CA1267911A - Process for producing 6-hydroxy-2-naphthoic acid - Google Patents
Process for producing 6-hydroxy-2-naphthoic acidInfo
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- CA1267911A CA1267911A CA000508727A CA508727A CA1267911A CA 1267911 A CA1267911 A CA 1267911A CA 000508727 A CA000508727 A CA 000508727A CA 508727 A CA508727 A CA 508727A CA 1267911 A CA1267911 A CA 1267911A
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- Prior art keywords
- hydroxy
- acid
- naphthalene
- propyl
- bon
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
- C07C51/16—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation
- C07C51/285—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation with peroxy-compounds
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- Organic Chemistry (AREA)
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- 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 6-hydroxy-2-naphthoic acid which is used as a monomer for producing aromatic polyesters having an ability of forming liquid crystals, comprising oxidizing 2-(2-hydroxy-2-propyl)naphthalene-6-carboxylic acid or a mixture of 2-(2-hydroxy-2-propyl)naphthalene-6-carbox-ylic acid and 2-(2-hydroperoxy-2-propyl)naphthalene-6-carboxylic acid by hydrogen peroxide in acetonitrile and/or dioxane in the presence of an inorganic acid.
Disclosed herein is a process for producing 6-hydroxy-2-naphthoic acid which is used as a monomer for producing aromatic polyesters having an ability of forming liquid crystals, comprising oxidizing 2-(2-hydroxy-2-propyl)naphthalene-6-carboxylic acid or a mixture of 2-(2-hydroxy-2-propyl)naphthalene-6-carbox-ylic acid and 2-(2-hydroperoxy-2-propyl)naphthalene-6-carboxylic acid by hydrogen peroxide in acetonitrile and/or dioxane in the presence of an inorganic acid.
Description
BAC~GROUND OF THE INVENTION:
The present invention relates to a process ~or producing 6-hydroxy-2-naphthoic acid which is used as a monomer for producing aromatic polyesters having an ability of forming liquid crystals.
Hitherto, as a process for producing 6-hydroxy-
The present invention relates to a process ~or producing 6-hydroxy-2-naphthoic acid which is used as a monomer for producing aromatic polyesters having an ability of forming liquid crystals.
Hitherto, as a process for producing 6-hydroxy-
2-naphthoic acid (hereinafter referred to as "BON-6"), the following processes have been known.
~ 1) A process comprising reacting a potassium salt of ~-naphthol with gaseous carbon dioxide at a high temperature and under a high pressure (refer to U.S.
Patents Nos. 1,593,816, 4,287,357, 4,345,095, 4,329,494 and 4,345,094), (2) A process comprising reacting a potassium salt of ~-naphthol with gaseous carbon dioxide at a high temperature and under a high pressure in a medium of a high boiling point (refer to Japanese Patent Applica-tions Laid-Open (KOKAI) No. 57-95939 and No. 58-99436), and
~ 1) A process comprising reacting a potassium salt of ~-naphthol with gaseous carbon dioxide at a high temperature and under a high pressure (refer to U.S.
Patents Nos. 1,593,816, 4,287,357, 4,345,095, 4,329,494 and 4,345,094), (2) A process comprising reacting a potassium salt of ~-naphthol with gaseous carbon dioxide at a high temperature and under a high pressure in a medium of a high boiling point (refer to Japanese Patent Applica-tions Laid-Open (KOKAI) No. 57-95939 and No. 58-99436), and
(3) A process comprising reacting 6-bromo-2-naphthol with carbon monoxide in methanol under a high pressure (refer to Japanese Patent Application Laid-Open (ROKAI) No. 57-91955).
However, these processes have the following defects, and accordingly, are not necessarily favorable as the industrial process for producing BON-6.
Namely, in the processes (1) and (2), ~-~2~7~
3-hydroxy-2-naphthoic acid which is an isomer of sON-6 is inevitably by-produced in addition to BON-6, and accordingly, the yield of BON-6 is as low as about 26.5 % and 45 ~ in the processes (1) and (2), respec-tively. In addition, in the processes (1) and (2), since a large amount of ~-naphthol is by-produced, complicated steps are necessary for separation thereof.
Moreover, since the process (3) is carried out under a pressure as high as 70 kg/cm2 by using a pressure-proof apparatus, the production cost is high, and the yield of BON-6 is only about 37 ~.
On the other hand, as a process for converting a compound represented by the formula (I):
Ar - C - X (I) wherein Ar represents an aromatic ring and X represents a hydroperoxy group or a hydroxyl group, into a compound represented by the formula of Ar-OH, the ollowing processes have been known.
(a) In the case where X is a hydroperoxy group, a process for producing phenol by acid-decomposi-tion of cumene hydroperoxide in the cumene process, and (b) In the case where X is a hydroxy group, a process for converting the compound into a phenol compound by oxidizing the compound by hydrogen i7~
peroxide in a solvent in the presence of a strong acid (refer to Japanese Patent Application Laid-Open (KOKAI) No. 52-5718, Japanese Patent Publication No. 35-7558, British Patent No. 910,735, TSUNODA and KATO (Journal of the chemical Soc. of Japan, 80(7), 689, 1959), and M.S. Kharasch et al (J. Org. Chem., 15, 748 and 775, 1950)).
However, when a compound represented by the formula (I) wherein X is a hydroxyl group is subjected ~o a similar reaction as in the process (a) the compound is not converted into a phenol compound but changed into a resin-like substance via a compound represented by the following formula (II):
Ar - C = CH2 (II) (refer to Japanese Patent Publication No. 51-29140).
Accordingly, the process (a) is not applicable in the case where a compound represented by the formula (I) wherein X is a hydroxyl group or a mixture of a compound represented by the formula (I) wherein X is a hydroxyl group and a compound represented by the formula (I) wherein X is a hydroperoxy group is subjected to oxidation to convert into Ar-OH.
On the other hand, the process (b) is, from the reaction disclosed in the above-mentioned references, a process for converting 2-hydroxy-2-propylbenzene, ~79~
p-di(2-hydroxy-2-propyl)benzene, p-2-hydroxy-2-propyl-2,2'-dimethylbenzyl-hydroperoxide, etc. into a phenol or hydroquinone, and there is no disclosure in the above-mentioned references concerning the process for converting a compound having the naphthalene ring, particularly carbinols having the skeletone of naphthoic acid which is the subject of the present invention, into BON-6.
In this connection, even in the case of attempting the reaction according to the present invention in each of the solvents disclosed in the above-mentioned references, such a solvent is unsuitable by the reasons that the starting substance is insoluble in the solvent, BON-6 is not formed, the solvent participates in the reaction or the reaction ra-te is lo~.
The present invention has been attained as a result of examining the industrially profitable processes in consideration of the above-mentioned problems in the production of BON-6.
Namely, the present inventors have found a process for profitably producing BON-6, which is useful as a monomer for aromatic polyesters having an ability of forming liquid crystals (liquid crystal polymer), by oxidizing 2-(2-hydroxy-2-propyl)naphthalene-6-carboxylic acid represented by the formula (III):
9L2~
= C - OH
HOOC CH3 (III) which is derived from 2,6-diisopropylnaphthalene easily available industrially, or a mixture of 2-(2-hydroxy-2-propyl)naphthalene-6-carboxylic acid and 2-(2-hydroperoxy-2-propyl)naphthalene-6-carboxylic acid represented by the formula (IV):
~ C - OOH
HOOC CH3 (IV) under the specified conditions, and based on the finding, the present inventors have attained the pre-sent invention.
SU~ARY OF THE INVENTION
In an aspect of the present invention, there is provided a process for producing 6-hydroxy-2-n~phthoic acid comprising oxidizing 2-(2-hydroxy-2-~ropyl)naphthalene-6-carboxylic acid or a mixture of 2-(2-hydroxy-2-propyl)naphthalene-6-carboxylic acld and 2-(2-hydroperoxy-2-propyl)naphthalene-6-carboxylic acid by hydrogen peroxide in acetonitrile and/or dioxane in the presence of an inorganic acid.
DETAILED DESCRIPTION OF THE INVENTION
The characteristic of the present invention lies in the production of 6-hydroxy-2-naphthoic acid ~'~167g~
(BON-6) by oxidizing 2-(2-hydroxy-2-propyl)naphthalene-6-carboxylic acid or a mixture of 2-(2-hydroxy-2-propyl)naphthalene-6-carboxyllc acid and 2-(2-hydro-peroxy-2-propyl)naphthalene-6-carboxylic acid by hydrogen peroxide in acetonitrile and/or dioxane in the presence of an inorganic acid.
Particularly in the present invention, it is important to use acetonitrile, dioxane or a mixture thereof as a solvent for the reaction, and by the use of the above-mentioned solvents, it has become possible to produce BON-6 not only from 2 (2-hydroxy-2-propyl)-naphthalene-6-carboxylic acid but also from a mixture of 2-(2-hydroxy-2-propyl)naphthalene-6-carboxylic acid and 2-(2-hydroperoxy-2-propyl)naphthalene-6-carboxylic acid.
Namely, in the production of BON-6 from these starting substances, the selectivity largely depends on the solvents used in the reaction. When the reac-tion is carried out in the solvent disclosed in the aforementioned references, for instance in acetone, it participates in the reaction and although BON-6 is partially formed, a large amount of by-products derived ~rom acetone is formed. When the reaction is carried out in ethanol, the reaction rate and yield of BON-6 are low. In acetic acid, although the starting substance is consumed, BON-6 i5 scarcely ~L267~
formed and the side reaction occurs preferentially.
Further, since the starting substance does not dissolve in hydrocarbons, hydrocarbons are unsuitable as the solvent of the present invention.
Tl~e starting substance according to the present invention, 2-(2-hydroxy-2-propy])naphthalene-6-carboxylic acid or a mixture of 2-(2-hydroxy-2-propyl)naphthalene-6-carboxylic acid and 2-(2-hydro-peroxy-2-propyl)naphthalene-6-carboxylic acid, are produced by a process for producing 6-substituted naphthalene-2-carboxylic acids represented by the formula (V):
X - C ~ COOH (V) wherein X represents a hydroperoxy group or a hydroxy ~roup, comprising the step of reacting 6-isopropyl-naphthalene-2-carboxylic acid with molecular oxygen at a temperature in the range of from 50 to 90C in the presence of a salt of persulfuric acid as a catalyst in an aqueous alkaline solution.
~`
~26~
The weight ratio of 2-(2-hydroxy-2-propyl)-naphthalene-6-carboxylic acid (hereinafter referred to as "NCC") to 2-(2-hydroperoxy-2-propyl)naphthalene-6-carboxylic acid (hereinafter referred to as "NMCA-HPO") in the mixture is not particularly limited, however, the mixture of the weight ratio of 40 - 60 :
5 - 10 (NMCA-HPO : NCC) is inexpensive and is easily available.
The solvent comprising acetonitrile and/or dioxane is used in an amount of from 3 to 30 ml per 1 g of the starting substance.
The commercialized aqueous 30 ~ solution of hydrogen peroxide may be used as the hydrogen peroxide in the present invention in an amount of from one to ten times by mol of the amount of NCC in the starting substance.
In the case where the amount of hydrogen peroxide to the amount of NCC is less than the amolmt set forth above, the rate of conversion of the starting substance is low. On the other hand, in the case of more than the amount set forth above, the remarkably colored reaction product is produced, and accordingly, the both cases are not favorable.
As the inorganic acid, sulfuric acid or perchloric acid is preferably used, and sulfuric acid may be a concentrated sulfuric acid or a sulfuric ~6~
acid containing up to 30 ~ of water. ~s perchloric acid, commercialized 70, 60 or 40 ~ perchloric acid may be preferably used.
The amount of the above-mentioned inorganic acid is preferaDly from 0.1 to 4, more preferably 0.5 to 3 times by ~eight of the starting substance. In the case where the amount of the inorganic acid used in the reaction is less than the amount set forth above, the reaction is not completed, and on the other hand, in the case of more than the amount set forth above, the selectivity is lowered, thereby resulting the coloration of the reaction product.
The inorganic acid is added to the starting substance by means of dropping, etc., simultaneously with hydrogen peroxide or after the addition of hydrogen peroxide. Namely, it is necessary that the inorganic acid is added so as to coexist wi~h hydrogen peroxide.
In addition, the reaction temperature according to the present invention may be selected from the range of from room temperature to 80C, preferably from the range o~ from 30 to 60C.
The reaction time depends on the composition of the reaction mixture and the reaction temperature, however, the reaction completes within from 10 min to 3 hours ordinarily.
~2~i7~
After finishing the reaction, the reaction mi~ture is adjusted to pH 2.5 - 3.5 by the addition of caustic alkali, sodium carbonate, sodium hydro-gencarbonate, etc., and after separating the precipi-tated salt by filtration, the solvent is distilled off from the filtrate to obtain the raw BON-6. By recrystallizing the thus obtained raw BON-6 from a suitable solvent, for instance, acetonitrile and acetic acid, the purified BON-6 can be obtained.
According to the present invention, 6-hydroxy-2-naphthoic acid (BON-5) which is useful as a monomer or liquid crystalline polymer can be profitably produced in a high yield as will be shown in the following Examples by using NCC or a mixture of NCC
and NMCA-HPO derived from 2,6-diisopropylnaphthalene which is easily available industrially via 2-isopropyl-6-naphthoic acid.
The present invention will be explained more in detail while referring to the following non-limitative Examples.
E~AMPLE 1:
After dissolving 0.5 g of NCC in 10 ml of acetonitrile, 1 g of an aqueous 30 % solution of hydrogen peroxide and 1 g of an aqueous 70 ~ solution of perchlo-ric acid were successively added to the solution, and the thus prepared mixture was stirred at 50C for 30 min.
~26~
After the reaction was over, the reaction mixture was examined by a high-speed liquid chromato-graphy (HPLC), thereby confirming that BON 6 was produced in an almost quantitative yield. After adjusting the reaction mixture to p~ 3 by an aqueous 20 % solution of sodium carbonate and removing the precipitated salts by filtration, acetonitrile was distilled of therefxom under a reduced pressure and the precipita~ed BON-6 was collected by filtration, washed with water and dried to obtain 0.4 g of crude BON-6.
The yield was nearly quantitative.
E~AMPLE 2:
In 6 litre of acetonitrile, 300 g of a mixture comprising 20 % by weight of NCC and 80 % by weight of NMCA-HPO was dissolved and a mixture of 120 g of an aqueous 30 % solution of hydrogen peroxide and 8~0 g of an aqueous 70 % solution of sulfuric acid was added to the thus prepared solution and the mixture was stirred at 50C for one hour.
After the reaction was over, the reaction mixture was examined by HPLC, thereby confirming that BON-6 was produced in an almost quantitative yield.
~ter adjusting the reaction mixture to pH 3 by addition of an aqueous 20 % solution of sodium carbonate and removing the precipitated salts by filtration, acetonitrile was distilled off therefrom under a reduced pressure and the precipitated BON-6 was collected by filtration, washed with water and î~67~
dried to obtain 225 g of crude BON-6.
By recrystallizing the thus obtained crude BON-6 from acetonitrile, the purified BON-6 of a purity of higher than 99 % was obtained.
EX~PLE 3:
Into 20 g of dioxane, 5 g of the same mixture of NCC and NMCA-HPO as in Example 2 was dissolved, and after adding successively 1 g of an aqueous 30 %
solution of hydrogen peroxide and 2.5 g of an aqueous 90 % solution of sulfuric acid to the thus prepared solution, the mixture was stirred at 50C for one hour.
After the reaction was over, the reaction mixture was examined by HPLC, thereby confirming that BON-6 was produced in an almost quantitative yield. After adjusting the reaction mixture to pH 3 with an aqueous 20 ~ solution of sodium carbonate and removing the precipitated salts by filtration, dioxane was distilled off therefrom under a reduced pressure. The precipitated BON-6 was collected by filtration, washed with water and dried to obtain 3.75 g of crude BON-6 .
E~AMPLE 4:
In the same procedures as in Example 3 except for using a 1 : 1 by volume mixture of acetonitrile and dioxane as the solvent instead of dioxane in Example 3, 3.8 g of crude BON-6 was obtained.
~7~
E~PLE 5:
After dissolving 0.1 g of the same mixture of NCC and NMCA-HPO as in Example 2 into 2 g of acetonitrile, 0.1 g of an aqueous 30 % solution of hydrogen peroxide and 0.2 g of an aqueous 40 ~ solu-tion of perchloric acid were successively added to the thus prepared solution, and the thus obtained mixture was stirred at 50C for 2 hours.
By examining the reaction liquid by HPLC, it was confirmed that BON-6 was obtained in a yield of g6 ~.
COlMPARATIVE EXAMPLE 1:
After dissolving 1 g of NCC in 20 ml of acetic acid, 1 g of an aqueous 30 % solution of hydrogen peroxide and 2 g of an aqueous 70 % solution of perchloric acid were successively added to the solution, and the thus prepared mixture was stirred at 50C for 30 min. After the reaction was over, the reaction mixture was examined by HPLC to confirm that only a small amount of BON-6 was formed while almost all of the starting substance was consumed.
COl~IPARATIVE EXAMPLE 2:
-In the same procedures as in ComparativeExample 1 except for using ethanol as a solvent instead of acetic acid in Comparative Example 1, the reaction was carried out. After the reaction was over, 79~
the reaction mixture was examinéd by HPLC to confirm that the yield of the thus obtained BON-6 was 10 %.
COMPARATIVE EXAMPLE 3:
In the same procedures as in Comparative Example 1 except for using toluene as a solvent instead o~ acetic acid in Comparative Example 1, the reaction was carried out. Both the starting substance and the reaction product scarcèly dissolved in toluene and accordingly, the yield of BON-6 was as low as 16 %.
COMPARATIVE EXMAPLE 4:
After dissolving 1 g of a mixture of 20 % by weight of NCC and 80 % by weight of NMCA-HPO into 20 g of ethanol, 2 g of an aqueous 30 % of hydrogen peroxide and 2 g of an aqueous 70 % solution of perchloric acid were successively added to the thus prepared solution, and the mixture was stirred at 50C for 30 min. The yield of BON-6 was 10 % and the most part of the starting substance remained unreacted.
COMPARATIVE EXAMPLE 5:
In the same procedures as in Comparative Example 1 except for using 2 g of an aqueous 70 %
solution of sulfuric acid instead of 2 g of the aqueous 70 % solution of perchloric acid, the reaction was carried out. Although the starting substance was consumed with the progress of the reaction, BON-6 was scarcely formed.
~79~
REFERENCE EXA~PLE:
To 20 ml of acetone, 1 g of an aqueous 30 %
solution of hydrogen peroxide and 2 g of an aqueous 70 % solution of perchloric acid were successively added, and the mixture was stirred for 30 min at 50C to obtain a white precipitate. The thus obtained precipitate had a stimulative odor and was seemed to be a condensate of acetone. It was thus found that acetone was unsuitable as the reaction solvent of the present invention.
However, these processes have the following defects, and accordingly, are not necessarily favorable as the industrial process for producing BON-6.
Namely, in the processes (1) and (2), ~-~2~7~
3-hydroxy-2-naphthoic acid which is an isomer of sON-6 is inevitably by-produced in addition to BON-6, and accordingly, the yield of BON-6 is as low as about 26.5 % and 45 ~ in the processes (1) and (2), respec-tively. In addition, in the processes (1) and (2), since a large amount of ~-naphthol is by-produced, complicated steps are necessary for separation thereof.
Moreover, since the process (3) is carried out under a pressure as high as 70 kg/cm2 by using a pressure-proof apparatus, the production cost is high, and the yield of BON-6 is only about 37 ~.
On the other hand, as a process for converting a compound represented by the formula (I):
Ar - C - X (I) wherein Ar represents an aromatic ring and X represents a hydroperoxy group or a hydroxyl group, into a compound represented by the formula of Ar-OH, the ollowing processes have been known.
(a) In the case where X is a hydroperoxy group, a process for producing phenol by acid-decomposi-tion of cumene hydroperoxide in the cumene process, and (b) In the case where X is a hydroxy group, a process for converting the compound into a phenol compound by oxidizing the compound by hydrogen i7~
peroxide in a solvent in the presence of a strong acid (refer to Japanese Patent Application Laid-Open (KOKAI) No. 52-5718, Japanese Patent Publication No. 35-7558, British Patent No. 910,735, TSUNODA and KATO (Journal of the chemical Soc. of Japan, 80(7), 689, 1959), and M.S. Kharasch et al (J. Org. Chem., 15, 748 and 775, 1950)).
However, when a compound represented by the formula (I) wherein X is a hydroxyl group is subjected ~o a similar reaction as in the process (a) the compound is not converted into a phenol compound but changed into a resin-like substance via a compound represented by the following formula (II):
Ar - C = CH2 (II) (refer to Japanese Patent Publication No. 51-29140).
Accordingly, the process (a) is not applicable in the case where a compound represented by the formula (I) wherein X is a hydroxyl group or a mixture of a compound represented by the formula (I) wherein X is a hydroxyl group and a compound represented by the formula (I) wherein X is a hydroperoxy group is subjected to oxidation to convert into Ar-OH.
On the other hand, the process (b) is, from the reaction disclosed in the above-mentioned references, a process for converting 2-hydroxy-2-propylbenzene, ~79~
p-di(2-hydroxy-2-propyl)benzene, p-2-hydroxy-2-propyl-2,2'-dimethylbenzyl-hydroperoxide, etc. into a phenol or hydroquinone, and there is no disclosure in the above-mentioned references concerning the process for converting a compound having the naphthalene ring, particularly carbinols having the skeletone of naphthoic acid which is the subject of the present invention, into BON-6.
In this connection, even in the case of attempting the reaction according to the present invention in each of the solvents disclosed in the above-mentioned references, such a solvent is unsuitable by the reasons that the starting substance is insoluble in the solvent, BON-6 is not formed, the solvent participates in the reaction or the reaction ra-te is lo~.
The present invention has been attained as a result of examining the industrially profitable processes in consideration of the above-mentioned problems in the production of BON-6.
Namely, the present inventors have found a process for profitably producing BON-6, which is useful as a monomer for aromatic polyesters having an ability of forming liquid crystals (liquid crystal polymer), by oxidizing 2-(2-hydroxy-2-propyl)naphthalene-6-carboxylic acid represented by the formula (III):
9L2~
= C - OH
HOOC CH3 (III) which is derived from 2,6-diisopropylnaphthalene easily available industrially, or a mixture of 2-(2-hydroxy-2-propyl)naphthalene-6-carboxylic acid and 2-(2-hydroperoxy-2-propyl)naphthalene-6-carboxylic acid represented by the formula (IV):
~ C - OOH
HOOC CH3 (IV) under the specified conditions, and based on the finding, the present inventors have attained the pre-sent invention.
SU~ARY OF THE INVENTION
In an aspect of the present invention, there is provided a process for producing 6-hydroxy-2-n~phthoic acid comprising oxidizing 2-(2-hydroxy-2-~ropyl)naphthalene-6-carboxylic acid or a mixture of 2-(2-hydroxy-2-propyl)naphthalene-6-carboxylic acld and 2-(2-hydroperoxy-2-propyl)naphthalene-6-carboxylic acid by hydrogen peroxide in acetonitrile and/or dioxane in the presence of an inorganic acid.
DETAILED DESCRIPTION OF THE INVENTION
The characteristic of the present invention lies in the production of 6-hydroxy-2-naphthoic acid ~'~167g~
(BON-6) by oxidizing 2-(2-hydroxy-2-propyl)naphthalene-6-carboxylic acid or a mixture of 2-(2-hydroxy-2-propyl)naphthalene-6-carboxyllc acid and 2-(2-hydro-peroxy-2-propyl)naphthalene-6-carboxylic acid by hydrogen peroxide in acetonitrile and/or dioxane in the presence of an inorganic acid.
Particularly in the present invention, it is important to use acetonitrile, dioxane or a mixture thereof as a solvent for the reaction, and by the use of the above-mentioned solvents, it has become possible to produce BON-6 not only from 2 (2-hydroxy-2-propyl)-naphthalene-6-carboxylic acid but also from a mixture of 2-(2-hydroxy-2-propyl)naphthalene-6-carboxylic acid and 2-(2-hydroperoxy-2-propyl)naphthalene-6-carboxylic acid.
Namely, in the production of BON-6 from these starting substances, the selectivity largely depends on the solvents used in the reaction. When the reac-tion is carried out in the solvent disclosed in the aforementioned references, for instance in acetone, it participates in the reaction and although BON-6 is partially formed, a large amount of by-products derived ~rom acetone is formed. When the reaction is carried out in ethanol, the reaction rate and yield of BON-6 are low. In acetic acid, although the starting substance is consumed, BON-6 i5 scarcely ~L267~
formed and the side reaction occurs preferentially.
Further, since the starting substance does not dissolve in hydrocarbons, hydrocarbons are unsuitable as the solvent of the present invention.
Tl~e starting substance according to the present invention, 2-(2-hydroxy-2-propy])naphthalene-6-carboxylic acid or a mixture of 2-(2-hydroxy-2-propyl)naphthalene-6-carboxylic acid and 2-(2-hydro-peroxy-2-propyl)naphthalene-6-carboxylic acid, are produced by a process for producing 6-substituted naphthalene-2-carboxylic acids represented by the formula (V):
X - C ~ COOH (V) wherein X represents a hydroperoxy group or a hydroxy ~roup, comprising the step of reacting 6-isopropyl-naphthalene-2-carboxylic acid with molecular oxygen at a temperature in the range of from 50 to 90C in the presence of a salt of persulfuric acid as a catalyst in an aqueous alkaline solution.
~`
~26~
The weight ratio of 2-(2-hydroxy-2-propyl)-naphthalene-6-carboxylic acid (hereinafter referred to as "NCC") to 2-(2-hydroperoxy-2-propyl)naphthalene-6-carboxylic acid (hereinafter referred to as "NMCA-HPO") in the mixture is not particularly limited, however, the mixture of the weight ratio of 40 - 60 :
5 - 10 (NMCA-HPO : NCC) is inexpensive and is easily available.
The solvent comprising acetonitrile and/or dioxane is used in an amount of from 3 to 30 ml per 1 g of the starting substance.
The commercialized aqueous 30 ~ solution of hydrogen peroxide may be used as the hydrogen peroxide in the present invention in an amount of from one to ten times by mol of the amount of NCC in the starting substance.
In the case where the amount of hydrogen peroxide to the amount of NCC is less than the amolmt set forth above, the rate of conversion of the starting substance is low. On the other hand, in the case of more than the amount set forth above, the remarkably colored reaction product is produced, and accordingly, the both cases are not favorable.
As the inorganic acid, sulfuric acid or perchloric acid is preferably used, and sulfuric acid may be a concentrated sulfuric acid or a sulfuric ~6~
acid containing up to 30 ~ of water. ~s perchloric acid, commercialized 70, 60 or 40 ~ perchloric acid may be preferably used.
The amount of the above-mentioned inorganic acid is preferaDly from 0.1 to 4, more preferably 0.5 to 3 times by ~eight of the starting substance. In the case where the amount of the inorganic acid used in the reaction is less than the amount set forth above, the reaction is not completed, and on the other hand, in the case of more than the amount set forth above, the selectivity is lowered, thereby resulting the coloration of the reaction product.
The inorganic acid is added to the starting substance by means of dropping, etc., simultaneously with hydrogen peroxide or after the addition of hydrogen peroxide. Namely, it is necessary that the inorganic acid is added so as to coexist wi~h hydrogen peroxide.
In addition, the reaction temperature according to the present invention may be selected from the range of from room temperature to 80C, preferably from the range o~ from 30 to 60C.
The reaction time depends on the composition of the reaction mixture and the reaction temperature, however, the reaction completes within from 10 min to 3 hours ordinarily.
~2~i7~
After finishing the reaction, the reaction mi~ture is adjusted to pH 2.5 - 3.5 by the addition of caustic alkali, sodium carbonate, sodium hydro-gencarbonate, etc., and after separating the precipi-tated salt by filtration, the solvent is distilled off from the filtrate to obtain the raw BON-6. By recrystallizing the thus obtained raw BON-6 from a suitable solvent, for instance, acetonitrile and acetic acid, the purified BON-6 can be obtained.
According to the present invention, 6-hydroxy-2-naphthoic acid (BON-5) which is useful as a monomer or liquid crystalline polymer can be profitably produced in a high yield as will be shown in the following Examples by using NCC or a mixture of NCC
and NMCA-HPO derived from 2,6-diisopropylnaphthalene which is easily available industrially via 2-isopropyl-6-naphthoic acid.
The present invention will be explained more in detail while referring to the following non-limitative Examples.
E~AMPLE 1:
After dissolving 0.5 g of NCC in 10 ml of acetonitrile, 1 g of an aqueous 30 % solution of hydrogen peroxide and 1 g of an aqueous 70 ~ solution of perchlo-ric acid were successively added to the solution, and the thus prepared mixture was stirred at 50C for 30 min.
~26~
After the reaction was over, the reaction mixture was examined by a high-speed liquid chromato-graphy (HPLC), thereby confirming that BON 6 was produced in an almost quantitative yield. After adjusting the reaction mixture to p~ 3 by an aqueous 20 % solution of sodium carbonate and removing the precipitated salts by filtration, acetonitrile was distilled of therefxom under a reduced pressure and the precipita~ed BON-6 was collected by filtration, washed with water and dried to obtain 0.4 g of crude BON-6.
The yield was nearly quantitative.
E~AMPLE 2:
In 6 litre of acetonitrile, 300 g of a mixture comprising 20 % by weight of NCC and 80 % by weight of NMCA-HPO was dissolved and a mixture of 120 g of an aqueous 30 % solution of hydrogen peroxide and 8~0 g of an aqueous 70 % solution of sulfuric acid was added to the thus prepared solution and the mixture was stirred at 50C for one hour.
After the reaction was over, the reaction mixture was examined by HPLC, thereby confirming that BON-6 was produced in an almost quantitative yield.
~ter adjusting the reaction mixture to pH 3 by addition of an aqueous 20 % solution of sodium carbonate and removing the precipitated salts by filtration, acetonitrile was distilled off therefrom under a reduced pressure and the precipitated BON-6 was collected by filtration, washed with water and î~67~
dried to obtain 225 g of crude BON-6.
By recrystallizing the thus obtained crude BON-6 from acetonitrile, the purified BON-6 of a purity of higher than 99 % was obtained.
EX~PLE 3:
Into 20 g of dioxane, 5 g of the same mixture of NCC and NMCA-HPO as in Example 2 was dissolved, and after adding successively 1 g of an aqueous 30 %
solution of hydrogen peroxide and 2.5 g of an aqueous 90 % solution of sulfuric acid to the thus prepared solution, the mixture was stirred at 50C for one hour.
After the reaction was over, the reaction mixture was examined by HPLC, thereby confirming that BON-6 was produced in an almost quantitative yield. After adjusting the reaction mixture to pH 3 with an aqueous 20 ~ solution of sodium carbonate and removing the precipitated salts by filtration, dioxane was distilled off therefrom under a reduced pressure. The precipitated BON-6 was collected by filtration, washed with water and dried to obtain 3.75 g of crude BON-6 .
E~AMPLE 4:
In the same procedures as in Example 3 except for using a 1 : 1 by volume mixture of acetonitrile and dioxane as the solvent instead of dioxane in Example 3, 3.8 g of crude BON-6 was obtained.
~7~
E~PLE 5:
After dissolving 0.1 g of the same mixture of NCC and NMCA-HPO as in Example 2 into 2 g of acetonitrile, 0.1 g of an aqueous 30 % solution of hydrogen peroxide and 0.2 g of an aqueous 40 ~ solu-tion of perchloric acid were successively added to the thus prepared solution, and the thus obtained mixture was stirred at 50C for 2 hours.
By examining the reaction liquid by HPLC, it was confirmed that BON-6 was obtained in a yield of g6 ~.
COlMPARATIVE EXAMPLE 1:
After dissolving 1 g of NCC in 20 ml of acetic acid, 1 g of an aqueous 30 % solution of hydrogen peroxide and 2 g of an aqueous 70 % solution of perchloric acid were successively added to the solution, and the thus prepared mixture was stirred at 50C for 30 min. After the reaction was over, the reaction mixture was examined by HPLC to confirm that only a small amount of BON-6 was formed while almost all of the starting substance was consumed.
COl~IPARATIVE EXAMPLE 2:
-In the same procedures as in ComparativeExample 1 except for using ethanol as a solvent instead of acetic acid in Comparative Example 1, the reaction was carried out. After the reaction was over, 79~
the reaction mixture was examinéd by HPLC to confirm that the yield of the thus obtained BON-6 was 10 %.
COMPARATIVE EXAMPLE 3:
In the same procedures as in Comparative Example 1 except for using toluene as a solvent instead o~ acetic acid in Comparative Example 1, the reaction was carried out. Both the starting substance and the reaction product scarcèly dissolved in toluene and accordingly, the yield of BON-6 was as low as 16 %.
COMPARATIVE EXMAPLE 4:
After dissolving 1 g of a mixture of 20 % by weight of NCC and 80 % by weight of NMCA-HPO into 20 g of ethanol, 2 g of an aqueous 30 % of hydrogen peroxide and 2 g of an aqueous 70 % solution of perchloric acid were successively added to the thus prepared solution, and the mixture was stirred at 50C for 30 min. The yield of BON-6 was 10 % and the most part of the starting substance remained unreacted.
COMPARATIVE EXAMPLE 5:
In the same procedures as in Comparative Example 1 except for using 2 g of an aqueous 70 %
solution of sulfuric acid instead of 2 g of the aqueous 70 % solution of perchloric acid, the reaction was carried out. Although the starting substance was consumed with the progress of the reaction, BON-6 was scarcely formed.
~79~
REFERENCE EXA~PLE:
To 20 ml of acetone, 1 g of an aqueous 30 %
solution of hydrogen peroxide and 2 g of an aqueous 70 % solution of perchloric acid were successively added, and the mixture was stirred for 30 min at 50C to obtain a white precipitate. The thus obtained precipitate had a stimulative odor and was seemed to be a condensate of acetone. It was thus found that acetone was unsuitable as the reaction solvent of the present invention.
Claims (5)
1. A process for producing 6-hydroxy-2-naphthoic acid comprising oxidizing 2-(2-hydroxy-2-propyl)naphthalene-6-carboxylic acid or a mixture of said 2-(2-hydroxy-2-propyl)naphthalene-6-carboxylic acid and 2-(2-hydroperoxy-2-propyl)naphthalene-6-carboxylic acid as the starting substance by hydrogen peroxide in acetonitrile and/or dioxane as the solvent in the presence of sulfuric acid or perchloric acid.
2. A process according to Claim 1, wherein 3 to 30 ml of said solvent is used per 1 g of said start-ing substance.
3. A process according to Claim 1, wherein said hydrogen peroxide is used in molar amount of from 1 to 10 times of the molar amount of said 2-(2-hydroxy-2-propyl)naphthalene-6-carboxylic acid in said starting substance.
4. A process according to Claim 1, wherein said inorganic acid is used in an amount by weight of from 0.1 to 4 times of the amount by weight of said starting substance.
5. A process accordingt to Claim 1, wherein said oxidizing is carried out at a temperature of from room temperature to 80°C for a period of from 10 min.
to 3 hours.
to 3 hours.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP99142/85 | 1985-05-10 | ||
| JP9914285A JPS61257942A (en) | 1985-05-10 | 1985-05-10 | Production of 6-hydroxy-2-naphthoic acid |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1267911A true CA1267911A (en) | 1990-04-17 |
Family
ID=14239449
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000508727A Expired - Fee Related CA1267911A (en) | 1985-05-10 | 1986-05-08 | Process for producing 6-hydroxy-2-naphthoic acid |
Country Status (5)
| Country | Link |
|---|---|
| JP (1) | JPS61257942A (en) |
| CA (1) | CA1267911A (en) |
| DE (1) | DE3615811A1 (en) |
| FR (1) | FR2581642B1 (en) |
| GB (1) | GB2174706B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3800989A1 (en) * | 1988-01-15 | 1989-07-27 | Hoechst Ag | METHOD FOR PURIFYING 2-HYDROXY-NAPHTHALINE-6-CARBONIC ACID |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1593816A (en) * | 1924-08-16 | 1926-07-27 | Grasselli Dyestuffs Corp | Making 2-hydroxy-naphthalene-6-carboxylic acid |
| BE608250A (en) * | 1960-09-17 | |||
| US4345095A (en) * | 1980-03-06 | 1982-08-17 | American Cyanamid Company | Process for the production of 6-hydroxy-2-naphthoic acid |
| JPS60243063A (en) * | 1984-05-17 | 1985-12-03 | Kureha Chem Ind Co Ltd | Methyl 2-(2-hydroperoxy-2-propyl)naphthalene-6-carboxylate and preparation thereof |
-
1985
- 1985-05-10 JP JP9914285A patent/JPS61257942A/en active Granted
-
1986
- 1986-05-08 CA CA000508727A patent/CA1267911A/en not_active Expired - Fee Related
- 1986-05-09 GB GB08611311A patent/GB2174706B/en not_active Expired
- 1986-05-09 FR FR8606720A patent/FR2581642B1/en not_active Expired
- 1986-05-10 DE DE19863615811 patent/DE3615811A1/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| FR2581642B1 (en) | 1989-06-02 |
| JPH0437060B2 (en) | 1992-06-18 |
| DE3615811C2 (en) | 1988-01-21 |
| GB2174706A (en) | 1986-11-12 |
| JPS61257942A (en) | 1986-11-15 |
| DE3615811A1 (en) | 1986-11-13 |
| GB8611311D0 (en) | 1986-06-18 |
| GB2174706B (en) | 1988-11-23 |
| FR2581642A1 (en) | 1986-11-14 |
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