METHOD FOR PRODUCING N,N-DISUBSTITUTED BENZTHIAZOLYL-SULFENAMIDES

Abstract

The invention relates to a method for preparing N,N-disubstituted benzthiazolylsulfenamides.

Claims

1. A method for preparing N,N-disubstituted benzothiazolylsulfenamides of the formula (I) ##STR00007## where R.sup.1, R.sup.2=each independently —CH(R.sup.3)(R.sup.4) where R.sup.3, R.sup.4=each independently H, C.sub.1-C.sub.3-alkyl, ##STR00008## and R.sup.5=C.sub.1-C.sub.3-alkyl, y=0 to 6, and n=0 to 5, by reacting 2-mercaptobenzothiazole salts of the formula (II) ##STR00009## where Z=Na or K, with amines of the formula (III)
NH(R.sup.1)(R.sup.2)  (III) in which Wand R.sup.2 have the definition above, wherein the reaction is carried out in the presence of sodium hypochlorite at a pH of 10 to 12.

2. The method as claimed in claim 1, wherein the N,N-substituted benzothiazolylsulfenamides of the formula (I) are N,N-dibenzylbenzothiazolylsulfenamide (DBBS) or N,N-diisopropylbenzothiazolylsulfenamide.

3. The method as claimed in claim 1, wherein the compound of the formula (II) used is ##STR00010## and the compound of the formula (III) used is ##STR00011##

4. The method as claimed in claim 1, wherein the reaction is carried out at temperatures of 30 to 50° C.

5. The method as claimed in claim 1, wherein the reaction is carried out in the presence of at least one C.sub.1-C.sub.4-alcohol and/or water.

6. The method as claimed in claim 4, wherein the compound of the formula (III) is initially charged, optionally in the presence of water and/or alcohol, and the compound of the formula (II) and sodium hypochlorite are metered in, the pH being adjusted with sulfuric acid during the metered addition.

7. The method as claimed in claim 4, wherein the pH is adjusted with aqueous sodium hydroxide solution after addition of the compound of the formula (II) and the sodium hypochlorite.

8. The method as claimed in claim 1, wherein the molar ratio of the compound of the formula (II) to the compound of the formula (III) used is from 1.4:1 to 0.8:1.

9. The method as claimed in claim 1, wherein y=0 to 2.

10. The method as claimed in claim 1, wherein y=0.

11. The method as claimed in claim 1, wherein n=0.

12. The method as claimed in claim 2, wherein the compound of the formula (II) used is ##STR00012## and the compound of the formula (III) used is ##STR00013##

13. The method as claimed in claim 6, wherein the pH is adjusted with aqueous sodium hydroxide solution after addition of the compound of the formula (II) and the sodium hypochlorite.

Description

WORKING EXAMPLES

Example 1

[0031] The apparatus used was a 2 l flat-flanged beaker, equipped with a Mig stirrer (3 blade); jacket heating/cooling; pH and redox measuring device; thermometer; metering pumps for sodium hypochlorite (NaOCl) and the aqueous solution of the sodium salt of 2-mercaptobenzothiazole (NaMBT) and a dropping funnel for pH-controlled metered addition of sulfuric acid or aqueous sodium hydroxide solution.

[0032] 203.4 g of dibenzylamine (97%) and 531 g of isopropanol (water content <1%) were initially charged in this flat-flanged beaker with 195 g of water. The reaction mixture was then stirred and the following mixture was metered in at an internal temperature of 46° C. over the course of 3 hours:

[0033] 446.1 g of 50.50% aqueous NaMBT solution (density: 1.245)=119 ml/h (358 ml)

[0034] 834.2 g of 14.21% aqueous NaOCl (density: 1.22)=228 ml/h (683.8 ml)

[0035] Then, 5 g of NaOCl was added to the chemicals initially charged in the flat-flanged beaker over 1-5 minutes.

[0036] During the metered addition, a pH of 10.5 was maintained in the reaction mixture, which was effected by means of sulfuric acid.

[0037] The pH was then adjusted to 11.5 with 1.6 g of 48% aqueous sodium hydroxide solution, 245 ml of water were added and the mixture was stirred for 15 minutes. The suspension was filtered off under suction at 40° C. through a 18.5 cm diameter black-band filter.

[0038] The product was filtered off, washed with 625 g of aqueous isopropanol (35%) at 40° C. and then with 1165 g of water at 60° C.

[0039] The filter cake was dried to constant mass in a drying cabinet at ca. 50° C.

[0040] This gave 283.6 g of N,N-dibenzylbenzothiazolylsulfenamide (DBBS). According to HPLC analysis, the active ingredient content (titration) was over 98%; free amine was measured at <0.7%. Furthermore, the melting point was in a range of 90-100° C., preferably 92.5-93.2° C.

Comparative Examples 1a, 1b and 1c

[0041] The method was carried out analogously to Example 1 but at a pH of 8, 9 and 12 respectively.

[0042] The following results were obtained:

TABLE-US-00001 Yield Purity Free amines Ex. no. pH [%] [%] [%] 1 (inv.) 10.5 >92 >97 0.20 1a (comp.) 8 60 85 0.85 1b (comp.) 9 80 90 0.58 1c (comp.) 13 No product No product

[0043] It was found that the method according to the invention made it possible to prepare N,N-substituted benzothiazolylsulfenamides of the formula (I) without the need to use elemental chlorine and afforded significantly improved results compared to the method known in the prior art (EP 0 195 738) using sodium hypochlorite and at a pH of 8 to 9.