Réaction #63758

Équation de réaction

sodium hydroxide

5-(trifluoromethyl)-2-benzimidazolethiol

2-chloromethyl-3-methylpyridine hydrochloride

→

5-(trifluoromethyl)benzimidazole

Solvants

—

alcohol

water

Conditions de réaction

Traitement

1. 1
   Températurewhile cooling
2. 2
   workup.WAITthe mixture is left
3. 3
   Températureat reflux overnight
4. 4
   Autresubsequently evaporated to dryness in vacuo
5. 5
   workup.DISSOLUTIONThe residue is dissolved in 950 ml of methylene chloride
6. 6
   LavageThe solution is washed firstly with 200 ml of 1.5N sodium hydroxide solution
7. 7
   Séchagedried over sodium sulphate
8. 8
   Autreevaporated in vacuo
9. 9
   AutreThe crude product is purified on 100 g of silica gel with ethyl acetate/methylene chloride (1:1) as the elution agent
10. 10
    AutreCrystallization from methylene chloride/petroleum ether

Mode opératoire

6.54 g of 5-(trifluoromethyl)-2-benzimidazolethiol are suspended in 200 ml of alcohol and treated with 5.34 g of 2-chloromethyl-3-methylpyridine hydrochloride while cooling wlth ice. Thereafter. a solution of 2.4 g of sodium hydroxide in 100 ml of water is added dropwise thereto, the mixture is left to boil at reflux overnight and subsequently evaporated to dryness in vacuo. The residue is dissolved in 950 ml of methylene chloride. The solution is washed firstly with 200 ml of 1.5N sodium hydroxide solution and then 3 x with 250 ml of water. dried over sodium sulphate and evaporated in vacuo. The crude product is purified on 100 g of silica gel with ethyl acetate/methylene chloride (1:1) as the elution agent. Crystallization from methylene chloride/petroleum ether gives 2-[[3-methyl-2-pyridyl)methyl]thio]-5-(trifluoromethyl)benzimidazole of melting point 180°-182°.

Source