ON THE STUDY OF HYDRO-AROMATIC SUBSTANCES. 155 
and ketohexahydrobenzene!; but at 250° to 300° the benzene ring is 
not hydrogenated, phenol being simply reduced to benzene ; whilst at still 
higher temperatures the benzene formed is partially decomposed into 
methane. 
Holleman, Van der Laan, and Slejper,? have shown that when phenol 
_is passed with hydrogen over reduced nickel at a temperature of 140° to 
150° a mixture of hydroxy- and ketohexahydrobenzene is formed. These 
two substances may he separated by taking advantage of the formation of 
a condensation product between the ketone and benzaldehyde. Similar 
experiments have been previously described by Sabatier and Senderens.* 
Hydroxy-derivatives. — On heating heptanaphthylene oxide* with 
water it is converted into 3 : 4-dihydroxy-1-methylhexahydrobenzene.* 
Ketohexahydrobenzene is readily converted by means of Grignard’s 
reaction into tertiary alcohols of the following type ® :— 
SENS 
CH, OR.OH 
SCH. On, 7 
substances which are insoluble in water, and which on treatment with 
dehydrating agents are converted into the corresponding tetrahydro- 
benzenes. Alcohols in which R may be replaced by the groups methyl, 
ethyl, propyl], isobutyl, isoamyl, phenyl, tolyl, benzyl and cyclohexyl, 
together with certain derivatives, and the corresponding tetrahydro- 
benzenes, are described. 
The hydrogenation of o-cresol’ takes place regularly in presence of 
reduced nickel at 200° to 220°, giving rise to 1-hydroxy-2-methylhexa- 
hydrobenzene. When this substance is heated with zine chloride two 
isomeric methyltetrahydrobenzenes are formed, boiling respectively at 
-109° and 103° to 105°. The hydroxy derivative can be converted by 
oxidation with chromic acid, or better by passing its vapour over copper 
heated to 300°, into 1-keto-3-methylhexahydrobenzene. m-Cresol on 
hydrogenation gives a mixture of 1-hydroxy- and 1-keto-3-methylhexa- 
hydrobenzene, which can be worked up for either alcohol or ketone, in the 
first case by passing the product with excess of hydrogen over reduced 
-nickel at a temperature of 140° to 150° ; and, in the second, by passing 
the mixture with hydrogen over copper at a temperature of 330°. Similar 
experiments have been carried out with p-cresol. 
The methyl and ethy] ethers of hydroxyhexahydrobenzene* may be 
prepared either by the action of alkyl iodide on the sodium derivative of 
the alcohol, or by the reduction of the corresponding alkyl phenyl ethers. 
Amines.—W hen aniline is passed with hydrogen over reduced nickel ° 
heated to 190° ammonia is evolved, and there are formed in nearly equal 
amountscyclohexylamineO,H, ,.NH,.;dicyclohexylamineC,H,,.NHC,H,,, 
and cyclohexylaniline C,H;.NH.C,H,,. Diphenylamine gives, under 
similar conditions, a mixture of cyclohexylaniline, dicyclohexylaniline, and 
small amounts of benzene, aniline, and cyclohexylamine. If the tempera- 
1 Compt. Rend., 1903, 187, 1025. 2 Rec. Trav. Chim., 1905, 24, 19. 
3 Compt. Rend , 1903, 187, 1025. 
4 Markownikoff and Stadnikoft, J. Russ. Chim. Soc., 1903, 35, 389 
5 Stadnikoff, ibid., 1904, 36, 485. 
5 Sabatier and Mailhe, Compt. Rend., 1904, 138, 1321. 
7 Tbhid., 140, 350. 
§ Brunel, Bull. Soc., 1905 (3), 33, 271. 
® Sabatier and Senderens, Compt. Rend., 1904, 138, 457. 
