Reaction #570141

Reaction equation

sodium sulfite

potassium chloride

sodium dithionite

sodium nitrite

hydrochloric acid

1C

7-amino-2,3-dihydro-2-methylbenzofuran

→

7-hydrazino-2,3-dihydro-2-methylbenzofuran

Solvents

water

water

water

water

Conditions

Workup

1. 1
   TemperatureThe mixture was warmed to 70° C.
2. 2
   Temperatureto cool
3. 3
   workup.WAITstand at room temperature for 18 hours
4. 4
   workup.ADDITIONwas added drop-by-drop (over 20 minutes)
5. 5
   workup.STIRRINGThe resulting solution was stirred at 5° C. for 1 hour
6. 6
   workup.STIRRINGThe resulting mixture was stirred at room temperature for 2 hours
7. 7
   workup.STIRRINGThe mixture was stirred for 2 hours at room temperature
8. 8
   workup.WAITat 70° C. for 15 minutes
9. 9
   workup.STIRRINGThe mixture was stirred at room temperature for 18 hours
10. 10
    Temperaturecooled to 4° C.
11. 11
    Filtrationfiltered
12. 12
    workup.ADDITION125 g of the resulting solid product was mixed with 500 ml of methanol
13. 13
    workup.STIRRINGThe resulting suspension was stirred at 0° C. while an excess of anhydrous hydrogen chloride
14. 14
    workup.ADDITIONwas added
15. 15
    workup.STIRRINGThe mixture was stirred for 1 hour at 0° C.
16. 16
    Othermost of the methanol was evaporated under reduced pressure at room temperature
17. 17
    workup.ADDITIONThe mixture was mixed with 500 ml of cold water
18. 18
    workup.ADDITIONmade basic by the addition of 50% aqueous sodium hydroxide solution
19. 19
    Extractionextracted with ether
20. 20
    DryingThe extract was dried (MgSO4)
21. 21
    Otherthe solvent was evaporated

Procedure

A mixture of 157 ml of concentrated hydrochloric acid and 66.1 g of 1C was stirred at room temperature for one hour, then 485 ml of water was added. The mixture was warmed to 70° C., then allowed to cool and stand at room temperature for 18 hours, then cooled to 5° C., while a solution of 33.7 g of sodium nitrite in 48 ml of water was added drop-by-drop (over 20 minutes). The resulting solution was stirred at 5° C. for 1 hour, then added drop-by-drop (over 10 minutes) to a stirred mixture of 393.5 g of sodium sulfite in 755 ml of water, at 5° C. The resulting mixture was stirred at room temperature for 2 hours, then a slurry of 77.2 g of sodium dithionite in 100 ml of water was added, in portions, to the stirred mixture. The mixture was stirred for 2 hours at room temperature, then at 70° C. for 15 minutes, when 1 pound of potassium chloride was added. The mixture was stirred at room temperature for 18 hours, cooled to 4° C. and filtered. 125 g of the resulting solid product was mixed with 500 ml of methanol. The resulting suspension was stirred at 0° C. while an excess of anhydrous hydrogen chloride was added. The mixture was stirred for 1 hour at 0° C., then most of the methanol was evaporated under reduced pressure at room temperature. The mixture was mixed with 500 ml of cold water, made basic by the addition of 50% aqueous sodium hydroxide solution, and extracted with ether. The extract was dried (MgSO4), and the solvent was evaporated to give 7-hydrazino-2,3-dihydro-2-methylbenzofuran (1D), as an amber syrup.

Source