Reaction #595342

Reaction equation

hydrogen chloride

2,3-pentanedione 2-oxime

4-chlorobenzaldehyde

acetic acid

→

2-(4-Chlorophenyl)-5-ethyl-4-methyl-1,3-oxazole 3-oxide

Solvents

diethyl ether

Conditions

Workup

1. 1
   workup.ADDITIONis then introduced for 30 min
2. 2
   OtherA precipitate is formed
3. 3
   Filtrationwhich is filtered off with suction
4. 4
   Washwashed twice with in each case 2 ml of diethyl ether
5. 5
   ExtractionThe suspension is then extracted four times with in each case 10 ml of dichloromethane
6. 6
   DryingThe combined organic phases are dried over magnesium sulfate
7. 7
   Otherthe solvent is removed on a rotary evaporator
8. 8
   OtherThe residue is used without further purification in the subsequent reaction

Procedure

1.00 g (8.69 mmol) of 2,3-pentanedione 2-oxime and 1.34 g (9.55 mmol) of 4-chlorobenzaldehyde are initially charged in 2 ml (34.94 mmol) of glacial acetic acid. With ice-cooling of the reaction mixture, hydrogen chloride gas is then introduced for 30 min. 10 ml of diethyl ether are then added to the reaction mixture. A precipitate is formed, which is filtered off with suction and washed twice with in each case 2 ml of diethyl ether. The precipitate is resuspended in about 5 ml of water, and the suspension is made basic using ammonia. The suspension is then extracted four times with in each case 10 ml of dichloromethane. The combined organic phases are dried over magnesium sulfate and the solvent is removed on a rotary evaporator. The residue is used without further purification in the subsequent reaction.

Source