Reaction #82977

Reaction equation

trichloroacetyl chloride

2,9-dimethylimidazo[1,2-a]benzimidazole

→

2,9-Dimethyl-3-trichloroacetylimidazo[1,2-a]benzimidazole

Solvents

xylene

Conditions

Workup

1. 1
   Otherobtained
2. 2
   TemperatureThe mixture is then heated
3. 3
   Temperatureat reflux for two hours until the product which
4. 4
   Otherhas initially precipitated
5. 5
   workup.DISSOLUTIONis completely dissolved
6. 6
   TemperatureCool
7. 7
   Filtrationfilter
8. 8
   ConcentrationConcentrate the mother liquors
9. 9
   workup.ADDITIONadd petroleum ether
10. 10
    OtherCombine with the precipitate obtained earlier
11. 11
    OtherThe combined precipitates
12. 12
    workup.ADDITIONare treated with an aqueous solution of sodium hydrogen carbonate
13. 13
    Otherrecrystallised from ethyl acetate

Procedure

Pour 5.45 g (30 mmol) of freshly distilled trichloroacetyl chloride dropwise into a boiling solution of 2,9-dimethylimidazo[1,2-a]benzimidazole (3.7 g; 20 mmol)--obtained as described in Khim. Geterotsikl Soedin, 86, (7), 918-925--in 50 ml of xylene, with vigorous stirring, over a period of 20 to 30 minutes. The mixture is then heated at reflux for two hours until the product which has initially precipitated is completely dissolved. Cool and filter. Concentrate the mother liquors and add petroleum ether. Combine with the precipitate obtained earlier and repeat the operation. The combined precipitates are treated with an aqueous solution of sodium hydrogen carbonate and then recrystallised from ethyl acetate.

Source