ORGANIC MEDICINAL CHEMICALS 41 



DOUBLE RING COMPOUNDS 



ii. INDIGO GROUP. Compounds containing double rings similar to those 

 of indigo thus, indigo, C 6 H 4 <** >C=C<^>C^ 4 ; isatin, 



indol, C 6 



12. DIPHENYL AND ITS DERIVATIVES. Compounds containing two phenyl 



groups joined directly to each other thus, diphenyl, CeHs-CeH*; 

 benzidine (p-diamidodiphenyl), CeH^NHg-CeEUNH^. 



13. DIPHENYL-METHANE AND SIMILAR COMPOUNDS. Compounds in which 



two H atoms of methane are replaced by two phenyl groups, 

 (C 6 H5) 2 , thus, diphenyl-methane, CHXCeHs^; benzophenone, 

 CO(C 6 H 5 ) 2 . 



14. TRIPHENYL-METHANE GROUP. Compounds in which three H atoms 



of methane are replaced by the phenyl radical thus, triphenyl- 

 methane, CH(C 6 H 5 )3; triphenyl-methane-carbinol, C(OH)- 



These compounds are of especial interest, including extensive 

 series of dyes. The following groups of dyes are distinguished: 



(1) Diamido-triphenyl-methane group (the bitter-almond-oil 

 green group). 



(2) Triamido-triphenyl-methane (the rosaniline group). 



(3) Trioxy-triphenyl-methane (the aurin group). 



(4) Triphenyl-methane-carboxylic acid, (the eosin group). 

 For a more complete description of these dyes the student is 



referred to works on organic chemistry. 



CONDENSED RING COMPOUNDS 



15. NAPHTHALENE AND ITS DERIVATIVES. Naphthalene contains two 



condensed rings and has the composition CioH 8 ; or, graphically, 

 HC CH- 

 c, 



This is an increment of CaH^ over benzene. The hydrogen 

 can be replaced as in benzene, forming derivatives thus, 

 -CioH 7 OH, naphthol; CioH 7 NH 2 , naphthylamine, etc. When 

 an atom of hydrogen connected to a carbon atom adjacent to 

 either of the atoms of carbon common to both rings is replaced, 

 alpha (a) derivatives of naphthalene are made. If those not 

 adjacent are replaced, we have beta (0) derivatives. 



