C.A. Vol. 83 58435a) teaches to react glyoxylic acid with pyrocatechol in 2 hours at 5.degree.-8.degree. C., then in 24 hours at 10.degree.-15.degree. C. and finally 24 hours at room temperature.
The Applicant in his French patent application No. 78-31123 claims a process for preparing racemic parahydroxy mandelic acid by condensation of glyoxylic acid with phenol in excess, in water in the presence of an alkaline agent, at a temperature between 30.degree. and 100.degree. C.
The Applicant has now found that glyoxylic acid condenses quickly in alkaline aqueous medium at a temperature between 35.degree.-50.degree. and 100.degree. C., advantageously between 50.degree. and 100.degree. C., and even better between 50.degree. and 85.degree. C., with an excess or not of an aromatic phenol derivative other than phenol, having at least one nuclear proton in the ortho or para position with respect to the hydroxy phenolic group, to produce a racemic ortho- or parahydroxyarylglycolic acid. This condensation is not site selective in view of resonance of phenolate anion communicating some carbanion nature to the ortho and para positions. Notwithstanding the lack of site selecti

REFERENCES:
Chem. Abst. 91:193005r, vol. 91, 1979.
Chem. Abst. 92:22263g, vol. 92, 1979.

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