Sulfuric Acid → 5-(p-chlorophenyl)-2,3,5,6-tetrahydro-1H-imidazo[1,2-a]imidazole hydrochloride

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Reaction Steps

3.4 parts of p-chloro-α-(2-imidazolin-2-ylaminomethyl)benzyl alcohol are added to 30 parts of sulfuric acid 80% while stirring and cooling in an ice-bath. Upon completion, the whole is stirred for 2 hours at room temperature. The reaction mixture is poured onto crushed ice, alkalized with a concentrated sodium hydroxide solution and the product in base form is extracted with methylene chloride. The extract is dried, filtered and evaporated. The residue is dissolved in 2-propanol. The solution is filtered over diatomaceous silica and the filtrate is acidified with an excess of 2-propanol previously saturated with gaseous hydrogen chloride. The precipitated salt is filtered off, washed with acetone and dried, yielding 5-(p-chlorophenyl)-2,3,5,6-tetrahydro-1H-imidazo[1,2-a]imidazole hydrochloride, m.p. 266.1°C.

Provenance & Evidence