反应详情

温度

90 °C

In a 1-litre pressure autoclave, a solution of 10.00 g (45.0 mmol) of (5)-2-(cyanoacetylamino)-3-(1H-imidazol-4-yl)propionic acid (prepared according to Example 3) in a mixture of 157 g of conc. NH3/methanol (m/m=3:2) was added to 0.88 g of Rh/C (0.4 mol % pure Rh, based on reactant used). The autoclave was closed and flushed twice with 40 bar of nitrogen and once with hydrogen. The mixture was heated to 90° C. and the autoclave was pressurized with 40 bar of hydrogen. After 3 h at 90° C., the reaction mixture was cooled to room temperature, the autoclave was depressurized and the catalyst was filtered off by filtration. An in-process analysis (HPLC) showed that the reaction solution (147.2 g) contained 6.38% (m/m) carnosine, corresponding to a selectivity of 92% for complete conversion. The reaction mixture was then concentrated in a rotary evaporator to 41.2 g. 124 g of ethanol were added dropwise at room temperature and the flask was stored in a refrigerator overnight. On the next day, the precipitate was filtered off, washed with ethanol and dried in a drying oven at 40° C./20 mbar. 7.96 g (78%) of a slightly greenish solid with a content (HPLC) of 98% (m/m) were obtained.

1. customThe autoclave was closed
2. customflushed twice with 40 bar of nitrogen and once with hydrogen
3. temperaturethe reaction mixture was cooled to room temperature
4. filtrationthe catalyst was filtered off by filtration
5. concentrationThe reaction mixture was then concentrated in a rotary evaporator to 41.2 g
6. addition124 g of ethanol were added dropwise at room temperature
7. customwas stored in a refrigerator overnight
8. filtrationOn the next day, the precipitate was filtered off
9. washwashed with ethanol
10. customdried in a drying oven at 40° C./20 mbar
11. custom7.96 g (78%) of a slightly greenish solid with a content (HPLC) of 98% (m/m) were obtained