DE2457082A1 - Dibenzothiophene dioxide derivs prodn - 3-nitro-and 3,7-dinitro-dibenzothiophen-5,5- dioxide prodn by oxidn of dibenzothiopene in substd (cyclo) alkane and direct nitration - Google Patents

Abstract

Prodn. of 3-nitro- and 3,7-dinitro-dibenzothiophen-5,5-dioxide (I) comprises dissolving dibenzothiophene (II) in (cyclo)aliphatic hydrocarbons (III) with one or more halogen (F, Cl, Br), NO2 or alkylsulphonyl substits., oxidising with H2O2 in the presence of a strong acid (IV) and nitrating the resultant dibenzothiophen-5,5-dioxide (V), without isolation, with a nitrating agent (VI), opt. with addn. of water-binding agent (VII). (I) are valuable intermediates for the prodn. of dyes, esp. azo dyes. The process is simple and gives good yields.

Description

Process for the preparation of 3-nitro- and 3,7-dinitro-dibenzothiophene-5,5-dioxide The invention relates to an improved process for the preparation of 3-nitro and 3,7-dinitro-dibenzothiophene-5,5-dioxide.

It is known to use dibenzothiophene in glacial acetic acid with 30% strength by weight aqueous To oxidize hydrogen peroxide to dibenzothiophene-5,5-dioxide and from the obtained To isolate the reaction mixture by filtering off (J. Am. Chem. Soc. 74, 2021 (1952)). It is also known to use dibenzothiophene-5,5-dioxide in concentrated sulfuric acid to nitrate with 98 wt .-% nitric acid and after subsequent dilution of the reaction mixture with water, the precipitated 3,7-dinitro-dibenzothiophene-5,5-dioxide separated from the aqueous solution by filtration (J. Chem.

Soc. 1936, 1435).

Disadvantages of the known process are the isolation of the dibenzothiophene-5,5-dioxide, the need for recovery or loss of the in the first stage considered Used glacial acetic acid and the use of large amounts of mineral acid as solvents Solvent in the nitration, which after subsequent dilution with large Effort must be worked up or to a corresponding, undesirable Lead to wastewater pollution.

There is therefore a need for an improved method of manufacture of 3-nitro and 3,7-dinitro-dibenzothiophene-5,5-dioxide, which have the disadvantages described does not have, especially because 3,7-dinitro-dibenzothiophene-5,5-dioxide can serve as an intermediate product for the production of benzidinesulfone. The production Benzidine sulfone by sulfonation of benzidine is because of its carcinogenicity the benzidine for health reasons questionable and therefore a different technical one A useful route to this important intermediate is highly desirable.

It has now been found that 5-nitro- and 7-dinitro-dibenzothiophene-5,5-dioxide can be produced in a simple manner and with good yields if one uses dibenzothiophene in aliphatic or cycloaliphatic hydrocarbons, one or more times by halogen, which is substituted by nitro or an alkylsulfonyl group, dissolves, oxidized with hydrogen peroxide in the presence of a strong acid -'nd the obtained 3ibenzothiophene-5,5-dioxide without intermediate isolation with a nitrating agent, if necessary with the addition of a water-binding agent, nitrated.

As substituted hydrocarbons for the invention Methods that can be used include aliphatic and alicyclic hydrocarbons with up to 12, preferably up to 6, carbon atoms mentioned one or more times substituted by halogen (fluorine, chlorine, bromine), the nitro or an alkylsulfonyl group are.

Correspondingly substituted hydrocarbons are used as the base body named for example: methane, ethane, propane, butane, pentane, hexane, cyclopentane and cyclohexane; This list of examples also includes, of course, the straight-chain and branched isomers and alkyl-substituted cycloalkanes.

The hydrocarbons substituted by chlorine are preferred named, e.g. methylene chloride, chloroform, carbon tetrachloride, 1,1-dichloroethane, 1,2-dichloroethane, 1,1,2-trichloroethane, 1,1,2,2-tetrachloroethane, pentachloroethane, 1,2-dichloropropane and 1,3-dichloropropane.

For hydrocarbons substituted by bromine, for example named: methylene bromide, bromoform, tetrabromomethane, 1,2-dibromoethane and 1,2-dibromopropane.

Hydrocarbons can also be used in the process according to the invention Find use, for example by fluorine or by various halogens are substituted at the same time. E.g.

Fluorotrichloromethane, difluorodichloromethane, difluorodibromomethane, 1,1,2-trifluoro-1,2 ? 2-trichloroethane and perfluoro-1,3-dimethylcyclohexane.

Of the hydrocarbons substituted by the nitro group are especially called nitromethane and nitroethane.

As hydrocarbons substituted by an alkylsulfonyl group are preferably mentioned dimethyl sulfone and tetramethylene sulfone.

Also mixtures of two or more of the aforementioned substituted ones Hydrocarbons can be used in the process according to the invention.

The amount of the substituted substance or substances used in accordance with the invention Hydrocarbons can be varied within wide limits. Generally amounts to they are about 0.5 to 25, preferably about 1 to about 10 and in particular from about 2 to about 5 parts by volume per part by weight of the dibenzothiophene used.

Hydrogen peroxide is known; it is undiluted and in the form of water Solutions of various concentrations available on the market.

In general, the process according to the invention is up to 10, preferably up to 5, in particular 2 to 4 moles of H 2 O 2 per mole of dibenzothiophene are used.

Preferred strong acids are non-oxidizing mineral acids in question, especially sulfuric acid and phosphoric acid.

In general, 0.01 to 10 moles per mole of dibenzothiophene are preferred 0.05 to 5 mol, in particular 0.1 to 4 mol, of strong acid are used.

In general, the process according to the invention is carried out so that one submits dibenzothiophene in the appropriately substituted hydrocarbon, the selected amount of the strong acid is added and then the selected amount of hydrogen peroxide or solution .. The hydrogen peroxide can be added at once, in batches or be added continuously.

The reaction temperature is generally from 0 to 170, preferably 20 to 130, especially 30 to 10,000.

Since the oxidation reaction is exothermic, it is particularly advantageous to to add the hydrogen peroxide continuously to the extent that the reaction temperature does not exceed the selected range even without additional cooling.

After the oxidation is over, what by usual analytical methods can be easily ascertained, if necessary, e.g. as a result of the use Aqueous phase formed from aqueous hydrogen peroxide solution is separated off.

However, it is advantageous to choose the temperature range for the reaction so that the water formed during the oxidation may be due to the heat of reaction distilled off as an azeotrope with the solvent used from the reaction mixture. After the condensation of the distillate, the water can be removed from the solvent separate and either reuse the solvent in a later batch or recirculate it directly, batchwise or continuously, into the reaction mixture.

Used for the subsequent nitration of dibenzothiophene-5,5-dioxide the preferred nitrating agent is nitric acid or those nitrating agents which, in addition to Nitric acid contain other strong mineral acids or Lewis acids, e.g. sulfuric acid, Oleum, sulfur trioxide, phosphoric acid, polyphosphoric acid, phosphorus pentoxide, hydrogen fluoride or alkanesulfonic acids, e.g.

Methanesulfonic acid, perfluoromethanesulfonic acid, perfluorobutanesulfonic acid.

Generally up to about 50, preferably up to about 15 and especially about 1 to 2 moles of nitric acid per mole into the dibenzothiophene-5,5-dioxide used nitro group to be introduced. Contains the nitrating agent in addition to nitric acid other of the acids mentioned above, the proportion of added mineral or Lewis acid generally up to about 5 moles, preferably up to about 3 moles and in particular 0.5 to 1.5 mol, calculated on the molar amount of nitric acid.

Generally nitric acid is used at a level of about 90 to 100% by weight of HN03 used, but more dilute nitric acid up to about 50% by weight HN03 can be used if the nitrating agent is also strong mineral or Lewis acids which are capable of binding water, e.g. the aforementioned. Mixtures of these acids and nitric acid can also be present in the nitrating agent can optionally completely or partially by nitrates, preferably ammonium and alkali nitrates be replaced.

Agents can also be added to the reaction mixture that of the water introduced by the nitrating agent and / or that of the reaction bind resulting water. In general, the aforementioned acids are used for this purpose as well as their mixtures are used. These funds in turn can already be up to Contain 20% by weight, but preferably up to 10% by weight, of bound water. In general these agents are used together with the nitrating agent, optionally also in a mixture in the reaction mixture, or added before or after the addition of the nitrating agent. Some, for example sulfur trioxide, can also be used as a solution in one of the invention organic solvents used are added.

The amount of the water-binding agent is expediently corresponding the amount of nitrating agent used, the water content and the temperature of the reaction mixture chosen.

Preference is given to up to 10, in particular up to 2, mol of the water-binding agent Means, based on 1 mole of the nitro group to be introduced into the dibenzothiophene-5,5-dioxide used. With the preferred use of 1 to 2 moles of nitric acid per mole in the dibenzothiophene-5,5-dioxide to be introduced nitro groups is the presence of the water-binding agent is generally required.

The reaction temperature can be varied within wide limits. In general, the reaction in the temperature range between -20 and + 125 ° C. is preferred between 0 and 105 0C and in particular in the temperature range between 20 and 90 0C carried out. The process according to the invention is generally carried out at normal pressure carried out, but it is also possible to work at reduced or increased pressure. When using low-boiling solvents in the process according to the invention can work at elevated temperatures to achieve the chosen reaction temperature Print may be absolutely necessary.

In general, the second stage of the process according to the invention carried out as follows: After the oxidation is complete and optionally one aqueous phase was separated, the oxidation mixture or optionally -rnlr their organic phase at the temperature chosen for the nitration Nitrating agents added all at once, batchwise or continuously. Here can one also proceeds in such a way that the addition of the nitrating agent is carried out at a lower temperature begins and uses the adiabatic heating of the reaction mixture, the ur the Nitriding to reach the selected temperature. This is used if necessary Finding water-binding agents beforehand, at the same time or in admixture with the nitrating agent or afterwards also added all at once, in batches or continuously. Given salls In this case, too, heating can occur when the water-binding agent is added to reach the temperature selected for nitration.

In this context, it has proven to be a particularly advantageous embodiment the use of small amounts of acid of about 0.01 to 0.5 mole ee mole of dibenzothiophene in the previous oxidation of the dibenzothiophene, the resulting water is distilled off from the reaction mixture.

After the reaction has ended, the sparingly soluble reaction product can be used isolate in different ways. For example, you can use the reaction mixture Add water and separate the organic phase or the organic solvent distill off and the reaction product, which is sparingly soluble in water, e.g.

isolate from the aqueous phase by filtration or centrifugation. The solvent that has been distilled off or the organic phase can be used again and be circulated, if necessary with the inclusion of e.g. a distillative Working up the organic phase.

Compared to the method according to the prior art, the inventive. Process significant advantages. So can be used in the method according to the invention substituted hydrocarbon either directly or optionally after work-up, e.g., by distillation, can be reused; also the water-containing acid phase, which is practically free of dissolved by-products can be obtained by adding the above Water-binding agents or e.g. corresponding acid anhydrides are concentrated again and be led in a circle.

In addition, the process according to the invention can carry out the oxidation of dibenzothiophene and the nitration of dibenzothiophene-5,5-dioxide in the same Solvent can be carried out without intermediate isolation.

Above all, however, the method according to the invention focuses on the use completely dispensed with mineral acid as a solvent or diluent. this not only results in a cost-reducing saving compared to the prior art of mineral acid, but at the same time solves the problems that would otherwise arise with processing or elimination of such amounts of acid.

3-nitro- and 3,7-dinitrodibenzothiophene-5,5-dioxide are we valuable Intermediates for the manufacture of dyes; for example they will converted by reduction into the corresponding amino compounds, which act as coupling components are of particular importance for the production of azo dyes.

In the examples below, percentages relate to the Weight, unless otherwise noted. The contents of the mineral acids are made in percent by weight, the remainder not mentioned is water.

The solvent that passes over during the azeotropic distillation of the water is returned in all examples.

Example 1 In a glass apparatus, consisting of a 1 liter four-necked flask with inserted stirrer and internal thermometer as well as reflux condenser and dropping funnel becomes a solution of 92 g (0.5 mol) of dibenzothiophene in 200 ml of methylene chloride and 3 ml of monohydrate under reflux during 70 mirnits of 80 ml (1.65 mol) of 50% by weight Hydrogen peroxide was added dropwise and the water was distilled off azeotropically on the water separator. After 2 hours, the reaction has ended and the reaction mixture is 22 ml 98 4-strength nitric acid added at a temperature of 40 ° C. Then during about 3 hours at the same temperature 30 ml of 100% sulfuric acid was added dropwise and then stirred for an hour. After cooling to room temperature the reaction mixture poured into 500 ml of water and the organic solvent then distilled off. The remaining aqueous suspension is filtered, the residue washed neutral with water and dried. The yield is 125.2 g of 3-nitro-dibenzothiophene-5,5-dioxide (96% of theory).

Example 2 To a solution of 18.4 g (0.1 mol) dibenzothiophene, 120 ml of ethylene chloride and 8.3 g of 96% sulfuric acid are simultaneously 19.6 g of 96 % sulfuric acid and 16 ml (0.339 mol) of 50% aqueous hydrogen peroxide solution added dropwise at a temperature of 400C. Then 3 hours at the same Stirred temperature and the suspension is then mixed with 28 g 98 volumes of nitric acid, the precipitated crystals go into solution and two phases are formed. The organic phase is separated off, and 4.5 g of 98% strength nitric acid are added and then 56.3 g of 20% strength oleum were added dropwise at a temperature of 40.degree. The resulting suspension is stirred at the same temperature for 3 hours and then mixed with 300 ml of water. The precipitated reaction product is Sucked off, washed neutral and dried. Yield 28.5 g of 3,7-dinitrodibenzothiophene-5,5-dioxide (93.3% of theory).

Example 3 In-a solution of 92 g (0.5 mol) of dibenzothiophene in 500 ml of ethylene chloride and 3 ml of monohydrate is refluxed for 30 minutes 80 ml. (.1.65 mol) 50 5% strength aqueous hydrogen peroxide was added dropwise and the water azeotropically distilled off. The resulting suspension is then mixed with 80 ml of 98% nitric acid and slowly drip 80 at a temperature of 600C ml of 20% oleum. The mixture is then stirred for 5 hours at the same temperature, then cooled to room temperature and poured 800ml of water. After distilling of the organic solvent, the remaining aqueous suspension is filtered, the filter cake washed neutral and dried.

148.5 g of 3, 3-, 7-dinitrosdibenzothiophene-5,5-dioxide (97% the theory).

Example: 4 23 g (0.125 mol) of dibenzothiophene are dissolved in 432 ml of methylene chloride dissolved, treated with 1 ml of monohydrate and refluxed 24 ml (0.508 mol) of 50% aqueous hydrogen peroxide was added dropwise. The water is made by azeotropic distillation separated at the water separator. After 2 hours the solution is cooled to - 1500, mixed with 374 ml of 9.8% nitric acid and at this temperature for 4 hours touched. The reaction mixture is then poured into 500 ml of water and the organic solvent is distilled off. The remaining aqueous suspension is filtered, the residue washed neutral with water and dried.

Yield: 31.2 g of 3-, 7-dinitro-dibenzothiophene-5,5-dioxide (81.5 vol the theory).

Example 5 23 g (0.125 mol) of dibenzothiophene are dissolved in 432 ml of methylene chloride dissolved, mixed with one ml of monohydrate and refluxed 24 ml (0.508 mol) 50 % aqueous hydrogen peroxide 'was added dropwise. The water is made by azeotropic distillation separated at the water separator. After the reaction has ended, the solution will rise OOC cooled and 210 ml of 98% nitric acid were added dropwise at this temperature and stirred for 4 hours. Then it is warmed to room temperature and that Poured the reaction mixture into 500 ml of water. Then the organic solvent distilled off and the remaining aqueous suspension filtered; the residue will washed neutral with water and dried.

Yield: 34.5 g of 3, 7-dinitro-dibenzothiophene-5, 5-dioxide (90% of the Theory).

Example 6 A solution of 23 g (0.125 mol) of dibenzothiophene in 108 ml of nitromethane are added to 1 ml of monohydrate and then refluxed 24 ml (0.508 mol) of 50% aqueous hydrogen peroxide were added dropwise and the resulting Water distilled off azeotropically from the reaction mixture. After the reaction has ended 20 ml of 98% strength nitric acid are added to the resulting suspension and then at a temperature of 40 ° C. 20 ml of 20% strength oleum were added dropwise to the reaction mixture. After stirring for 4 hours, the reaction mixture is poured into 500 ml of water and then the organic solvent is distilled off. The remaining aqueous The suspension is filtered, the residue is washed neutral with water and dried. Yield: 35.7 g of 3,7-dinitro-dibenzothiophene-5,5-dioxide (93.3% of theory).

Claims (1)

Claim Process for the production of 3-nitro- and 3,7-dinitro-dibenzothiophene-5,5-dioxide, characterized in that one dibenzothiophene in aliphatic or cycloaliphatic Hydrocarbons, one or more times by halogen, the nitro or a Alkylsulfonyl group are substituted, dissolves, with water, rstoffperoxid in the presence a strong acid oxidized and the resulting dibenzothiophene-5, 5-dioxide without Intermediate insulation with a nitrating agent, optionally with the addition of water binding agent, nitrided.