Miscellaneous Dyes 235 



DIAZO SALT OF AMINOAZOTOLUENE 



CH3 CH3 



/ / 



N=N_/— \_N=NCI 

 \_/ 



Trade names: Fast garnet salt B (Gurr); Garnet GBC salt (Nat- 

 Aniline) 



DIAZO SALT OF P-NITROPHENYL-AZO-2,5-DIMETHOXYAMINE 



OCH3 



/ 



02N_/— \_X=N_/~\_N=NC1 



/ 

 OCH3 



Trade names : Fast black salt K (Gurr) ; Black K salt (Nat. Aniline) 



5. TETRAZOLIUM SALTS 



Among the important histochemical reagents, other than dyes, 

 are certain derivatives of tetrazole: 



N\ 



II N 

 HC II 



11 N 



N/ 



A useful reference to consult concerning the chemistry of these 

 compounds and their biological applications is Smith, F. E. 

 (1951). The earliest prepared and best known of the derivatives 

 is 2,3,5-triphenyl tetrazolium chloride, which is commonly called 



TETRAZOLIUM SALT 



{Abbreviation TTC) 



N = C" 



/-\_ I I 



\_/ N N 



\ il 

 CI N 



This reduces to the red compound, formazan, a compound con- 

 taining the azo-group: 



N_C— ^ 



/-\ II I 

 \_/-N N 



\ . 

 HN 



