Sulfuric Acid → (-)-Mandelic acid

HRID 1731511Notes

Reaction equation

HRID 1731511 reaction equation
P([O-])([O-])([O-])=O.[K+].[K+].[K+].[C:9]1([CH2:15][C:16](=[O:20])[C:17]([O-:19])=[O:18])[CH:14]=CC=C[CH:10]=1.[C:21]1([C:27](C)([OH:31])[C:28]([OH:30])=[O:29])[CH:26]=[CH:25][CH:24]=[CH:23][CH:22]=1.S(=O)(=O)(O)O>>[C:28]([OH:30])(=[O:29])[C@@H:27]([C:21]1[CH:26]=[CH:25][CH:24]=[CH:23][CH:22]=1)[OH:31].[OH:20][C@H:16]([CH2:15][CH:9]([CH3:14])[CH3:10])[C:17]([O-:19])=[O:18]

Participants

6

Reactant 4

HCID 1118Sulfuric AcidHCID 1303Atrolactic acidHCID 62657Potassium Phosphate, TribasicHCID 45926973-Phenylpyruvate

Product 2

HCID 11914(-)-Mandelic acidHCID 6951542HCID 6951542, compound

Procedure

In an electrochemical cell, 25 ml of a solution of 100 mM potassium phosphate buffer at pH 7.0, 4 mM methylviologen and 40 mM phenylpyruvate were reduced with 0.5 mg of 2-oxoacid reductase according to Example 3 at a voltage of -700 mV, against a standard calomel electrode. The current of 5.8 mA decreased sharply after 9 hours. According to HPLC analysis, the reaction solution contained 88% of the phenyllactic acid expected. The solution was acidified to pH 1.8 with dilute sulfuric acid and then extracted with ether. The crystalline residue (78% of theory) was converted to the sodium salt, which had a specific rotation of [α]RT 589=21.1° (0.09 millimole/ml of H2O). A pure commercial preparation of (2S)-sodium phenyllactate gave a value of -21.4°, measured under the same conditions. (R)-mandelic acid and (R)-2-hydroxy-4-methylpentanoate were prepared by a similar method.

Workup

  1. extractionextracted with ether
  2. customa specific rotation of [α]RT 589=21.1° (0.09 millimole/ml of H2O)
  3. customA pure commercial preparation of (2S)-sodium phenyllactate
  4. customgave a value of -21.4°

Sources & evidence

ORD record
ord-46b68111dc4847aab1521034186962f7
Source dataset
uspto-grants-1986_11
Patent number
US04622301

Reaction notes

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