[Li+].[CH2:2]1[C:5](=[O:6])[N:4]2[C@@H:7]([C:13]([O-:15])=[O:14])/[C:8](/[O:12][C@H:3]12)=[CH:9]/[CH2:10][OH:11].[F-].[K+:17].[F-].[Li+]>O>[CH2:2]1[C:5](=[O:6])[N:4]2[C@@H:7]([C:13]([O-:15])=[O:14])/[C:8](/[O:12][C@H:3]12)=[CH:9]/[CH2:10][OH:11].[K+:17]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).
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