Tetrazotized o-dianisidine

Dimethoxybiphenyl has been prepared by methylating 3,3 -dihydroxybiphenyl with methyl iodide 3 or dimethyl sulfate 4 and by deaminating tetrazotized o-dianisidine with alcohol.8,8,7 The present procedure is a slight modification of Mai s directions. 

Figure 8 Reaction of trypsin inhibitors and enzymatically modified soy albumin samples with trypsin after native PAGE. Samples run were (1) Kun-itz trypsin inhibitor (KTI) (2) a-chymotryptic hydrolysate of soy albumin (3) a-chymotryptic EPM of soy albumin (4) Bowman-Birk inhibitor (BBI) (5) peptic hydrolysate of soy albumin (6) peptic EPM of soy albumin (7) KTI (8) proteolytic hydrolysate of soy albumin (9) EPM product of soy albumin (10) BBI. The bands were visualized by exposure to trypsin and its substrate A-acetyl-DL-phenylalanine /3-naphthyl ester followed by negative staining with tetrazotized o -dianisidine-ZnCl2 complex.

A direct dye of importance is Direct Blue 1 (Sky Blue FF). It is made by coupling tetrazotized o-dianisidine twice with Chicago acid (SS acid). Direct Blue 1 is used as a dye for cellulosic textiles, paper, and nylon. It is applied to cellulosic textiles and paper under neutral conditions, and it dyes them by adsorption. It also is used as an acid dye on nylon and must be applied under acidic conditions. 

Gringras and Sjostedt273 reduced sulphonyl chlorides on paper chromatograms with a sodium sulphite reagent, then visualizing the sulphinate reaction product with tetrazot-ized o-dianisidine. Direct titrations of sulphonyl chlorides with sodium sulphide have also been performed, with instrumental or visual end-point indication (the latter depending on the formation of yellow polysulphide from the excess reagent and the sulphur produced)274-276. 

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