A number of p-nitrophenyl substituted tetrazolium salts have been synthesized for the histochemical demonstration of de, hydrogenase in tissues. One of these, 2,2′-di-p-mtrophenyl-5,5′-diphenyl-3,3′-(3,3′-dimethoxy-4,4′-biphenylene)-ditetrazolium chloride (XA, “nitro-BT”) (Table IV) was found to be superior to any tetrazole so far developed for histochemistryand makes possible the demonstration of the dehydrogenases at the cytological level. It was also found that during the coupling of a tetrazotized biphenylenediamine with a phenylhydrazone, one of the diazonium groups could be replaced by hydrogen to form a phenyl group. Thus, in the formation of the above-mentioned ditetrazolium salt, a monotetrazolium salt, 2-p-nitrophenyl-5-phenyl-3-(3,3′-dimethoxy-4-biphenylyl)-tetrazolium chloride (IIIA) (Table III), was obtained concomitantly. The isolation of the mono- and diformazans is described and mechanisms for the formation of the monoformazans are discussed. The nature of the monotetrazole that is found as a contaminant in commercial preparations of ditetrazoles is thus ellucidated.
ASJC Scopus subject areas
- Colloid and Surface Chemistry