NZ200478A

NZ200478A - A selective oxidising system for the preparation of orthodihyroxylated or orthodialkoxylated aromatic derivatives

Info

Publication number: NZ200478A
Application number: NZ200478A
Authority: NZ
Inventors: M Maumy; P Capdevielle; P Dostert; M Langlois
Original assignee: Delalande Sa
Priority date: 1981-05-04
Filing date: 1982-04-30
Publication date: 1985-03-20
Also published as: ZA823000B; NL8201833A; ES8304053A1; IT8221048A0; BE893055A; JPS5830339A; IL65649A0; KR830010033A; FR2504917A1; GB2098878B; FR2504917B1; LU84117A1; SE8202635L; NO821439L; GR76084B; AU8321482A; FI821476L; ES512554A0; DK195982A; FI821476A0

Description

<div class="application article clearfix" id="description"> New Zealand Paient Spedficaiion for Paient Number £00478 20 r,^ >' -J Priori/j- I at&Js): . Compltts G'psc^fscation FUacl:^ Publication Dste: .. .. ■ P.O. Journal, f^o: CO-764-1 ^02,O4- . <2-<=><i-3T//5«/ foo Cc7C-+l /o I Q32?C C) n ^ MSP alii Patents Form No.5 30 APR $82 - NEW ZEALAND PATENTS ACT 19 53 COMPLETE SPECIFICATION "A NOVEL SELECTIVE OXIDIZING SYSTEM AND APPLICATION THEREOF TO THE PREPARATION OF OKTHO-DIHYDRQXYLATED OR ORTHO-DIALKOXYLATED AROMATIC DERIVATIVES" -^VTE DELALANDE S.A. of 32 rue Henri Regnault, 92400 Courbevoie (France), a company organised under the French laws hereby declare the invention, for which -I/we pray that a patent may be granted to «>e/us,,and the method by which it is to be performed, to be particularly described in and by the following statement:- -1- (foHowed by page I A ) 200478 The present invention relates to a new selective oxidizing system and application thereof to the preparation or ortho-dihydroxylated or ortho-dialkoxylated aromatic derivatives. These latter form undeniably very important compounds for the chemical and parachemical, particularly the pharmaceutical industry. Unfortunately the methods and techniques used up to present for the synthesis of such compounds are often complex, difficult to implement industrially and only result in the desired derivatives being obtained with unsatisfactory yields. An ever more urgent need is then felt for a process for obtaining simply and inexpensively ortho-dihydroxylated or ortho-dialkoxylated aromatic derivatives from readily available raw materials and with yields sufficient for it to be used on an industrial scale. The Applicant has thus been led to study the selective oxidation of monohydroxylated aromatic derivatives with a view to obtaining the desired derivatives. The reagents used up to now for oxidizing the monohydroxylated aromatic derivatives lead preponderantly to para-dihydroxylated derivatives, the ortho-dihydroxylated derivatives only being possible secondary products. Furthermore, with these reagents oxidation does not generally stop at the stage of the ortho-dihydroxylated derivatives but continues as far as the formation of ortho-quinone derivatives which are unstable and so able to be isolated only with difficulty. The essential object of the Applicant has then been to perfect an oxidizing system for selectively obtaining more particularly, from monohydroxylated aromatic derivatives, ortho-dihydroxylated (or ortho-dialkoxylated) aromatic derivatives, without formation of para-dihydroxylated (or para-dialkoxylated) aromatic derivatives. This object has been attained and the present invention resides then first of all in a new selective oxidizing system which comprises essentially a) metallic copper, b) a cuprous salt, a cupric salt or mixtures thereof and c) molecular oxygen. In the present state of knowledge of the mode of action of this system, it appears that oxidation is made possible through activation of the molecular oxygen by the cuprous salt present in the system or resulting from reduction of the cupric salt by the metallic copper. The cuprous or cupric salt is preferably the cuprous or cupric chloride and the molecular oxygen may be atmospheric oxygen, pure oxygen or mixtures thereof. 200478 . '2 The oxidizing system of the invention will be advantageously used in the presence of a solvent allowing good solubility of the copper salts in the form of complexes, and more especially in the presence of a cyano aliphatic solvent, preferably acetonitrile, possibly mixed with a chlorinated organic solvent, preferably methylene chloride, dichloro-ethane and mixtures thereof. The present invention then relates to an application of the above-defined oxidizing system and more precisely to a process for preparing -aromatic at least once ortho-dihydroxylated derivatives (or pyrocatechols) or aromatic at least once ortho-dialkoxylated derivatives, which process in characterized in that it consists in subjecting aromatic derivatives comprising at least one phenolic hydroxyl radical, one at least of the ortho positions with respect to this radical being free, respectively to the action of the above-defined oxidizing system, then in causing the intermediate cupric pyrocatecholates obtained to hydrolysis or alkylation. The simplest starting hydroxylated aromatic derivative will of course be phenol but, more particularly, all the monosubstituted or poly-substituted phenols or polyphenols, whether they are monocyclic or poly-cyclic, also come within the scope of the invention, the only condition being obviously that at least one of the ortho positions with respect to the hydroxyl radicals is free. By way of non-limiting examples, the following can be cited : di-t-butyl-2,4 phenol ; hydroxy-3 acetophenone ; p-hydroxyphenylacetic acid and the esters thereof ; p-hydroxyacetophenone ; p-hydroxypropiophenone p-hydroxybenzoic acid and the esters thereof ; m-hydroxybenzoic acid and the esters thereof ; p-hydroxybenzaldehyde ; m-hydroxybenzaldehyde ; vanillin ; hydroxy-3 methoxy-5 benzoic acid and the esters thereof ; p-hydro-xybenzophenone ; and estrone. The presence of metallic copper is fundamental for it is that which allows formation of the cupric pyrocatecholates, which are stable compounds, able to be precipitated in mono-hydrated form and isolated. . Consequently, metallic copper will be used in at least stoechiometric amounts with respect to the starting hydroxylated aromatic derivatives (for 1 mole of starting derivative , as many atom-grammes of copper are required as there are phenolic hydroxyl radicals having at least one ortho-position free), and will preferably be used in excess. It is certain that if the starting aromatic derivative comprises a substituent able to react with one or other of the elements of the oxi-dizing system, and this will for example be the case of an acid group (particularly carboxyl or hydroxyl having no free ortho position) which may react with metallic copper, this group may be, if desired and within the bounds of possibility, blocked, for example by forming the ester in the case of the carboxyl group. Failing such blocking, it will be advisable to operate in the presence of larger quantities than normally required of the element capable of reacting. It should be noted that depending on the position of the subs-tituents carried by the starting hydroxylated aromatic derivatives to be oxidized and consequently on the number of free ortho positions (with respect to the phenolic hydroxyl radicals), there will be formation of one or , more different cupric pyrocatecholates. Thus, if the starting aromatic derivative is for example a monohydroxylated aromatic derivative substituted in the meta position, there will be formation of two cupric pyrocatecholates each corresponding to one of the two free ortho positions. It should further be noted that the use of a catalytic amount of the cuprous or cupric salt is sufficient to obtain the desired oxidation ; of course results just as satisfactory are obtained with larger amounts of salt. Advantageously, the oxidizing step will be carried out at a pressure greater than or equal to the atmospheric pressure and preferably in the presence of a dehydrating agent such as a molecular sieve, or an alkaline or alkaline earth metal sulfate such as sodium, magnesium or calcium sulfate. Furthermore, the temperature employed during the reaction may preferably vary between 0 and 50° C. The hydrolysis reaction of the second step of the process of the invention may be carried out in an acid, reducing or acido-reducing medium, obtained respectively for example by using hydrochloric or sulfuric acid, sodium hydrosulfite and the sodium hydrosulfite-sodium bicarbonate or stannous chloride-hydrochloric acid mixture. Although the acid medium is preferred because it is industrially the least expensive, it is nevertheless desirable to use a reducing or acido-reducing medium when the pyrocatecholates released by hydrolysis are very oxidizable and so capable of undergoing degradation into ortho-quinones . The alkylation reaction, another possible alternative in the second step of the process of the invention, is generally carried out in the presence of a base such as sodium carbonate, by means of an alkylating deri vative which may be chosen from alkyl sulfate, chloride, bromide, tosylate and mesylate, the nature of the alkyl group depending of course of the final ortho-dialkoxylated aromatic derivative desired. Finally, it should be noted that the process of the invention further offers the advantage of allowing the recovery of the starting hydroxylated aromatic derivatives blocked in the form of copper phenates, by simple hydrolysis of these latter for example by means of a methanol-water mixture, at reflux. The following preparations are given to illustrate the invention. EXAMPLE 1 : Preparation of di-t-butyl-3,5 pyrocatechol from di-t-butyl-2,4 phenol 1st step : Obtaining cupric di-t-butyl-3,5 pyrocatecholate in accordance with the following reaction diagram : '^\ TT Cu11, H20 (I) (ID A mixture of 5.5 g of di-t-butyl-2,4 phenol (I), 5 g of (commercial) powdered copper, 0.3 g of anhydrous cupric chloride and 4 g of mole- O cular sieve (3 A ) in 70 ml of dry acetonitrile is agitated for 6 hours at 0°C then 18 hours at 20° C in an oxygen atmosphere (atmospheric pressure) . Then 10 ml of water are added and after an additional agitation for 15 min., the precipitate obtained is filtered and washed with 30 ml of acetonitrile containing 10 % of water. Then the cupric pyrocatecholate (II)' is extracted from the precipitate by abundant washing of this latter with an aprotic organic solvent (such as ethyl ether, methylene chloride or chloroform for example), the filtrates are evaporated and 7-3 g (yield : 92 %)of the expected cupric pyrocatecholate (II) are obtained. 2nd step : Obtaining di-t-butyl-3,5 pyrocatechol according to the following reaction diagram : ... ■■ t ■ "i 2 HC1 ■ X.„0I! ! ■ —^ CUC1 2+ »2° ("> (III) An ether solution of the cupric pyrocatecholate (II) obtained in the preceding step is agitated in the presence of r%j 2N hydrochloric acid until the organic phase takes on a red coloring. Then the mixture 2 00478 is decanted, the ether phase is agitated with a dilute hydrochloric solution of stannous chloride until discoloration (reduction of the di-t-butyl-3, 5 benzoquinone-1,2 partially formed during hydrolysis) and washed with water. Then the ether phase is evaporated and the residue dried in a vacuum in the presence of P^0^. Thus 5.1 g (yield : 84 %) of a compound is obtained identical for its physico-chemical properties to a genuine sample of di-t-butyl-3,5 pyrocatechol. EXAMPLE 2 : Preparation of dihydroxy-2,3 and dihydroxy-3,4 acetophenones from hydroxy-3 acetophenone. 1st step : obtaining cupric acetyl-3 and acetyl-4 pyrocatecholates according to the following reaction diagram : <? COCH (IV) OH * <X>" h20 + COCH- (V) H20 A mixture of 4 g of hydroxy-3 acetophenone (IV), 6 g of (commercial) powdered copper and 0.1 g of cupric chloride in 80 ml of dry acetonitrile and 40 ml of methylene chloride is agitated for 70 hours at room temperature in an oxygen atmosphere (atmospheric pressure). Then the solvents are evaporated in a vacuum, the residue is taken up in 150 ml of a methanol (80 %) - water (20 %) mixture and heated to reflux for one hour. Then the precipitate obtained is filtered and washed with 40 ml of methanol. After evaporation of the filtrate/21 % of not reacted hydroxy-3 acetophenone was recovered. The precipitate is formed of the mixture of two cupric pyrocatecholates (V) and (V1), metallic copper and copper oxide. 2nd step : obtaining the dihydroxy-2,3 and dihydroxy-3,4 acetophenones according to the following reaction diagram : OH (V) + (V) ■ ■ . it OH COCH- COCK (VI) 3 ■ (VP) The precipitate obtained in the preceding step, in 40 ml of an aqueous solution containing 6 g of sodium hydrosulfite (Na^S^O^) and 2 g of sodium bicarbonate, is agitated vigorously. Then the mixture obtained is acidified to pH n)4 with 10 % sulfuric acid and extracted 2 00478 6 with ether, the ether phase is dried on magnesium sulfate, filtered, the filtrate is evaporated and 2.5 g (yield 71 %) of a mixture of dihydroxy-2,3 and dihydroxy-3,4 acetophenones (VI) and (VI1) is isolated, which is sublimated. Thus, 60 % of dihydroxy-2,3 acetophenone (VI) (melting point : 98-99°C) and 10 % of dihydroxy-3,4 acetophenone (VI1) (melting point : 115-116°C) are obtained. EXAMPLE 3 : Preparation of dimethoxy-2,3 and dimethoxy-3,4 benzaldehydes from hydroxy-3 benzaldehyde. A mixture of 4 g of hydroxy-3 benzaldehyde, 5 g of powdered copper and 0.T gof cupric chloride in 80 ml of dry acetonitrile and 40 ml of methylene chloride is agitated for 72 hours at room temperature in an oxygen atmosphere (atmospheric pressure). Then 19 g of sodium carbonate and 17 g of methyl sulfate are added and the mixture is heated for 12 hours at reflux. It is filtered, the filtrate is evaporated, the residue is taken up in ether, the solution obtained is washed with water, dried on magnesium sulfate, filtered and the solvent evaporated. A raw product (yield : 80 %) is obtained which is formed of 25 % of dimethoxy-2,3 benzaldehyde, 3 % of dimethoxy-3,4 benzaldehyde and 50 % of methoxy-3 benzaldehyde (determined by vapor phase chromatography). By one or the other of the processes according to examples 1 and 2, there are also obtained for example : - from phenol : benzenediol-1,2 ; - from the methyl ester of p-hydroxyphenylacetic acid : the methyl ester of dihydroxy-3,4 phenylacetic acid ; - from p-hydroxyacetophenone : dihydroxy-3,4 acetophenone ; - from the methyl ester .of p-hydroxybenzoic acid : the methyl ester of dihydroxy-3,4 benzoic acid ; - from the methyl ester of m-hydroxybenzoic acid : the methyl ester of dihydroxy-2,3 benzoic acid (preponderant) and the methyl ester of dihydroxy-3, 4 benzoic acid ; - from p-hydroxybenzaldehyde : dihydroxy-3,4 benzaldehyde ; - from m-hydroxybenzaldehyde : dihydroxy-2,3 benzaldehyde (preponderant) and dihydroxy-3,4 benzaldehyde ; - from vanillin : dihydroxy-3,4 methoxy-5 benzaldehyde ; - from the methyl ester of hydroxy-3 methoxy-5 benzoic acid : the methyl ester of dihydroxy-2,3 methoxy-5 benzoic acid (preponderant) and the methyl ester of dihydroxy-3,4 methoxy-5 benzoic acid ; - from p-hydroxybenzophenone : dihydroxy-3,4 benzophenone ; </div>

Claims

<div class="application article clearfix printTableText" id="claims"> -from methoxy-4 phenol : dihydroxy-1,2 methoxy-4 benzene ; - from chloro-4 phenol : dihydroxy-1,2 chloro-4 benzene ; - from [hydroxy-4 phenyl]-2 dioxolan-1,3 *• [dihydroxy-3,4 phenyl]-2 dioxolan-1,3;;- from [hydroxy-4 methoxy-3 phenyl]-2 dioxolan-1,3 : [dihydroxy-4,5 methoxy-3 phenyl]-2 dioxolan-1,3 ;;- from [hydroxy-4 phenyl] propanone : [dihydroxy-3,4 phenyl] propanone;- from p-hydroxypropiophenone : dihydroxy-3,4 propiophenone.;WfWT WE CLAIM IS:;- 8 -;200478;1. A selective oxidizing system, comprising metallic copper; a cuprous salt, a cupric salt or mixtures thereof; ard molecular oxygen.;2. The oxidizing system according to claim 1, wherein the cuprous or cupric salt is cuprous or cupric chloride.;3. The oxidizing system according to claim 1 or 2, wherein the molecular oxygen is selected fran atmospheric oxygen, pure oxygen or mixtures thereof.;4. The oxidizing system according to claim 1, 2 or 3, further comprising a cyano aliphatic solvent optionally mixed with a chlorinated organic solvent.;5. The oxidizing system according to claim 4, wherein the cyano aliphatic solvent is acetonitrile and the chlorinated organic solvent is chosen frcm methylene chloride, dichloroethane and mixtures thereof.;6. A process for preparing aromatic at least once ortho-dihydroxylated or ortho-dialkoxylated derivatives, consisting of subjecting aromatic derivatives comprising at least one phenolic hydroxyl radical, one at least of the ortho positions with respect to this radical being free, respectively to the action of the oxidizing system according to any one of the preceding claims, then subjecting the intermediate cupric pyrocatecholates to hydrolysis or alkylation.;7. The process according to claim 6, wherein the metallic copper is employed in at least a stoichiometric amount with respect to the starting hydroxylated arcmatic derivative,;8. The process according to claim 6 or 7, wherein the metallic copper is enployed in an amount in excess of a stoichiometric amount with respect to the starting hydroxylated arcmatic derivative.;9. The process according to claim 6,7 or 8, wherein the cuprous or cupric salt is used in a catalytic amount.;V"* i5 \ \ 31 OCT 1984 - 9 - 2o<>V7$r 10. The process according to claim 6, 7, 8 or 9, wherein the oxidizing step is carried out under an oxygen pressure of at least one atmosphere. 11. The process according to any one of claims 6 to 10, wherein the oxidation reaction is carried out in the presence of a dehydrating agent. 12. The process according to claim 11, wherein the dehydrating agent is chosen from the group comprising : molecular sieves, an alkaline or alkaline-earth metal sulfate. 10 15 13. The process according to any one of claims 6 to 11, vdierein the hydrolysis is carried out in an acid, reducing or acido-reducing medium. 14. The process according to claim 13, wherein the acid, reducing or acido-reducing medium is obtained respectively by using hydrochloric or sulfuric acid, sodium hydrosulfite and a sodium hydrosulfite-sodium bicarbonate mixture or stannous chloride-hydrochloric acid mixture. 20 25 15. The process according to any one of claims 6 to 12, wherein the alkylation is carried out in the presence of a base with the help of an alkylating derivative chosen from the alkyl sulfates, chlorides, bromides, tosylates and mesylates. 16. The process according to claim 15, wherein the base is sodium carbonate. 17. A selective oxidising system substantially as specifically described herein in any one of ths Examples 1, 2 and 3. 18. A process for preparing arcmatic derivatives substantially as specifically described herein with reference to any one of the Examples 1, 2 and 3. </div>