Reaktion #56344

Reaktionsgleichung

sodium chloride

L-thyroxine

trifluoroacetic acid

trifluoroacetic anhydride

→

thyroxine

N-Trifluoroacetylthyroxine

Lösungsmittel

H2O

ethyl acetate

Reaktionsbedingungen

Aufarbeitung

1. 1
   Sonstigea suspension formed which
2. 2
   SonstigeThe organic phase of the mixture was separated
3. 3
   Waschenwashed with saturated aqueous sodium chloride solution
4. 4
   Trocknendried over anhydrous magnesium sulfate
5. 5
   Filtrationfiltered
6. 6
   Sonstigeevaporated

Vorschrift

A solution of 20 g [25.6 millimoles (mmol)] of L-thyroxine (Sigma Chemical Co., St. Louis, Missouri USA) in 240 ml of dry ethyl acetate containing 46 ml of trifluoroacetic acid and 7.6 ml of trifluoroacetic anhydride was stirred at 0° C. for one hour. Upon warming to room temperature and adding 200 ml of H2O, a suspension formed which was then saturated with sodium chloride. The organic phase of the mixture was separated, washed with saturated aqueous sodium chloride solution, dried over anhydrous magnesium sulfate, filtered and evaporated to give 21.3 g of the N-protected thyroxine derivative (6). A sample was recrystallized from ether-pentane to give fine crystals, m.p. 233°-235° C. (decomposed).

Quelle