Ethanol → L-Pyroglutamic Acid

Temperature

62.5 °C

In a 2 L flask equipped with mechanical stirrer and condenser, add ethanol (945 ml) and (±)-2-amino-1,2,3,4-tetrahydro-cyclopenta[b]indole-7-carbonitrile (40 g, 0.203 mmol). Stir the mixture and heat to 60-65° C. until complete solution is achieved. Add D-pyroglutamic acid (28.4 g, 0.192 mmol) and water (55 ml). Heat the mixture to reflux for 20 min. Cool to 40-45° C. over 90 min. Stir at 40-45° C. for one hour, and then cool to 24° C. over 2 h. Stir at this temperature for two additional hours. Isolate a crystalline solid by filtration and wash with a mixture of EtOH/water (95:5) (3×50 mL). Dry the solid in vacuo at 50° C. overnight to give 23 g pyroglutamic acid salt.

1. customIn a 2 L flask equipped with mechanical stirrer and condenser
2. temperatureHeat the mixture
3. temperatureto reflux for 20 min
4. temperatureCool to 40-45° C. over 90 min
5. stirringStir at 40-45° C. for one hour
6. temperaturecool to 24° C. over 2 h
7. stirringStir at this temperature for two additional hours
8. customIsolate a crystalline solid
9. filtrationby filtration
10. washwash with a mixture of EtOH/water (95:5) (3×50 mL)
11. customDry the solid in vacuo at 50° C. overnight

ORD record

ord-197e6fa26e0b40d69ce514b499790fe9

Source dataset

uspto-grants-2011_06

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07968587B2