DMSO is used as a reaction solvent in certain norfloxacin manufacturing routes. One documented application is the reaction of a boron-chelated quinolone intermediate with piperazine, which introduces the piperazine group into the molecule. Hydrolysis follows to obtain norfloxacin (CAS 70458-96-7).
Where DMSO enters the route
The piperazine substitution forms the carbon–nitrogen bond at the 7-position of the quinolone ring. DMSO provides the reaction medium; piperazine supplies the group incorporated into the product.
A published preparation describes DMSO or acetonitrile for this step. Public manufacturing documentation also identifies a DMSO–toluene system in a piperazine-containing operation. The solvent composition therefore depends on the route and plant procedure.
This use belongs to intermediate conversion in production, rather than simply dissolving a sample of the finished antibiotic. A plant carrying out the step repeatedly can have recurring DMSO demand. A site purchasing a more advanced intermediate may have a different requirement.
What matters in the solvent
Use the established process specification for DMSO assay, water and relevant impurities. If DMSO is charged with another solvent, control the mixture as well as the individual incoming materials.
When changing supply, compare starting-material conversion, the impurity profile and isolated product quality. Include hydrolysis, crystallization, washing and drying in the evaluation, since a satisfactory reaction result alone does not describe the complete process.
After the reaction
Any DMSO remaining in the product must be addressed by work-up and the applicable residual-solvent specification. The incoming DMSO COA describes the solvent supplied; a separate suitable analysis is needed to establish residual DMSO in norfloxacin.
Where solvent is recovered, fresh purchasing demand depends on make-up and recovery losses. Reuse criteria should cover water and process-related carryover, not just DMSO content. Compatibility and thermal controls should cover the complete reaction mixture.
For supply enquiries, share the DMSO specification, expected fresh consumption and packaging requirement with YUJI.