ox nVDRO-AROMATIC COMPOUNDS M'lTH SINGLE NUCLEUS. 133 



•and hexahydroterephthalic acid is obtained by saponi6cation and elimina- 

 tion of 200-2 from the product of the interaction of ethylene dibromide 

 «,nd ethyl sodiobutanetetracarboxylate,'^ 



CH„ . CH, CH., . OH., 



(COOCHJ., C : Na 

 iBr 



\, 



Na 

 Br 



I I 



CH, - CH„ 



(COOC„Hi).,-> (COOCH,)., . 1 : C (COOCH Jj 



' ■ \ /- 



CH...tH., 



.a reaction which may be extended to the preparation of hexaliydro- 

 isophthalic acid,^ in which case both the cis and trans modifications were 

 •obtained.^ 



Hydroxy- and ketohydro-dicarboxylic acids. — Dihydroxyhexahydro- 

 isophthalic acid (see above), 1 : i:-dihydroxyhexa1iydroterephthalic acid, 

 results from the addition of hydrocyanic acid to diketohexahydro- 

 benzene '' and the ethyl salts of 2 : ft-dihydroxytetra- and hexahydrotere- 

 jphthalic acid by the reduction of ethyl succinosuccinate.* 



Succinosuccinic acid is formed by the saponification of its ethyl salt 



CO . CH, 



/ \ + 



COOCHs . CH + OH . COOCJIs 



\ / 



CH, . CO 



prepared by the action of potassium or sodium on ethyl succinate, &c.*' 

 "The ethyl salt is capable of reacting in two forms, as a diketone or a^ 

 "ethyl dibydroxydihydroterephthalic acid J 



COOCH- 



The two hydrogen atoms (marked above +) can be replaced by sodium, 

 thus afibrding a method for the production of homologues. The chemical 

 changes which this substance is capable of undergoing have been 

 frequently alluded to. 



Ethyl dihydroxydiketohexahydrohenzenedicarboxylate,^ ethyl diketo- 

 Jiexahydrohenzenetetracarboxylate,^ hexahydrobenzenehexacarboxylic (hexa- 

 Jiydrornellitic) acid.^'^ 



In conclusion it may be of interest to draw attention to the close 

 relationship existing between aliphatic, hydro-aromatic, and aromatic 

 bodies, as illustrated by the passage of substances belonging to the 

 aliphatic series into hydro-aromatic bodies, and of the latter into members 



' Mackenzie and Perkin, J.C.S., 1892, 61, 172. 



" Perkin, J.C.S., 1891, 69, 798. 



' Compare Villiger, Amialen, 1893, 276, 255. 



♦ Ber. 1889, 22, 2176. * Ber., 1900, 33, 390. 

 « Annalen, 1882, 211, 306 ; 1888, 245, 74 ; 1889, 253, 182. 



' Ber., 1891, 24, 2692. 



« Ber., 1886, 19, 2385 ; 1887, 20, 1307; 1889, 22, 1290; 1890, 23, 265. 



* Ber., 1889, 22, R. 289. . '" Beilstein, 3" Avjt., ii. 210t. 



