Über die Verwendung von Tüpfelreaktionen zum Nachweis von organischen Verbindungen. (VII.)

4-Thiazolidinones.

“…Another test uses l,2-naphthoquinone-4-sulfonic acid, which condenses with the nucleophilic carbon atom of rhodanine, forming in acid solution a red precipitate which turns blue-violet in the presence of base (517). When used in spot tests, this method will indicate the presence of 0.6 y of the compound (231). Substances which participate in the synthesis of 4-thiazolidinones O can, by the addition of the appropriate reagent, be detected by this test (232).…”

Fluorimetric determination of pyridine after hydroxylation with the Hamilton hydroxylation system

“…The high specificity of the present reaction is due to simultaneous requirement of two different functional groups, active methylene and adjoining carbonyl groups, for the formation of fluorophores. Therefore, indole and pyrrole, which can be detected with colorimetric reagents for active methylenes such as sodium nitroprusside (23,24), 1,2naphthoquinone-4-sulfonic acid (25,26) and p-dimethylaminobenzaldehyde (25), are not detectable in the present fluorescent reaction. Moreover, some other typical active methylenes such as creatinine, resorcinol, orcinol, and phloroglucinol which may produce a cyclic n-methylene carbonyl group and show positive response to the colorimetric reagents or some cyclic -methylene carbonyls such as dimedone, camphor, and isoketopinic acid gave no fluorescence, probably because of the steric hindrance around the amethylene carbonyl groups.…”

Nitrogen in oil shale and shale oil, Part VIII. The detection of tar bases

“…(b) Condensation with Sodium 1 : 2-napMJiaquinone-4-sulp}ionate. Feigl and Frehden (1934) observed that ^-alkyl pyridinium compounds readily condense with 1 : 2-naphthaquinone-4-sulphonic acid to give coloured compounds. The test was carried out using methyl iodide and dimethyl sulphate as alternative alkylating agents and gave yellow to red colours with the bases.…”