JPS5824576A - Preparation of 2-mercaptobenzothiazole - Google Patents

Abstract

PURPOSE:To obtain the titled substance useful as a vulcanization accelerator, etc. effectively in high yield without producing industrial wastes, by adding impure substances contained in a raw reaction product obtained by reacting aniline with carbon disulfide and sulfur to raw materials for preparing the titled compound, dissolving it under heating. CONSTITUTION:Aniline is reacted with carbon disulfide and sulfur at high temperature under high pressure, to give raw 2-mercaptobenzothiazole. A tar substance consisting of unreacted aniline and sulfur separated from the raw 2- mercaptobenzothiazole (2-MBT for short) and a mixture of by-products in the reaction is blended with one or more of aniline, carbon disulfide, and S necessary for the following preparation of 2-MBT, and, if necessary, it is heated, dissolved, reacted at high pressure at high temperature, to give the desired compound in high yield.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides aniline, carbon disulfide and sulfur at high temperature.
A tar-like substance consisting of unreacted aniline, sulfur, and a mixture of several reaction by-products was collected from the crude 2-mercaptobenzothiazole (hereinafter abbreviated as 2-MBT) obtained by the reaction under high pressure. Any one of aniline, carbon disulfide, and sulfur necessary for the production of 2-MBT
A method for producing 2-MBT, which comprises mixing one or two types of 2-MBT, heating, stirring and dissolving as necessary, and then reacting at a high temperature with a high temperature in a conventional manner. The object relates to a method for producing 2-MBT in high yield.

2-MBT is an important rubber vulcanization accelerator and also
Dibenzothiazyl disulfide derived from 2-MBT and several sulfenamide promoters are produced. Currently, these thiazole-based accelerators are the most consumed and important vulcanization accelerators for natural and synthetic rubbers, and their parent substance 2-MBT.
A large number of patent documents have been published regarding the manufacturing method.

For example, in PB REBO-) BIO3, N011124,
Both the raw material aniline and a carbon disulfide solution containing sulfur were continuously charged into an autoclave, and the reaction temperature was 250°C.
A method is described in which 2-MBT is obtained by reacting at ~280° C. and a reaction pressure of 150° C., dissolving the produced crude 2-MBT in an alkali, separating impurities, and then performing acid precipitation. Also, Usp, No. 1631875, Rubber Age, 89
Vol., No. 3, p. 453 (1961) describes a low-pressure reaction method in which aniline, carbon disulfide, and sulfur are
C, the reaction force was maintained at 30 Kg/cJ while successively discharging hydrogen sulfide gas produced as a by-product during the reaction, and 2-M
A method of manufacturing BT is described.

Furthermore, in USP No. 2090233, No. 3030373, No. 3031073, etc., after reacting aniline, carbon disulfide and sulfur at high temperature under high temperature, crude 2-M
A method of purifying BT by adding a surfactant and adding it to a solution of carbon disulfide dispersed in water, dissolving 2-MBT in an alkali, and obtaining 2-MBT by acid precipitation, crude 2
- A method is described in which MBT is charged into an autoclave again, carbon disulfide is added thereto, and purification is carried out by heating at 140 to 150°C for 130 to 40 minutes. Despite the publication of numerous documents and patents, 1,2-MBT
The yield is about 80-85%.

Impurities produced as by-products during the production of 2-MBT include phenylisothiocyanate, anilinobenzothiazole, diphenylthiourea, 0-aminothiophenol, and benzothiazole.

However, the most distinctive feature of the present invention is that it also includes matters relating to the handling of tar-like impurities of unknown composition. Literature and patents have also reported methods for recovering and reusing the above-mentioned phenylisothiocyanate, anilinobenzothiazole, diphenylthiourea, 0-aminothiophenol, and benzothiazole other than tar-like impurities by distillation, extraction, etc. However, industrial recovery of these substances poses various problems in terms of equipment and operations, and cannot be said to be a substantially effective means.

Furthermore, in the USP No. 3031073, aniline,
Carbon disulfide and sulfur were reacted in a conventional manner, and after the reaction was completed (cooled to double temperature, crude 2-MBT was taken out, carbon disulfide was added to this crude 2-MBT, and the mixture was charged into the autoclave again for 150 ℃, pressure of about 10M4, 30
After reacting for ~40 minutes, it is cooled again and carbon disulfide is separated to obtain 2-MBT.The separated carbon disulfide is concentrated to remove by-product impurities. It is stated that the amount of nitrogen and sulfur in the 2-MBT is analyzed and then used again for production of 2-MBT; however, the production process for 2-MBT is complicated, and due to the handling of solid materials, it is difficult to carry out the process due to the equipment. There are various problems with the operation, and industrial 2-
This cannot be said to be a practically effective method for manufacturing MBT.

We decided to use 2-MB from the standpoint of saving resources and reducing costs.
As a result of various studies to improve the yield of T, 2-MBT
Considering the shape and composition of impurities by-produced during production or impurities generated during purification of 2-MBT, it was discovered that these could be efficiently used as raw materials for the production of 2-MBT in the following manner. C: Complete the present invention. 1. The total amount of by-product impurities is mixed with 1 of the aniline necessary for producing 2-MBT, and this is mixed with 40 to 13
The mixture is stirred and dissolved at a temperature of 0° C. for 30 to 90 minutes and subjected to reaction. It is added to a mixture of the entire amount of by-product impurities, pure sulfur and aniline necessary for the production of 2-MBT, heated, stirred and dissolved, and subjected to reaction.

3. All of the by-produced impurities are stirred and dissolved in the carbon disulfide necessary for the production of IJ2-MBT (at a temperature of 40°C or less), and subjected to the reaction. 4. The total amount of by-product impurities is 2-
The mixture is added to a mixture of sulfur and carbon disulfide in an amount necessary for producing MBT (at a temperature of 40° C. or lower), stirred and dissolved, and subjected to reaction. 5. The entire amount of by-product impurities is dissolved in the required amount of carbon disulfide (2-
Aniline in an amount necessary for producing MBT is added and the mixture is immediately subjected to reaction. It has been found that by the above method, by-product impurities can be efficiently used as a raw material for producing 2-MBT.

To summarize the features of the present invention, firstly, by performing the reaction after dissolving the entire amount of by-product impurities in each reaction raw material, the yield is dramatically increased, and the yield relative to aniline is 94%.
~96% 2-MBT is obtained. Second, 2-MB
By dissolving the by-product of T in the manufacturing raw material, 2-MB
All by-products can be used regardless of the production method or purification method of T. Third, by-products obtained when crude 2-MBT is dissolved in alkali and purified can also be dissolved in the production raw material. If the water is separated by using 4C, it can be used in the reaction without any problems. 4C2: Even if the by-products are used in the reaction, no increase in by-products is observed after the reaction, and no problem occurs even if the by-products are used repeatedly. No.Fifth, the quality of the obtained 2-MBT is the same as that of one without the addition of by-products, and there is no problem.Sixth, the by-products of 2-MBT are dissolved in the manufacturing raw materials. Because it can be handled as a liquid, it can be easily charged using a pump regardless of whether the reaction equipment is a batch type or a continuous type.
No waste is produced during the manufacturing process.

Hereinafter, as shown in L, the present invention has two advantages that are extremely advantageous in terms of economy, yield, quality, and operability.
- A method for manufacturing MBTn is provided.

That is, the present invention involves separating by-product impurities contained in crude 2-MBT obtained by reacting aniline, carbon disulfide, and sulfur from crude 2-MBT, and producing Prefectural fee (2-M B T after adding and heating, melting)
The present invention relates to a method for obtaining high-yield, high-purity 2-MBT by recycling it into the reaction, but what is noteworthy is that industrial waste, which was difficult to dispose of, is no longer used.

Next, the method of the present invention will be explained in detail with reference to Examples, but the present invention is not limited to the following Examples unless the gist thereof is exceeded.

Example 1 Aniline 3000P, carbon disulfide 318.7y, and sulfur 113°5Li were charged into an autoclave with content 11 equipped with a pressure gauge, temperature regulator, gas release valve, and safety valve.
The crude 2-MBT obtained by the reaction for 2 hours at 250°C and 13oKV-pressure was pulverized and poured into 11 carbon disulfide, and unreacted substances and side reaction products were extracted at room temperature for 60 minutes. It was filtered to obtain 2-MBT powder and extract.

2-MBT powder was dried, 48% caustic soda aqueous solution 220 g and water were added, stirred and dissolved, insoluble substances were filtered off, and 10% sulfuric acid was added to the sodium salt of 2-MBT. In addition, when the mixture was made into an acidic aqueous solution, a pale yellow precipitate was deposited. After filtration, washing and drying, melting point 178-1
81°C, pale yellow 2-MBT with purity 99.0%
435.39 was obtained. The yield based on aniline was 80. ．． 8%
Met.

Carbon disulfide was recovered from the extract by distillation, and a tar-like distillation residue 887 was obtained. Aniline 3007 heated to 70°C was added to the resulting 88 g of tar-like by-product,
Stir for 30 minutes to dissolve, carbon disulfide 318.79
, charged in an autoclave with sulfur 113.59, 2
The reaction was carried out for 2 hours at 50°C and a pressure of 130 yen. The 2-MBT obtained by this reaction was purified in the same manner as above to obtain 2-MBT513.2F as a pale yellow powder having a melting point of 177-180°C and a purity of 98.6%. The yield based on ani-phosphorus C2 was 95.2%.

Example 2 A carbon disulfide extract of crude 2-MBT obtained by the same operation as in Example 1 was distilled to obtain a tar-like byproduct 9 (l).This tar-like substance 907 and the sulfur surface 113. 5P, 80
300 g of aniline heated to 300 °C, heated for 60 minutes, stirred, and dissolved, and charged into an autoclave with 318.79 carbon disulfide, 250 °C, pressure 130 K9/c1. Then, the reaction was carried out for 2 hours. The obtained 2-MBT was purified as described above to obtain pale yellow 2-MBT 515.5 F having a melting point of 177-180°C and a purity of 988%. The yield for aniline was 957%. Example 3 Tar-like byproduct 85 obtained by the same operation as Example 1.
Aniline 3007 and sulfur 1113.59
and put it in an autoclave at 230°C1 pressure 11
The reaction was carried out at 0 K9/d for 2 hours. Obtained crude 2
- MBT was purified as described above, melting point 177-180 °C
, pale yellow 2-MBT510.7 with purity 988%
I got a 7. The yield for aniline was 94.8%.

Example 4 Tar-like substance 88y obtained by the same operation as Example 1 and powdered sulfur 113.59 were mixed with carbon disulfide 31B, 7 at 30°C.
Stir and dissolve in f for 10 minutes, charge in an autoclave with aniline 3002, and at 230°C and pressure 1101,
The reaction was allowed to proceed for 2 hours. The resulting crude 2-MBT was purified as described above to obtain pale yellow 2-MBT514.19 having a melting point of 177-180°C and a purity of 98.7%. The yield based on aniline was 95.4%.

Example 5 87 g of a tar-like substance obtained by the same operation as in Example 1 was mixed with sulfur heated to 120°C, and aniline 3002,
It was charged into an autoclave with 318.7 fi' of carbon disulfide and reacted. The resulting crude 2-MBT was purified as described above to obtain pale yellow 2-MBT513.99 with a melting point of 177-180°C and a purity of 98.6%. The yield based on aniline was 95.4%.

Example 6 In an autoclave, 300y of aniline, 31y of binary carbon
8.7Ii, 230℃ with 113.5g of sulfur
The crude 2-MBT obtained by reacting for 2 hours at a pressure of 110 Krcd was dissolved in 48% caustic soda 2652 and 10% water, and a moderate amount of 20% sulfuric acid was added during air stirring to precipitate a tar-like substance. Thereafter, it is filtered, washed, and separated from the sodium salt of 2-MBT. By neutralization, the sodium salt of 2-MBT has a melting point of 178-182°C and a purity of 98.9%.
A pale yellow 2-MBT431.77 was obtained. The yield based on aniline was 801%. The separated tar-like substance is
The reaction by-product of 91y was dried, dissolved in aniline 300Li heated to 70°C with stirring for 60 minutes, and charged into an autoclave with 318.75i' of carbon disulfide and 113.5P of sulfur at 220°C and pressure of 96°C. KIcA
Then, the reaction was carried out for 2 hours. Crude 2-MBT was purified in the same manner as in Example 1, with a melting point of 177-180°C and a purity of 98.8%.
A pale yellow 2-MBT512.4 having the following properties was obtained. The yield based on aniline was 951%.

Claims (1)

[Claims] A tar-like substance consisting of a mixture of unreacted aniline, sulfur, and several reaction by-products is collected from crude 2-mercaptobenzothiazole, which is obtained by reacting aniline, carbon disulfide, and sulfur at high temperature and high pressure. , the next 2-
Aniline, required for the production of mercaptobenzothiazole,
2-mercapto, which is characterized in that one or two of carbon disulfide and sulfur are mixed, heated and stirred as necessary, dissolved, and then reacted at high temperature and under controlled pressure using a textile method. Method for producing benzothiazole,