IE904369A1 - Method of preparing substituted hydroquinones - Google Patents
Method of preparing substituted hydroquinonesInfo
- Publication number
- IE904369A1 IE904369A1 IE436990A IE436990A IE904369A1 IE 904369 A1 IE904369 A1 IE 904369A1 IE 436990 A IE436990 A IE 436990A IE 436990 A IE436990 A IE 436990A IE 904369 A1 IE904369 A1 IE 904369A1
- Authority
- IE
- Ireland
- Prior art keywords
- hydroquinone
- reaction
- fornula
- hydroxy acetophenone
- hydroxy
- Prior art date
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C45/00—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds
- C07C45/45—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by condensation
- C07C45/46—Friedel-Crafts reactions
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C37/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom of a six-membered aromatic ring
- C07C37/50—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom of a six-membered aromatic ring by reactions decreasing the number of carbon atoms
Abstract
Process for the preparation of monosubstituted hydroquinones, characterised in that a phenol substituted in ortho or meta position relative to the OH groups is reacted with an acetylating agent chosen from acetyl halides, acetic acid, acetic anhydride or acetic acid esters, in hydrogen fluoride, in order to form the corresponding R-substituted hydroxyacetophenone and the said hydroxyacetophenone is oxidised with hydrogen peroxide in the presence of an inorganic base. The process of the invention is more particularly advantageous for preparing methylhydroquinone because of the low cost of ortho-cresol or meta-cresol used as raw material.
Description
The invention concerns a method of preparing monosubetituted hydroquinones.
Hydroquinones which are monosubetituted, especially by hydrocarbon radicals, may be used mainly for preparing monomers. This is particularly so with methyl hydroquinone, which is the best known conpound of the family.
Many methods of obtaining methyl hydroquinone have been preposed.
US Patent No. 2 041 593 describes hydrolysis of 4-chloro 2-methyl phenol to methyl hydroquinone in an aqueous soda medium. This method has poor selectivity for methyl hydroquinone.
Patent EP-A-0 041 441 described hydroxylation of orthocresol to hydrogen fluoride at - 40°C in the presence of antimony pentafluoride. Despite the very difficult operating conditions the yields are inadequate.
US Patent No. 4 482 756 reconroends oxidation of orthocresol by oxygen in the presence of cupric chloride in acetonitrile. This method involves using high pressures.
Ihe invention concerns a method of preparing monosubetituted hydroquinones of general fornula (I):
OH
R (I)
OH wherein R represents:
. a straight or branched alkyl radical with 1 to 4 carbon atone . a phenyl radical . a cyclohexyl radical characterised in that:
- a substituted phenol of general fornula (II):
OH
(Π) wherein R has the meanings indicated for fornula (I) and is in the ortho or meta position relative to the OH group, is reacted with an acetylating agent selected from^halides, odfr -rruatyT, acetic acid, acetic anhydride or esters of acetic acid, in hydrogen fluoride, to form the corresponding R-substituted hydroxy acetophenone
- and the hydroxy acetophenone is oxidised by hydrogen peroxide in the presence of an inorganic base.
The fornula (I) oonpounds which are currently regarded as most inportant include methyl hydroquinone, ethyl hydroquinone, cyclohexyl hydroquinone and phenyl hydroquinone.
The method of the invention is more particularly inportant for preparing methyl hydroquinone, because of the low cost of the ortho-cresol or meta-cresol which are the raw materials.
The most convenient acetylating agent to use in the invention is an acetyl halide, for the by product of the reaction is then a hydrogen halide, which does not interfere with the final treatment or with the recycling of hydrogen fluoride. Of these halides it is preferable to use acetyl chloride; the hydrogen chloride which forms can easily be separated from the reactive medium.
The acetylating reaction according to the invention is carried out in hydrogen fluoride, which is preferably anhydrous.
The quantity of acetylating agent is such that the molar ratio of acetylating agent to fornula (II) R substituted phenol is usually from 1 to 5:1.
The molar ratio is preferably from 1 to 2:1.
The quantity of hydrogen fluoride used is such that the molar ratio of HF to fornula (II) phenol is generally from 5 to 50:1.
The tenperature at which the acetylating reaction is carried out varies widely. It is generally from -10 to 120°C.
The tenperature is preferably from 20 to 100°C.
The pressure in the reactor is generally the autogenic pressure of the various reagents or solvents at the selected tenperature.
Ihe acetylating reaction may conveniently be carried out by charging a reactor with anhydrous hydrogen fluoride in the liquid state, generally at a temperature of 0 to 1CPC, then with the fornula (II) substituted phenol.
The acetylating agent, preferably acetyl chloride, is then added gradually.
When the acetylating agent has been added, the reactor is closed and the reaction mixture heated to the selected tenperature for a period ranging from a few minutes to several hours, under autogenic pressure.
At the end of the acetylating reaction the hydroxy acetophenone formed may be separated by methods commonly used in chemistry such as extraction, decantation or evaporation.
In the invention one can alternatively siaply remove the hydrogen fluoride, for exanple by distillation, and involve the crude hydroxy acetophenone in the oxidation stage.
The reaction in which substituted hydroxy acetophenone is oxidised to fornula (I) hydroquinone is carried out with a molar ratio of hydrogen peroxide to hydroxy acetophenone generally from 1 to 2:1.
It is not desirable to have a large excess quantity of hydrogen peroxide for economic reasons, and the ratio is most commonly from 1 to 1.2:1.
The hydrogen peroxide is normally used in the form of commercially available aqueous solutions, which are usually at a concentration of 20 to 70%.
Ihe inorganic base used in the oxidation reaction is preferably an alkali metal hydroxide and more particularly sodium hydroxide.
The total molar ratio of inorganic base to substituted hydroxy acetophenone is generally from 1 to 1.2:1.
The inorganic base is generally used in the form of an aqueous solution.
The pH of the reaction medium is kept at a level from 8 to 11 and preferably from 8.5 to 10.5 during the oxidation reaction.
It is checked by measuring the pH and gradually adding the inorganic base during the reaction.
Ihe solvent used in the operation is water. In appropriate cases one could also use a third solvent which is inert under the conditions of the reaction.
Some non-restrictive exanples of such third solvents are alcohols and particularly methanol.
Ihe concentration in the reaction mixture, of substituted hydroxy acetophenone involved in the reaction and/or of substituted hydroquinone formed in the reaction, is not critical. The concentration of substituted hydroxy acetophenone involved is normally from 10 to 60% by weight relative to the total weight of the reaction mixture. The concentration is preferably from 30 to 50% by weight.
The tenperature at which the oxidation reaction is carried out is meet commonly from 10 to 60¾ and preferably from 25 to 35°C.
A convenient embodiment of the oxidation reaction comprises admixing the substituted hydroxy acetophenone obtained in the acetylating reaction with water and possibly with part of the inorganic base, to adjust the pH of the mixture to the desired level.
The mixture is agitated and heated to 10 to 6G°C, and a solution of hydrogen peroxide and a solution of inorganic base are poured out simultaneously but independently of one another. The pH of the reaction mixture and the tenperature are kept at the chosen levels.
When the hydrogen peroxide and inorganic base have been added, agitation of the reaction mixture at the selected tenperature is continued for a period which may range from a few minutes to a few hours.
The final reaction mixture is treated by methods oonmonly used in chemistry, to separate the substituted hydroquinone thus prepared.
The method of the invention nay be applied discontinuously or continuously.
The following exanples are given to illustrate the invention.
EXAMPLE 1
A) Acetylation of ortho-cresol to 4-hydroxy 3-methyl acetophone
A 250 cm reactor made of Hastelloy is charged with the following at 0°C;
- hydrogen fluoride (HF): 100 g (5 mol)
- ortho-cresol : 21.6 g (0.2 mol)
.7 g (0.2 mol) of acetyl chloride is introduced in one hour 20 minutes, and the hydrogen chloride which forms is liberated.
Ihe reactor is then closed and heated for one hour at 50°C (the autogenic pressure is 0.3 MPa).
The reactor is cooled and about 85% of the hydrogen fluoride is evaporated at reduced pressure.
The reaction mixture thus obtained is poured into a vessel containing 300 g of ice, and the reactor is rinsed with three times 100 cm of dichloromethane.
After decantation and separation the organic phase is washed with twice 100 cm3 of water, then dried over sodium sulphate.
When the solvent has evaporated 29.8 g of a solid of a light beige colour is obtained. High performance liquid chromatography (HPLC) shews it to contain 98% of 4-hydroxy
3-methyl acetophenone.
After recrystallisation 26 g of pure 4-hydroxy 3-methyl acetophenone is obtained, and its structure is confirmed by nuclear magnetic resonance (M4R).
The following results are obtained:
- conversion rate (CR) of ortho-cresol: 99%
- yield of 4-hydroxy 3-methyl acetophenone analysed, relative to the ortho-cresol converted: 98%
- yield of 2-hydroxy 3-methyl acetophenone analysed, relative to the ortho-cresol converted: less than 2%.
B) Oxidation of 4-hydroxy 3-methyl acetophenone to methyl hydroquinone
A 50 cm3 glass reactor fitted with a central agitator is charged with the following in a stream of argon:
- pure 4-hydroxy 3-methyl acetophenone prepared in A): 6 g (0.04 mol)
- water : 8 cm3
- 35% weight for weight (w/w) sodium hydroxide: 0.7 cm3 (0.008 mol)
Ihe mixture is agitated and heated to 30¾. This tenperature is maintained throughout the reaction.
□
3.5 cmJ (0.040 mol) of a 35% w/w aqueous solution of hydrogen peroxide and 3.3 cm (0.032 mol) of 35% w/w sodium hydroxide are poured in simultaneously in the course of one hour, through two separate inlets. The pH of the reaction mixture ranges from
.5 to 9 while these materials are being poured in.
Ihe agitation and tenperature are then maintained for 2 h 30.
2.2 cm of a IM solution of sodium sulphite is added to the final reaction mixture.
Ihe reaction mixture is extracted with ethyl acetate.
The organic phase is analysed by high perfornance liquid chromatography (HPLC) and potentiometric titration, and the chemical structure of the conpounds is confirmed ty nass spectrometry.
The following results are obtained:
- % conversion rate of 4-hydroxy 3-methyl acetophenone (HMA): 95%
- yield of methyl hydroquinone (MeHQ) relative to HMA converted: 90%
- % yield of 4-hydroxy 3-methyl benzoic acid: 9%
EXAMPLE 2
A) Acetylation of ortho-cresol to 4-hydroxy 3-methyl acetophenone
A 250 cm3 reactor made of Hastelloy is charged at 0°C with:
- hydrogen fluoride (HF): 100 g (5 mol)
- ortho-cresol : 21.6 g (0.2 mol)
.7 g (0.2 mol) of acetyl chloride is introduced in one hour, and the hydrogen chloride which forms is liberated. The reactor is then closed and heated for 2 hours at 40¾.
The reactor is cooled and about 85% of the hydrogen fluoride is evaporated at reduced pressure.
The reaction mixture thus obtained is poured into a vessel containing 300 g of ice, and the reactor is rinsed with 100 cm of chloroform.
After decantation and separation the organic phase is washed with twice 100 cm3 of water, then dried over sodium sulphate.
When the solvent has evaporated 29.4 g of a solid of a light beige colour is obtained, which high performance liquid chromatography (HPLC) shows to be 98% 4-hydroxy 3-methyl acetophenone.
After recrystallisation 27.3 g of pure 4-hydroxy 3-methyl acetophenone is obtained, and its structure is confirmed by nuclear magnetic resonance (NMR).
The following results are obtained:
- conversion rate (CR) of ortho-cresol: 99% u
- yield of 4-hydroxy 3 methyl acetophenone analysed, relative to the ortho-cresol converted: 97%
- yield of 2-hydroxy 3-methyl acetophenone analysed, relative to the ortho-cresol coverted: less than 2%.
B) Oxidation of 4-hydroxy 3-methyl acetophenone to methyl hydroquinone
A 50 cm3 glass reactor fitted with a central agitator is charged with the following in a stream of argon:
- pure 4-hydroxy 3-methyl acetophenone prepared in A): 6 g (0.04 mol)
- water : 4 cm
- methanol: 4 cm
Hie mixture is agitated and heated to 30°C. This tenperature is maintained throughout the reaction.
3.5 cm (0.040 mol) of a 35% w/w aqueous solution of hydrogen peroxide and 3.4 cm3 (0.040 mol) of 35% w/w sodium hydroxide are poured in sinultaneously through two separate inlets.
The hydrogen peroxide is poured in in the course of an hour.
The sodium hydroxide solution is poured in subject to the pH of the reaction mixture, which is automatically regulated to 9.
The agitation and tenperature are maintained all in all for 3 h 30.
2.2 cm3 of a 1 M solution of sodium sulphite is then added to the final reaction mixture.
The reaction mixture is extracted with ethyl acetate.
Ihe organic phase is analysed by high performance liquid chromatography (HPLC) and potentiometric titration, and the chemical structure of the conpounds is confirmed by mass spectrometry.
The following results are obtained:
- % conversion rate of 4-hydroxy 3-methyl acetophenone (HMA): 96%
- yield of methyl hydroquinone (MeHQ) relative to HMA converted: 99%
EXAMPLE 3:
Oxidation of 4-hydroxy 3-methyl acetophenone to methyl hydroquinone
A 50 cm* 3 glass reactor fitted with a central agitator is charged with the following in a stream of argon:
- pure 4-hydroxy 3-methyl acetophenone prepared in Exanple 2 A):
9 (0.04 mol)
- water : 4 cnr
- methanol: 4 cm
Ihe mixture is agitated and heated to 30°C. This tenperature is maintained throughout the reaction.
3.5 cm3 (0.040 mol) of a 35% w/w aqueous solution of hydrogen peroxide and 3.4 cm (0.040 mol) of 35% w/w sodium hydroxide are poured in sinultaneously through two separate inlets.
Ihe hydrogen peroxide is poured in in the course of an hour.
Ihe sodium hydroxide solution is poured in subject to the pH of the reaction mixture, which is automatically regulated to 10.
The agitation and tenperature are maintained all in all for 3 h 30.
2.2 cm3 of a 1 M solution of sodium sulphite is then added to the final reaction mixture.
The reaction mixture is extracted with ethyl acetate.
The organic phase is analysed by high performance liquid chromatography (HPLC) and potentiometric titration, and the chemical structure of the oonpounds is confirmed by mass spectrometry.
The following results are obtained:
- % conversion rate of 4-hydroxy 3-roethyl acetcphenone (HMA): 83%
- yield of methyl hydroquinone (MeHQ) relative to HMA converted: 83%
EXAMPLE 4: Oxidation of 4-hydroxy 3-methyl acetophenone to methyl hydroquinone
A 50 cm glass reactor fitted with a central agitator is charged with the following in a stream of argon:
- pure hydroxy 3-methyl acetophenone prepared in Exanple 2 (A) 6 g (0.04 mol)
- water: 8 cm3
- 35% weight by weight (w/to) sodium hydroxide: mol)
0.7 cm3 (0.008
The mixture is agitated and heated to 30°C. This tenperature is maintained throughout the reaction.
3.5 cm3 (0.040 mol) of a 35% w/W aqueous solution of hydrogen peroxide and 3.3 cm3 (0.032 mol) of 35% w/w sodium hydroxide are poured in sinultaneously, through two separate inlets, in the course of one hour. The pH of the reaction mixture varies from
.5 to 9 while these materials are being poured in.
The tenperature is raised to 40°C and agitation is na intai ned for a further 2 h 30.
2.2 cm3 of a 1 M sodium sulphite solution is then added to the final reaction mixture.
The reaction mixture is extracted with ethyl acetate.
The organic phase is analysed by high performance liquid chromatography (HPLC) and potentiometric titration, and the chemical structure of the conpounds is confirmed by mass spectrometry.
The following results are obtained:
- % conversion rate of 4-hydroxy 3-methyl acetophenone (HMA): 90%
- yield of methyl hydroquinone (KeHQ) relative to HMA converted: 68%
EXAMPLE 5: Oxidation of 4-hydroxy 3-methyl acetophenone to hydroquinone
A 50 cm glass reactor fitted with a oentral agitator is charged with the following in a stream of argon:
- crude 4-hydroxy 3-methyl acetophenone prepared in Exanple 1 (A): 6.12 g (0.04 mol)
- water: 4 cm
- methanol: 4 era
Ihe mixture is agitated and heated to 30°C. This tenperature is maintained throughout the reaction.
3.5 cm3 (0.040 mol) of a 35% w/u aqueous solution of hydrogen peroxide and 3.4 cm (0.040 mol) of 35% w/V sodium hydroxide are poured in sinultaneously through two separate inlets.
The hydrogen peroxide is poured in in the course of an hour.
Ihe sodium hydroxide solution is poured in subject to the pH of the reaction mixture, which is automatically regulated to 9.
The agitation and tenperature are maintained all in all for 3 h 30.
2.2 cm3 of a 1 M sodium sulphite solution is then added to the final reaction mixture.
The reaction mixture is extracted with ethyl acetate.
The organic phase is analysed by high perfornance liquid chromatography (HPLC) and potentiometric titration, and the chemical structure of the conpounds is confirmed by mass spectrometry.
The following results are obtained:
- % conversion rate of 4-hydroxy 3-methyl acetophenone (HMA): 95%
- yield of methyl hydroquinone (MeHQ) relative to HMA converted: 86%
Claims (15)
1. A method of preparing monosubstituted hydroquinones of general fornula (I): OH OH wherein R represents: . a straight or branched alkyl radical with 1 to 4 carbon atoms . a phenyl radical . a cyclohexyl radical characterised in that: o - a substituted of general fornula (II): OH R wherein R has the meanings indicated for fornula (I) and is in the ortho or meta position relative to the OH group, acetyi is reacted with an acetylating agent selected from/nalides,ofi’ acetic acid, acetic anhydride or esters of acetic acid, in hydrogen fluoride, to form the corresponding R-subetituted hydroxy acetophenone - and the hydroxy acetophenone is oxidised by hydrogen peroxide in the presence of an inorganic base.
2. The method of Claim 1, characterised in that the fornula (I) conpound is selected from methyl hydroquinone, ethyl hydroquinone, cyclohexyl hydroquinone and phenyl hydroquinone.
3. The method of Claim 1 or 2, characterised in that the acetylating agent is an acetyl halide and preferably acetyl chloride.
4. The method of any of Claims 1 to 3, characterised in that the guantity of acetylating agent is such that the molar ratio of acetylating agent to fornula (II) R-subetituted phenol is from 1 to 5:1 and preferably from 1 to 2:1.
5. The method of any of Claims 1 to 4, characterised in that the quantity of hydrogen fluoride used is such that the molar ratio of HF to fornula (II) phenol is from 5 to 50:1.
6. The method of ary of Claims 1 to 5, characterised in that the tenperature at which the acetylating reaction is carried out is from -10 to 120¾ and preferably from 20 to 100°C.
7. The method of any of Claims 1 to 6, characterised in that the reaction in which substituted hydroxy acetophenone is oxidised to fornula (I) hydroquinone is carried out with a molar ratio of hydrogen peroxide to hydroxy acetophenone from 1 to 2:1 and preferably from 1 to 1.2:1.
8. Ihe method of any of Claims 1 to 7, characterised in that the inorganic base used in the oxidation reaction is an alkali metal hydroxide and preferably sodium hydroxide.
9. The method of any of Claims 1 to 8, characterised in that the total molar ratio of inorganic base to substituted hydroxy acetophenone is from to 1 to 1.2:1.
10. Ihe method of any of Claims 1 to 9, characterised in that the pH of the reaction medium is kept at a level from 8 to 11 and preferably from 8.5 to 10.5 during the oxidation reaction.
11. The method of any of Claims 1 to 10, characterised in that the concentration of substituted hydroxy acetophenone involved is from 10 to 60% by weight relative to the total weight of the reaction mixture, and preferably from 30 to 50%.
12. The method of any of Claims 1 to 11, characterised in that the tenperature at which the oxidation reaction is carried out is from 10 to 60¾ and preferably from 25 to 35°C.
13. The method of any of Claims 1 to 12, characterised in that after the acetylating reaction the hydrogen fluoride is removed and the crude hydroxy acetophenone is involved in the oxidation stage.
14. A method according to Claim 1 of preparing a monosubstituted hydroquinone of general formula (I) given and defined therein, substantially as hereinbefore described and exemplified.
15. A monosubstituted hydroquinone of general formula (I) given and defined in Claim 1, whenever prepared by a method claimed in a preceding claim.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR8916310A FR2655331A1 (en) | 1989-12-05 | 1989-12-05 | PROCESS FOR THE PREPARATION OF SUBSTITUTED HYDROQUINONES |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| IE904369A1 true IE904369A1 (en) | 1991-06-05 |
Family
ID=9388330
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| IE436990A IE904369A1 (en) | 1989-12-05 | 1990-12-04 | Method of preparing substituted hydroquinones |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP0436410A1 (en) |
| JP (1) | JPH03227947A (en) |
| CA (1) | CA2031483A1 (en) |
| FR (1) | FR2655331A1 (en) |
| IE (1) | IE904369A1 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0591799B1 (en) * | 1992-10-09 | 1997-01-15 | Hoechst Aktiengesellschaft | Oxidation of hydroxybenzaldehydes to dihydroxybenzene compounds |
| GB0318209D0 (en) * | 2003-08-04 | 2003-09-03 | Great Lakes Chemical Europ | Production of disubstituted hydroquinones |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3764629A (en) * | 1970-06-22 | 1973-10-09 | Hoffmann La Roche | Process for the preparation of pyrocatechols |
| JPS56147737A (en) * | 1980-04-15 | 1981-11-16 | Sumitomo Chem Co Ltd | Preparation of dihydroxybenzene derivative |
| CA1257291A (en) * | 1984-10-17 | 1989-07-11 | Harold R. Gerberich | Process for producing aromatic diols and their ester and ether derivatives |
| JPS62120334A (en) * | 1985-11-19 | 1987-06-01 | Dainippon Ink & Chem Inc | Synthesis of catechol compound |
| FR2624507B1 (en) * | 1987-12-11 | 1990-06-15 | Rhone Poulenc Chimie | PROCESS FOR THE PREPARATION OF HYDROXYLATED AROMATIC DERIVATIVES BY THE BAEYER-VILLIGER REACTION |
-
1989
- 1989-12-05 FR FR8916310A patent/FR2655331A1/en not_active Withdrawn
-
1990
- 1990-11-23 EP EP90403317A patent/EP0436410A1/en not_active Withdrawn
- 1990-11-30 JP JP33090190A patent/JPH03227947A/en active Pending
- 1990-12-04 IE IE436990A patent/IE904369A1/en unknown
- 1990-12-04 CA CA 2031483 patent/CA2031483A1/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| CA2031483A1 (en) | 1991-06-06 |
| JPH03227947A (en) | 1991-10-08 |
| FR2655331A1 (en) | 1991-06-07 |
| EP0436410A1 (en) | 1991-07-10 |
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