Hydrochloric Acid → trans-3-Ethyl-DL-proline

HRID 1439707Notes

Reaction equation

HRID 1439707 reaction equation
[CH2:1]([CH:3]1[C:7](C(OCC)=O)([C:8]([O:10]CC)=[O:9])[NH:6][CH:5]=[CH:4]1)[CH3:2].[OH-].[Na+].[BH4-].[Na+].Cl>C(O)C>[CH2:1]([C@@H:3]1[CH2:4][CH2:5][NH:6][C@H:7]1[C:8]([OH:10])=[O:9])[CH3:2]

Participants

6

Reactant 4

HCID 313Hydrochloric AcidHCID 14798Sodium HydroxideHCID 4311764Sodium borohydrideHCID 21866300Diethyl 3-ethyl-1,3-dihydro-2H-pyrrole-2,2-dicarboxylate

Product 1

HCID 10154109trans-3-Ethyl-DL-prolineYield 75.6%

Reagents, catalysts & solvents 1

HCID 702EthanolSolvent

Procedure

The pyrroline (4.68 g, 19.5 mM) was added to a mixture of 1M NaOH (80 ml) and ethanol (80 ml) and the solution stirred at 50° for 4 hrs. The solution was then cooled, sodium borohydride (1.0 g) added, and stirred at 25° for a further 10 hours. The solution was then carefully acidified with dilute HCl to pH 4, concentrated and applied to a column of Dowex 50WX8 resin (H+ form, 100 ml) Elution with aqueous ammonia (2 M) yielded a solution which on evaporation gave trans-3-ethyl-dl-proline (2.1 g) m.p. 208≈-209°; RF 3B 0.43. Analysis on a Jeol 6AH amino acid analyser (50 cm column, sodium citrate buffer 0.2 N, pH 3.25 temperature 57°) showed a single peak (elution time 117 mins).

Workup

  1. temperatureThe solution was then cooled
  2. stirringstirred at 25° for a further 10 hours
  3. concentrationconcentrated
  4. washapplied to a column of Dowex 50WX8 resin (H+ form, 100 ml) Elution with aqueous ammonia (2 M)
  5. customyielded a solution which
  6. customon evaporation

Sources & evidence

ORD record
ord-78139d2248db4102a824ac78fd8f37ad
Source dataset
uspto-grants-1977_11
Patent number
US04060603

Reaction notes

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