Process of production of n-alkyl-2-benzthiazolysulfeneimides, device for their production and method of their purification
View Patent ↗The solution concerns a process of production of N-alkyl-2-benzthiazolylsulfeneimides by means of a reaction of 2-benzthiazolylsulfenyl chloride with an excess of a corresponding alkylamine in an anhydrous reaction medium. Removement of water and moisture from the reaction medium is ensured by azeotropic distillation of a part of the solvent. The method solves also trapping of the excess amine by extraction with water to recycle it in the process, removing of the unconverted raw material from the crude product by chemical refining with aqueous lye and extraction of by-products and pitches by elutriating the product in an organic solvent with the aim to obtain pure benzthiazolylsulfeneimide containing no less than 95% of the active substance, which can be used as a vulcanization accelerator in ruber mixtures. A device for performing this method consists of a reactor with a multiple propeller mixer on a common shaft
1. A method for the production of N-alkyl-2-benzthiazolyl-sulfeneimides of the formula I
where R is selected from the group consisting of a C 1 to C 12 unbranched or branched alkyl and a C 3 to C 9 cycloalkyl group, the method comprising reacting a 2-benzthiazolylsulfenyl chloride with an excess of a corresponding alkylamine in an inert solvent reaction medium, wherein the reaction of the sulfenyl chloride with the corresponding alkylamine is performed at a temperature of from +5 to +15° C. using a 10 to 100% excess of the alkylamine compared with a theoretical amount, removing moisture of equipment, solvent, and raw material by distilling off a part of the solvent by azeotropic distillation at an atmospheric or reduced pressure, and removing disulfide which has not reacted by adding aqueous sodium hydroxide at a temperature of 20 to 50° C., while separating the sulfeneimide by filtration.
2. A method according to claim 1 , wherein the reaction of the sulfenyl chloride with the corresponding alkylamine is performed with an excess of 3.5 to 4 equivalents of amine per 2 equivalents of sulfenyl chloride.
3. A method according to claim 1 , wherein alkylammonium chloride and alkylamine are isolated from the reaction mixture by extraction with water or diluted acid and subsequent separation of phases.
4. A method according to claim 1 , wherein the solvent is removed by distilling it off using azeotropic distillation in the presence of water, at a reduced pressure and at a temperature no greater than 50° C.
5. A method according to claim 1 , additionally comprising purification of crude product N-alkyl-2-benzthiazoylsulfenemide by elutriating crude product for 0.5 to 2 hours at a temperature of 10 to 50° C. in a suitable polar organic solvent or in its azeotropic mixture with water, and subsequently separating the sulfeneimide by filtration.
6. A method according to claim 1 , additionally comprising purification of crude product N-alkyl-2-benzthiazoylsulfenemide by mixing an aqueous suspension of the crude product with a suitable nonpolar organic solvent or with a mixture of such organic solvents, and mixing the resulting mixture for 0.5 to 2 hours at a temperature of 10 to 50° C. and subsequently separating the sulfeneimide by filtration.
7. A method according to claim 2 , wherein alkylammonium chloride and alkylamine are isolated from the reaction mixture by extraction with water or diluted acid and subsequent separation of the phases.
8. A method according to claim 2 , wherein the solvent is removed by distilling it off using azetropic distillation in the presence of water, at a reduced pressure and at a temperature no greater than 50° C.
9. A method according to claim 3 , wherein the solvent is removed by distilling it off using azetropic distillation in the presence of water, at a reduced pressure and at a temperature no greater than 50° C.
10. A method according to claim 2 , additionally comprising purification of crude product N-alkyl-2-benzthiazoylsulfenemide by elutriating crude product for 0.5 to 2 hours at a temperature of 10 to 50° C. in a suitable polar organic solvent or in its azetropic mixture with water, and subsequently separating the sulfeneimide by filtration.
11. A method according to claim 3 , additionally comprising purification of crude product N-alkyl-2-benzthiazoylsulfenemide by elutriating crude product for 0.5 to 2 hours at a temperature of 10 to 50° C. in a suitable polar organic solvent or in its azetropic mixture with water, and subsequently separating the sulfeneimide by filtration.
12. A method according to claim 4 , additionally comprising purification of crude product N-alkyl-2-benzthiazoylsulfenemide by elutriating crude product for 0.5 to 2 hours at a temperature of 10 to 50° C. in a suitable polar organic solvent or in its azetropic mixture with water, and subsequently separating the sulfeneimide by filtration.
13. A method according to claim 2 , additionally comprising purification of crude product N-alkyl-2-benzthiazoylsulfenemide by mixing an aqueous suspension of the crude product with a suitable nonpolar organic solvent or with a mixture of such organic solvents, and mixing the resulting mixture for 0.5 to 2 hours at a temperature of 10 to 50° C. and subsequently separating the sulfeneimide by filtration.
14. A method according to claim 3 , additionally comprising purification of crude product N-alkyl-2-benzthiazoylsulfenemide by mixing an aqueous suspension of the crude product with a suitable nonpolar organic solvent or with a mixture of such organic solvents, and mixing the resulting mixture for 0.5 to 2 hours at a temperature of 10 to 50° C. and subsequently separating the sulfeneimide by filtration.
15. A according to claim 4 , additionally comprising purification of crude product N-alkyl-2-benzthiazoylsulfenemide by mixing an aqueous suspension of the crude product with a suitable nonpolar organic solvent or with a mixture of such organic solvents, and mixing the resulting mixture for 0.5 to 2 hours at a temperature of 10 to 50° C. and subsequently separating the sulfeneimide by filtration.