Hydrochloric Acid → 2(3H)-Benzothiazolone, 6-nitro-

HRID 234128

Reaction equation

HRID 234128 reaction equation
N[C:2]1[S:3][C:4]2[CH:10]=[C:9]([N+:11]([O-:13])=[O:12])[CH:8]=[CH:7][C:5]=2[N:6]=1.Cl.N([O-])=[O:16].[Na+]>O>[N+:11]([C:9]1[CH:8]=[CH:7][C:5]2[NH:6][C:2](=[O:16])[S:3][C:4]=2[CH:10]=1)([O-:13])=[O:12]

Participants

5

Reactant 3

HCID 313Hydrochloric AcidHCID 227042-Amino-6-nitrobenzothiazoleHCID 23668193Sodium Nitrite

Product 1

HCID 6415712(3H)-Benzothiazolone, 6-nitro-Yield 94.5%

Reagents, catalysts & solvents 1

HCID 962WaterSolvent

Conditions

Temperature
50 °C

Procedure

28.75 g of 2-amino-6-nitrobenzothiazole, 210 g of 30% hydrochloric acid and 29.5 g of water are introduced into a 750 ml pressure vessel at room temperature and subsequently heated to 50° C. After the reaction mixture has been stirred for 30 minutes, it is cooled to 20° C. 50.75 g of aqueous sodium nitrite solution are then metered in at a uniform rate in the course of 3 hours at 20°-30° C., with very vigorous stirring. After metering in has ended, stirring is continued for 2.5 hours at 20°-30° C. Then, excess nitrite is removed by adding approximately 15 g of 18% aqueous urea solution. The reaction vessel is subsequently sealed, and the reaction mixture is heated for 5 hours at 140°-150° C. (pressure approximately 4 bar). After the mixture has cooled to 20° C., the crystalline product is filtered off with suction, washed until neutral and dried at 60° C. to constant weight. 27.3 g of 6-nitrobenzothiazol-2-one with a pure substance content of 97.8% are obtained (corresponding to 92.4% yield). The product which is redissolved under alkaline conditions has a DSC melting point of 252.5° C.

Workup

  1. temperatureit is cooled to 20° C
  2. customare then metered in at a uniform rate in the course of 3 hours at 20°-30° C., with very vigorous stirring
  3. stirringstirring
  4. waitis continued for 2.5 hours at 20°-30° C
  5. customThen, excess nitrite is removed
  6. additionby adding approximately 15 g of 18% aqueous urea solution
  7. customThe reaction vessel is subsequently sealed
  8. temperaturethe reaction mixture is heated for 5 hours at 140°-150° C. (pressure approximately 4 bar)
  9. temperatureAfter the mixture has cooled to 20° C.
  10. filtrationthe crystalline product is filtered off with suction
  11. washwashed until neutral and
  12. customdried at 60° C. to constant weight

Sources & evidence

ORD record
ord-c47f4b64c5f64156bdbc0bdf10274d42
Source dataset
uspto-grants-1997_01
Patent number
US05594145

Linked notes

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