CS257386B1 - A process for preparing 2-benzothiazole sulfenic acid morpholide - Google Patents

Abstract

The solution concerns the method of preparing 2-benzthiazolesulfenic acid morpholide of the formula I * (I) by oxidizing a solution or suspension of 2-mercaptobenzthiazole (2-MBT) in morpholine or in a morpholine-water mixture with hydrogen peroxide in a molar excess of 5 to 25% to the total substance amount of 2-MBT at a temperature of 5 to 40 °C. 2-MBT and an oxidizing agent are simultaneously added to the presented solution of 2-MBT in morpholine or in a morpholine-water mixture with a 2-MBT concentration of 2.5 to 40.0% by weight, which represents 10 to 75% of the total amount of 2-MBT entering the reaction, whereby the oxidizing agent is dosed over 3 to 12 hours and the 2-MBT dosing time is a maximum of 90 pere. oxidizing agent dosing times.

Description

The invention relates to a process for the preparation of 2-benzothiazolesulfonic acid morpholide of formula I

(i) oxidative condensation of 2-mercaptobenzothiazole and morpholine under the action of hydrogen peroxide. Said sulfenamide is used as a safe accelerator in vulcanizing mixtures of natural and butadiene rubber.

Several methods of its preparation are described in the literature: by reaction of 2-mercaptobenzothiazole, its sodium salt or disulfide with N-chloromorpholine (DE 1 900 133, EP 10 477), oxidation of 2-mercaptobenzothiazole and morpholine with sodium hypochlorite solution (US 3,178,428, SU 178,822), by catalytic oxygen oxidation (US 4,182,873, EP 29,718) or by electrochemical oxidation of 2-mercaptobenzothiazole or its disulfide and morpholine in dimethylformamide (JP 80 06 423). Hydrogen peroxide is disclosed as an oxidizing agent in patents GB 519 617, GB 655 668 and US 2,419,283. The disadvantage is low yield, while the desired quality is not achieved. According to Soviet patent SU 689 174, a solution of hydrogen peroxide in morpholine is used to oxidize a mixture of 2-mercaptobenzothiazole and morpholine, yielding 90-94% sulfenamide. When hydrogen peroxide solution alone is used, the yield is only 70%. The disadvantage of this process is the large excess of morpholine, the molar ratio of 2-mercaptobenzothiazole: morpholine of 1: 9.4 to 11.3% will have a negative effect on the increase in equipment volume as well as on the cost of morpholine recovery. According to DE 2 726 901, 2-benzothiazole sulfenoic acid morpholide is prepared by deposition of hydrogen peroxide to 2-mercaptobenzothiazole in a morpholine solution, requiring at least eight times the stoichiometric amount of morpholine relative to 2-mercaptobenzothiazole (yield under the following conditions:

88.4%, active ingredient 86.7%). The maximum yield (95.7%, active substance 98.0%) is obtained at a molar ratio of 2-mercaptobenzothiazole: morpholine of 1: 17.5.

Concentration. % of hydrogen peroxide should be higher than 15.0% by weight, preferably in excess of 30.0 mol%. The water content of the initial solution should not exceed 15% by weight. The product is isolated after distillation of 80-90 washes. This process has a number of drawbacks. In order to obtain a sulfenamide with an active ingredient content of at least 97.0%, it is necessary to use a large excess of morpholite amount based on 2-mercapne (almost 2-mercapene). Twelve times the stoichiometrobenzothiazole) yields a yield of 91.9% at lower product morpholine molar excesses, and the high morpholine volumes also complicate the isolation of the sulfenamide, which is a two-stage process. According to AO 209 594, N-substituted benzothiazole-2-sulfenamides are prepared by oxidation of the amine salt of 2-mercaptobenzothiazole in the presence of 0.05 to 3 moles of free amine with a hypochlorite solution. sodium or hydrogen peroxide, wherein the concentration by weight of 2-mercaptobenzothiazole in the solution or suspension is 5 to 20%. A disadvantage of the process is the low concentration of 2-mercaptobenzothiazole in the solution or suspension, thereby increasing the amount of mother liquors after separation. product and hence the demands (energy) for amine recovery.

The above disadvantages are overcome by the process for the preparation of 2-benzothiazolesulfonic acid morpholide of formula I

l · Π

According to the invention, by oxidizing a solution or suspension of 2-mercaptobenzothiazole in morpholine or in a morpholine-water mixture with hydrogen peroxide in a molar excess of 5 to 25% to the total amount of 2-mercaptobenzothiazole at a temperature of 5 to 40 ° C. SUMMARY OF THE INVENTION The present invention is based on the simultaneous addition of a hydrogen peroxide oxidizing agent and 2-mercaptobenzothiazole to the present solution of 2-mercaptobenzothiazole in morpholine or a morpholine-water mixture with a concentration of 2-mercaptobenzothiazole of 2.5 to 40% by weight. 0 to 75.0% of the total amount of 2-mercaptobenzothiazole. The hydrogen peroxide solution is added with vigorous stirring and cooling over 3-12 hours, with a 2-mercaptobenzothiazole dosing time of at most 90% of the oxidizing agent dosing time.

The advantage of the process according to the invention is the reduction of the total amount of morpholine in the process, which results in savings in the costs of regeneration of morpholine as well as in the reduction.

25738G nl volume device. Further, with the gradual addition of 2-mercaptobenzothiazole, the viscosity of the reaction mixture remains within the boundaries ensuring good transport properties of the mixture as well as an inactive heat transfer.

Another advantage of the process is to minimize the formation of 2-mercaptobenzothiazole morphcine salt increments on the heat exchange surfaces of the reactors.

These examples illustrate but do not limit the scope of the invention.

Example 1

To a solution of 2-mercaptobenzothiazole in morpholine (concentration of 2-mercaptobenzothiazole 2,55% by weight) prepared from 17,0 g of 2-mercaptobenzothiazole (0,1 mol, active substance content 98,68%) and 640,4 g of morpholine (7, 21 mol, active ingredient content 98.18 pere.) 272.0 g of hydrogen peroxide solution (1.2 mol; concentration 15.0% by weight) are added with vigorous stirring and cooling over 12 hours simultaneously with 2-mercaptol-benzothiazole, with 152 5 g of 2-mercaptobenzothiazole (0.9 mol; active ingredient content 98.68%) is added to the reaction mixture over 10.5 hours. The temperature is maintained between 15-20 ^° C. After the addition of the oxidizing agent, the suspension is cooled to 15 degrees Celsius, the 2-benzothiazolesulfonic acid morpholide is filtered off, and the filter cake is washed with a 40.0% morpholine solution (200.0 g). , water (900.0 g) and dried. 233.9 g (92.7%) are obtained with an active substance content of 98.3%, m.p. 84-85 ° C. Unreacted morpholine is recovered from the mother liquors and returned to the process.

Example 2

To a solution of 2-mercaptobenzothiazole in a morpholine-water mixture (2-mercaptobenzothiazole concentration of 18.4% by weight) prepared from 127.1 g of 2-mercaptobenzothiazole (0.75 mol; active ingredient content 98.68%) and 555.3 grams of solution of morpholine in water (4.8 mol; morpholine concentration of 75.3% by weight) is added with vigorous stirring and cooling 185.5 g of hydrogen peroxide solution (1.2 mol; concentration of 22.0% by weight) over 3 hours simultaneously with 2 -mercaptobenzothiazole (0.25 mol; active ingredient content 98.68%) is added to the reaction mixture over 1 hour. The temperature was maintained between 20-25 C. ⁼ after addition of the oxidizing agent, the suspension is cooled to 15 DEG C., 2-morpholide benztiazclsulfé · propionic acid is filtered, the cake was washed with a 40.0% solution of morpholine (200.0 g), water (900.0 g) and dried. 232.4 g (92.1%) are obtained with an active substance content of 97.6%, m.p. 82-83 ^° C. Unreacted morpholine is recovered from the mother liquors and returned to the process.

Example 3

To a solution of 2-mercaptobenzothiazole in morphine (concentration of 2-mercaptobenzothiazole 38.9% by weight) prepared from 127.1 g of 2-mercaptobenzothiazole (0.75 mol; active ingredient content 98.68%) and 195.2 g of morpholine (2 (2 mole; active ingredient content 98.18%) was added with vigorous stirring and cooling 136.0 g of hydrogen peroxide solution (1.2 mol; 30.0% by weight) over 6 hours simultaneously with 2-mercaptobenzothiazole wherein 42.4 g of 2-mercaptobenzothiazole (0.25 mol; active ingredient content 98.68%) is added to the reaction mixture over a period of 1.5 hours, maintaining the temperature in the range of 30 to 35 ° C. The suspension is cooled to 15 ° C, 2-benzothiazolesulfonic acid morpholide is filtered off, the filter cake is washed with 30.0% morpholine (200.0 g), water (900.0 g) and dried.

232.8 g (92.2%) are obtained with an active substance content of 98.3%, m.p. 84-85 ° C. Unreacted morpholine is recovered from the mother liquors and returned to the process.

Claims (3)

2S738G nl volume device. Further, in the gradual addition of 2-mercaptobenzothiazole, the viscosity of the reaction mixture remains within the limits of good transport properties of the mixture as well as the intense heat transfer. Another advantage of the process is to minimize the formation of 2-mercaptobenzothiazole morpholine salt encrustations on reactor heat exchangers. These examples illustrate, but do not limit the invention. Example 1 To a solution of 2-mercaptobenzothiazole in morpholine (2.55% by weight 2-mercaptobenzothiazole) prepared from 17.0 g of 2-mercaptobenzothiazole (0.1 mol, active ingredient content 98.68%) and 640%. 4 g of morpholine (7.21 mol, 98.18% active ingredient) was added with vigorous stirring and cooling to 272.0 g of a solution of hydrogen peroxide (1.2 moles; concentration of 15.0% by weight). for 12 hours simultaneously with the 2-mercaptothiazole, with 152.5 g of 2-mercaptobenzothiazole (0.9 mol; 98.68% active ingredient) being metered into the reaction mixture during 10.5 hours clock. The temperature is maintained between 15-20 ° C. After addition of the oxidizing agent, the suspension was cooled to 15 ° C, 2-benzothiazole sulphonic acid morpholide was filtered off, the filter cake was washed with 40.0% morpholine (200.0 g), water (900.0 g) and dried . 233.9 g (92.7%) of an 98.3% active substance with a melting point of 84-85 ° C are obtained. Unreacted morpholine is recovered from the mother liquors and returned to the process. Example 2 To a solution of 2-mercaptobenzothiazole in a mixture of morpholine-water (concentration of 2-mercapto-benzothiazole 18.4% by weight) prepared from 127.1 g of 2-mercaptobenzothiazole (0.75 mol; active substance content 98.68%) and 555, 185.5 g of hydrogen peroxide solution (1.2 mole; concentration 22.0% by weight) are added with vigorous stirring and 3 g of a solution of morpholine in water (4.8 mole; morpholine concentration 75.3% by weight) with vigorous stirring. 3 hours simultaneously with 2-mercaptobenzothiazole (0.25 mol; 98.68% active substance) was metered into the reaction mixture for 1 hour. The temperature is maintained at 20-25 = C. After addition of the oxidizing agent, the suspension was cooled to 15 ° C, the 2-benzothiazolesulfonic acid morpholide was filtered off, the filter cake was washed with 40.0% morpholine (200.0 g), water (900.0 g) and dried . 232.4 g (92.1%) with an effective content of 97.6% are obtained, m.p. 82-83 ° C. Unreacted morpholine is recovered from the mother liquors and returned to the process. Example 3 To a solution of 2-mercaptobenzothiazole in morpholine (2-mercapto-benzothiazole concentration 38.9% by weight) prepared from 127.1 g of 2-mercaptobenzothiazole (0.75 mol; active ingredient content 98.68%) and 195.2 g of morpholine ( 2.2 moles, active substance content of 98.18%), with vigorous stirring, 136.0 g of a peroxide solution of hydrogen peroxide (1.2 mol; 30.0% by weight) are added simultaneously with 2-mercaptobenzothiazole for 6 hours, wherein 42.4 g of 2-mercaptobenzothiazole (0.25 mol; 98.68% active ingredient) is metered into the reaction mixture for 1.5 hours. The temperature is maintained between 30 and 35 ° C. After addition of the oxidizing agent, the suspension was cooled to 15 ° C, the 2-benzothiazole sulfenic acid morpholide was filtered off, the filter cake was washed with a 30.0% solution of morpholine (200.0 grams), water (900.0 grams). ) and dried. 232.8 g (92.2%) of an active substance content of 98.3% are obtained, m.p. 84-85 ° C. Unreacted morpholine is recovered from the mother liquors and returned to the process. OBJECT OF THE INVENTION A process for preparing 2-benzothiazole sulfenic acid morpholide of formula I (i) oxidizing a solution or suspension of 2-mercaptobenzothiazole in morpholine or in a mixture of morpholine-water with hydrogen peroxide in a molar excess of 5 to 25% by weight of the total amount of 2-mercaptobenzothiazole at 5 to 40 ° C; of a solution of 2-mercaptobenzothiazole in morpholine or in a morpholine-water mixture with a 2-mercaptobenzothiazole concentration of 2.5 to 40.0% by weight, which represents 10-75% of the total amount of 2-mercaptobenzothiazole in 2-mercaptobenzothiazole and hydrogen peroxide are added at the same time as the inlet reaction, wherein the oxidant dosing time is 3-12 h and the 2-mercaptobenzothiazole dosing rate is at least 90% of the peroxide hydrogen feed time.