Zwikker reaction

ZSM-5 catalyst ZSM-5 zeolite Zudopenthixol [53772-Zvyagintsevite Zweifel alkene synthesis Zwikker reaction... 

Hydantoin itself can be detected ia small concentrations ia the presence of other NH-containing compounds by paper chromatography followed by detection with a mercury acetate—diphenylcarba2one spray reagent. A variety of analytical reactions has been developed for 5,5-disubstituted hydantoias, due to their medicinal iaterest. These reactions are best exemplified by reference to the assays used for 5,5-diphenylhydantoiQ (73—78), most of which are based on their cycHc ureide stmcture. Identity tests iaclude the foUowiag (/) the Zwikker reaction, consisting of the formation of a colored complex on treatment with cobalt(II) salts ia the presence of an amine (2) formation of colored copper complexes and (3) precipitation on addition of silver(I) species, due to formation of iasoluble salts at N. ... 

The ZwiKKER reaction involving Co + salts is frequently used for the detection barbituric acid derivatives [31-35], but some purine, pyridine and piperidine derivati and heterocyclic sulfonamides also yield colored derivatives. The Zwkker reaction particularly sensitive when it is possible to form a tetrahedral complex [Co(Barb) Xj] (X = donor ligand, e.g. amine) [4]. 

Detection of barbituric acids is possible non-specifically by chromatography on so-called fluorescent layers, e. g., silica gel GF254. If not present in too small amounts, they appear in short wave UV light as spots of quenched fluorescence. A popular method of detection has been with mercury compounds, especially mercurous nitrate (Rgt. No. 157) which yields insoluble barbiturates [10, 34, 43, 56, 77, 140, 166]. The sensitivity of response varies with the barbituric acid. A combined spray reagent of a mercuric salt and diphenylcarbazone solutions (No. 156) has been often used the spots then stand out better against the background [32, 93, 160]. Cobalt salts have been used with various bases for detection (Zwikker-reaction and modifications, Rgt. No. 51) [56, 152, 170, 174]. N-methylated barbituric acids do not react since the second nitrogen atom cannot take part in enolisation [98]. A further, non-specific method... 

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