CS209594B1 - Method of preparation of the n-substituted benzthiazole-2-sulphenamides - Google Patents

Description

The present invention relates to a novel process for the preparation of sulfenamides derived from 2-mercaptobenzothiazole from the amine salts of 2-mercaptobenzothiazole by oxidative condensation.

N-substituted benzothiazole-2-sulfenamides, used as safe accelerators of vulcanization of rubber, are usually prepared by oxidative condensation of 2-mercaptobenzothiazole, optionally with its salts, with the appropriate amine:

-N, cs. , R ^X

Me + n HIT

IN ; *

^ R ²

Me ^{n +} + nOH - where Me H, Na, Ca, NH 4 n = 1,2 (according to Me)

R, R = the same or different, H, primary, secondary, or tertiary, straight or branched alkyl of two to four C atoms, cycloalkyl, or alkylcycloalkyl of five to eight atoms. C, or form a six to eight membered ring which optionally contains an oxygen or nitrogen atom.

The most common subject of patents, and probably the most widely used, is the sodium salt process (e.g. CAA. pat. 114,693, brit. No. 642,597, Hemec. 855,564, U.S. Pat. No. 2,191,657, and calcium salt procedures are also used. pat. 113,006, German 1,940,364) and from the ammonium salt of 2-mercaptobenzothiazole (U.S. Pat. No. 176,040, J84). 052, German 1 940 364 /. all

209,594 of a number of patents protect the preparation from the amine salt of 2-mercaptobenzothiazole / e.g. US Pat.

339 002, 2,772,279, 3,144,652, British Pat. (+420) 413 296, (+420) 452 041, (+420) 519 617, 655 668,

106 577, 1 289 407, German Pat. 615 580, 2 056 762, French 852 118, 950 693,

54.9 002, Japanese 74 110 664, 74 134 674 /.

The intermediate product for the preparation of N-substituted benzothiazole-2-sulfenamides, the amine salt of 2-mercaptobenzothiazole, is obtained in up to three production steps for all known Bpd & The crude 2-mercaptobenzothiazole, contaminated with by-products, is purified by conversion to a water-soluble salt (sodium, calcium, ammonium) from which the amine salt is prepared directly by reaction with the appropriate amine, or after precipitation with a mineral acid to liberate 2-mercaptobenzothiazole. after washing with water until neutral, it is reacted with an amine. These processes have a number of disadvantages. The inorganic bases used (in addition to ammonia) and the acid pass in the form of salts into the waste water, with the use of calcium salts a considerable amount of calcium sludge contaminated by pitch is eliminated and the product must be free of calcium ions by washing with mineral acid. Sulfenamides from sodium and calcium salts are not always of the required quality and additional purification is required (e.g. German pat.). 194 365, French Pat. 2,056,749, British Pat. 756,464, US Pat. 2762 814 /.

The process according to the invention has a number of advantages over the processes known to date for the preparation of N-substituted benzothiazole-2-sulfenamides. Stage AO 209 594 provides the amine salt of 2-mercaptobenzothiazole in one step directly from the melt of crude 2-mercaptobenzothiazole, without the need for mineral bases and acids, the sulfenamide is of the required quality, so no additional purification is required water, the pollution of which is approximately half that of the known production methods. The new method also allows for better utilization of the working time pool, since less deposits are formed on the walls of the production equipment, which need to be periodically removed. Since there is no need to prepare the amine salt, the manufacturing apparatus is also simpler.

'- i

The procedure for preparing N-substituted benzothiazole-2-sulfenamides depends on the type of amine used and the reaction conditions of the oxidative coupling reaction. There are basically two possible procedures. In the solution of the amine salt of 2-mercaptobenzothiazole after extraction. in the case of pbtr reb, the temperature, the concentration of the amine salt and the amine are adjusted, the suspension or solution is used to produce the sulfenamide. In a second treatment, the solid amine salt is suspended either in water or after drying, if necessary, in an organic solvent, and optionally after drying. The amine content preparation is used to prepare the sulfenamide.

The sulfenamides are prepared by oxidative condensation. solution or suspension of the amine salt of 2-mercaptobenzothiazole, with 1.05-4 moles of amine and 1.1-1.7 moles of oxidizing agent per mole of 2-mercaptobenzothiazole. The concentration of the amine salt is 5-20% of 2-mercaptobenzothiazole. The oxidizing agent, sodium hypochlorite solution or hydrogen peroxide is uniformly dosed to the solution or solution. to the suspension! of the amine salt of 2-mercaptobenzothiazole with vigorous stirring at 20-60 ° C. The end of the oxidation can be determined by changing the redox. potential indicated by a pair of platinum-calomel electrodes or iodine-woven paper. With precise dosing of the components to be analyzed, this control is not strict. The sulphenamide aa is separated from the mother liquors by filtration, decanting, if appropriate, by centrifugation, the solids are washed neutral with water, brought to a pre-grit form and dried. The yield of sulfenamides is above 90%. Unreacted amine is recovered from the mother liquors and returned to the process.

The preparation of the R-substituted benzothiazole-2-sulfenamides according to the invention can be carried out by a batch or continuous process, optionally by a combination thereof, and can be non-independent of the 2-mer captobenzothiazole independent of the crude melt 2-mercaptobenzothiazole, or .

Example 1.

300 g of an aqueous solution of 2-mercaptobenzothiazole morpholine salt (10.88%, 0.128 mol of salt and 7.5% 0.302 mol of free morpholine) are introduced into a flask. At 50-52 ° C, 92.2 ml of sodium hypochlorite solution (14.8 active chlorine (100 ml, 0.192 mol)) is uniformly metered with vigorous stirring. After dispensing sodium hypochlorite solution and 15 min. The solids were removed by filtration, washed neutral with water and dried. 29.6 g of 2-mercaptobenzothiazylsulphonol-ol are obtained, having a melting point of 79-81 ° C, an active compound content of 96.1% and an insoluble fraction of 0.3%. Yield 91.6%.

Example 2.

A flask was charged with 1000 g of an aqueous suspension containing 142.1 g of 2-mercaptobenzothiazole diethylamine salt (0.591 mol) and 9.1 g of free diethylamine (0.125 mol). At 25 [deg.] C., 383 ml of sodium hypochlorite solution (1.64 g active chlorine / 100 ml / 0.886 mol) are added uniformly with vigorous stirring such that the temperature does not exceed 30 [deg.] C. After oxidation was complete and 15 min. After the reaction, the liquid product is separated from the aqueous layer, washed with water until neutral, filtered and dried. 130.74 g / yield. 92.8% / brown liquid containing 95.7% active ingredient.

Example 3. . '

250 kg of wet salt containing 153.75 kg of the cyclohexylamine salt of 2-ercaptobenzothiazole (0.577 per mole), 5.8, are added to the first boiler of the reaction cascade. kg of cyclohexylamine (99.4% - 0.058 to mol) and 894.4 l of water and the suspension is heated to 40 ° C. A total of 350 L of sodium hypochlorite solution (152 g of active chlorine-1) - (0.75 mol) was metered into the second and third boilers evenly with vigorous stirring. The temperature is maintained at 40-45 ° C. In the fourth boiler, the reaction mixture reacted at the same temperature. After filtration, washing, granulation and drying, 140.9 kg are obtained. N-cyclohexylbenzothiazyl-2-sulfonamide. Yield 92.4%. The product had a melting point of 9b - 100 ° 0, an active substance content of 97.6% and an insoluble content of 0.28%.

Salts of the other amines not mentioned in the examples are also suitable for the preparation of the sulfenamides of the invention. -

Claims (2)

OBJECT OF THE INVENTION 1. A process for the preparation of an N-substituent. benzothiazel-2-selfenamide of the formula ## STR6 ## wherein R @ 1 and R @ 2 are the same or different and add hydrogen, primary, seleunder or tertiary, straight or branched alkyl of 2 to 4 carbon atoms, cycloalkyl or Alkylcycloalkyl of 5 to 5 carbon atoms; 8 atoaaai carbon, or form a Seat up to eight-membered circle, which optionally contains as. Another hetero atom of the atoa oxygen or nitrogen atom, which is suited to converting the oxidation kendenization of the aminoxyl ether of 2-mercaptebenzothiazole of the general formula. Wherein R and R are as described above with an amine of the formula R @ 1 NH, wherein R and R are as defined above in solution or suspension of the amine salt of 2-aercaptobenzothiaxel in the amine of the above formulas; 60 ° C in the presence of,, 55 to 3 moles of free amine, 1.1 to 1.7 moles of sodium hypochlorite or hydrogen peroxide per mole of amine salt of 2-mercaptobenmtiazole, by addition of 2-mercaptobenzothiazole solution by weight in solution or suspension and amine the salt is 5 to 26%. 2. The methods of claim 1 characterized in TYW the _{ζ ροβ2Μ} £ Ainínová salt is cyklohexylamímeví salt of 2-merkaptobsnztiazolu.