Reaktion #92941

Reaktionsgleichung

4-methyl-3,4,5,6-tetrahydro-2-pyranone

ethanol

hydrogen bromide

→

desired product

5-Bromo-3-methylpentanoic acid ethyl ester

Lösungsmittel

water

Reaktionsbedingungen

Aufarbeitung

1. 1
   workup.WAITleft
2. 2
   Extraktionextracted with diethyl ether
3. 3
   TrocknenThe combined ether extracts are dried over anhydrous sodium sulphate
4. 4
   Sonstigeevaporated
5. 5
   workup.DISTILLATIONthe residue is distilled in a vacuum
6. 6
   Sonstigeto give 21.9 g

Vorschrift

A solution of 16.0 g. (0.14 mol) 4-methyl-3,4,5,6-tetrahydro-2-pyranone in 50 ml. anhydrous ethanol is saturated with hydrogen bromide gas at 0°-5° C., left to stand overnight, poured into water and extracted with diethyl ether. The combined ether extracts are dried over anhydrous sodium sulphate and evaporated and the residue is distilled in a vacuum to give 21.9 g. (70% of theory) of the desired product in the form of a colourless liquid; b.p. 85°-87° C./0.1 mm.; nD20 =1.4590.

Quelle