Claims
- 1. A process for the synthesis of phenyl substituted aromatic diols comprising dehydrogenating products having the general formula I: ##STR3## wherein A means a single, double, triple or fused C.sub.6 -C.sub.18 aromatic radical, either unsubstituted or substituted with C.sub.1 -C.sub.4 alkyl radicals, in a solvent medium in the presence of a supported palladium catalyst, wherein said supported palladium catalyst is prepared by a process comprising:
- a) adding an acid solution of a palladium compound selected among palladium halide or palladite to an alkaline suspension of a carrier selected from the group consisting of activated carbons, activated aluminas, silicas, TiO.sub.2 and MgO, thereby forming a slurry;
- b) treating the slurry of a) at 20.degree.-100.degree. C. with sodium hypophosphite or sodium formate to turn said palladium compound into palladium metal;
- c) recovering the solid product of the slurry of b) by filtration, rinsing said solid product with water at 20.degree.-100.degree. C. until halide ions are removed;
- d) optionally, drying the solid at 100.degree.-120.degree. C. and wherein the dehydrogenation reaction is carried out at 220.degree.-350.degree. C., at atmospheric pressures under nitrogen flow or under vacuum.
- 2. A process according to claim 1 wherein the products having general formula (I) are products having the two hydroxyl groups in parallel or coaxial alignment.
- 3. A process according to claim 1 wherein the solvent medium is selected among products having the property of dissolving the reagents under the reaction conditions and a boiling point at atmospheric pressure of at least 200.degree. C.
- 4. A process according to claim 1 wherein the catalyst is used in a molar ratio of produce (I)/Pd ranging from 50 to 10,000.
- 5. A process according to claim 1 wherein said activated carbon has a specific surface ranging from 400 to 1200 m.sup.2 /g.
- 6. A process according to claim 1 wherein said activated alumina has specific surfaces below 400 m.sup.2 /g.
- 7. A process according to claim 1 wherein said silica has specific surfaces ranging from 100 to 800 m.sup.2 /g.
- 8. A process according to claim 1 wherein said titanium oxide has a specific surface ranging from 10 to 300 m.sup.2 /g.
- 9. A process according to claim 1 wherein said catalyst contains an alkali, said alkali being obtained by treating the catalyst with a solution of carbonates or bicarbonates of alkaline or alkaline-earth metals.
- 10. A process according to claim 1 wherein the palladium compound is PdCl.sub.2 or Na.sub.2 PdCl.sub.4.
- 11. A process comprising (i) preparing a palladium catalyst by a process comprising:
- a) adding an acid solution of a palladium compound selected among palladium halide or halopalladite to an alkaline suspension of a carrier selected from the group consisting of activated carbons, activated aluminas, silicas, TiO.sub.2 and MgO, thereby forming a slurry;
- b) treating the slurry of a) with sodium formate or sodium hypophosphite at 20.degree.-100.degree. C. to turn said palladium compound into palladium metal;
- c) recovering the solid product of the slurry of b) by filtration, rinsing the solid with water at 20.degree.-100.degree. C. until halides are removed;
- d) optionally, drying the solid of c) at 100.degree.-120.degree. C. and (ii) dehydrogenating at 220.degree.-350.degree. C. at atmospheric pressure under nitrogen flow or under vacuum, in a solvent medium, products having the formula I: ##STR4## wherein A means a single, double, triple or fused C.sub.6 -C.sub.18 aromatic radical, or products of formula I which are substituted with C.sub.1 -C.sub.4 alkyl radicals, using the rinsed solid of c) or the dried solid of d) as a catalyst.
- 12. A process according to claim 11 wherein the products having general formula (I) are products having the two hydroxyl groups in parallel or coaxial alignment.
- 13. A process according to claim 11, wherein the products having general formula (I) are:
- cyclohexylhydroquinone,
- 3-cyclohexyl-4,4'-dihydroxydiphenyl,
- 1-cyclohexyl-2,6-dihydroxynaphthaline and
- 2-cyclohexyl-1,4-dihydroxynaphthalene.
- 14. A process according to claim 11, wherein the solvent medium is selected among the products having the property of dissolving the reagents under the reaction conditions and a boiling point at atmospheric pressure of at least 220.degree. C.
- 15. A process according to claim 3 wherein the solvent is tetraethylene glycol dimethyl ether, diphenyl ether, diphenyl or polyethylene glycols having an average molecular weight ranging from 200 to 1500.
- 16. A process according to claim 11 wherein the catalyst is used in a molar ratio of produce (I)/Pd ranging from 50 to 10,000.
- 17. A process according to claim 11 wherein said activated carbon has a specific surface ranging from 400 to 1200 m.sup.2 /g.
- 18. A process according to claim 11 wherein said activated alumina has specific surfaces below 400 m.sup.2 /g.
- 19. A process according to claim 11 wherein said silica has specific surfaces ranging from 100 to 800 m.sup.2 /g.
- 20. A process according to claim 11 wherein said titanium oxide has a specific surface ranging from 10 to 300 m.sup.2 /g.
- 21. A process according to claim 11 wherein said catalyst contains an alkali, said alkali being obtained by treating the catalyst with a solution of carbonates or bicarbonates of alkaline or alkaline-earth metals.
- 22. A process according to claim 11 wherein the palladium compound is PdCl.sub.2 or Na.sub.2 PdCl.sub.4.
Priority Claims (1)
Number |
Date |
Country |
Kind |
20983 A/88 |
Jun 1988 |
ITX |
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TECHNICAL FIELD
This is a continuation-in-part of pending U.S. application Ser. No. 07/569,215 filed August 16, 1990, now abandoned, which in turn was a continuation of now abandoned application U.S. Ser. No. 07/367,548 filed Jun. 16, 1989, both of which applications are hereby incorporated by reference.
US Referenced Citations (2)
Number |
Name |
Date |
Kind |
4160113 |
Muller et al. |
Jul 1979 |
|
4798911 |
Lentz et al. |
Jan 1989 |
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Foreign Referenced Citations (4)
Number |
Date |
Country |
0346913 |
Dec 1989 |
EPX |
1036445 |
Mar 1976 |
JPX |
51-91215 |
Aug 1976 |
JPX |
1091215 |
Aug 1976 |
JPX |
Continuations (1)
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Number |
Date |
Country |
Parent |
367548 |
Jun 1989 |
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Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
569215 |
Aug 1990 |
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