Hydrochloric Acid → Benzothiazole

87.9 g of 95% pure 2-mercaptobenzothiazole, 111.7 g of iron filings, 11.8 g of nickel chloride (NiCl2 ×6H2O) and 250 ml of methanol were first introduced into a stirred flask, and the mixture was heated to the reflux temperature with stirring. 165 ml of conc. aqueous hydrochloric acid were added dropwise at 70° C. over a period of 2 hours, and the evolving hydrogen sulphide was trapped in aqueous sodium hydroxide solution. The mixture was additionally stirred at 70° C. for 1 hour and then diluted with 200 ml of water. 200 ml of methanol were distilled off. The remaining mixture was brought to a pH of 5.6 with aqueous sodium hydroxide solution and steam distilled. The steam distillate was extracted with toluene. Removal of the solvent by distillation gave 66.3 g of crude, colourless benzothiazole, 93.7% pure (GC), which corresponds to a yield of 92% of theory, having a residual toluene content of 5.3%.

1. temperaturethe mixture was heated to the reflux temperature
2. stirringThe mixture was additionally stirred at 70° C. for 1 hour
3. distillation200 ml of methanol were distilled off
4. distillationdistilled
5. extractionThe steam distillate was extracted with toluene
6. customRemoval of the solvent
7. distillationby distillation

ORD record

ord-0f642ab882f14506a34825afe4910be1

Source dataset

uspto-grants-1995_10

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05463068