Hydrochloric Acid → 3-Cyclohexyl-L-alanine

Temperature

55 °C

20 g (121 mmol) L-phenylalanine are dissolved or suspended in 200 ml deionised water, 200 ml isopropanol and 12.2 ml (146 mmol) 37% hydrochloric acid. After addition of 2 g of the Pt/Rh catalyst, 4% Pt+1% Rh on activated carbon (water content approx. 50%, corresponding to approx. 5 wt. % catalyst relative to L-phenylalanine used), the reaction mixture is introduced into a 1 l hydrogenation autoclave. After being rendered inert with nitrogen three times, it is rinsed with hydrogen twice, then a hydrogen overpressure of 8-10 bar is established and the reaction solution heated to 50-60° C. After approximately 6 to 8 hours, hydrogen uptake is completed (theoretical amount of H2 8.1 l). The hydrogenator is depressurised and once again rendered inert with nitrogen three times. The still hot reaction solution is extracted with a nutsch filter and the catalyst is washed with 50 ml deionised water. The filtrate is first concentrated to low volume in vacuo (the isopropanol largely removed), the residue then adjusted to a pH of 5-6 with 50% sodium hydroxide solution. It is cooled to a temperature of 0-10° C., the product is extracted with a nutsch filter, rinsed with 50 ml deionised water and dried in a drying oven in vacuo at 50-70° C.

1. additionthe reaction mixture is introduced into a 1 l hydrogenation autoclave
2. washis rinsed with hydrogen twice
3. extractionThe still hot reaction solution is extracted with
4. filtrationa nutsch filter
5. washthe catalyst is washed with 50 ml
6. concentrationThe filtrate is first concentrated to low volume in vacuo (the isopropanol
7. customlargely removed), the residue
8. temperatureIt is cooled to a temperature of 0-10° C.
9. extractionthe product is extracted with a nutsch filter
10. washrinsed with 50 ml
11. customdried in a drying oven in vacuo at 50-70° C.

ORD record

ord-d722964064474ef39e9406cd0d73ae49

Source dataset

uspto-grants-2012_04

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08148430B2