0.087 g (0.444 millimoles) of barium carbonate is dissolved in 8.87 ml of a 0.1 N aqueous perchloric acid solution under slight warming whereupon water is removed in vacuo. The residue is taken up in 10 ml of methanol and added to a suspension of 1.0 g (0.887 millimoles) of primycin sulfate in 80 ml of methanol. The reaction mixture is heated to boiling for 20 minutes under stirring. The primycin perchlorate thus formed remains in the solution and the barium sulfate is precipitated. The hot solution is filtered over Celite and the solid is thoroughly washed on the filter with 10 ml of a 2:1 mixture of acetone and water. Thus 0.94 g of white primycin perchlorate is obtained, yield 88.7%. Mp.: 170°-171° C., /α/D25 =+20°.
