CA1271492A - Process for producing 2,6-dihydroxynaphthalene - Google Patents
Process for producing 2,6-dihydroxynaphthaleneInfo
- Publication number
- CA1271492A CA1271492A CA000542065A CA542065A CA1271492A CA 1271492 A CA1271492 A CA 1271492A CA 000542065 A CA000542065 A CA 000542065A CA 542065 A CA542065 A CA 542065A CA 1271492 A CA1271492 A CA 1271492A
- Authority
- CA
- Canada
- Prior art keywords
- naphthalene
- hydroxy
- propyl
- dihydroxynaphthalene
- amount
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- 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
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
Disclosed herein is a process for producing 2,6-dihydroxynaphthalene, which process comprises the step of oxidizing 2,6-di(2-hydroxy-2-propyl)naphthalene with hydrogen peroxide in acetonitrile, 1,4-dioxane or a mixture thereof in the presence of an inorganic acid of an amount not less than 0.001 time by weight and less than 0.1 time by weight to the amount of the 2,6-di(2-hydroxy-2-propyl)naphthalene.
Disclosed herein is a process for producing 2,6-dihydroxynaphthalene, which process comprises the step of oxidizing 2,6-di(2-hydroxy-2-propyl)naphthalene with hydrogen peroxide in acetonitrile, 1,4-dioxane or a mixture thereof in the presence of an inorganic acid of an amount not less than 0.001 time by weight and less than 0.1 time by weight to the amount of the 2,6-di(2-hydroxy-2-propyl)naphthalene.
Description
TITLE OF THE INVENTION:
PROCESS FOR PRODUCING 2,6-DIHYDROXYNAPHrr~I~LENE
BACKGROUND OF THE INVENTION:
The present invention relates to a process for producing 2,6-dihydroxynaphthalene which is utilized as a monomer in the production of aromatic polyesters having a capacity of forming liquid crystals. More in detail, the present invention relates to a process for producing
PROCESS FOR PRODUCING 2,6-DIHYDROXYNAPHrr~I~LENE
BACKGROUND OF THE INVENTION:
The present invention relates to a process for producing 2,6-dihydroxynaphthalene which is utilized as a monomer in the production of aromatic polyesters having a capacity of forming liquid crystals. More in detail, the present invention relates to a process for producing
2,6-dihydroxynaphthalene, which process comprises the step of oxidizing 2,6-di~2-hydroxy-2 propyl)naphthalene with hydrogen peroxide in acetonitrile, 1,4 dioxane or a mixture thereof in the presence of an inorganic acid of an amount of not less than 0.001 time by weight and less than 0.1 time by weight to the amount of 2,6 di(2-hydroxy-2-propyl)naphthalene.
Recently, in the development of various polymers known as the engineering plastics, aromatic polyesters, particularly -the aromatic polyesters having a capacity of forming liquid crystals have attracted attention.
As the raw material of the polymer of aromatic polyesters, terephthalic acid, hydroquinone, p-hydroxy-benzoic acid and the like may be mentioned. In order to improve the physical and chemical properties of the aromatic polyesters, however not only benzene derivatives but also naphthalene derivatives have come -to be used as the raw material of the aromatic polyesters in recent years.
~,....~
49~
Of the naph-thalenic raw materials, 2,6-clihydroxy-naphthalene has at~racted attention as -the monomer utilized in the production of the aromatic polyesters from the viewpoint that the physical properties of the liquid crystalline polymer derived from 2,6-dihydroxynaphtha-lene are e~cellent and that terephthalic acid used as the comonomer of the polymer ls a~ailable at a low price.
However, since 2,6-dihydroxynaphthalene itself is not industrially produced at present, there is a problem that 2,6-dihydroxynaphthalene is not available at a low price.
As the process for producing 2,6-dihydroxy-naphthalene, an old process has hitherto been known, wherein naphthalene or ~-naphthol is sulfonated and then the thus .sulfonated product is subjected to alkali fusion, and such a process has been introduced in Beilstein t S
"Handbuch der organischen Chemie". However! as is seen, for instance, in the description of Japanese Patent Publ.ication No. 56-77,254(1981), the by-production of the isomers other than the 2,6-isomer is inevitable according to this process and consequently, it is impossible to obtain the 2,6-isomer in a high yiela. Furthermore, the yield of 2,6-dihydroxynaphthalene at the step of alkali fusion of sodium 2-naphthol-6-sulfonate is in the extent of 50 % as is described in A.P. Kuriakose et al.
in J. Indian Chem. Soc., 43, 437(1966). Consequently, the ~7~
yield of 2,6-dihydroxynaphthalene produced by the process comprising the steps o~ sulforlation of naphthalene or ~-naphthol and of alkali fusion of the thus sulfonated product is extremely poor.
Further, since it is difficult to separate the 2,6-isomer and it is necessary to carry out a drainage treatment specific to the step of alkali fusion, there is a problem of a high production cost. Namely, this process is industrially poor in practical use~
A process for producing hydroquinone from p-diisopropylbenzene while applying the principle in the production of phenol by the cumene process has hitherto been known ~refer to Japanese ~atent Publication No. 51-33 100 (1976)].
A process has been proposed while applying the process to the production of 2,6~dihydroxynaphthalene.
Namely, 2,6-diisopropylnaphthalene as the starting material is oxidized to obtain 2~6.diisopropylnaphthalene dihydro-peroxide and the thus obta~ned dihydroperoxide is converted into 2,6-dihydroxynaphthalene by acid decomposition [refer to Japanese Patent Applicatlons Laid-Open(KOKAI) Nos. 61-93 156 (1986), 61-100 558(.1986) and 61-191 638(1986)~.
However, in this case, since it is difficult to separate the thus ormed dlhydroperoxide, even this process cannot be ~egarded suitable industrially.
Still more, a process of converting arom~tic carbinols represented by the formula:
Ar- C - OH
(wherein Ar represents an aromatic ring) into a compound represented by the formula: Ar--OH has also been known.
Namely the aromatic carbinol is oxidized with hydrogen peroxide in a solvent in the presence of a strong acid [for instance, refer to Japanese Patent Application Laid-open(KoKAI) No.
52-5 718(1977), Japanese Patent Publication No. 35-7 558(1960), British Patent No. 910,735, TSUNODA and KATO, J. Chem~ Soc.
Japan, 80(7), 689/1959 and M.S. KHARASCH et al., J. Org. Chem., 5, 743(1959)].
However, the examples described in the literature concern processes for converting 2-hydroxy-2-propylbenzene, p-di~2-hydroxy-2-propyl)benzene, p-~2-hydroxy-2-propyl)-~, ~'-dimethylbenzyl hydroperoxide and the like into phenol or hydroquinone ! and there has not been disclosed a process ~or converting the 2-hydroxy-2-propyl group which is directly bound to the naphthalene ring into the hydroxy group in the literature.
By the way, even in the case where 2,6-di~2-hydroxy-2-propyl)naphthalene[hereinafter referred to as 2~6- DHPN
is oxidized in the solvent used in the process described in the literature, it is impossible to produce ~7~49~:
industrially 2,6-dihydroxynaphthalene by t~e following reasons:
Namely, (1) 2,6~ DHPN does not dissolve in the solvent, (2) in spite of the disappearance of 2,6- DI-IPN from the reaction system, 2,6-dihydroxynaphthalene is scarcely formed, (3~ the solvent itself reacts in the system or (4) the reaction velocity is small.
These facts are considered to be derived from the substantial difference of the physical and chemical properties between 2 t 6-dihydroxynaphthalene which is a naphthalene derivative and the carbinols disclosed in the literatures, which are benzene derivatives.
Under the circumstances, as a result of the present inventors' study concerning the industrially feasible process for producing 2,6-dihydro~ynaphthalene, it has been fcund out that 2,6-dihydroxynaphthalene represented by the following formula(III) can be advantageously produced by using 2,6- DHPN represented by the following formula(II) and derived from 2,6-diisopropylnaphthalene represented by the followin~ formula~I) which is easily available industrially, as the starting material, namely, by oxidizing 2,6-DHPN under the specified conditions, 2,6-dihydroxynaphthalene of the formula(III) can be advantageously produced, and on the basis of the finding, the present invention has been attained.
Recently, in the development of various polymers known as the engineering plastics, aromatic polyesters, particularly -the aromatic polyesters having a capacity of forming liquid crystals have attracted attention.
As the raw material of the polymer of aromatic polyesters, terephthalic acid, hydroquinone, p-hydroxy-benzoic acid and the like may be mentioned. In order to improve the physical and chemical properties of the aromatic polyesters, however not only benzene derivatives but also naphthalene derivatives have come -to be used as the raw material of the aromatic polyesters in recent years.
~,....~
49~
Of the naph-thalenic raw materials, 2,6-clihydroxy-naphthalene has at~racted attention as -the monomer utilized in the production of the aromatic polyesters from the viewpoint that the physical properties of the liquid crystalline polymer derived from 2,6-dihydroxynaphtha-lene are e~cellent and that terephthalic acid used as the comonomer of the polymer ls a~ailable at a low price.
However, since 2,6-dihydroxynaphthalene itself is not industrially produced at present, there is a problem that 2,6-dihydroxynaphthalene is not available at a low price.
As the process for producing 2,6-dihydroxy-naphthalene, an old process has hitherto been known, wherein naphthalene or ~-naphthol is sulfonated and then the thus .sulfonated product is subjected to alkali fusion, and such a process has been introduced in Beilstein t S
"Handbuch der organischen Chemie". However! as is seen, for instance, in the description of Japanese Patent Publ.ication No. 56-77,254(1981), the by-production of the isomers other than the 2,6-isomer is inevitable according to this process and consequently, it is impossible to obtain the 2,6-isomer in a high yiela. Furthermore, the yield of 2,6-dihydroxynaphthalene at the step of alkali fusion of sodium 2-naphthol-6-sulfonate is in the extent of 50 % as is described in A.P. Kuriakose et al.
in J. Indian Chem. Soc., 43, 437(1966). Consequently, the ~7~
yield of 2,6-dihydroxynaphthalene produced by the process comprising the steps o~ sulforlation of naphthalene or ~-naphthol and of alkali fusion of the thus sulfonated product is extremely poor.
Further, since it is difficult to separate the 2,6-isomer and it is necessary to carry out a drainage treatment specific to the step of alkali fusion, there is a problem of a high production cost. Namely, this process is industrially poor in practical use~
A process for producing hydroquinone from p-diisopropylbenzene while applying the principle in the production of phenol by the cumene process has hitherto been known ~refer to Japanese ~atent Publication No. 51-33 100 (1976)].
A process has been proposed while applying the process to the production of 2,6~dihydroxynaphthalene.
Namely, 2,6-diisopropylnaphthalene as the starting material is oxidized to obtain 2~6.diisopropylnaphthalene dihydro-peroxide and the thus obta~ned dihydroperoxide is converted into 2,6-dihydroxynaphthalene by acid decomposition [refer to Japanese Patent Applicatlons Laid-Open(KOKAI) Nos. 61-93 156 (1986), 61-100 558(.1986) and 61-191 638(1986)~.
However, in this case, since it is difficult to separate the thus ormed dlhydroperoxide, even this process cannot be ~egarded suitable industrially.
Still more, a process of converting arom~tic carbinols represented by the formula:
Ar- C - OH
(wherein Ar represents an aromatic ring) into a compound represented by the formula: Ar--OH has also been known.
Namely the aromatic carbinol is oxidized with hydrogen peroxide in a solvent in the presence of a strong acid [for instance, refer to Japanese Patent Application Laid-open(KoKAI) No.
52-5 718(1977), Japanese Patent Publication No. 35-7 558(1960), British Patent No. 910,735, TSUNODA and KATO, J. Chem~ Soc.
Japan, 80(7), 689/1959 and M.S. KHARASCH et al., J. Org. Chem., 5, 743(1959)].
However, the examples described in the literature concern processes for converting 2-hydroxy-2-propylbenzene, p-di~2-hydroxy-2-propyl)benzene, p-~2-hydroxy-2-propyl)-~, ~'-dimethylbenzyl hydroperoxide and the like into phenol or hydroquinone ! and there has not been disclosed a process ~or converting the 2-hydroxy-2-propyl group which is directly bound to the naphthalene ring into the hydroxy group in the literature.
By the way, even in the case where 2,6-di~2-hydroxy-2-propyl)naphthalene[hereinafter referred to as 2~6- DHPN
is oxidized in the solvent used in the process described in the literature, it is impossible to produce ~7~49~:
industrially 2,6-dihydroxynaphthalene by t~e following reasons:
Namely, (1) 2,6~ DHPN does not dissolve in the solvent, (2) in spite of the disappearance of 2,6- DI-IPN from the reaction system, 2,6-dihydroxynaphthalene is scarcely formed, (3~ the solvent itself reacts in the system or (4) the reaction velocity is small.
These facts are considered to be derived from the substantial difference of the physical and chemical properties between 2 t 6-dihydroxynaphthalene which is a naphthalene derivative and the carbinols disclosed in the literatures, which are benzene derivatives.
Under the circumstances, as a result of the present inventors' study concerning the industrially feasible process for producing 2,6-dihydro~ynaphthalene, it has been fcund out that 2,6-dihydroxynaphthalene represented by the following formula(III) can be advantageously produced by using 2,6- DHPN represented by the following formula(II) and derived from 2,6-diisopropylnaphthalene represented by the followin~ formula~I) which is easily available industrially, as the starting material, namely, by oxidizing 2,6-DHPN under the specified conditions, 2,6-dihydroxynaphthalene of the formula(III) can be advantageously produced, and on the basis of the finding, the present invention has been attained.
3~
~1/~ ( I ) HC~ \CH3 ~I3C
CH
31 ~ 1--OH ( I I
HO--C~ 1H3 ~ OH ( III ) Namely, the object of the present invention is to provide a process for advantageously and industrially producing 2,6-dihydroxynaphthalene which is useful as the raw material for producing -the so-called liquid crystal polymer which has a capacity of forming liquid crystals.
. ' . ~ .
. . .
. .
L4~
SUMM~Y OF THE INVENTION:
In an aspect of the present invention, there is provided a process for producing 2,6-dihydroxynaphthalene, which process comprises the step of oxidizing 2,6~di(2-hydroxy-2-propyl)naphthalene with hydro~en peroxide in acetonitrile, 1,4-dioxane or a mixture thereof in the presence of an inorganic acid of an amount not less than 0.001 time by weight and less than 0.1 time by weight to the amount of the 2,6-di(2-hydroxy-2-propyl)naphthalene.
DETAILED DESCRIPTION OF THE INVENTION:
The feature of the present invention lies in producing 2,6-dihydroxynaphthalene by oxidizing 2,6- DHPN of the formula (II) with hydrogen peroxide in acetonitrile, 1,4-dioxane or a mixture thereof in the presence of a specified amount of an inorganic acid.
The compound, 2,6- DHPN , represented by the formula ~II), which is used as the starting substance in the present invention, is easily available by applying a known method ~or producing dimethylphenylcarbinol from c~nene to 2,6-diisopropylnaphthalene.
According to the present invention, in oxidizing the starting substance, 2,6- DHPN , to convert it to 2,6-dihydroxynaphthalene, it is suitable to use acetonitrile, 1,4-dioxane or a mixed solvent thereof as the reaction solvent in an amount of from 7 to 25 times by volume to the weight of the starting substance (ml/g).
' ~L~7~
Although the present inventors forme.rly proposed that the oxidation of 2,6- DHPN i9 carried out in the reaction solvent [refer to Canadian Patent Application S.N~
510,8~2, June 4(l986]], since the added clmount of the inorganic acid in the reaction system is too much~ a rapid generation of heat is caused in the reaction and consequently, there was a fear of inability to control the reaction temperature.
In order to solve this problem, the present invention discloses, by reducing the amount of the inorganic acid, which is added to the reaction system, to a specifically limited range and increasing the concentration of hydrogen peroxide which is used for oxidation as well as the use of the above-mentioned reaction solvent, the control of the reaction temperature is possible.
Namely, in the present invention, the oxidation of the starting substance, 2,6~ DHPN, is carried out by adding not less than O.OOl time and less than O.l time by weight, preferably from 0.005 to 0.05 time by weight of the inorganic acid to the amount of 2,G- DHPN and an aqueous solution of hydrogen peroxide of a concentration of not less than 60 % to a solution of 2,6 DHPN in acetonitrile, l,4-dioxane or a mixture thereof, and by such an operation,. the reaction temperature is controlled to the preferred temperature, whereby it is possible to convert 2,6- DHPN rapidly into 2,6-dihydroxynaphthalene.
, . i : .
.
.
~ ~ 7~t~
As the inorganic acid, sul~uric acid and perchloric acid may be used, and the inorganic acid is dropped together with hydrogen peroxide in the 2,6- DHPN solution.
In the case where the amount of the added inorganic acid is less than 0.001 time by weight, the reaction is not completed, and on the other hand, in the case where the amount thereof is more than 0.1 time by weight, the selectivity becomes poor and coloration of the product is caused.
Furthermore, it is preferable to use hydrogen peroxide in an amount of from 2 to 3 moles to the star-ting substance. In the case where the amount used is too small !
the conversion rate of the starting substance is poor, and on the other hand, in the case where the amount used is too much, the coloration of the product becomes remarkable.
In adding the inorganic acid and hydrogen peroxide to the starting substance, it is preferable to mix the inorganic acid and hydrogen peroxide and then to drop the thus formed mixture onto the starting substance ! or after dropping h~drogen peroxide onto the starting substance~ it is preferable to drop the inorganic acid thereonto~
In the case where the inorganic acid is added in advance, olefin is formed by dehydration of the starting substance and the olefln further reacts to cause the reduction in the production of the ob~ective, and consequently, such an operation is undesirable.
The reaction temperature in -the presen~ invention is preferably not lower tha~ 60~C and not higher than the boiling point of the solution, and although the reaction time depends on the reaction temperature, the reaction is completed usually within 30 min.
After the reaction is over, for instance, an aqueous saturated saline solution is added to the thus obtained reaction mixture, whereby the organic layer is separated.
~hen, the organic layer is washed with an aqueous saturated saline solution and the solvent was distilled off from the organic layer to o~tain the crude 2,6-dihydroxynaphthalene.
By recrystallizing the thus obtained crude 2,6-dihydroxynaphthalene from a suitable solvent, for instance, acetic acid, it is possible to obtain the purified 2,6-dihydroxynaphthalene.
According to the process of the present invention, it is possible to produce 2,6-dihydroxynaphthalene which is useful as the raw material ~or producing the liquid crystal polymer, advantageously in a high yield as shown in the following Examples while using ~,6- DHPN which is derived from the industrially and easily available 2,6-diisopropyl-naphthalene, as the starting material. ConsequentLy, the process of the present invention is useful in the production of the liquid crystal polymer of aromatic polyesters.
.
~ ' ~ ~714~
The present invention is explained more in de-tail in the following Examples; however, it should be recognized that the scope of the present invention is not restricted to these Examples.
EXAMPLE 1:
Into 240 ml of acetonitrile, 10.0 g(41 mmol) of 2,6- DHPN were dissolved at 70C! and 4 ml of an aqueous 70 % solution of hydrogen peroxide were added to the thus formed solution. Then, a solution o~ 0.1 g of concentrated sulfuric acid in 10 ml of acetonitrile was added to the thus formed mixture, and the whole mixture was reacted under agitation for 20 min in an oil bath kept at 70~C. After the reaction was over, an aqueous saturated saline solution was added to the liquid reaction mixture and after separating the acetonitril layer, the thus obtained acetonitrile layer was washed with an aqueous saturated saline solution until the acetonitrile layer became neutral. After separating the acetonitrile layer, the solvent was distilled off from the acetonitrile layer and the residue was dried to obtain 6.6 g of crude 2,6-dihydroxynaphthalene (yield : 99 %).
EXAMPLE 2:
The reaction was carried out in the same manner as in Example 1 except for using 1!4-dioxane instead of acetonitrile in Example 1, On quantitatively analyzing the thus obtained reaction mixture with the high performance liquid chromatography, 2,6-dihydroxynaphthalene was obtained (yield :
99 %).
COMPARAT:IVE E~AMPLE:
Into 50 ml of acetoni-trile, 10.1 g(41 mmol) of 2,6- D.HPN were suspended, and after adding 10 ml of an aqueous 31 ~ solution of hydrogen peroxide to the thus formed suspension, the thus formed mixture was stirred in an oil bath kept at 30C.
On adding a solution of 5 g of concentrated sulfuric acid in 10 ml of acetonitrile to the thus stirred mixture, the mixture became transparent at a time and then began to be turbid, and although the dropping of the diluted sulfuric acid was stopped, the temperature of the reaction mixture rose suddenly beyond control and the reaction mixture bumped.
~1/~ ( I ) HC~ \CH3 ~I3C
CH
31 ~ 1--OH ( I I
HO--C~ 1H3 ~ OH ( III ) Namely, the object of the present invention is to provide a process for advantageously and industrially producing 2,6-dihydroxynaphthalene which is useful as the raw material for producing -the so-called liquid crystal polymer which has a capacity of forming liquid crystals.
. ' . ~ .
. . .
. .
L4~
SUMM~Y OF THE INVENTION:
In an aspect of the present invention, there is provided a process for producing 2,6-dihydroxynaphthalene, which process comprises the step of oxidizing 2,6~di(2-hydroxy-2-propyl)naphthalene with hydro~en peroxide in acetonitrile, 1,4-dioxane or a mixture thereof in the presence of an inorganic acid of an amount not less than 0.001 time by weight and less than 0.1 time by weight to the amount of the 2,6-di(2-hydroxy-2-propyl)naphthalene.
DETAILED DESCRIPTION OF THE INVENTION:
The feature of the present invention lies in producing 2,6-dihydroxynaphthalene by oxidizing 2,6- DHPN of the formula (II) with hydrogen peroxide in acetonitrile, 1,4-dioxane or a mixture thereof in the presence of a specified amount of an inorganic acid.
The compound, 2,6- DHPN , represented by the formula ~II), which is used as the starting substance in the present invention, is easily available by applying a known method ~or producing dimethylphenylcarbinol from c~nene to 2,6-diisopropylnaphthalene.
According to the present invention, in oxidizing the starting substance, 2,6- DHPN , to convert it to 2,6-dihydroxynaphthalene, it is suitable to use acetonitrile, 1,4-dioxane or a mixed solvent thereof as the reaction solvent in an amount of from 7 to 25 times by volume to the weight of the starting substance (ml/g).
' ~L~7~
Although the present inventors forme.rly proposed that the oxidation of 2,6- DHPN i9 carried out in the reaction solvent [refer to Canadian Patent Application S.N~
510,8~2, June 4(l986]], since the added clmount of the inorganic acid in the reaction system is too much~ a rapid generation of heat is caused in the reaction and consequently, there was a fear of inability to control the reaction temperature.
In order to solve this problem, the present invention discloses, by reducing the amount of the inorganic acid, which is added to the reaction system, to a specifically limited range and increasing the concentration of hydrogen peroxide which is used for oxidation as well as the use of the above-mentioned reaction solvent, the control of the reaction temperature is possible.
Namely, in the present invention, the oxidation of the starting substance, 2,6~ DHPN, is carried out by adding not less than O.OOl time and less than O.l time by weight, preferably from 0.005 to 0.05 time by weight of the inorganic acid to the amount of 2,G- DHPN and an aqueous solution of hydrogen peroxide of a concentration of not less than 60 % to a solution of 2,6 DHPN in acetonitrile, l,4-dioxane or a mixture thereof, and by such an operation,. the reaction temperature is controlled to the preferred temperature, whereby it is possible to convert 2,6- DHPN rapidly into 2,6-dihydroxynaphthalene.
, . i : .
.
.
~ ~ 7~t~
As the inorganic acid, sul~uric acid and perchloric acid may be used, and the inorganic acid is dropped together with hydrogen peroxide in the 2,6- DHPN solution.
In the case where the amount of the added inorganic acid is less than 0.001 time by weight, the reaction is not completed, and on the other hand, in the case where the amount thereof is more than 0.1 time by weight, the selectivity becomes poor and coloration of the product is caused.
Furthermore, it is preferable to use hydrogen peroxide in an amount of from 2 to 3 moles to the star-ting substance. In the case where the amount used is too small !
the conversion rate of the starting substance is poor, and on the other hand, in the case where the amount used is too much, the coloration of the product becomes remarkable.
In adding the inorganic acid and hydrogen peroxide to the starting substance, it is preferable to mix the inorganic acid and hydrogen peroxide and then to drop the thus formed mixture onto the starting substance ! or after dropping h~drogen peroxide onto the starting substance~ it is preferable to drop the inorganic acid thereonto~
In the case where the inorganic acid is added in advance, olefin is formed by dehydration of the starting substance and the olefln further reacts to cause the reduction in the production of the ob~ective, and consequently, such an operation is undesirable.
The reaction temperature in -the presen~ invention is preferably not lower tha~ 60~C and not higher than the boiling point of the solution, and although the reaction time depends on the reaction temperature, the reaction is completed usually within 30 min.
After the reaction is over, for instance, an aqueous saturated saline solution is added to the thus obtained reaction mixture, whereby the organic layer is separated.
~hen, the organic layer is washed with an aqueous saturated saline solution and the solvent was distilled off from the organic layer to o~tain the crude 2,6-dihydroxynaphthalene.
By recrystallizing the thus obtained crude 2,6-dihydroxynaphthalene from a suitable solvent, for instance, acetic acid, it is possible to obtain the purified 2,6-dihydroxynaphthalene.
According to the process of the present invention, it is possible to produce 2,6-dihydroxynaphthalene which is useful as the raw material ~or producing the liquid crystal polymer, advantageously in a high yield as shown in the following Examples while using ~,6- DHPN which is derived from the industrially and easily available 2,6-diisopropyl-naphthalene, as the starting material. ConsequentLy, the process of the present invention is useful in the production of the liquid crystal polymer of aromatic polyesters.
.
~ ' ~ ~714~
The present invention is explained more in de-tail in the following Examples; however, it should be recognized that the scope of the present invention is not restricted to these Examples.
EXAMPLE 1:
Into 240 ml of acetonitrile, 10.0 g(41 mmol) of 2,6- DHPN were dissolved at 70C! and 4 ml of an aqueous 70 % solution of hydrogen peroxide were added to the thus formed solution. Then, a solution o~ 0.1 g of concentrated sulfuric acid in 10 ml of acetonitrile was added to the thus formed mixture, and the whole mixture was reacted under agitation for 20 min in an oil bath kept at 70~C. After the reaction was over, an aqueous saturated saline solution was added to the liquid reaction mixture and after separating the acetonitril layer, the thus obtained acetonitrile layer was washed with an aqueous saturated saline solution until the acetonitrile layer became neutral. After separating the acetonitrile layer, the solvent was distilled off from the acetonitrile layer and the residue was dried to obtain 6.6 g of crude 2,6-dihydroxynaphthalene (yield : 99 %).
EXAMPLE 2:
The reaction was carried out in the same manner as in Example 1 except for using 1!4-dioxane instead of acetonitrile in Example 1, On quantitatively analyzing the thus obtained reaction mixture with the high performance liquid chromatography, 2,6-dihydroxynaphthalene was obtained (yield :
99 %).
COMPARAT:IVE E~AMPLE:
Into 50 ml of acetoni-trile, 10.1 g(41 mmol) of 2,6- D.HPN were suspended, and after adding 10 ml of an aqueous 31 ~ solution of hydrogen peroxide to the thus formed suspension, the thus formed mixture was stirred in an oil bath kept at 30C.
On adding a solution of 5 g of concentrated sulfuric acid in 10 ml of acetonitrile to the thus stirred mixture, the mixture became transparent at a time and then began to be turbid, and although the dropping of the diluted sulfuric acid was stopped, the temperature of the reaction mixture rose suddenly beyond control and the reaction mixture bumped.
Claims (6)
1. A process for producing 2,6-dihydroxynaphthalene, which process comprises the step of oxidizing 2,6-di(2-hydroxy-2-propyl)naphthalene with hydrogen peroxide in acetonitrile, 1,4-dioxane or a mixture thereof in the presence of an inorganic acid of an amount not less than 0.001 time by weight and less than 0.1 time by weight to the amount of the 2,6-di(2-hydroxy-2-propyl)naphthalene.
2. A process according to claim 1, wherein said inorganic acid is sulfuric acid or perchloric acid.
3. A process according to claim 1, wherein oxidation of said 2,6-di(2-hydroxy-2-propyl)naphthalene is carried out by using hydrogen peroxide of an amount of from 2 to 3 times by mole to the amount of the 2,6-di(2-hydroxy-2-propyl)naphthalene.
4. A process according to claim 1, wherein oxidation of said 2,6-di(2-hydroxy-2-propyl)naphthalene is carried out at a temperature of not lower than 60°C and not higher than the boiling point of the solution of the 2,6-di(2-hydroxy-2-propyl)naphthalene in acetonitrile or 1,4-dioxane.
5. A process according to claim 1, wherein oxidation of said 2,6-di(2-hydroxy-2-propyl)naphthalene is carried out in the presence of the inorganic acid of an amount of from 0.005 to 0.05 time by weight of the amount to the 2,6-di(2-hydroxy-2-propyl)naphthalene.
6. A process according to claim 1, wherein the concentra-tion of the aqueous hydrogen peroxide solution is not lower than 60 % by weight.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP166080/86 | 1986-07-15 | ||
| JP61166080A JPS6322532A (en) | 1986-07-15 | 1986-07-15 | Production of 2,6-naphthalenediol |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1271492A true CA1271492A (en) | 1990-07-10 |
Family
ID=15824608
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000542065A Expired - Fee Related CA1271492A (en) | 1986-07-15 | 1987-07-14 | Process for producing 2,6-dihydroxynaphthalene |
Country Status (5)
| Country | Link |
|---|---|
| JP (1) | JPS6322532A (en) |
| CA (1) | CA1271492A (en) |
| DE (1) | DE3722796A1 (en) |
| FR (1) | FR2601671B1 (en) |
| GB (1) | GB2192632B (en) |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3618643A1 (en) * | 1985-06-07 | 1986-12-11 | Kureha Kagaku Kogyo K.K., Tokio/Tokyo | METHOD FOR PRODUCING 2,6-NAPHTHALINDIOL, AND 2,6 DIACETOXYNAPHTHALINE |
| WO1987001700A1 (en) * | 1985-09-20 | 1987-03-26 | Mitsui Petrochemical Industries, Ltd. | Process for oxidizing 2,6-diisopropylnaphthalene |
-
1986
- 1986-07-15 JP JP61166080A patent/JPS6322532A/en active Granted
-
1987
- 1987-07-10 DE DE19873722796 patent/DE3722796A1/en active Granted
- 1987-07-14 CA CA000542065A patent/CA1271492A/en not_active Expired - Fee Related
- 1987-07-14 GB GB8716572A patent/GB2192632B/en not_active Expired - Fee Related
- 1987-07-15 FR FR878709939A patent/FR2601671B1/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6322532A (en) | 1988-01-30 |
| GB2192632A (en) | 1988-01-20 |
| DE3722796A1 (en) | 1988-01-28 |
| JPH0317813B2 (en) | 1991-03-11 |
| GB2192632B (en) | 1990-07-18 |
| GB8716572D0 (en) | 1987-08-19 |
| DE3722796C2 (en) | 1989-07-27 |
| FR2601671B1 (en) | 1990-05-11 |
| FR2601671A1 (en) | 1988-01-22 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| EP1966114B1 (en) | Selective oxidation of alkylbenzenes | |
| Aoki et al. | One-pot synthesis of phenol and cyclohexanone from cyclohexylbenzene catalyzed by N-hydroxyphthalimide (NHPI) | |
| US4237319A (en) | Process for liquid-phase oxidation of m-diisopropylbenzene | |
| CA1271492A (en) | Process for producing 2,6-dihydroxynaphthalene | |
| US4906790A (en) | Method of oxidizing secondary alkyl substituted naphtalenes and a process of producing isopropylnaphthols | |
| KR102271104B1 (en) | Method for producing propylene oxide | |
| GB2104892A (en) | A process for producing phloroglucin | |
| US4814521A (en) | Process for producing 2,6-dihydroxynaphthalene and 2,6-diacetoxynaphthalene | |
| CA1253884A (en) | Process for producing 2,6-naphthalenediol | |
| CA1270849A (en) | Process for producing highly pure 2,6- diacetoxynaphthalene | |
| US4835325A (en) | Process for producing hydroxybenzenes | |
| GB2176188A (en) | Process for producing 2,6-naphthalenediol and 2,6-diacetoxynaphthalene | |
| JPH0470290B2 (en) | ||
| US5639922A (en) | Process for treatment of hydroperoxide mixture | |
| CA1267911A (en) | Process for producing 6-hydroxy-2-naphthoic acid | |
| EP0149176A2 (en) | Process for producing m-hydroxyacetophenone | |
| US5091592A (en) | Process for preparing 4,4'-dihydroxybiphenyl | |
| EP0553874B1 (en) | Process for production of cresols | |
| US5399791A (en) | Process for production of cresols | |
| JPS63258826A (en) | Production of hydroxy aromatic hydrocarbon | |
| JPS6270332A (en) | Production of 2,6-dihydroxynaphthalene | |
| JPS6270334A (en) | Production of 2,6-dihydroxynaphthalene | |
| JPS63310839A (en) | Production of hydroxynaphthalene | |
| JPH0667863B2 (en) | Method for producing 2,6-dihydroxynaphthalene | |
| JPS63246362A (en) | Production of hydroperoxide |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |