Patent ID: 7728126

Claim:
A process for converting into 7α-methoxy-cephalosporins 7α-methylthio-cephalosporins contained as impurities in the 7α-methoxy-cephalosporins, wherein a 7α-methoxy-cephalosporin containing an amide group in position 7, and impure with 0.5% of the corresponding 7α-methylthio analogue, is treated with a halogenating agent chosen from the group consisting of bromine, N-bromosuccinimide, N-chlorosuccinimide, N-chloroacetamide, chloramine T, dichlorourethane and 1,3-dibromo-5,5-dimethylhydantoin, in methanolic solution, at a temperature between 0° and +5° C. for a time between 30 minutes and 3 hours, to obtain the complete conversion of the sulphurated impurity into the corresponding methoxy analogue.