DE1165011B - Process for the preparation of thiuram disulfides. - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Boarding school Class: C 07 c

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German class: 12 ο -17/02

U8941IVb / 12o
May 10, 1962
March 12, 1964

The invention relates to a process for the production of thiuram disulfides, in particular of tetraalkylthiuram disulfides, by catalytic oxidation of an alkali salt of a dialkyldithiocarbamic acid. the Thiuram disulfides are compounds that have extensive application, especially as accelerators Improvement of the vulcanization of synthetic and natural rubber compounds, but also as fungicides and Found insecticides. Most of the compounds mentioned are alkyl derivatives of thiuram disulfide, such as bis (N, N-dimethylthiocarbamyl) disulfide, bis (N, N-diethylthiocarbamyl) disulfide, bis (N, N-diisopropylthiocarbamyl) disulfide and bis- (N, N-dibutylthiocarbamyl) disulfide and can be used without the addition of sulfur as a vulcanizing agent or with sulfur as Ultra accelerators as well as activators for thiazole type accelerators are used. Such Compound also makes vulcanizates resistant to staining, and discoloration in particular against heat aging.

The invention is particularly directed to an economical, commercially feasible method of manufacture of tetraalkylthiuram disulfides by catalytic oxidation of an alkali salt of a dialkyldithiocarbamic acid directed using a special class of catalysts and very easily accessible and in no way aggressive reactants.

According to the invention, a thiuram disulfide substituted with hydrocarbon radicals is produced by having an alkali salt of an appropriately substituted dithiocarbamic acid in which the hydrocarbon substituent is at least one radical from the group consisting of the alkyl and aryl radicals has, oxidized by contacting it with an oxygen-containing gas in the presence of a treated aqueous solution of a sulfonated or carboxylated metal phthalocyanine, wherein the metal is selected from Group VIII of the Periodic Table, while the ρπ value of the solution is within of the range from about 7 to about 12.

As indicated, is an alkyl-substituted, especially a dialkyl-substituted, dithiocarbamic acid a preferred reactant because the latter leads to the formation of tetraalkylthiuram disulfides, such as to the highly effective product bis (N, N-dimethylthiocarbamyl) disulfide and the corresponding N, N-diethyl, Ν, Ν-diisopropyl and N, N-dibutyl-substituted compounds.

Dithiocarbamic acids substituted with hydrocarbon radicals, the alkali metal salts thereof according to the process to the appropriately substituted thiuram process for the production of thiuram disulfides

Applicant:

Universal Oil Products Company,

Des Piaines, JU. (V. St. A.)

Representative:

Dr. H.-H. Willrath and Dipl.-Ing. H. Roever,
Patent attorneys, Wiesbaden, Hildastr. 18th

Named as inventor:

William Lester Cox, Mount Prospect, JIl.,

Alexander Gaydasch, Chicago, JIl. (V. St. A.)

Claimed priority:

V. St. ν. America 11 May 1961

(No. 109 249)

are oxidized disulfides, are z. B. substituted on nitrogen and Ν, Ν-disubstituted dithiocarbamic acids, in which the hydrocarbon substituent consists of an alkyl or aryl radical. The salt can So an alkali salt of an alkyldithiocarbamic acid, such as N-methyldithiocarbamic acid, N-ethyldi-thiocarbamic acid, N-n-propyldithiocarbamic acid, N-isopropyldithiocarbamic acid, N-n-butyldithiocarbamic acid, N-sec-butyldithiocarbamic acid, N-tert-butyldithiocarbamic acid, N - amyldithiocarbamic acid or an alkali salt of a dialkyldithiocarbamic acid, such as Ν, Ν-dimethyldithiocarbamic acid, N, N-diethyldithiocarbamic acid, Ν, Ν-di-n-propyldithiocarbamic acid, Ν, Ν-diisopropylthiocarbamic acid, N, N-di-n-butyldithiocarbamic acid, N, N-di-sec-butyldithiocarbamic acid, Ν, Ν-di-tert-butyldithiocarbamic acid, Ν, Ν-diamyldithiocarbamic acid or N-methyl-N-ethyldithiocarbamic acid, N-methyl-N-propyldithiocarbamic acid, N - methyl - N - butyldithiocarbamic acid, N-methyl-N-amyldithiocarbamic acid, N-ethyl-N-propyldithiocarbamic acid, N-ethyl-N-butyldithiocarbamic acid, N-ethyl-N-amyldithiocarbamic acid, N-propyl-N-butyldithiocarbamic acid, N-propyl - N - amyldithiocarbamic acid, N - butyl-N-amyldithiocarbamic acid. Also suitable are the alkali salts of aryl-substituted dithio-carbamic acids, such as N-phenyldithiocarbamic acid, N-o-tolyldithiocarbamic acid, N-m-tolyldithiocarbamic acid, N-p-tolyldithiocarbamic acid, Ν, Ν-Diphenyldithiocarbamic acid, Ν, Ν-Di-o-tolyldithiocarbamic acid, N, N-Di-m-

409 538/521

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tolyldithiocarbamic acid, N, N - di - ρ - tolyldithiocarbamic acid. The alkali salts of alkylaryldithiocarbamic acids, e.g. B. N-methyl-N-phenyldithiocarbamic acid, N - methyl - N - ο - tolyldithiocarbamic acid, N - methyl - N - ρ - tolydithiocarbamic acid, N-ethyl-N-phenyldithiocarbamic acid, N-ethyl-N-o-tolyldithiocarbamic acid, N-methyl-N-mtolyldithiocarbamic acid or N-ethyl-N-p-tolyldithiocarbamic acid.

The alkali salts of the above-described dithiocarbamic acids can be any conventionally known Way to be made. For example, carbon disulfide can be added to an aqueous solution of diethylamine and sodium hydroxide are added to the sodium salt of Ν, Ν-diethyldithiocarbamic acid to win. Sodium hydroxide and potassium hydroxide are usually compared to the more expensive lithium hydroxide, Rubidium hydroxide and cesium hydroxide preferred.

As indicated, the desired hydrocarbon radical substituted thiuram disulfides are used according to the invention by oxidation of an alkali salt of an appropriately substituted dithiocarbamic acid in the presence of an aqueous solution of a sulfonated metal phthalocyanine as a catalyst made, the metal of the latter being selected from Group VIII, which includes iron, cobalt, Includes nickel, rhodium, ruthenium, palladium, osmium, iridium and platinum. Iron, cobalt and Nickel phthalocyanine are particularly suitable. For example, it is known to use the cobalt phthalocyanine sulfonates Can be obtained by adding cobalt phthalocyanine with 20% fuming sulfuric acid implements. The sulfonates are easily soluble in an aqueous alkaline solution.

Although the sulfenic acid derivatives of the metal phthalocyanines carboxylated derivatives of metal phthalocyanines can also be preferred as catalysts can be used according to the invention. The carboxylated derivatives can be used in a known manner, for. B. by the action of trichloroacetic acid on the metal phthalocyanine or by the action of Phosgene and aluminum chloride are produced. In the latter reaction, the is formed Acid chloride converted to the desired carboxylated derivative by conventional hydrolysis methods. the different derivatives do not have the same effect in quantitative terms.

The catalysts are not only very active, but also highly stable and are produced in extremely small concentrations in the range of about 5 to about 500, preferably about 10 to about 100 parts per million, based on the weight of the alkali hydroxide equivalent of the alkali salt of dithiocarbamic acid is used, although lower or higher concentrations can be used in some cases.

The desired substituted thiuram disulfide is produced by catalytic oxidation an alkali salt of an appropriately substituted dithiocarbamic acid in the presence of an oxygen-containing one Gas. Air is the preferred oxidizing agent, although oxygen or other oxygen-containing ones Gas can be used.

Admittedly, good results are usually achieved by maintaining the pn value of the reaction mixture to about 7 to about 12 to obtain the most favorable yields of the desired products. A However, pH within the range of about 7 to about 8.5 is preferred. A suitable method pH control consists in adding acidic materials to the reaction mixture during the course of the Reaction. Carbon dioxide is preferably used for this purpose, although others are acidic Materials such as acetic acid or mineral acids can be used.

The process of the invention can be carried out in single feed or in continuous operation will. When working in batches, the alkali salt of the substituted dithiocarbamic acid be placed in a suitable reaction vessel containing an aqueous alkaline solution and the phthalooyanine catalyst contains. Air can be introduced or at a speed and in a manner are blown through so that one is as close as possible to a saturated reaction mixture. The sour ones Materials used to control the pH of the reaction mixture can be added dropwise from a dropping funnel or, in the case of carbon dioxide, through the reaction mixture be blown through at a suitable speed. It is useful in this mode of operation that suitable stirring means for the vessel contents, e.g. mechanical stirrers or other mixing devices, be provided to ensure a permanent and intimate contact of the reactants, so that the cheapest conversion is guaranteed. In the continuous process, a aqueous alkaline solution of the alkali salt of substituted dithiocarbamic acid, which contains the phthalocyanine catalyst contains, through a reaction zone in countercurrent to the ascending flow of air and carbon dioxide. The product is withdrawn from the lower part of the reaction zone.

The process of the invention can be carried out at about 15 to about 200 ° C, although a temperature of about 25 to about 100 ° C. is preferably used. In some cases it can it may be expedient to carry out the procedure in a sealed vessel; in this case will Air or other oxygen-containing gas is introduced into the vessel and enclosed in it under excess pressure, an adequate amount of air or other oxygen-containing gas as an oxidizing agent to provide. Otherwise, pressure does not appear to be a meaningful variable in the present To be a process that is operated at air pressure, overpressure or autogenous pressures can.

The following examples serve to further illustrate the process.

example 1

Bis (N, N-diethylthiocarbamyl) disulfide was made in a single batch process, by continuously passing a stream of air through an aqueous solution which is in a glass vessel found and 171 g of the sodium salt of N, N-diethyldithiocarbamic acid and about 100 parts per million, based on the NaOH content of the aqueous solution, containing cobalt phthalocyanine disulfonate. The contents of the vessel was constantly stirred and kept at about 25 ° C. 2N hydrochloric acid was added dropwise to the reaction mixture added in the course of the reaction at a rate that the pH of the Reaction mixture held at about 7 to about 8.5. After a reaction time of about 8 hours

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the precipitate was filtered, washed with water and dried. Analysis showed it to be off 120 g of practically pure bis (N, N-diethylthiocarbamyl) disulfide existed.

5 Example 2

Bis- (N, N-diethylthiocarbamyl) disulfide was prepared by adding an aqueous solution with 171 g of the sodium salt of Ν, Ν-diethyldithiocarbamic acid and about 100 parts per million, based on the NaOH content of the solution, of cobalt phthalocyanine disulfonate and about Placed 45 g of dry ice in a steel shaking autoclave. The autoclave was closed and pressurized with air to about 100 atm. The contents of the autoclave was stirred at room temperature for ¹ S 8 hours, drained after which the pressure and recovering the precipitated product by filtration, washed with water and was dried. 115 g of bis (N, N-diethylthiocarbamyl) disulfide were obtained.

Example 3

With a rapidly stirred aqueous solution of about 143 g of the sodium salt of Ν, Ν-dimethyldithiocarbamic acid and about 50 parts per million cobalt phthalocyanine disulfate based on the weight of the Sodium salt (14 parts per million based on the NaOH equivalent of the salt), air became continuous introduced and dispersed. The pn value of the resulting reaction mixture was through Addition of ground dry ice maintained at about 7 to about 8.5 over the course of the reaction. the Implementation was practically brought to completion, as evidenced by a constant pH indicated within the aforementioned limits without further addition of dry ice. The contents of the vessel was filtered and the residue washed with water and dried to a practically pure To give bis (N, N-dimethylthiocarbamyl) disulfide.

40 Example 4

In this example, air was passed continuously and by a rapidly stirred aqueous solution of the sodium salt of Ν, Ν-Dibutyldithiocarbaminsäure and about 100 parts per million Eisenphthalocyanindisulfonat, based on the weight of the sodium salt, in a reaction vessel at about 20 to 30 ⁰ C dispersed therein. The pH of the resulting reaction mixture was maintained at about 7 to about 8.5 by adding ground dry ice during the course of the reaction. The reaction was carried out practically to completion, which was indicated by a constant pH value within the aforementioned limits without further addition of dry ice. The contents of the vessel were filtered and the residue washed with water and dried to yield a practically pure bis (N, N-dibutylthiocarbamyl) disulfide.

B e i s ρ i e 1 5

In this example, air was continuously per million Kobaltphthalocyanindisulf onate by a rapidly stirred aqueous solution of the sodium salt of Ν, Ν-Diisopropylthiocarbamylsäure and about 100 parts, based on the weight of the sodium salt, introduced into a reaction vessel at about 20 to 30 ⁰ C and dispersed therein . The pH of the resulting reaction mixture was maintained at about 7 to about 8.5 by adding ground dry ice during the course of the reaction. The reaction was carried out practically to completion, which was indicated by a constant pH value within the aforementioned limits without further addition of dry ice. The contents of the vessel were filtered and the residue washed with water and dried to provide a substantially pure bis (N, N-diisopropylthiocarbamyl) disulfide.

Claims (7)

Patent claims: 1. Process for the preparation of a thiuram disulfide substituted with hydrocarbon radicals, characterized in that an alkali salt of an appropriately substituted dithiocarbamic acid oxidized at about 15 to about 200 ° C by placing it in the presence of an aqueous Solution of a sulfonated or carboxylated metal phthalocyanine, the metal of which is from the Group VIII of the Periodic Table is selected as the catalyst at a pH of about 7 to brings about 12 into contact with an oxygen-containing gas. 2. The method according to claim 1, characterized in that an alkali salt of such substituted Dithiocarbamic acid is used, the substituent of which consists of at least one alkyl or aryl radical. 3. The method according to any one of claims 1 and 2, characterized in that as sulfonated Metal phthalocyanine, sulfonated iron phthalocyanine or sulfonated nickel phthalocyanine is used will. 4. The method according to any one of claims 1 to 3, characterized in that the pH value of the aqueous reaction mixture is preferably maintained at about 7 to about 8.5. 5. The method according to claim 4, characterized in that the pH value by adding Carbon dioxide, acetic acid or mineral acids is regulated to the reaction mixture. 6. The method according to any one of claims 1 to 5, characterized in that the oxygen-containing Gas air is used. 7. The method according to any one of claims 1 to 6, characterized in that the alkali salt of Dithiocarbamic acid is oxidized in the presence of an amount of the sulfonated metal phthalocyanine which is within the range of 5 to 500 parts per million by weight of the alkali hydroxide equivalent of the alkali salt of the dithiocarbamic acid present. Considered publications:
German Auslegeschrift No. 1 023 030;
U.S. Patent Letter No. 2,777,878. 409 538/521 3.64 © Bundesdruckerei Berlin