1-aminoimidazolidine-2-thione

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 1-Aminoimidazolidine-2-thione (2.34 g) and methyl p-toluenesulfonate (4.1 g) in ethanol (15 ml) are heated to reflux for 10 minutes, then kept at room temperature for 16 hours. The crystalline precipitate is filtered out and washed with isopropanol to give 4.613 g of 1-amino-2-methylthio-2-imidazoline p-toluenesulfonate as colorless needles, of which 3.79 g is placed in methanol (15 ml) and treated with concentrated aqueous ammonia. After stirring for 6 hours, the mixture is diluted with 20 ml isopropanol. After another 12 hours, 5 ml of liquid is distilled off at atmospheric pressure, and 10 ml isopropanol is added to the remainder. The crystals which separate on cooling are filtered out and washed with isopropanol to give 2.323 g of 1,2-diamino-2-imidazoline p-toluenesulfonate, melting point 190°-190.5° C. to reflux for 10 minutes The crystalline precipitate is filtered out washed with isopropanol