title: [Color reactions for identification of nalidixic acid].
abstract: Nalidixic acid (1) gives with 2-naphthol a yellow charge-transfer complex. The 7-methyl group of 1 condenses with vanillin (2) and Ehrlich's reagent (4) to the coloured (E)-benzylidene compounds 3 and 5. Treating 1 with thionyl chloride and subsequent reaction with aminopyrazolone (6) and sodium acetate leads to a mixture of trichloronalidixic acid (7) and its 3-carboxamide 8. The trichloromethyl group of 7 is converted with 6 in pyridine to form the amide 9. Nalidixic acid reacts with 1,3-dimethylbarbituric acid (10) in acetanhydride/acetic acid to yield the polymethine dyes 11-13, whose structures are confirmed by X-ray crystal structure analysis. The dyes 3 and 12 inhibit the growth of staphylococcus aureus and Escherichia coli, respectively.
authors.affiliation: Institut für Pharmazeutische Chemie, Technischen Universität Braunschweig, Germany. k.goerlitzer@tu-bs.de
authors.forename: K
authors.initials: K
authors.lastname: Görlitzer
authors.forename: G
authors.initials: G
authors.lastname: Badia
authors.forename: P G
authors.initials: PG
authors.lastname: Jones
authors.forename: A K
authors.initials: AK
authors.lastname: Fischer
mesh_terms: D000890:Anti-Infective Agents / Q000737:chemistry*; D001419:Bacteria / Q000187:drug effects; D001547:Benzaldehydes; D004396:Coloring Agents / Q000494:pharmacology; D018360:Crystallography, X-Ray; D008826:Microbial Sensitivity Tests; D009268:Nalidixic Acid / Q000737:chemistry*
chemical_list: D000890:Anti-Infective Agents; D001547:Benzaldehydes; D004396:Coloring Agents; D009268:Nalidixic Acid; C510241:p-dimethylaminobenzaldehyde