Patent ID: 7893254

Claim:
A process for preparing 7-amino-3-[(E/Z)-2-(4-methylthiazol-5-yl)vinyl]-3-cephem-4-carboxylic acid of the formula (1) or an alkali metal salt thereof, said acid or said salt being higher in the weight % content of 7-amino-3-[(Z)-2-(4-methylthiazol-5-yl)vinyl]-3-cephem-4-carboxylic acid of the formula (2) or of an alkali metal salt thereof than the weight % content of a starting salt, the process comprising: providing an aqueous solution of an alkali metal salt of 7-amino-3-[(E/Z)-2-(4-methylthiazol-5-yl) vinyl]-3-cephem-4-carboxylic acid of the formula (1), treating said aqueous solution with active carbon as added thereto, and, optionally, adding an acid to said treated aqueous solution to convert the salt into an acid