KR20010046567A - Process for preparation of the n,n-dicyclohexyl-2-benzothiazole sulfenamide - Google Patents

Abstract

PURPOSE: A method for producing N,N-dicyclohexyl-2-benzothiazole sulfanamide is provided, thereby high purity N,N-dicyclohexyl-2-benzothiazole sulfanamide can be produced in higher yield. CONSTITUTION: The method for producing N,N-dicyclohexyl-2-benzothiazole sulfanamide comprises the steps of: reacting N-chlorodicyclohexylamine with 2-mercaptobenzothiazol and alkali metal salt of carbonic acid in an alcohol solvent at 40 to 80 deg. C; and adding water into the mixture to precipitate N,N-dicyclohexyl-2-benzothiazole sulfanamide, in which the alcohol solvent is selected from the group consisting of methanol, ethanol, propylalcohol and isopropylalcohol; the alkali metal salt of carbonic acid is selected from the group consisting of NaCO3, NaHCO3 and CaCO3; the equivalent ratio of 2-mercaptobenzothiazol to N-chlorodicyclohexylamine is 1:1 to 1:1.3; the equivalent ratio of 2-mercaptobenzothiazol to alkali metal salt of carbonic acid is 1:1 to 1:1.3; and the weight ratio of water to alcohol is 1:1 to 4:1.

Description

Process for preparing N, N-dicyclohexyl-2-benzothiazole sulfenamide {PROCESS FOR PREPARATION OF THE N, N-DICYCLOHEXYL-2-BENZOTHIAZOLE SULFENAMIDE}

The present invention reacts N, N-dicyclohexyl-2-benzothiane by reacting 2-mercaptobenzothiazole (MBT) with alkali metal or alkaline earth metal salts of carboxylic acid and N-chlorodicyclohexylamine in an alcohol solvent. It relates to a process for preparing sol sulfenamides.

Compounds of sulfenamides are used as rubber vulcanization accelerators and various synthetic methods have been proposed.

For example, U.S. Patent No. 4,461,897 (European Patent No. 29718) and U.S. Patent No. 4,182,873 describe the synthesis of sulfenamides from MBT and amines, using oxygen as an oxidant and water and a metal catalyst. It is characteristic.

U.S. Patent No. 4,252,942 discloses a method for preparing benzothiazole sulfenamide by reacting a mixture of benzothiazole disulfide, an amine halogen hydrate and an N-halogen amine derivative. Is characteristic.

British Patent No. 856,421 discloses sulfenamides by reacting (a) disulfides such as benzothiazole disulfide, (b) secondary amines, (c) N-chloroamines of (b), and (d) alkali metal salts of carboxylic acids. It is presented a method of preparing a method characterized by using disulfide as a raw material.

U.S. Patent Nos. 4,801,707 and 4,751,301 disclose a method for producing benzothiazole sulfenamide by reacting benzothiazole disulfide with a water-soluble amine, which is characterized by using benzothiazole disulfide as a raw material and no oxidizing agent. . However, these are disadvantages that do not react with secondary amines and that the product contains a lot of benzothiazole disulfide.

EP 195738 discloses a method for synthesizing N, N-diisopropylbenzothiazole-2-sulfenamide from diisopropylamine and MBT using water as a solvent and an oxidizing agent, using water as a solvent. And using a base. However, this requires expensive amines to be used in excess, and excess amines are not easy to recover, resulting in higher cost.

US Pat. No. 4,258,197 discloses a method for synthesizing sulfenamide using MBT and excess amine using an oxidizing agent (NaOCl), which is characterized by using water and ethylene glycol monoalkyl ether as a solvent. However, this requires expensive amines to be used in excess, and excess amines are not easy to recover, resulting in higher cost.

U.S. Patent No. 4,719,305 discloses the synthesis of N, N-diisopropylbenzothiazole-2-sulfenamide using an oxidizing agent (NaOCl) using MBT and excess amine (especially diisopropylamine) as water solvent. A method is presented, characterized by the use of water as a solvent. However, this requires expensive amines to be used in excess, and excess amines are not easy to recover, resulting in higher cost.

British Patent No. 2,080,294 discloses a process for preparing N-cyclohexylbenzothiazole-2-sulfenamide using 2-mercaptobenzothiazole, excess cyclohexylamine and oxidizing agent. However, this requires expensive amines to be used in excess, and excess amines are not easy to recover, resulting in higher cost.

British Patent No. 2,053,205 discloses a method for synthesizing 2-benzothiazole sulfenamide using an oxidizing agent using MBT and an excess of primary or secondary amine as water as a solvent, which is characterized by using water as a solvent. . However, this requires expensive amines to be used in excess, and excess amines are not easy to recover, resulting in higher cost.

US Patent No. 3,022,300 discloses a process for preparing sulfenamide by reacting disulfide with N-chloroamine of ammonia, secondary amines and secondary amines with alcohol as a solvent.

EP 721,946 (Japanese Patent Laid-Open No. 8-253463) reacts 2-mercaptobenzothiazoles and / or corresponding disulfides with amines such as N, N-dialkyl or N, N-dicycloalkyl amines. A method for producing N, N-dialkyl, or N, N-dicycloalkylbenzothiazole sulfenamides is disclosed, characterized by using alcohol as a solvent and chlorine.

European Patent No. 314,663 describes a method for synthesizing benzothiazole sulfenamide from MBT and amines, in which MBT is particularly solid in a solvent containing water and an organic substance (alcohol) mixed with water and amine and NaOCl as an oxidizing agent. It is characterized by feeding in the state. However, this also makes it difficult to add 2-mercaptobenzothiazole in a particularly solid state and has a disadvantage in that a large amount of benzothiazole disulfide is produced.

U.S. Patent No. 2,930,794 discloses that in synthesizing N-cycloalkyl benzothiazole sulfenamide, N-dicyclohexylamine is oxidized with NaOCl to form N-chlorodicyclohexylamine, and 2-mer using acetone as a solvent. A sodium salt of captobenzothiazole is added dropwise to synthesize it. However, this is characterized by using the sodium salt of 2-mercaptobenzothiazole as a raw material, the acetone used as a solvent is expensive, easy to recover and has a disadvantage in that a large amount of dibenzothiazyl disulfide is produced.

As described above, the conventional manufacturing method has disadvantages such as using a large amount of expensive amine, using an expensive solvent, using dangerous chlorine, or containing a large amount of benzothiazole disulfide in the product.

It is an object of the present invention to use N, N-dicyclohexyl-2-benzothia without using a large amount of expensive amines, using expensive solvents, using hazardous chlorine to handle, or producing large amounts of benzothiazole disulfide. It is to provide a method for preparing sol sulfenamide.

In order to achieve the above object, the present invention provides 2-mercaptobenzothiazole (MBT), N-chlorodicyclohexylamine, and alkali metal salt or alkali of carboxylic acid in an alcohol solvent. Reacting the earth metal salt to produce N, N-dicyclohexyl-2-benzothiazole sulfenamide; Water is added to precipitate N, N-dicyclohexyl-2-dibenzothiazole sulfenamide.

The reaction scheme of the reaction step is represented by the following formula (I).

The N-chlorodicyclohexylamine used here as a reactant is obtained by reacting dicyclohexylamine with NaOCl. In the present invention, N-chlorodicyclohexylamine is a starting material, and in the known technology, an intermediate is different from the known technology for reacting excess amine. This makes it possible to use only an appropriate amount of amine based on the final target of N-chlorodicyclohexylamine, eliminating the need to separate the amine from the final product and reducing the production of by-products (especially benzothiazole disulfide).

The process of obtaining N-chlorodicyclohexylamine by reacting dicyclohexylamine with NaOCl is easy and the yield is high, and the effectiveness of this invention is ensured.

The alcohol used as the solvent is selected from the group consisting of C ₁ to C ₃ alcohols, that is, methanol, ethanol, propyl alcohol and isopropyl alcohol.

Alkali or alkaline earth metal salts of carboxylic acids are selected from the group consisting of Na ₂ CO ₃ , NaHCO ₃ and CaCO ₃ , which react with chlorine in the N-chlorodicyclohexylamine molecule to form chlorides of alkali or alkaline earth metals. It is dissolved in water and removed at the precipitation stage.

The reaction is to be carried out at 40 to 80 ℃ and preferably at 50 to 65 ℃.

The raw material is added so that the equivalent ratio of 2-mercaptobenzothiazole: N-chlorodicyclohexylamine is 1: 1 to 1: 1.3.

In addition, the raw material is added so that the equivalent ratio of 2-mercaptobenzothiazole: carboxylic acid alkali metal salt or alkaline earth metal salt may be 1: 1-1: 1.3.

The amount of water added in the precipitation step is added so that the weight ratio of alcohol and water is 1: 1 to 4: 1, preferably 2: 1 to 3: 1.

If the amount of alcohol is small, N-chlorodicyclohexylamine, which remains unreacted, is precipitated together with N, N-dicyclohexyl-2-dibenzothiazole sulfenamide as the final object, and if the amount of water is small, alkali metal or alkali Chloride of earth metal precipitates together with the final target.

The configuration of the present invention will be apparent in the following examples.

<Example 1>

35.29 g (0.211 mol) of 2-mercaptobenzothiazole, 54.63 g (0.253 mol; 1.2 eq.) Of N-chlorodicyclohexylamine and 13.42 g (0.127 mol; 0.6 eq.) Of Na ₂ CO ₃ were added to 200 g of methanol. After mixing well, the reaction mixture was heated to 65 ° C. for 2 hours, cooled to 10 ° C., and slowly added 100 g of water while stirring to precipitate N, N-dicyclohexyl-2-dibenzothiazole sulfenamide.

The precipitated product was washed three times with water and dried in an oven at 60 ° C., yielding 68.89 g of N, N-dicyclohexyl-2-dibenzothiazole sulfenamide with a purity of 98.95%, yielding 94.2% of theory. . Purity was measured by HPLC.

<Example 2>

In Example 1 was conducted in the same manner was used instead of Na ₂ CO ₃ 13.42g, sodium bicarbonate (NaHCO ₃₎ 20g.

71 g of N, N-dicyclohexyl-2-dibenzothiazole sulfenamide with 98.50% purity were obtained, and the yield was 96.9% of theory.

<Example 3>

It was carried out in the same manner as in Example 1 and used isopropyl alcohol instead of methanol. Reaction temperature was 55 degreeC and reaction time was 4 hours.

70 g of N, N-dicyclohexyl-2-dibenzothiazole sulfenamide with 99.10% purity was obtained and the yield was 95.5% of theory.

<Example 4>

It was carried out in the same manner as in Example 2 and used isopropyl alcohol instead of methanol. The reaction temperature was 70 deg. C and the reaction time was 2 hours.

67 g of N, N-dicyclohexyl-2-dibenzothiazole sulfenamide of 98.90% were obtained, and the yield was 91.5% of theory.

Comparative Example 1

N, N-dicyclohexyl-2-dibenzothiazole sulfenamide was synthesized by the method described in US Pat. No. 2,930,794.

50 g (0.232 mol, 1.1 eq. For MBT) of N-chlorodicyclohexylamine, which was presynthesized, was mixed with 100 g of acetone, and heated to 35 ° C., and 35.29 g (0.211) of sodium salt of 2-mercaptobenzothiazole was stirred. mol), NaOH 18.57g (0.232mol) and water 50g were mixed and added dropwise over 1 hour, and then aged at 35 ° C for 30 minutes and 45 ° C for 30 minutes.

The product was filtered, washed once with 100 ml of 2% acetic acid aqueous solution, twice with 100 ml of pure water, and dried in an oven at 60 ° C. Yield 80% and purity 94.6%.

Comparing Comparative Example 1 with the examples of the present invention, it can be seen that the yield of the present invention is remarkably high and the purity is high despite the simple process.

Comparative Example 2

N, N-dicyclohexyl-2-dibenzothiazole sulfenamide was synthesized from dicyclohexylamine and 2-mercaptobenzothiazole by the method described in EP 314,663.

58.7 g (0.324 mol) of dicyclohexylamine was mixed with 250 g of water and 170 g of isopropanol, and heated to 55 ° C., followed by stirring 60.2 g (0.36 mol) of solid 2-mercaptobenzothiazole and 12.05% NaOCl aqueous solution 222.4 while stirring g (0.36 mol) was added dropwise simultaneously.

After dropping, the mixture was aged at 55 ° C. for 30 minutes, and an aqueous Na ₂ SO ₃ solution (2.9 g of Na ₂ SO ₃ + 14.4 g of water) was added thereto, followed by cooling to 20 ° C.

The product was filtered, washed twice with 170 g of 76% isopropanol aqueous solution and 650 g of pure water and dried in an oven at 60 ° C. Yield was 80.95%, purity 71.95%, and dibenzothiazyl disulfide produced 25%.

Based on the synthesis of N, N-dicyclohexyl-2-benzothiazole sulfenamide as a target from dicyclohexylamine, N-chloro, which is a starting material of the present invention, is compared with Example 2 of the present invention. Dicyclohexylamine can be obtained in a yield of more than 99% of theory by a known method from dicyclohexylamine and NaOCl, it can be seen that the embodiments of the present invention produced much less impurities than Comparative Example 2.

Since all the raw materials are added and reacted at the same time, the process is simple and the production of by-product dibenzothiazyl disulfide is minimized, so that a high purity target product can be obtained in high yield.

In addition, since the amine is not included in the final product because the amine is not used as a raw material, the amount of expensive amine is minimized, and a separate amine separation process is not required, and the product is easily separated.

Claims (7)

Reacting N-chlorodicyclohexylamine with 2-mercaptobenzothiazole and an alkali metal or alkaline earth metal salt of carboxylic acid in an alcohol solvent; A method for producing N, N-dicyclohexyl-2-dibenzothiazole sulfenamide comprising the step of precipitating N, N-dicyclohexyl-2-dibenzothiazole sulfenamide produced by adding water. The preparation of N, N-dicyclohexyl-2-dibenzothiazole sulfenamide according to claim 1, wherein the alcohol used as the solvent is selected from the group consisting of methanol, ethanol, propyl alcohol and isopropyl alcohol. Way. The N, N-dicyclohexyl-2-dibenzothiazole sulfenamide of claim 1, wherein the alkali metal or alkaline earth metal salt of carboxylic acid is selected from the group consisting of NaCO ₃ , NaHCO ₃ and CaCO ₃ . Manufacturing method. The method for producing N, N-dicyclohexyl-2-dibenzothiazole sulfenamide according to claim 1, wherein the reaction is performed at 40 to 80 ° C. The N, N-dicyclohexyl-2-di according to claim 1, wherein the equivalent ratio of 2-mercaptobenzothiazole: N-chlorodicyclohexylamine is 1: 1 to 1: 1.3. Process for preparing benzothiazole sulfenamide. The N, N-dicyclohexyl-2 according to claim 1, wherein the equivalent ratio of 2-mercaptobenzothiazole: alkali metal salt or alkaline earth metal salt of carboxylic acid is 1: 1 to 1: 1.3. Method for preparing dibenzothiazole sulfenamide. The N, N-dicyclohexyl-2-dibenzothiazole sulfenamide according to claim 1, wherein the amount of water introduced in the precipitation step is added so that the weight ratio of alcohol and water is 1: 1 to 4: 1. Manufacturing method.