GB1560507A

GB1560507A - Process for producing 1,4-dihydroanthranquinone

Info

Publication number: GB1560507A
Application number: GB4733077A
Authority: GB
Original assignee: Kawasaki Kasei Chemicals Ltd
Current assignee: Kawasaki Kasei Chemicals Ltd
Priority date: 1977-11-14
Filing date: 1977-11-14
Publication date: 1980-02-06

Description

(54) PROCESS FOR PRODUCING 1,4-DIHYDROANTHRAQUINONE (71) We, KAWASAKI KASEI CHEMICALS LTD., a Japanese Company of 3-8-2, Nihon- bashi, Chuo-ko, Tokyo, Japan, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to a process for producing 1 ,4-dihydroanthraquinones.

More particularly, it relates to a process for producing 1 ,4-dihydroanthraquinones by oxidizing 1,4,4a,9a,-tetrahydroanthraquinone, 1,4-dihydroanthrahydroquinone or a derivative thereof having an inert substituent.

1,4-Dihydroanthraquinones are important starting materials for producing agrochemicals, dyes and other fine chemicals and are also useful as agrochemicals by themselves.

Heretofore, it has been known to produce 1,4-dihydroanthraquinone (1 ,4-DHAQ) by several processes as follows.

(1) 1 4,4a,9a-Tetrahydroanthraquinone THAQ) is oxidized in ethanol with ferric chloride; (2) THAQ is oxidized with ferric cloride in the presence of a wetting agent (Chemical Abstracts 56, 7237e (1962)); (3) THAQ is oxidized with potassium bromate (Chemical Abstracts 52, l2830b (1958)); (4) THAQ is oxidized with gaseous oxygen in an aqueous medium at pH of 4 to 8, preferably 6 to 7 at 85 to 100 C, preferably 90 to 950C (B.P. 896,911 (March 23, 1962)).

In the processes (1) and (2), expensive ferric chloride is used, which increases cost.

The process (3) is an experimental process and is not an industrial process. The process (4) is superior to the other processes as an industrial process. However, the reaction velocity is remarkably low, the process generally taking longer than 4 hours, and the purity of the resulting 1 ,4-DHAQ is 96 ', as maximum.

The inventors have studied various processes for producing 1,4-DHAQ having high purity from THAQ with industrial advantages.

The present invention provides a process for producing a 1,4-dihydroanthraquinone wherein 1,4,4a,9a-tetrahydroanthraquinone, 1,4-dihydroanthrahydroquinone or a derivative thereof having an inert substituent is oxidised with molecular oxygen in the presence of a quinone-type redox catalyst, at a reaction temperature of not more than 70"C at a pH of 8.5 to 12 in an aqueous medium.

The process of the present invention enables 1,4-dihydroanthraquinones to be produced at high reaction velocity giving a product of high purity without using an expensive oxidizing agent.

1,4-Dihydroanthraquinones which may be produced by the process of the invention hereinafter referred to as 1 ,4-DHAQs include inert substituted derivative thereof which have a substituent, for example an alkyl group such as a (11 alkyl group; a halogen atom such as chlorine or bromine or a haloalkyl group or phenyl group (non-substituted 1,4-dihydroanthraquinone is referred to as 1,4-DHAQ).

1,4,4a,9a-Tetrahydroanthraquinones include inert- substituted derivatives which typically have the same substituents as defined above and are hereinafter referred to as THAQs. Non-substituted 1,4,4a,9a-tetrahydroanthraquinone is referred to as THAQ.

1,4-Dihydroanthrahydroquinones include inert substituted derivatives which typically have the same substituents as above and are hereinafter referred to as 1,4-DHAHQs.

Non-substituted 1 ,4-dihydroanthrahydroqui none is referred to as 1,4-DHAHQ.

In order to simplify the description the invention will be mainly discussed with reference to lA-DHAQ, THAQ and lA- DHAHQ since the inert substituted deriva tives have similar characteristics in the reaction.

THAQs used in the process of the present invention can be easily obtained as addition compounds of naphthoquinone and a diene produced by a Diels-Alder reaction.

The dienes can be those disclosed in British Patent 896,911. Suitable dienes include butadiene, alkyl substituted butadienes such as isoprene, 2,3-dimethyl butadiene and '-but!-l butadiene; halogen substituted butadienes such as 2-chlorobutadiene and 2bromobutadiene; phenyl substituted butadienes such as 2-phenylbutadiene; cyclopentadienes and pentadienes.

1,4-Dihydroanthrahydroquinones can be easily obtained by treating the addition compounds obtained by the Diels-Alder reaction with a catalytic amount of a base such as an alkali metal hydroxide or ammonia or an acid such as chloroacetic acid in an aqueous medium or an organic medium.

As the starting material, THAQs or 1, DHAHQs can be used.

The reaction velocity is relatively faster when lA-DHAHQs are used. However, THAQs are usually used because of an elimination of the isomerization step. It is preferable to use finely divided powder obtained by pulverizing the starting material.

As the aqueous medium, water is usually used. It is possible to dissolve a small amount of a salt in water or to add an inert organic solvent such as an alcohol to water.

The molecular oxygen is usually air from the economic viewpoint.

A typical process in accordance with the present invention is as follows: An aqueous medium is charged in a vessel equipped with a stirrer and a gas inlet and the pH is adjusted to 8.5 to 12 with a pH modifier, and then the starting material of THAQs or 1,4-DHAHQs is dispersed in the aqueous medium. The concentration of the starting material is adjusted to about 1 to 20 wt. %. It is also possible to disperse the starting material in an aqueous medium before adjusting the pH to 8.5 to 12 with a with a pH modifier.

Of course, when the starting material is obtained as an aqueous slurry in the previous step, it can be used without separating it. In this case, the starting material of THAQs or 1,4-DHAHQs is not completely dissolved but forms a slurry. The quinone-type redox catalyst is usually added to the slurry before the reaction and air is fed from the gas inlet into the aqueous slurry at the reaction temperature of 10 to 700C preferably 30 to 60"C. During the reaction, the mixture is stirred so as to contact thoroughly the gas-liquid-solid components. The reaction mixture is white or purplish white at the initiation and is changed to dark purple caused by quinhydrone and is further changed to a yellowish color caused by the oxidation. When the starting material is substantially converted to 1,4-DHAQs, the reaction is completed to form the desired yellow ish crystals. Air is further fed for several minutes and the reaction is finished in less than 3 hours, usually 10 to 120 minutes.

During the reaction, most of the starting material and the product are present in the form of a suspension. Accordingly, it is desirable to stir with high shear and/or to add a surfactant for performing the reaction smoothly.

The reaction product is filtered and washed with water and dried in a nitrogen flow.

The melting point and the infrared spectrum of the resulting 1,4-DHAQs are the same with those of 1,4-DHAQs produced by the conventional process using ferric chloride. The infrared spectrum of the starting material of THAQs or 1,4-HAHQs is remarkably different from that of the product of 1,4-DHAQs. Accordingly, they can be easily identified. The filtrate can be reused after adjusting its pH.

The process of the present invention can be also applied for 1,4,4a,9a-tetrahydroanthraquinone having a substituent or 1Adihydroanthrahydroquinone having a substituent.

The pH modifiers can be any suitable ones for adjusting pH to 8.5 to 12 which are inert to the starting material and the product.

Suitable pH modifiers include alkali metal hydroxides such as sodium hydroxide, and potassium hydroxide; alkali metal carbonates such as sodium carbonate and potassium carbonate; ammonia and alkyl amines such as diethyl amine and triethyl amine.

In order to maintain the pH during the reaction, it is possible to add buffer agents such as a mixture of boric acid and potassium chloride or a phosphate.

It is essential to maintain pH in a range of 8.5 to 12. When pH is lower, for example from 8.5 to 7 the reaction velocity becomes slow. When pH is higher than 12, the product of 1,4-DHAQs is further oxidized to produce anthraquinones (hereinafter referred to as AQ), and the resulting product of 1,4 DHAQs is contaminated with AQ. When pH is higher than 13, the product of 1,4 DHAQs is substantially converted to AQ.

The reaction temperature is not more than 70"C, but is preferably at least 5"C and more preferably in a range of 30 to 600C.

At temperatures lower than 10 C, it is possible to decrease the amount of AQ to less than 0.1 wt. %, but the reaction velocity is slow. At temperatures higher than 70 C, AQ is easily produced to decrease the purity of the product. At temperatures of 30 to 60 C, the reaction velocity is fast and the velocity of the side reaction producing AQ is advantageously slow.

The quinone type redox catalysts used in the process of the invention can be water soluble quinones such as 1,4-naphthoquinone-2-sulfonates, 1 ,2-naphthoquinone-4-sul- fonates or anthraquinone disulfonates.

The cation components forming such salts can be alkali metals such as sodium, potassium and ammonium. In the use of the quinone redox catalysts, they can be either the quinone type oxidation form or the hydroquinone type or reduction form.

The amount of the quinone type redox catalyst is generally less than 1 mole, usually in a range of 0.01 to 0.1 mole per 1 mole of the starting material in the solution. When the amount of the redox catalyst is smaller, the effect is insufficient. On the other hand.

when the amount of the redox catalyst is larger, it is not economical. Using the quinone type redox catalyst, the reaction time can be shortened to i- to A under the same conditions of pH, reaction temperature and concentration in comparison with a process not using a catalyst. Moreover, the formation of AQ can be inhibited by the addition of the quinone type redox catalyst.

The quinone type redox catalyst is usually added to the slurry before the reaction, that is, before feeding the molecular oxygen. Thus, when the filtrate obtained by separating 1 A-DHAQ after the reaction is used, it is enough to replenish a part of the catalyst.

The present invention will be illustrated by the following examples and references in detail.

Reference 1: In a reactor equipped with a stirrer, 2.12 wt. parts of sodium carbonate was dissolved in 100 wt. parts of water, and 2.12 wt. parts of THAQ was added whilst stirring the solution. The mixture was in the form of a slurry having pH of 11.3.

The mixture was heated to 500C and air was fed into the mixture with thorough stirring to react them. During the reaction, the white slurry was changed to purplish color and changed to a dark purple color of quinhydrone (adduct of 1,4-DHAHQ and lA-DHAQ) and then changed to yellowish color and finally changed to the specific yellow slurry of 1 ,4-DHAQ. The color of the slurry was not further changed. At this point, the feeding of air was stopped to complete the reaction. The reaction time was 1 hour and pH at the end of the reaction was 10.3.

The reaction product was filtered, washed with water and dried in nitrogen flow to obtain 2.06 wt. parts of yellow crystals of crude 1,4-DHAQ. The yield was 98 mole %.

The product has a melting point of 204 to 208"C. It was found by the speed liquid chromatography that the product contained 2.1 wt. % of AQ.

The product was recrystallized from orthoxylene to obtain purified 1,4-DIIAQ having a melting point of 208.5 to 209.50C which was the same as in the data of prior art reference. It was further confined by infrared spectrum analysis that the product was 1 ,4-DHAQ.

In the mixed examination of the product and 1,4-DHAQ obtained by the known process oxidizing with ferric chloride, no difference of melting point was found.

Reference 2: 2.12 wt. parts of THAQ was added to 100 wt. parts of a buffer solution having pH of 7 (0.2 mole of potassium dihydrogen phosphate, sodium hydroxide and water) and air was fed into the mixture at 50"C for 2 hours with stirring to react them. The reaction mixture was treated in accordance with the process of Reference 1. It was found by the infrared spectrum analysis that the product was substantially the unreacted material.

The product was further oxidized with air under the same conditions for 4 hours. However, the mixture did not change to the specific yellow slurry of 1,4-DHAQ which indicates the completion of the reaction. It was found by the infrared spectrum analysis that the product was substantially the unreacted material.

Reference 3: A 2.12 wt. parts of THAQ was added to 100 wt. parts of an aqueous solution of sodium hydroxide having pH of 13, and air was fed into the mixture at 500C for 1 hour with stirring to react them. The reaction mixture was treated in accordance with the process of Reference 1 to obtain 2.05 wt.

parts of yellowish oranged crystals. It was found by high speed liquid chromatography analysis that the content of AQ in the product was 62 wt. %.

Example 1: In a reactor equipped with a stirrer, 4.24 wt. parts of sodium carbonate was dissolved in 100 wt. parts of water and then, 8.48 wt. parts of THAQ was added to the mixture with stirring and then, 0.26 wt. part of sodium 1,4-naphthoquinone-2-sulfonate was added and pH was adjusted to 11.3 by adding 56-NaOH aq. sol.

The mixture was heated to 50"C and air was fed into the mixture with stirring to react them. After about 30 minutes, the dark purple slurry was changed to the specific yellow slurry of 1,4-DHAQ. The color was not further changed. The reaction was stopped after 45 minutes from the initiation. The reaction mixture was treated in accordance with the process of Reference 1 to obtain 8.24 wt. parts of yellow crystals having a melting point of 206 to 208.5 C.

It was found by the high speed liquid chromatography analysis that the content of AQ was 1.1 wt. 0t. It was confirmed by infrared spectrum naln sis that the product was 1,4-DHAQ.

Exaznple 2: In accordance with the process of Example 1 except feeding air at 20 C, th > reaction was carried out. After 1 hour, the slurry was changed from the dark purple slurry to yellowish slurry. After 2 hours, it was completely changed to the specific yellow slurry of 1,4-DHAQ and the feed of air was stopped.

The reaction mixture was treated in accordance with the process of Example 1 to obtain 8.22 wt. parts of yellow crystals having a melting point of 206 to 208.5"C.

It was found by high speed liquid chromatography analysis that the content of AQ was 1.0 wt. %.

The process was repeated except using l,4-DHAHQ as the starting material instead of THAQ. The results were the same. In the experiments, the infrared spectra of the compounds were identified with those of the prior art.

WHAT WE CLAIM IS : - 1. A process for producing a 1,4-dihydroanthraquinone wherein 1 ,4,4a,9a-tetrahydro- anthraquinone, 1 ,4-dihydroanthrahydroqui- none or a derivative thereof having an inert substituent is oxidised v;ith molecular oxygen, in the presence of a quinone-tSe redox catalyst, at a reaction temperature of not more than 70"C at a pH of 8.5 to 12 in an aqueous medium.

2. A process according to claim 1 wherein the reaction temperature is in the range of 10 to 705C.

3. A process according to claim 2 wherein the reaction temperature is in the range of 30 to 60"C.

4. A process according to any preceding claim wherein a 1 ,4,4a,9a-tetrahydroanthra- quinone or 1,4-dihydroanthrahydroquinone is substituted with an alkyl group, a halogen atom a haloalkyl group or a phenyl group.

5. A process according to claim 4 wherein the substituent is a chlorine or bromine atom or a C,--C, alkyl group.

6. A process according to any preceding claim wherein the starting material is in the form of a finely divided powder.

7. A process according to claim 1 substantially as herein described with reference to the Examples.

8. A 1,4-dihydroanthraquinone made by a process according to any preceding claim.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. accordance with the process of Reference 1 to obtain 8.24 wt. parts of yellow crystals having a melting point of 206 to 208.5 C. It was found by the high speed liquid chromatography analysis that the content of AQ was 1.1 wt. 0t. It was confirmed by infrared spectrum ánaln sis that the product was 1,4-DHAQ. Exaznple 2: In accordance with the process of Example 1 except feeding air at 20 C, th > reaction was carried out. After 1 hour, the slurry was changed from the dark purple slurry to yellowish slurry. After 2 hours, it was completely changed to the specific yellow slurry of 1,4-DHAQ and the feed of air was stopped. The reaction mixture was treated in accordance with the process of Example 1 to obtain 8.22 wt. parts of yellow crystals having a melting point of 206 to 208.5"C. It was found by high speed liquid chromatography analysis that the content of AQ was 1.0 wt. %. The process was repeated except using l,4-DHAHQ as the starting material instead of THAQ. The results were the same. In the experiments, the infrared spectra of the compounds were identified with those of the prior art. WHAT WE CLAIM IS : -

1. A process for producing a 1,4-dihydroanthraquinone wherein 1 ,4,4a,9a-tetrahydro- anthraquinone, 1 ,4-dihydroanthrahydroqui- none or a derivative thereof having an inert substituent is oxidised v;ith molecular oxygen, in the presence of a quinone-tSe redox catalyst, at a reaction temperature of not more than 70"C at a pH of 8.5 to 12 in an aqueous medium.