Lithium fluoride → Potassium Clavulanate

Lithium clavulanate (7.15 g, estimated purity 68% pfa 0.025 moles) was stirred in water (45 mls) and cooled in ice. Potassium fluoride solution (3.5 g KF.2H2O in 9 mls solution; 1.5 equivalents) was added slowly to the cloudy brown solution and lithium fluoride separated out as a fairly gummy deposit. The mixture was made up to 100 ml with acetone over 3/4hr and then up to 800 mls with acetone over 1/2 hr. The solid which had separated now was dark brown and was removed by filtration through celite (4 gm). The almost colourless filtrate was added to acetone (1750 ml) over 1 hr with rapid agitation, then filtered and washed with acetone (3×50 ml) and fluid bed dried to give a fine granular just off-white solid potassium clavulanate (3.6 g, 83.1% pfa, 62% recovery).