Ph-neutral aqueous solutions of quinolone-carboxylic acids

Abstract From the Canadian patent

A pH-neutral aqueous solution of a, quinolone-carboxylic acid of the formula (see fig. I), in which, R1 represents halogen C1-4-alkyl or C2-4-alkenyl, R2 and R3 represent hydrogen C1-4-alkyl, or together with, the adjacent nitrogen atom form an optionally substituted morpholine or piperazine ring R4 represents optionally substituted C1-4-alkyl or C3-6-cycloalkyl, X represents -N= or -CR5= and, R5 represents hydrogen, halogen, OH or C1-4-alkyl or, R4 and R5, together with the C and N atoms positioned between them, form a saturated 5- or 6-membered ring which can contain other hetero atoms and which is optionally substituted, the solution containing calcium ions in at least an equimolar …