| abstract |
A process for preparing a crystalline, carbapenem monosodium salt of formula IIa: characterized by the steps a) adding about 10 to 30% of an organic solvent to an aqueous solution of the carbapenem, b) cooling the resulting solution to less than -5° C., c) adjusting the pH using a solution containing an acid in an organic solvent to give the appropriate pH for crystallization, and d) crystallizing the compound by adding methanol, and a C<SUB>2-5 </SUB>alcohol at between -5 and -25° C. |