Preparation of Sugar Tetrazolium Compounds

With the objective of obtaining a biological indicator less toxic than T.T.C., and in view of a new and gradually increasing interest in tetrazolium compounds, attempts have been made to prepare them by the oxidation of sugar formazans.  

Using oxidants generally employed for the oxidation of simple formazans (for example, amyl nitrite and lead tetraacetate), the sugar formazans 

—Formation of L-Rhamnose IV.iV -Diphenylformazan at Various Time Intervals (-----in water,-------in 50% ethanol,.in pyridine). 

Similar difficulties were encountered on employing lead tetraacetate as the oxidant. 

the sugar portion sensitive to oxidation was protected by means of acetylation, and the penta-O-acetyl-n-galactose diphenylformazan was oxidized with lead tetraacetate. By the action of the calculated amount of the oxidant, penta-O-acetyl-n-galactose diphenyltetrazolium chloride CG.T.C. acetate) was obtained as characteristically shaped, colorless prisms upon addition of an appropriate quantity of hydrochloric acid. Owing to its ionic structure, this compound is quite soluble in water and is readily reduced to the corresponding acetylated formazan, which is red. Saponification of the penta-O-acetyl-D-galactose diphenyltetrazolium 

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