ON THE STUDY OF HYDRO-AROMATIC SUBSTANCES. 111 
If alcoholic sulphuric acid be used as condensing agent, then Mannich ! 
finds that ketohexahydrobenzene behaves similarly to acetone, yielding 
bodies analogous, as regards method of formation, to mesityl oxide, 
phorone, and mesitylene, and having the respective formule C,,.H,,0, 
C,,H,,0, and C,gH,,. The latter would obviously be produced from 
three molecules of ketohexahydrobenzene, according to the following 
scheme : 
H, 
H, H, 
He 
H, H, : 
O H, 
O : + 3H,0 
H =r 
H; whee H, 
H, 
H, H, 
H, 
which shows it to contain a benzene ring and three hydrogenised benzene 
rings, and it would therefore be dodecahydrotriphenylene. It crystallises 
in compact prisms melting at 232°-233°, when oxidised with fuming nitric 
acid yields mellitic acid, and on distillation with zinc-dust in an atmo- 
sphere of hydrogen ? is converted into triphenylene, identical with the sub- 
stance previously described by Schmidt and Schultz? The ketones 
C,H,,0 and C,,H,,O0 have probably the following constitutions : 
Homologues of ketohexahydrobenzene can be produced by the slow 
distillation of the anhydrides of substituted pimelic acids, when they lose 
carbon dioxide. Blanc‘ has by this means prepared from /33-dimethy]- 
pimelic anhydride 3-keto-1 ; 1-dimethylhexahydrobenzene,* which when 
reduced with sodium and absolute alcohol gives 3-hydroxy-1 : 1-dimethy]- 
hexahydrobenzene, identical in every respect with the product obtained 
by Crossley and Renouf® by the reduction of chloroketodimethyltetra- 
hydrobenzene. 3-Keto-1 : 1 : 4-trimethylhexahydrobenzene has been pre- 
pared by a similar reaction. 
1; 2-, 1: 3-, and 1 : 4-ketomethylhexahydrobenzenes.? 
2-Chloro-1-ketohexahydrobenzene is obtained by treating ketohexa- 
1 Ber., 1907, 40, 153. , * Tbid., p. 159. 
3 Annalen, 1880, 208, 135. 4 Compt. rend., 1307, 144, 143. 
5 Compare p. 105 of this report. ° Compare p. 104 of this report. 
7 Wallach, Annalen, 1906, 346, 249. 
