DD153548A5 - PROCESS FOR THE PREPARATION OF 1,4-NAPHTHOCHINONE - Google Patents

Abstract

The invention relates to a process for the preparation of 1,4-naphthalene by oxidation of naphthalene with cerium (IV) salts, which comprises reacting the naphthalene in powdery state with the aid of a dispersant in the solution of cerium (IV) - Salts suspended.

Description

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description

Field of application of the invention;

The invention relates to an improvement of the process for the preparation of 1,4-naphthoquinone and more particularly to a process which consists in oxidizing naphthalene with the aid of a sulfuric acid solution of cerium (IV) salts.

Characteristic of known technical solutions The oxidation of naphthalene with cerium (IV) salts has been known for many years (see US Pat. No. 729,502, filed May 26, 1903). The compounds of the 4-valent cerium have proven to be the most active and selective oxidizing agents over, for example, the compounds of 5-valent vanadium, 6-valent chromium and 3-valent or 7-valent manganese. This chemical oxidation is often combined for economic reasons with an electrochemical regeneration of the oxidant. FR-PS 1 591 651, filed on 23 October 1968, is representative of this state of the art.

To facilitate the separation of the products has already been proposed to use a water immiscible solvent, wherein the naphthalene is dissolved in this solvent and the oxidizing agent is present in aqueous solution. These two

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Phases are emulsified in the oxidation reactor and then separated again in a decanter. The aqueous phase is returned to the electrolysis cell while the organic phase is treated for extraction of the naphthoquinone.

The implementation of this method entails a number of disadvantages:

It is not possible to find a completely inert solvent. For example, if one uses a heavy paraffin, one must work in the absence of air, otherwise auto-oxidation of the solvent will result, forming by-products which collect in the form of a slurry in the decanter and block its functioning

 Furthermore, this undesired secondary oxidation leads to the formation of dangerous peroxides.

Furthermore, it is difficult to completely prevent the entrainment of the solvent in the aqueous phase, so that even a low solubility of this solvent in the field of electrolysis cell to considerable technical difficulties cause (due to the sensitivity of the plastic materials and the diaphragms to the organic solvents) ,

Moreover, the productivity of the process is limited by the solubility of the product, which is often Case: 2566.C

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different from that of the reagent. This applies to the naphthalene / naphthoquinone system.

According to the invention it has now been found that it is possible to dispense with the use of a solvent.

Loan , the essence of the invention;

The invention therefore provides a process for the preparation of 1 , 4-naphthoquinone by oxidation of naphthalene with cerium (IV) salts, which is characterized in that the naphthalene in a powdered state with the aid of a dispersant in the solution of cerium (IV ) salt suspended.

Anionic or nonionic surfactants are preferably used for carrying out the process according to the invention. Examples include alkyl sulfates or alkyl sulfonates and the products obtained by the condensation of a hydrophilic substrate with an olefin oxide.

The amount of dispersant used is generally between 0.01 and 0.5 percent by weight, based on the naphthalene used. For economic reasons, there is no interest in increasing this share. The powdery used

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Naphthalene is practically made of particles with a mean dimension of less than 25 μπι.

Suitable cerium (IV) salts for the process according to the invention may be the sulfate, the nitrate, the acetate, the chloroacetate, the fluoroacetate and the like.

To the solutions of these salts in sulfuric acid or nitric acid are added the dispersant and the naphthalene in a powdery state. The mixture is often agitated in a manner known per se to form a homogeneous suspension. The formation of 1,4-naphthoquinone is, as is well known, already at room temperature, but is accelerated by elevated temperatures. The separation of the product is carried out in a very simple manner by decantation, filtration or centrifugation, wherein the aqueous phase is returned to the electrolytic cell for regenerating the oxidizing agent. The regeneration is carried out in a manner known per se (see, for example, Chemical Engineering (June 5, 1967), 128 to 135, U.S. Patent 3,486,992; Document ORNL-TM-657 REMC Henry (February 1965): "Separation of cerium from other rare earths by electrolytic oxidation and differential extraction ";

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4476

Przemysl. Chem. 44 (5) 239-243 (1965) Lucja Kohman and Mieczyslaw Pezec "Electrolytic oxidation of Ce (III) to Ce (IV)"; U.S. Patent No. 3,413,203, issued August 18, 1965, "Electrolytic Oxidation of Cerium"; Technical Report Osaka Univ. 10 Nos. 363-391 (1960) 261-269, Toshio Ishino and Jiro Shiokawa "Oxidation of cerium by electrolysis").

The process according to the invention thus represents a notable improvement in the production of 1,4-naphthoquinone, in particular by making it possible to achieve a marked acceleration in the rate of conversion of naphthalene, those of the following. Examples of significant time savings to a considerable efficiency of the continuous process carried out for the oxidation of naphthalene.

Ausfühlungsbeispiele

The following examples serve to further illustrate the invention.

example 1

In 1200 ml of a solution of cerium (IV) in sulfuric acid (100 g / l) containing 0.25 mol of cerium per liter, with good stirring (1700 min) and at a temperature of 55 ⁰ C 6 g of powdered naphthalene (with an average particle size of 25 μτη) Half of the oxidizing agent is in the course of

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35 minutes consumed while 86% of the oxidizing agent are reacted in 120 minutes.

Example 2

In 50 cm ^{3 of} the cerium (IV) solution described in Example 1, 6 g of naphthalene and 30 mg of a condensate of one mole of nonylphenol and 10 moles of ethylene oxide are introduced and the materials are dispersed under the action of ultrasound. This dispersion is mixed with stirring in the reactor using the conditions described in Example 1, with half of the oxidizing agent consumed in 10 minutes and 86% of the oxidizing agent in 30 minutes.

Example 3

2.4 g of micronised naphthalene (with an average particle diameter of 10 μm) in 450 ml of a cerium (IV) solution in sulfuric acid containing 0.25 mol of cerium per liter are slowly stirred (580 min). at a temperature of 55 ° C. Here, half of the oxidizing agent is consumed in 45 minutes and 86% of the oxidizing agent in a reaction time of 180 minutes.

Example 4

It causes a predispersion of 2.4 g of micronized naphthalene (with an average particle size of 10 μπι) in 10 ml of the cerium (IV) solution of Example 1 Case: 2566.C

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in the presence of 0.5% sodium dodecylbenzenesulfonate, based on naphthalene. The suspension is introduced into the reaction vessel using the conditions of Example 3. Here, half of the oxidizing agent is consumed in 10 minutes and 86% of the oxidizing agent in 25 minutes.

Example 5 .

2.4 g of ground naphthalene (average particle diameter 25 μm) are introduced into a solution of cerium (IV) in sulfuric acid, the conditions of Example 3 being used. Here, half of the oxidizing agent is consumed in 70 minutes and 86% of the oxidizing agent over a reaction time of 200 minutes.

Example 6

It forms a predispersion of 2.4 g of ground naphthalene (with an average particle diameter of 25 μπι) and 0.5% sodium dodecylbenzenesulfonate. Then, this suspension is transferred to the reaction vessel and the reaction is carried out using the conditions of Example 3. Here, half of the oxidizing agent is consumed in 12 minutes and 86% of the oxidizing agent in 30 minutes.

Example 7

The reaction is carried out using the conditions of Example 6, but using only 0.1% of the dispersant. In doing so, half of the oxidation

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consumed over the course of 16 minutes and 86% of the oxidizing agent over 45 minutes.

Example 8 , ·.

The procedure of Example 6 is repeated except that a condensation product of one mole of nonylphenol and 10 moles of ethylene oxide is used as the dispersant. Here, half of the oxidizer is consumed over 17 minutes and 86% of the oxidizer over 45 minutes.

End of the description

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Claims (3)

4476 invention claim 1. A process for the preparation of 1,4-naphthoquinone by oxidation of naphthalene with cerium (IV) salts, characterized in that , the naphthalene is suspended in powdered state with the aid of a dispersing agent in the solution of the cerium (IV) salt. 2. The method according to item 1, characterized in that is used as a dispersant 'a nonionic dispersant. 3. The method according to item 1, characterized in that the dispersant used is an anionic dispersant. Case: 2566.C