Picolinic acid → 2-(2'-Pyridyl)benzimidazole
Reaction equation
[C:1]1([NH2:8])[CH:6]=[CH:5][CH:4]=[CH:3][C:2]=1[NH2:7].[N:9]1[CH:14]=[CH:13][CH:12]=[CH:11][C:10]=1[C:15](O)=O>>[N:9]1[CH:14]=[CH:13][CH:12]=[CH:11][C:10]=1[C:15]1[NH:7][C:2]2[CH:3]=[CH:4][CH:5]=[CH:6][C:1]=2[N:8]=1Participants
Conditions
- Temperature
- 210 °C
Procedure
A 2 liter 3-neck round-bottom flask fitted with a reflux condenser, N2 (g) inlet, mechanical stirrer, and heating mantle was charged with 88.7 g of 1,2-phenylenediamine, 100.0 g of picolinic acid, and 500 g of polyphosphoric acid. The resulting slurry was slowly heated (over a period of approximately three hours) to 210° C. under a positive nitrogen atmosphere, with mechanical stirring. The reaction mixture was heated for an additional six hours while maintaining the temperature between 200°-220° C. The reaction mixture was cooled to below 100° C. and cautiously poured into 2 liters of hot distilled water. The resulting slurry was stirred for approximately one hour, cooled and the pH adjusted to approximately 6-7 using concentrated aqueous NaOH. The slurry was stirred for an additional hour, cooled, and filtered. The precipitate was thoroughly washed with distilled water and dried.
Workup
- customA 2 liter 3-neck round-bottom flask fitted with a reflux condenser, N2 (g) inlet, mechanical stirrer
- temperatureheating mantle
- temperatureThe reaction mixture was heated for an additional six hours
- temperaturewhile maintaining the temperature between 200°-220° C
- temperatureThe reaction mixture was cooled to below 100° C.
- additioncautiously poured into 2 liters
- distillationof hot distilled water
- temperaturecooled
- stirringThe slurry was stirred for an additional hour
- temperaturecooled
- filtrationfiltered
- washThe precipitate was thoroughly washed with distilled water
- customdried
Sources & evidence
- ORD record
- ord-2aeb8f8fe1c445869a46297fe4f19d80
- Source dataset
- uspto-grants-1994_07
- Patent number
- US05326502
Reaction notes
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