SK278656B6 - Method of the continual production of n-cyclohexylbenzothiazolyl-2-sulphenamide - Google Patents

Abstract

This patent describes the procedure closed to the continual production of N-cyclohexylbenzothiazolyl-2-sulphenamide based on the reaction of 2-merkaptobenzothiazole in form of non-refined melt with sodium hypochlorite, at the temperature of 20 up to 50 Celsius degrees, while the mole ratio of 2-merkaptobenzothiazole to sodium hypochlorite is 1 : 1,1 up to 1,3 and the cyclohexylamine surplus in the quantity of 2,2 up to 3,5 moles according to 1 mole of merkaptobenzothiazole in one mixing reactor is present and the simultaneous feeding to all of three reaction components is provided, or two subsequent mixing reactors exist so that, in the first stage and adiabatic temperature of 45 up to 65 Celsius degrees cyclohexylammonium benzothiazolyl-2-merkaptide is prepared and it is oxidised in the second stage, with the use of the sodium hypochlorite, at the temperature of 20 up to 50 Celsius degrees and N-cyclohexylbenzothiazolyl-2-sulphenamide is created, as a result of that. When talking about the raw material stream coming to one reactror or to both reactors together, the concentration of sodium chloride is represented by 1,2 up to 2,8 percent of moles and water 87 up to 94 percent of moles. This solution is utilised in the chemical industry.

Description

Technical field

The invention relates to a process for the continuous production of N-cyclohexylbenzothiazolyl-2-sulfenamide.

BACKGROUND OF THE INVENTION

The prior art processes for the preparation of N-cyclohexylbenzothiazolyl-2-sulfenamide are based on the oxidation of cyclohexylammonium-2-benzothiazolyl-mercaptide, which is obtained in the first step by the reaction of sodium, calcium and calcium. ammonium salt of 2-mercaptobenzothiazole with cyclohexylamine. Sodium hypochlorite and hydrogen peroxide are particularly used as oxidizing agents. All these procedures are briefly described in the literature review MS. of the author's certificate no. 215 179 and their drawbacks are that the product obtained has a low sulphenamide content and its preparation is accompanied by the formation of a considerable amount of solid waste and chemically contaminated waste water.

Principally, more recent processes for the preparation of N-cyclohexylbenzothiazole-2-sulfenamide are presented in U.S. Pat. AO č. 215 179, MS. AO č. 225 046, MS. AO č. 260 786, MS. AO č. 263,560 and are based directly on the crude product of the high pressure reaction of aniline, carbon disulphide and sulfur-free volatiles and an excess of cycolhexylamine, which shows a solvent effect with respect to impurities, thus avoiding contamination of the product. The unused amine is removed from the reaction mixture and reused according to MS. AO 221 005. The condensation of cyclohexylamine with 2-mercaptobenzothiazole and the oxidation of cyclohexylammonium-2-benzothiazolyl mercaptide can be carried out simultaneously in one step or in one step. in several successive stages. By these processes, the production of N-cyclohexylbenzothiazolyl-2-sulfenamide is substantially simplified, the quality of the final product is improved and the ecology of the whole process is improved.

Subject of MS. AO 215 179 is a process for the preparation of N-cyclohexylbenzothiazolyl-2-sulfenamide by reacting unrefined 2-mercaptobenzothiazole with cyclohexylamine and sodium hypochlorite, first preparing cyclohexylammonium-2-benzothiazolylmercaptide by reaction of 2-mercaptobenzylamine with 20- C.

Procedure according to MS. AO 225 046 relates to a process for the preparation of N-cyclohexylbenzothiazolyl-2-sulfenamide by reacting unrefined 2-mercaptobenzothiazole, cyclohexylamine and sodium hypochlorite without the preliminary preparation of cyclohexylammonium-2-benzothiazolylmercaptide in one technological operation at 40 to 60 ° C.

Solution according to MS. AO 260 786 defines a concentration range of free cyclohexylamine in the reaction mixture after oxidation in the range of 1.1 to 1.5 moles per liter of emulsified liquid phase, the observance of which is to ensure greater stability of the amine component in the emulsified liquid mother liquor obtained by filtering the N-cyclohexylbenzothiazolyl suspension. 2-sulfenamide and a higher process yield of 1 to 5%.

Continualization of methods of preparation according to MS. AO 15 179 9, MS. AO 225 046, resp. MS. AO 260 786 in industrial production brings high raw material consumption per unit of product and adversely affects the process ecology. These negative effects are due to several factors resulting from the high demands on the dosing accuracy of the feed components and their variable composition, in particular aqueous sodium hypochlorite solution depending on the degree of decomposition containing different amounts of active chlorine, sodium chloride and sodium chlorate. Defining the free cyclohexylamine concentration interval in the reaction mixture after 5 oxidation without taking into account other factors does not ensure that the desired reaction selectivity and raw material consumption, in particular cyclohexylamine per unit product, are achieved. This follows from a comparison of the examples given in the next section of the invention. Influences caused by 10 inaccuracy of dosing are eliminated by the method in the sense of the article of the MS. AO 263 560 by preparing, in a first continuous reactor, by condensation of cyclohexylamine and 2-mercaptobenzothiazole at an adiabatic temperature of 45-65 ° C, cyclohexylammoniumbenzothiazolyl-2-mer15 captides, which are accurately metered into a second continuous reactor where it is oxidized with sodium hypochlorite at the concentration of N-cyclohexylbenzothiazolyl-2-sulfenamide 13 to 18% by weight.

SUMMARY OF THE INVENTION

We have found that in the industrial production of N-cyclohexylbenzothiazolyl-2-sulfenamide of the formula

Οζ C-S-NH-O

With the reaction of an unrefined melt of 2-mercaptobenzothiazole with sodium hypochlorite at 20 to 50 ° C, a molar ratio of 2-mercaptobenzothiazole to sodium hypochlorite of 1: 1.1 to 1.3 in excess of 2.2 to 3.5 moles of cyclohexylamine per mole of 2 -mercaptobenzothiazole in one stirred reactor by simultaneous feeding of all three reaction components or two successive continuous stirred reactors, in the first step to prepare cyclohexylammonium benzothiazolyl-2-mercaptide, which in the second step is oxidized at 20 to 50 ° C with sodium hypochlorite to N-cyclohexylbenzothiazolyl-2-sulfenamide, the negative effects of the variable composition of the feed components on the economics and ecology of the process are eliminated by the process of the invention, which consists in adjusting the composition and total ionic strength of the reaction mixture by respecting the following concentrations of the components in the feed stream into one or two reactors - sodium chloride 1.2 to 2.8 mol%, water 87 to 94 mol%.

It is an advantage of the invention that it allows to maintain a lower raw material consumption per unit of product, especially cyclohexylamine and lower solid waste production, while at the same time minimizing increment formation on the heat exchange surfaces of the cooled reactors and 55 optimum filter resistance of N-cyclohexylbenzothiazolyl-2-sulfenamide filter cake. By observing the above-mentioned concentration conditions and the resulting total ionic strength of the components in the solution, it is possible to achieve 88-90% recovery of the process while at the same time reducing the side reactions of cyclohexylamine in the reaction mixture but also in the mother liquors obtained by filtering the N suspension. -cyklohexylbenzotiazolyl-2sulľénamidu.

The advantageous use of the subject matter of the invention results from 65 comparisons of the following two examples which illustrate but do not limit the subject matter of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Example 1

The following amounts of components are simultaneously fed into the stirred continuous reactor:

1,883 kmol / h of 2-mercaptobenzothiazole in the form of a melt with a temperature of 190 to 210 ° C with an average content of 89,5% by weight of 2-mercaptobenzothiazole and 3,5% by weight of benzothiazole,

5,173 kmol / h cyclohexylamine as a 50% aqueous solution prepared by mixing concentrated and regenerated cyclohexylamine mother liquors,

2.320 kmol / h of sodium hypochlorite in the form of an aqueous solution containing, on average, 179.93 g of sodium hypochlorite and 187.88 g of sodium chloride, corresponding to 3.086 km of sodium chloride per hour.

The molar ratio of 2-mercaptobenzothiazole: cyclohexylamine: sodium hypochlorite is 1: 2.75: 1.23. The content of the individual components in the incoming feed stream is 2.14 mol% 2-mercaptobenzothiazole, 5.89 mol% cyclohexylamine, 2.64 mol% sodium hypochlorite, 3.34 mol% sodium chloride and 85.50 mol% water. The temperature in the stirred reactor is maintained at 35-42 ° C. In further steps, the N-cyclohexylbenzothiazolyl-2-sulfenamide suspension is cooled to 15 ° C, filtered, the filter cake is washed with a 15% aqueous cyclohexylamine solution and dried to constant weight. An aqueous solution of cyclohexylamine is obtained from the mother liquors and washing solutions by distillation at atmospheric pressure, which is reused as a raw material in the process of preparing N-cyclohexylbenzothiazolyl-2-sulfenamide.

Under the above conditions, the N-cyclohexylbenzothiazolyl-2-sulfenamide suspension after cooling to 15 ° C contains an average of 15.57% by weight of the product, representing a reaction yield of 81.1% by mole and a consumption of cyclohexylamine of 570 kg per t product. , drying and distillation of cyclohexylamine. The final concentration of free cyclohexylamine is 1.38 moles per liter of emulsified liquid phase, obtained by filtration of a suspension of N-cyclohexylbenzothiazolyl-2-sulfenamide. The active compound content of the product obtained is 98.48% by weight.

Example 2 illustrates the convenience of the subject invention

The following amounts of components are simultaneously fed into the stirred continuous reactor:

1,883 kmol / h of 2-mercaptobentiazole in the form of a melt with a temperature of 190 to 210 ° C and an average content of 89,5% by weight of 2-mercaptobenzothiazole and 3,5% by weight of benzothiazole,

5,173 kmol / h cyclohexylamine as a 40% aqueous solution prepared by mixing concentrated and regenerated cyclohexylamine mother liquors,

2.320 kmol / h of sodium hypochlorite in the form of an aqueous solution containing, per liter, an average of 176.69 g of sodium hypochlorite and 175.23 g of sodium chloride, corresponding to 2.931 kmol of sodium chloride per hour.

The molar ratio of 2-mercaptobenzothiazole: cyclohexylamine: sodium hypochlorite is 1: 2.75: 1.23. The constituents in the feed stream are 1.83 mol% mercaptobenzothiazole, 5.01 mol% cyclohexylamine, 2.22 mol% sodium hypochlorite, 2.67 mol% sodium chloride and 87.86 mol% water. The temperature in the stirred reactor is maintained at 35-42 ° C. Further work-up of the reaction mixture is similar to that of Example 1. First

Under the above conditions, the N-cyclohexylbenzothiazolyl-2-sulfenamide slurry, after cooling to 15 ° C, contains an average of 15.55% by weight of the product, representing a reaction yield of 88.9 mol% and a consumption of cyclohexylamine of 480 kg per t product. , drying and distillation of cyclohexylamine. The final concentration of free cyclohexylamine is 1.33 moles per liter of emulsified liquid phase obtained by filtration of a suspension of N-cyclohexylbenzothiazolyl-2-sulfenamide. The active compound content of the product obtained is 98.54% by weight.

Claims (1)

PATENT CLAIMS Process for the continuous production of N-cyclohexylbenzothiazolyl-2-sulfenamide of the formula: by reacting 2-mercaptobenzothiazole as an unrefined melt with sodium hypochlorite at a temperature of 20 to 50 ° C, a molar ratio of 2-mercaptobenzothiazole to sodium hypochlorite of 1: 1.1 to 1.3 in excess of 2.2 to 3.5 moles of cyclohexylamine per mole mercaptobenzothiazole in one stirred reactor by simultaneous dosing of all three reaction components, optionally in two consecutive continuous stirred reactors, so that in the first stage at an adiabatic temperature of 45 to 65 ° C, cyclohexylammonium benzothiazolyl-2-mercaptide is prepared which is oxidized in the second stage at 20 up to 50 ° C with sodium hypochlorite to N-cyclohexylbenzothiazolyl-2-sulenamide, characterized in that the concentration of sodium chloride is between 1.2 and 2.8% by moles of water in the feed stream entering one or both reactors. at intervals of 87 to 94 mole%.