Hydrochloric Acid → 5-Nitrobenzothiazole
Reaction equation
[CH:1]([NH:3][C:4]1[CH:9]=[C:8]([N+:10]([O-:12])=[O:11])[CH:7]=[CH:6][C:5]=1Br)=O.O.O.O.O.O.O.O.O.O.[S-2:23].[Na+].[Na+].O.Cl>CCO>[N+:10]([C:8]1[CH:7]=[CH:6][C:5]2[S:23][CH:1]=[N:3][C:4]=2[CH:9]=1)([O-:12])=[O:11]Participants
Reactant 4
Product 1
Reagents, catalysts & solvents 1
Procedure
A solution of formamide from Step 1 (5.83 g, 23.8 mmol) and sodium sulfide nonahydrate (8.60 g, 35.8 mmol) in EtOH (120 ml) was heated to reflux for 2 h under nitrogen. After this time the reaction was cooled to RT then poured into cold water (600 ml). The resulting solution was cooled in an ice bath and acidified to pH 1 with 37% HCl. The solution was cooled in an ice bath for a further 1 h, during which time an orange precipitate formed. This solid was isolated by filtration and dried under vacuum to afford 5-nitrobenzothiazole as an orange solid (2.28 g). The above filtrate was extracted with EtOAc (3×200 ml), and the combined organic extracts dried over Na2SO4, filtered and concentrated under vacuum to afford additional 5-nitrobenzothiazole (0.89 g) as an orange solid. NMR and TLC analysis indicated that both crops of product were identical; the combined yield was 3.17 g. 1H NMR (CDCl3) δ 9.19 (s, 1H), 9.02 (d, 1H), 8.35 (dd, 1H), 8.12 (d, 1H); 13C NMR (CDCl3) δ 157.3, 153.1, 147.0, 140.2, 122.5, 120.1, 119.3. MS (ESI+) for m/z 181 [M+H]+.
Workup
- temperatureto reflux for 2 h under nitrogen
- temperatureThe resulting solution was cooled in an ice bath
- temperatureThe solution was cooled in an ice bath for a further 1 h, during which time an orange precipitate
- customformed
- customThis solid was isolated by filtration
- customdried under vacuum
Sources & evidence
- ORD record
- ord-f2983904f8c44514b1d87a5745369054
- Source dataset
- uspto-grants-2008_12
- Patent number
- US07462600B2
Reaction notes
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