Reaktion #543780

Reaktionsgleichung

diethylamine hydrochloride

2-methyl-quinoxaline

formaldehyde

hydrochloric acid

→

ammonia

Ausbeute 0.1%

diethyl-(2-quinoxalin-2-yl-ethyl)-amine

Ausbeute 66.5%

Lösungsmittel

ethanol

water

ethanol

triethylamine

triethylamine

Reaktionsbedingungen

Aufarbeitung

1. 1
   EinengenThe solvent was concentrated
2. 2
   workup.ADDITIONthe residue was diluted with water
3. 3
   Extraktionextracted with diethyl ether
4. 4
   Sonstigeto remove the unreacted quinoxaline
5. 5
   Extraktionextracted with ethyl acetate
6. 6
   TrocknenThe organic phase was dried over magnesium sulfate
7. 7
   Einengenconcentrated
8. 8
   SonstigeThe residue was chromatographed on silica gel eluting with dichloromethane-methanol (first 95-5

Vorschrift

A solution of diethylamine hydrochloride (3.82 g, 35 mmol) and triethylamine (0.23 ml) in ethanol (1.75 ml) and water (1.75 ml) was added dropwise, at 60° C., to a mixture of 2-methyl-quinoxaline (5.0 g, 35 mmol), formaldehyde (2.81 g of 37% solution, 35 mmol), triethylamine (0.17 ml) and ethanol (4.6 ml). The pH was adjusted to 7–7.5 by mean of dilute aqueous hydrochloric acid. Stirring was maintained 16 hours at 60° C. The solvent was concentrated, the residue was diluted with water and extracted with diethyl ether to remove the unreacted quinoxaline. The aqueous phase was basified with 20% aqueous sodium hydroxide (10 ml) and extracted with ethyl acetate. The organic phase was dried over magnesium sulfate and concentrated. The residue was chromatographed on silica gel eluting with dichloromethane-methanol (first 95-5 then 90-10 and finally 90-10 plus 0.1% of ammonia) to give diethyl-(2-quinoxalin-2-yl-ethyl)-amine (2.67 g, 37%).

Quelle