JPH0352461B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention is based on the general formula () (In the formula, R ₁ is a hydrogen atom or a lower alkyl group, R ₂ is a hydrogen atom, a lower alkyl group, a lower alkenyl group, a lower alkynyl group, a cycloalkyl group, an aralkyl group, or an aryl group, and R ₃ is a hydrogen atom or The present invention relates to a 2,2,6,6-tetramethylpiperidine derivative represented by (representing a methyl group), a method for producing the same, and a rubber additive containing the same as an active ingredient. Natural and synthetic rubbers such as styrene-butadiene rubber, nitrile rubber, butadiene rubber,
Various vulcanization accelerators are used for sulfur vulcanization of isoprene rubber, etc., but most of them are sulfenamides such as N-cyclohexylbenzothiazyl-2-sulfenamide and N-t-butylbenzothiazyl-2-sulfenamide. It is a derivative. However, these sulfenamide derivatives have the disadvantage that they cause color staining on vulcanized rubber products and are generally difficult to use for white to brightly colored products. As a result of various studies to solve these problems, the present inventors found that the 2,2,6,6-tetramethylpiperidine derivative represented by the general formula () is colorless and non-staining. The present inventors have discovered that it is useful as a vulcanization accelerator, and that vulcanized rubber products made from it have excellent ozone resistance and other excellent properties as a rubber additive, leading them to complete the present invention. . The 2,2,6,6-tetramethylpiperidine derivative represented by the general formula () is a new compound synthesized by the present inventors for the first time and has not been described in any literature. (wherein R ₁ and R ₂ have the same meanings as above) and a 2,2,6,6-tetramethylpiperidine compound represented by the general formula () (In the formula, R ₃ has the same meaning as above.) It can be produced by reacting a 2-mercaptobenzothiazole compound represented by the following formula. In each of the above formulas, the substituent R ₁ is a hydrogen atom or a lower alkyl group, and examples of the lower alkyl group include methyl, ethyl, and propyl. The substituent R ₂ is a hydrogen atom, a lower alkyl group, a lower alkenyl group, a lower alkynyl group, a cycloalkyl group, an aralkyl group, or an aryl group. In addition to unsubstituted lower alkyl groups such as methyl, ethyl, propyl, and butyl, the lower alkyl group referred to herein may be substituted. Examples of such substituted lower alkyl groups include, for example, 2-hydroxyethyl. hydroxyalkyl groups such as 2-ethoxyethyl and ethoxymethyl, aryloxyalkyl groups such as 2-phenoxyethyl, and aromatic or aliphatic aryl groups such as 2-benzoyloxyethyl and 2-acetoxyethyl. Examples include a siloxyalkyl group, a halogenoalkyl group such as 2-chloroethyl, a cyanoalkyl group such as 2-cyanoethyl and cyanomethyl, and an alkoxycarbonylalkyl group such as ethoxycarbonylmethyl and 2-methoxycarbonylethyl. The lower alkenyl group represented by R ₂ may be an unsubstituted lower alkenyl group such as allyl, or a substituted lower alkenyl group. Examples of such substituted lower alkenyl groups include 2-ethoxycarbonylvinyl and 1-methyl- Examples include alkoxycarbonylalkenyl groups such as 2-methoxycarbonylvinyl.
In addition, the lower alkynyl group represented by R ₂ is:
Examples include 2-propynyl, cycloalkyl groups include cyclohexyl, aralkyl groups include benzyl, p-methylbenzyl, p-chlorobenzyl, and aryl groups include phenyl. In addition, o-, m- or p-tolyl, o-, m
- or p-methoxyphenyl, α- or β-naphthyl, and the like. Furthermore, R ₃ in each of the above formulas is a hydrogen atom or a methyl group. In these reaction raw materials, 4-amino-2,
2,6,6-tetramethylpiperidine is produced by converting 4-oxo-2,2,6,6-tetramethylpiperidine, which is obtained by reacting acetone and ammonia, into oxime and then reducing it. obtained, 1-lower alkyl-4-amino-
2,2,6,6-tetramethylpiperidine is 4
-1-lower alkyl-4-oxo- obtained by reacting oxo-2,2,6,6-tetramethylpiperidine with an alkyl halide corresponding to each alkyl group in the presence of a deoxidizer.
It is obtained by converting 2,2,6,6-tetramethylpiperidine into an oxime and then reducing it. In addition, the compound in which the substituent R ₂ represents a group other than a hydrogen atom is 4-amino-2,2,6,6-tetramethylpiperidine or 1-lower alkyl-4-
It is obtained by reacting amino-2,2,6,6-tetramethylpiperidine with the corresponding halide in the presence of an acid absorbing agent. In addition, the 2-mercaptobenzothiazole compound represented by the general formula () is specifically 2-mercaptobenzothiazole, 2-mercapto-4-
Methylbenzothiazoles, which are obtained by reacting aniline or o-toluidine with carbon disulfide and sulfur in a known manner. 2,2,6,6- represented by the general formula ()
The reaction between the tetramethylpiperidine compound and the 2-mercaptobenzothiazole compound represented by the general formula () is carried out in an aqueous solution, and 2,2,6,
The 6-tetramethylpiperidine compound is used in the form of an acid addition salt such as hydrochloric acid, sulfuric acid, p-toluenesulfonic acid, or the like. On the other hand, the 2-mercaptobenzothiazole compound is used in the form of an alkali metal salt such as sodium or potassium. The reaction is carried out in the presence of an oxidizing agent. The oxidizing agent used is one that is generally used in oxidation reactions, and suitable examples include hydrogen peroxide, sodium hypochlorite, and iodine. The amount of oxidizing agent used is about 1 to 1.5 molar equivalents, preferably about 1 to 1.1 molar equivalents, relative to the 2,2,6,6-tetramethylpiperidine compound. Further, the reaction molar ratio between the 2,2,6,6-tetramethylpiperidine compound and the 2-mercaptobenzothiazole compound is usually 1:0.8 to 1.3. The reaction is usually carried out at a temperature of 10 to 50°C, preferably 10 to 20°C. The reaction is preferably carried out using a solution of an alkali metal salt of a 2-mercaptobenzothiazole compound dissolved in water while the 2,2,6,6-tetramethylpiperidine compound is dissolved in water in the form of an acid addition salt. This is carried out by simultaneously dropping an aqueous solution of an oxidizing agent. After the completion of the reaction, the product can be separated and collected from the reaction mixture according to a conventional method, for example, the reaction mixture is filtered, the filtrate is dried, and then recrystallized with an appropriate solvent to obtain a pure target product. can. Representative examples of the piperidine compounds of the present invention that can be produced in this manner are shown in the following table.

【table】

【table】

[Table] When using such 2,2,6,6-tetramethylpiperidine derivatives as rubber additives, they can be used not only in natural rubber but also in styrene-butadiene copolymer rubber, acrylonitrile-butadiene copolymer rubber, It is added to synthetic rubbers such as polybutadiene, polyisoprene, polychloroprene, and ethylene-propylene copolymer rubber. The amount added to rubber is usually 0.3 to 7 parts by weight, and it can be used in the same manner as ordinary vulcanization accelerators or ozone deterioration inhibitors. Of course, during use, other vulcanization accelerators, ozone deterioration inhibitors, or antiaging agents can be used in combination depending on the respective conditions and purposes. Thus, the 2,2,6,6-tetramethylpiperidine derivative of the present invention has excellent effects on accelerating vulcanization and preventing ozone deterioration, and exhibits excellent effects as an additive for rubber. The present invention will be explained below with reference to Examples. Example 1 Production of N-(2,2,6,6-tetramethyl-4-piperidyl)benzothiazyl-sulfenamide 5.0 g (0.032 mol) of 4-amino-2,2,6,6-tetramethylpiperidine was added to 30% by weight % aqueous sulfuric acid solution (0.018 mol), and 5.7 g of sodium salt of 2-mercaptobenzothiazole was dissolved in this.
(0.030 mol, dissolved in 30 ml water) and 14.4% by weight
At the same time, 18.2 g (0.035 mol) of an aqueous solution of sodium hypochlorite was added dropwise over a period of 1 hour. The temperature inside the flask at this time was 40°C. After cooling, the resulting solid was separated, washed with water, and dried at a temperature of 50°C for 12 hours to obtain the desired product as white crystals with a melting point of 137-138°C.
get g. Yield: 93% The parent ion peak in the mass spectrum was 321. Elemental analysis value C(%) H(%) N(%) S(%) Calculated value 59.8 7.2 13.1 19.9 (as C ₁₆ H ₂₃ N ₃ S ₂ ) Experimental value 59.5 7.2 13.1 19.7 Example 2 N-(1, 2,2,6,6-pentamethyl-4
-Piperidyl) Production of 6-methylbenzothiazyl-sulfenamide 5.5 g (0.032 mol) of 4-amino-1,2,2,6,6-pentamethylpiperidine was dissolved in 5.9 g (0.018 mol) of a 30% by weight aqueous sulfuric acid solution. And this 2-
6.7 g (0.033 mol, dissolved in 30 ml of water) of the sodium salt of mercapto-4-methylbenzothiazole and a 14.4% by weight aqueous solution of sodium hypochlorite
18.2 g (0.035 mol) was reacted in exactly the same manner as in Example 1, and post-treatment was performed to obtain a melting point of 127-128°C.
10.5 g of the desired product was obtained as white crystals. Yield: 91% The parent ion peak in the mass spectrum was 349. Elemental analysis value C(%) H(%) N(%) S(%) Calculated value 61.8 7.8 12.0 18.3 (as C ₁₈ H ₂₇ N ₃ S ₂ ) Experimental value 61.5 7.7 11.7 18.2 Example 3 N-Methyl-N -Production of (2,2,6,6-tetramethyl-4-piperidyl)benzothiazyl-sulfenamide 5.5 g (0.032 mol) of 4-methylamino-2,2,6,6-tetramethylpiperidine was dissolved in a 30% by weight aqueous sulfuric acid solution. Dissolved in 6.0g (0.018mol) and added 2
-Sodium salt of mercaptobenzothiazole
5.7g (0.030 mol, dissolved in 30ml water) and
18.0g of 14.4% by weight sodium hypochlorite aqueous solution
(0.035 mol) was reacted in exactly the same manner as in Example 1 and post-treated to obtain 9.1 g of the desired product as white crystals with a melting point of 140-142°C. Yield: 90% The parent ion peak in the mass spectrum was 335. Elemental analysis value C(%) H(%) N(%) S(%) Calculated value 60.8 7.5 12.5 19.1 (as C ₁₇ H ₂₅ N ₃ S ₂ ) Experimental value 61.1 7.5 12.4 18.7 Example 4 N-Methyl-N -(1,2,2,6,6-pentamethyl-4-piperidyl)benzothiazyl-
Production of sulfenamide 5.9 g (0.032 mol) of 4-methylamino-1,2,2,6,6-pentamethylpiperidine was dissolved in 6.0 g (0.018 mol) of a 30% by weight aqueous sulfuric acid solution, and 2-mercaptobenzothiazole was added to the solution. 6.1 g (0.032 mol, dissolved in 30 ml water) of the sodium salt of
18.0g of 14.4% by weight sodium hypochlorite aqueous solution
(0.035 mol) was reacted in exactly the same manner as in Example 1 and post-treated to obtain 10.5 g of the desired product as white crystals with a melting point of 139-140°C. Yield: 94% The parent ion peak in the mass spectrum was 349. Elemental analysis value C(%) H(%) N(%) S(%) Calculated value 61.8 7.8 12.0 18.3 (as C ₁₈ H ₂₇ N ₃ S ₂ ) Experimental value 61.9 7.7 11.8 18.2 Example 5 N-(2- hydroxyethyl)-N-(2,2,
Production of 6,6-tetramethyl-4-piperidyl)benzothiazyl-sulfenamide 4-(2-hydroxyethyl)amino-2,2,
6.4 g (0.032 mol) of 6,6-tetramethylpiperidine was dissolved in 6.0 g (0.018 mol) of a 30% by weight aqueous sulfuric acid solution, and 5.7 g (0.030 mol) of the sodium salt of 2-mercaptobenzothiazole was dissolved in 30 ml of water. ) and 18.0 g (0.035 mol) of a 14.4% by weight aqueous sodium hypochlorite solution were reacted in exactly the same manner as in Example 1, post-treated, and recrystallized from alcohol to form a compound with a melting point of 148-149°C. 9.2 g of the desired product was obtained as white crystals. Yield: 83% The parent ion peak in the mass spectrum was 367. Elemental analysis value C(%) H(%) N(%) S(%) Calculated value 59.1 7.5 11.5 17.5 (as C ₁₈ H ₂₇ N ₃ S ₂ O) Experimental value 59.3 7.7 11.2 17.2 Example 6 N-ethoxymethyl -N-(2,2,6,6-
Production of tetramethyl-4-piperidyl)benzothiazyl-sulfenamide 4-ethoxymethylamino-2,2,6,6-
Tetramethylpiperidine 6.9g (0.032mol) 30
Dissolved in 6.0g (0.018mol) of wt% sulfuric acid aqueous solution.
5.7 g (0.030 mol, dissolved in 30 ml water) of sodium salt of 2-mercaptobenzothiazole and 4.0 g (0.035 mol) of 30% by weight hydrogen peroxide were added to a 100 ml flask over a period of 1 hour. It's dripping down. At this time, reduce the temperature inside the flask to 0.
Keep at ~10°C. After the temperature was returned to room temperature, the same post-treatment as in Example 1 was carried out to obtain 10.6 g of the desired product as white crystals with a melting point of 150 to 151°C. Yield: 93% The parent ion peak in the mass spectrum was 379. Elemental analysis value C(%) H(%) N(%) S(%) Calculated value 60.1 7.7 11.1 16.9 (as C ₁₉ H ₂₉ N ₃ S ₂ O) Experimental value 59.8 7.7 10.8 17.2 Example 7 N-(2 -cyanoethyl)-N-(2,2,6,
Production of 6-tetramethyl-4-piperidyl)benzothiazyl-sulfenamide 4-(2-cyanoethyl)amino-2,2,6,
6-tetramethylpiperidine 6.7g (0.032mol)
was dissolved in 6.0 g (0.018 mol) of a 30% by weight aqueous sulfuric acid solution, and 6.1 g (0.032 mol, dissolved in 30 ml of water) of the sodium salt of 2-mercaptobenzothiazole was dissolved in this.
and 4.0 g (0.035 mol) of 30% by weight hydrogen peroxide solution were reacted in exactly the same manner as in Example 6, post-treated, and recrystallized from alcohol to produce light yellow crystals with a melting point of 146-148°C. as an object
Obtain 9.0g. Yield: 75% The parent ion peak in the mass spectrum was 374. Elemental analysis value C(%) H(%) N(%) S(%) Calculated value 60.9 7.0 15.0 17.1 (as C ₁₉ H ₂₆ N ₄ S ₂ ) Experimental value 60.8 7.0 15.1 17.3 Example 8 N-ethoxycarbonylmethyl -N-(2,2,
Production of 6,6-tetramethyl-4-piperidyl)benzothiazyl-sulfenamide 4-ethoxycarbonylmethylamino-2,
2,6,6-tetramethylpiperidine 7.8g
(0.032 mol) in a 30% by weight sulfuric acid aqueous solution 5.2 g (0.016
5.7 g (0.030 mol, 30 ml) of the sodium salt of 2-mercaptobenzothiazole
(dissolved in water) and 18.0 g (0.035 mol) of a 14.4% by weight aqueous sodium hypochlorite solution were reacted in exactly the same manner as in Example 1, followed by post-treatment to form white crystals with a melting point of 153-154°C. Obtain 10.2g of the target product. Yield: 83% The parent ion peak in the mass spectrum was 407. Elemental analysis value C(%) H(%) N(%) S(%) Calculated value 58.9 7.2 10.3 15.7 (as C ₂₀ H ₂₉ N ₃ S ₂ O ₂ ) Experimental value 58.8 7.1 10.2 15.9 Example 9 N-allyl -N-(2,2,6,6-tetramethyl-4-piperidyl)benzothiazyl-sulfenamide 6.3 g (0.032 mol) of 4-allylamino-2,2,6,6-tetramethylpiperidine was added to 30% by weight sulfuric acid. Dissolved in 6.0 g (0.018 mol) of an aqueous solution and added 2
-Sodium salt of mercaptobenzothiazole
5.7g (0.030 mol, dissolved in 30ml water) and 14.4
Weight% sodium hypochlorite aqueous solution 18.0g
(0.035 mol) was reacted in exactly the same manner as in Example 1 and post-treated to obtain 9.4 g of the desired product as white crystals with a melting point of 131-132°C. Yield: 87% The parent ion peak in the mass spectrum was 361. Elemental analysis value C(%) H(%) N(%) S(%) Calculated value 63.1 7.5 11.6 17.7 (as C ₁₉ H ₂₇ N ₃ S ₂ ) Experimental value 63.0 7.8 11.3 17.9 Example 10 N-benzyl-N -Production of (2,2,6,6-tetramethyl-4-piperidyl)benzothiazyl-sulfenamide 7.9 g (0.032 mol) of 4-benzylamino-2,2,6,6-tetramethylpiperidine at 30% by weight
Sodium salt of 2-mercaptobenzothiazole was dissolved in 6.0 g (0.018 mol) of sulfuric acid and hydrogen sulfur solution.
5.7g (0.030 mol, dissolved in 30ml water) and 14.4
Weight% sodium hypochlorite aqueous solution 18.0g
(0.035 mol) was reacted in exactly the same manner as in Example 1 and post-treated to obtain 11.5 g of the desired product as pale brown crystals with a melting point of 139-140°C. Yield: 93% The parent ion peak in the mass spectrum was 411. Elemental analysis value C(%) H(%) N(%) S(%) Calculated value 67.1 7.1 10.2 15.6 (as C ₂₃ H ₂₉ N ₃ S ₂ ) Experimental value 66.9 7.1 10.2 15.9 Example 11 N-phenyl-N -Production of (2,2,6,6-tetramethyl-4-piperidyl)benzothiazyl-sulfenamide 7.4 g (0.032 mol) of 4-phenylamino-2,2,6,6-tetramethylpiperidine at 30% by weight
Sodium salt of 2-mercaptobenzothiazole was dissolved in 6.0 g (0.018 mol) of sulfuric acid aqueous solution.
6.1 g (0.032 mol, dissolved in 30 ml of water) and 4.0 g (0.035 mol) of 30% by weight hydrogen peroxide were reacted in exactly the same manner as in Example 6, and after treatment, a 11.1 g of the desired product was obtained as brown crystals. Yield: 88% The parent ion peak in the mass spectrum was 397. Elemental analysis value Calculated value 66.4 6.9 10.6 16.1 (as C ₂₂ H ₂₇ N ₃ S ₂ ) Experimental value 66.1 6.9 10.8 16.2 Example 12 N-(2-ethoxycarbonylvinyl)-N-
Production of (2,2,6,6-tetramethyl-4-piperidyl)benzothiazyl-sulfenamide 4-(2-ethoxycarbonylvinyl)amino-2,2,6,6-tetramethylpiperidine 8.2
g (0.032 mol) in 30% by weight sulfuric acid aqueous solution 5.2 g
(0.016 mol) and 5.7 g (0.030 mol, dissolved in 30 ml of water) of the sodium salt of 2-mercaptobenzothiazole and 18.0 g (0.035 mol) of a 14.4% by weight aqueous sodium hypochlorite solution were added to the solution. The reaction was carried out in exactly the same manner as in 1, followed by post-treatment, and the desired product was obtained as white crystals with a melting point of 128-129°C.
Obtain 10.1g. Yield: 80% The parent ion peak in the mass spectrum was 420. Elemental analysis value C(%) H(%) N(%) S(%) Calculated value 60.0 7.2 10.0 15.2 (as C ₂₁ H ₃₀ N ₃ S ₂ O ₂ ) Experimental value 59.9 7.1 10.2 15.2 In addition, 4-cyclohexylamino -2, 2, 6,
Example 1 was prepared using 6-tetramethylpiperidine and 2-mercaptobenzothiazole as raw materials, and using 4-(2-propyl)amino-2,2,6,6-tetramethylpiperidine and 2-mercaptobenzothiazole as raw materials, respectively. By reacting in a similar manner, N-cyclohexyl-N-(2,2,6,6-tetramethyl-4-piperidyl)benzothiazyl-sulfenamide and N-(2-propyl)-N-(2,2 ,6,6
-tetramethyl-4-piperidyl)benzothiazyl-sulfenamide can be prepared. Example 13 A rubber compound having the following compounding ratio was prepared using an open roll according to a conventional method. (Composition) Natural rubber 100 parts by weight Stearic acid 2〃 Zinc white 5〃 Light calcium carbonate 75〃 Process oil 10〃 Wax 3〃 Sulfur 2.5〃 Test sample Attachment〃 The obtained rubber compound was compliant with JIS K-6300. A Mooney scorch test was conducted to determine the vulcanization rate, and a rheometer vulcanization test was conducted to determine the vulcanization rate. In addition, press vulcanization was performed at a vulcanization temperature of 140℃ for 60 minutes, and JIS K
-6301, the hue and physical properties of vulcanized rubber and ozone deterioration tests were conducted. The ozone deterioration test was conducted in an ozone weather meter at an ozone concentration of 50 pphm, a temperature of 40°C, and a dynamic elongation rate of 20%.
The time until cracks that can be observed with the naked eye occur was measured. The results are shown in Table-1. The compound numbers used as test samples correspond to the compound numbers shown in the table in the text. In addition, CZ, OS means the following: CZ: Soxinol CZ, Sumitomo Chemical product (vulcanization accelerator) OS: Antigene OS, Sumitomo Chemical product (ozone deterioration inhibitor)

【table】

[Table] Example 14 A rubber compound having the following compounding ratio was prepared using an open roll according to a conventional method. (Composition) Styrene-butadiene rubber 100 parts by weight Stearic acid 3〃 Zinc white 5〃 HAF black 50〃 Process oil 5〃 Wax 3〃 Sulfur 2〃 Test sample Separate notes For the obtained rubber compound, Mooney was used in the same manner as in Example 13. A scorch test and a rheometer test were conducted. Further, press vulcanization was performed at a vulcanization temperature of 145° C. for 40 minutes, and the physical properties of the vulcanized rubber and ozone deterioration tests were conducted in the same manner as in Example 13. These results are shown in Table-2. Note that the test sample was the same as in Example 13.

【table】

【table】

Claims (1)

[Claims] 1. General formula (In the formula, R ₁ is a hydrogen atom or a lower alkyl group, R ₂ is a hydrogen atom, a lower alkyl group, a lower alkenyl group, a lower alkynyl group, a cycloalkyl group, an aralkyl group, or an aryl group, and R ₃ is a hydrogen atom or A 2,2,6,6-tetramethylpiperidine derivative represented by (representing a methyl group). 2 General formula (In the formula, R ₁ represents a hydrogen atom or a lower alkyl group, and R ₂ represents a hydrogen atom, a lower alkyl group, a lower alkenyl group, a lower alkynyl group, a cycloalkyl group, an aralkyl group, or an aryl group.) , 2,6,6-tetramethylpiperidine compound and the general formula (In the formula, R ₃ represents a hydrogen atom or a methyl group.) A general formula characterized by reacting a 2-mercaptobenzothiazole compound represented by (In the formula, R ₁ , R ₂ and R ₃ have the same meanings as above.) A method for producing a 2,2,6,6-tetramethylpiperidine derivative represented by the following formula. 3 General formula (In the formula, R ₁ is a hydrogen atom or a lower alkyl group, R ₂ is a hydrogen atom, a lower alkyl group, a lower alkenyl group, a lower alkynyl group, a cycloalkyl group, an aralkyl group, or an aryl group, and R ₃ is a hydrogen atom or An additive for rubber containing as an active ingredient a 2,2,6,6-tetramethylpiperidine derivative represented by (representing a methyl group).