Reaktion #1817407

Reaktionsgleichung

Bromine

ethyl 8-acetyl-12-acetoxyheptadecanoate

Ethyl 8-Acetyl-12-acetoxyheptadecanoate

→

Ethyl 8-acetyl-8-bromo-12-acetoxyheptadecanoate

Lösungsmittel

carbon tetrachloride

carbon tetrachloride

Reaktionsbedingungen

Aufarbeitung

1. 1
   workup.DISTILLATIONThe solvent is distilled in vacuo
2. 2
   workup.DISSOLUTIONThe residual oil is dissolved in ether
3. 3
   Waschenwashed with dilute sodium bicarbonate, water and brine
4. 4
   Trocknendried over sodium sulfate
5. 5
   SonstigeEvaporation of the ether
6. 6
   Sonstigeleaves the crude bromo ester as a yellow oil
7. 7
   SonstigeIt is purified by column chromatography on silica gel with benzene as the eluant
8. 8
   Sonstigeto separate the desired bromo ester from a small amount of a by-product, ethyl 8-bromoacetyl-8-bromo-12-acetoxyheptadecanoate

Vorschrift

Bromine (16.7 g., 0.104 mole) dissolved in carbon tetrachloride (100 ml.) is added dropwise to a stirred solution of ethyl 8-acetyl-12-acetoxyheptadecanoate (Example 1, Step C) (37.4 g., 0.094 mole) in carbon tetrachloride (200 ml.) during one hour. The solvent is distilled in vacuo. The residual oil is dissolved in ether and washed with dilute sodium bicarbonate, water and brine and dried over sodium sulfate. Evaporation of the ether leaves the crude bromo ester as a yellow oil weighing 43 g. It is purified by column chromatography on silica gel with benzene as the eluant. This procedure serves to separate the desired bromo ester from a small amount of a by-product, ethyl 8-bromoacetyl-8-bromo-12-acetoxyheptadecanoate. Ethyl 8-acetyl-8-bromo-12-acetoxyheptadecanoate is thus obtained as a pale yellow oil weighing 12.7 g. (28%).

Quelle