136 REPORT— 1902. 



Nitric acid. — It is generally stated that nitric acid has no action on 

 the saturated paraffins, but it acts readily on unsaturated and aromatic 

 bodies, producing oxidation in the first case and nitro-compounds in the 

 second. This statement is, however, not strictly true as regards the 

 paraffins. Much work has recently been done in this direction, for a 

 detailed account of which the following, among other papers, may be 

 consulted. "^ 



It is true that at ordinary temperatures the paraffins remain practi- 

 cally unacted on by nitric acid in any form, and that normal paraffins are 

 slowly decomposed by fuming nitric acid on heating,^ but the isoparaffius, 

 e.g., isohexane, isopeptane, isooctane, and diisohuty\ are very readily 

 attacked by fuming nitric acid, a moderate yield of nitro-compound beinig 

 obtained in each case.^ 



Hexahydrobenzene is only attacked when heated with fuming nitric 

 acid, giving a dibasic acid, and its methyl derivative is directly broken 

 down. Less concentrated nitric acid at high temperatures gives secondary 

 nitro-compounds in addition to dibasic acids, and with methylhexahydro- 

 benzene a tertiary nitro-derivative is obtained. 



On hydro-aromatic substances containing double bonds nitric acid acts 

 as an oxidising agent ; in some cases niti'o-derivatives are formed, which 

 are usually aromatic bodies. Presumably nitric acid first removes 

 hydrogen atoms by oxidation, and then nitrates the aromatic bodies so 

 formed, e.g., the production of nitro-xylenes from dimethyldihydrobenzenc 

 (see p. 134). 



With aromatic substances nitric acid nitrates, and when oxidation 

 does take place the side chain is the attackable point. 



Oxidising agents. — These react with hydro-aromatic substances exactly 

 as with aliphatic bodies, oxidation taking place at a double bond, e g., 

 1:1- dimethyl - A 2 : 4 - dihydrobenzene gives aadimethylsuccinic acid,* 



,CH = CH .COOH 



(CH3),C ^CH -♦ (CH3),.C 



^CH^-CH "^CH, .COOH 



and dimethyl dihydroresorcin, which contains a double bond and also a 

 carboayl group, yields jS/3-dimethylglutaric acid on oxidation. The 



.CH^ .CO XH„ . COOH 



(CH3), . C J>CH -> (CHj); . 



^CHj . COB \CH„ . COOH 



methyl groups, however, remain intact, whereas in an aromatic body 

 the side chain is the attackable point and the ring remains unbroken. 



Two other points may be worth mentioning in connection with 

 dimethyldihydroresorcin. The hydroxyl group has the characteristics of 

 a phenolic rather than an alcoholic group. The substance gives a violet 



' Konowaloff. Ber., 1892. 25, R. Kig ; J. Riiss. Phys. Cliem. >%e., 1899, 31, 57, 

 254, 1027 ; and 1901, 33, 48, 393 ; Ber., 1899, 32, 144.5 ; Markownikoflf, Ber., 1897, 

 30,974, 1222; and 1899, 32, 1441; 1902, 35, l.')84; also 386; Annalm, 1898, 301, 

 201 : Zelinsky, 1897, 30, 389 ; Francis and Young, J.(JS., 1898, 73, 928 ; Pimi Cent. 

 Blatt., 1902. ii. IG. 



^ Normal hexane and octane yield with dilute nitric acid secondary nitro com- 

 pounds in nearly theoretical amount (Konowaloff, Ber , 1892, 25, R. 168). 



» Francis and Young (ibid.). ' Crnssley and Le Sueur, J.C.S., 1902, 81,836. 



