Reaction #1285

Reaction equation

sodium nitrite

toluene

L-phenylalanine

potassium bromide

→

(S)-α-Bromobenzenepropanoic acid

Solvents

acetic acid

sulfuric acid

Conditions

Workup

1. 1
   Extractionafter which the reaction mixture was extracted with ether (3×250 ml.)
2. 2
   WashThe combined organic extracts were washed with water (100 ml.) and brine (50 ml.)
3. 3
   Dryingdried (anhydrous magnesium sulfate)
4. 4
   Filtrationfiltered
5. 5
   Otherevaporated to dryness
6. 6
   Otherdried in vacuo
7. 7
   Otherto give 34.46 g

Procedure

A solution of L-phenylalanine (30.0 g., 0.175 mole) and potassium bromide (73.5 g., 0.618 mole) in 2.5N sulfuric acid (365 ml.) was cooled down to 0° (ice-salt bath) and treated portionwise with sodium nitrite (19.3 g., 0.28 mole) over a period of 1.0 hour. Stirring was continued for 1.0 hour at 0° and at room temperature for 1.0 hour after which the reaction mixture was extracted with ether (3×250 ml.). The combined organic extracts were washed with water (100 ml.) and brine (50 ml.), dried (anhydrous magnesium sulfate), filtered, evaporated to dryness and dried in vacuo to give 34.46 g., of product; Rf =0.45 (toluene:acetic acid, 95:5).

Source