Formic Acid → 1,3-Benzothiazole-5-carboxylic acid

HRID 723514Notes

Reaction equation

HRID 723514 reaction equation
Cl[C:2]1[CH:10]=[CH:9][C:5]([C:6](O)=O)=[CH:4][C:3]=1[N+:11]([O-])=O.[OH-:14].[Na+].[OH2:16].[S-2:17].[Na+].[Na+].[CH:20](O)=O>O.[Zn]>[S:17]1[C:2]2[CH:10]=[CH:9][C:5]([C:6]([OH:16])=[O:14])=[CH:4][C:3]=2[N:11]=[CH:20]1

Participants

7

Reactant 4

HCID 284Formic AcidHCID 73204-Chloro-3-nitrobenzoic acidHCID 14798Sodium HydroxideHCID 19906495Sodium sulfide monohydrate

Product 1

HCID 27354601,3-Benzothiazole-5-carboxylic acid

Reagents, catalysts & solvents 2

HCID 23994ZincCatalystHCID 962WaterSolvent

Procedure

4-Chloro-3-nitrobenzoic acid (22 g, 0.11 mol) was suspended in water, sodium hydroxide (4.33 g, 0.11 mol) and sodium sulfide hydrate (32 g) were added, and the mixture heated at reflux for 24 hours. After acidification with 5M hydrochloric acid the mixture was extracted with ethyl acetate. The extracts were dried over magnesium sulfate and evaporated under reduced pressure. The product from this reaction (1 g, 5.9 mmol) was dissolved in formic acid and heated at reflux in the presence of zinc (0.1 g) for 6 hours. The mixture was allowed to cool and was concentrated under reduced pressure. The residue was diluted with water and neutralised with saturated aqueous sodium hydrogen carbonate. Extraction with tetrahydrofuran and ethyl acetate (1:1) gave a pale yellow solid (0.48 g) that was purified on silica gel using a methanol dichloromethane gradient.

Workup

  1. temperaturethe mixture heated
  2. temperatureat reflux for 24 hours
  3. extractionAfter acidification with 5M hydrochloric acid the mixture was extracted with ethyl acetate
  4. dry with materialThe extracts were dried over magnesium sulfate
  5. customevaporated under reduced pressure
  6. customThe product from this reaction (1 g, 5.9 mmol)
  7. temperatureheated
  8. temperatureto cool
  9. concentrationwas concentrated under reduced pressure
  10. additionThe residue was diluted with water and neutralised with saturated aqueous sodium hydrogen carbonate
  11. extractionExtraction with tetrahydrofuran and ethyl acetate (1:1)

Sources & evidence

ORD record
ord-b180797e3b754bef8259584a8416c77f
Source dataset
uspto-grants-2006_11
Patent number
US07141564B2

Reaction notes

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