112 REPORTS ON THE STATE OF SCIENCE. 
hydrobenzene suspended in water with chlorine in presence of calcium 
carbonate.! When boiled with a strong solution of potassium carbonate 
it is converted into 2-hydroxy-1-ketohexahydrobenzene, and when treated 
by Grignard’s reaction yields ketomethyl-(ethyl, &c.)-hexahydrobenzene. 
A compound isomeric with Pinner’s xylitone is formed by the action 
of sodium ethoxide on a mixture of ethyl acetoacetate and phorone,? and is 
supposed to be 1-keto-3-isobutenyl-5 : 5-dimethyl- A *-tetrahydrobenzene, 
Cos cH 
CHL So—cu =0(CH,),. 
Nc(CH,),—CH/ 
It yields a tetrabromide, and when reduced with sodium and alcohol 
gives 1-hydroxy-3-isobutyl-5 : 5-dimethylhexahydrobenzene, which under 
the influence of phosphorus pentoxide loses water to form 3-isobuteny]- 
5 : 5-dimethyl- A !-tetrahydrobenzene. 
Acids.—Marckwald and Meth? have further investigated 1-methyl- 
cyclohexylideneacetic acid, to which allusion was made in the last report.* 
pe eee 
CH,. CH C=CH.COOH. 
hee 
This acid shows the general property of an a/3-unsaturated acid, in that, 
when heated, it readily loses the elements of carbon dioxide to give a 
hydrocarbor, CyH,4, which is optically inactive and has already been 
proved by Wallach to be 1-methy1l-4-ethylenehexahydrobenzene. 
CH,—CH, 
CH,. cH De= CH, 
OH,—CH, 
Further, as is well known, the bromo-additive compounds of a/3-un- 
saturated acids readily lose carbon dioxide and hydrogen bromide to give 
brominated hydrocarbons :— 
R.CHBr.CHBr.COOH ~> R.CH:CHBr. 
Methyleyclohexylideneacetic acid behaves in a similar way,’ for when 
treated with bromine in aqueous sodium carbonate solution it is converted 
into 1-methyl-4-bromomethylenehexahydrobenzene, which on heating with 
CH,—CH, 
CH,.oHe «=. SO=0HBr 
\cu,—CH,/ 
water forms hexahydro-p-tolualdehyde. Perkin and Pope °® prepared their 
methylcyclohexylideneacetic acid by eliminating the elements of hydrogen 
bromide from a-bromohexahydro-p-tolylacetic acid, and, asshown by Ruppe, 
CH,—CH, 
CH,. cag cH ~CHBr—COOH 
CH,—CH;, 
Roners, and Lotz,? both a/3 and /y-unsaturated acids are formed by loss of 
hydrogen bromide from a-bromo acids. Marckwald and Meth suggest that 
1 Bouveault und Chereau, Compt. rend., 1906, 142, 1086. 
2 Knoevenagel and Schwartz, Ber., 1906, $9, 3441. 
3 Ber., 1906, 39, 2035. * Reports 1906, p. 264. 
> Marekwald and Meth, Be7., 1906, 39, 2404. 
8 Proc. C. S., 22, 107. 7 Ber., 1902, 35, 4265. 
