EXAMPLE 1 Biguanide (3.0 g, 101.11 g/mol; 2.96×10 -2 mol) was added gradually as a solid to perchloric acid (10.3 mol, 5.78 N) in an ice bath. The
solution was evaporated under vacuum with a dry ice trap. The white crystals (8.6 g 96.5%) of biguanide diperchlorate were dried under vacuum over P 2
O 5 and KOH. Concentration of a saturated ethyl acetate/acetonitrile solution gave crystals, mp 217°-219° C. |