40 ORGANIC MEDICINAL CHEMICALS 



4. NITRO DERIVATIVES are analogous to those of the methane series, but 



are more stable, and can be made by the direct treatment of 

 the hydrocarbon with nitric acid thus, nitro-benzene, CeHsNCv, 

 tri-nitro-toluene, C 6 H 2 CH 3 (NO2)3. 



5. AMIDO DERIVATIVES. (i) Compounds formed by replacing one or 



more atoms of hydrogen in benzene or derivative hydrocarbons 

 by one or more amido groups thus, aniline (amido-benzene), 

 C 6 H 6 NH 2 ; phenylene-diamine, C6H 4 (NH 2 )2. 



(2) Compounds formed by replacing one or more atoms of 

 hydrogen in ammonia by the aromatic hydrocarbon radicals 

 thus, diphenyl-amine, (CeH^NH. 



6. OTHER NITROGEN DERIVATIVES. Diazo, azo-compounds, and hydra- 



zines: (a) Diazo-compounds are intermediate products in the 

 conversion of amido compounds to alcohols by means of nitrous 



acid. They contain the characteristic group -N = N thus, 



diazo-benzene-chloride, CeHs-N = N Cl. 



(b) Azo-compounds contain the same group as the diazo-com- 

 pounds, but joined on each side to an alkyl radical thus, azo- 

 benzene (benzene-azo-benzene), C 6 H 5 -N = N-C 6 H 5 



(c) Hydrazines are compounds derived by the replacement 

 of the hydrogen of hydrazine (N2H4) by one or more aromatic 

 hydrocarbon radicals thus, phenylhydrazine, CeHsNH-NH^. 

 They contain the charactistic group = N-N = . 



7. PHENOLS are oxygenated derivatives of the benzenes. Chemically, they 



are midway between the alcohols and acids, and are formed by 

 the replacement of H of the benzene nucleus by hydroxyl 

 thus, phenol (carbolic acid), C 6 H 6 OH; creosol, C 6 H 4 (CH 3 )OH. 

 When two or more of the hydrogen atoms are replaced by 

 the hydroxyl group, the polyacid phenols are obtained thus, 

 pyrocatechin (o-dioxy-benzene), CeH 4 (OH)2; resorcin (m-di- 

 oxybenzene; and hydroquinone (p-dioxy-benzene). Tri-acid- 

 phenols: C 6 H 3 (OH) 3 , pyrogallic acid = o-trioxy-benzene; phloro- 

 glucin (s-trioxybenzene), oxyhydroquinone (a-trioxybenzene). 



8. ALCOHOLS, ALDEHYDES, AND KETONES. Analogous to the same com- 



pounds of the methane series, containing the same groups, re- 

 placing the hydrogen of the side-chains thus, Ce 

 benzyl alcohol; C 6 H 5 CHO, benzaldehyde; C6H 6 

 acetophenone. 



9. ACIDS. Compounds analogous to the acids of the methane series, 



capable of forming the same kinds of derivatives thus, ben- 

 zoic acid, C 6 H 5 COOH; toluic acid, C 6 H 4 CH 3 COOH; phthalic 

 acid, C 6 H 4 (COOH) 2 . 



10. COMBINATIONS OP THE ABOVE CLASSES. 



