Ethanol → 7-Chloro-2-ethoxybenzothiazole

HRID 223396

Reaktionsgleichung

Reaktionsgleichung von HRID 223396
[Cl:1][C:2]1[CH:3]=[C:4]([NH:8][C:9](=[S:13])[O:10][CH2:11][CH3:12])[CH:5]=[CH:6][CH:7]=1.C(O)C.[OH-].[Na+]>O.[C-]#N.[C-]#N.[C-]#N.[C-]#N.[C-]#N.[C-]#N.[K+].[K+].[K+].[Fe+3]>[Cl:1][C:2]1[C:3]2[S:13][C:9]([O:10][CH2:11][CH3:12])=[N:8][C:4]=2[CH:5]=[CH:6][CH:7]=1

Komponenten

6

Edukt 3

HCID 702EthanolHCID 14798Sodium HydroxideHCID 54084842O-Ethyl (3-Chlorophenyl)-thiocarbamate

Produkt 1

HCID 205222777-Chloro-2-ethoxybenzothiazole

Reagenzien, Katalysatoren, Lösungsmittel 2

HCID 26250Potassium ferricyanideKatalysator2×HCID 962WaterLösungsmittel3×

Reaktionsbedingungen

Temperatur
90 °C

Versuchsvorschrift

20 ml-portions of a mixture of 49.5 gm (0.24 mol) of O-ethyl (3-chlorophenyl)-thiocarbamate, 60 ml of ethanol, 350 ml of an aqueous 30% sodium hydroxide solution, and 300 ml of water were added at intervals of 5 minutes to a solution of 494 gm (1.5 mol) of potassium hexacyanoferrate (III) in 600 ml of water at 80°-90° C. After heating the mixture for 2 hours at 90° C., 200 gm (0.61 mol) of potassium hexacyanoferrate (III) were added again, and the mixture was heated for another 3 hours at 90° C. After cooling, the mixture was diluted with 3 liters of water, extracted exhaustively with ether, and the separated organic phase was washed with water and dried over sodium sulfate. The residue remaining after evaporation of the solvent was purified by chromatography on 500 gm of silica gel, using dichloromethane/petroleum ether (volume ratio of 1:1) for elution. The fractions containing the two principal products were combined and evaporated. The residual crystal sludge yielded, after two successive recrystallizations from petroleum ether, 7.5 gm of colorless crystals having a melting point of 74°-75° C., which consisted according to spectroscopic examination of 5-chloro-2-ethoxy-benzothiazole. For the purpose of isolating the desired 7-chloro-2-ethoxybenzothiazole, i.e. the substance with the lower Rf value, the combined mother liquors were chromatographed on 500 gm of silica gel, using petroleum ether/dichloromethane as the eluant. The 7-chloro-2-ethoxy-benzothiazole, a light yellow oil obtained after evaporation of the corresponding eluates, was used in the next step without further purification. Yield: 15.5 gm (32% of theory).

Aufarbeitung

  1. temperaturethe mixture was heated for another 3 hours at 90° C
  2. temperatureAfter cooling
  3. extractionextracted exhaustively with ether
  4. washthe separated organic phase was washed with water
  5. dry with materialdried over sodium sulfate
  6. customafter evaporation of the solvent
  7. customwas purified by chromatography on 500 gm of silica gel
  8. washfor elution
  9. additionThe fractions containing the two principal products
  10. customevaporated
  11. customThe residual crystal sludge yielded
  12. customafter two successive recrystallizations from petroleum ether, 7.5 gm of colorless crystals

Quellen und Nachweise

ORD-Eintrag
ord-d72bb97cacea4543908527a25e6ba505
Quelldatensatz
uspto-grants-1982_10
Patentnummer
US04353919

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