The experimental details of this work Hake in the iene ‘bebe ‘U0 
Wallach*) elsewhere, so that now we are in the position to supplement | our 
abstract. The primary raw material for his investigations were two easily acct | 
. ketones, i. e., menthone and tetrahydrocarvone (carvomenthone), from. which vari 
dibromo derivatives may be prepared readily. Hereby the following dibromomentho es” 
are obtainable: — 1. 4,8-Dibromomenthone, by addition of bromine to pulegone; a 
2. 1,2-dibromomenthone, by addition of bromine to At-menthenone-3; 3. 4, 5-dibrom = 
menthone by addition of bromine to A*-menthenone-3; 4. 2, 4-dibromomenthone by 
direct bromination of menthone. — In the carvomenthone series, there is formed 
3,4-dibromocarvomenthone by addition of bromine to cauehene: 8, 9-dibromocarv. 
menthone by addition of bromine to dihydrocarvone; 1,6-dibromocarvomenthone b 4 
addition of bromine to carvotanacetone; 1,3-dibromocarvomenthone by direct bromi : 
ation of carvomenthone, and 1,8-dibromocarvomenthone by brominating | dihydrocarvone ; 
in acetic acid-+ hydrogen bromide. As to the course of the reactions with these iso- 
merides, which were partly investigated in their various optical modifications, diffe 
ences were noted in their behaviour to aqueous alkalies, depending on the position 
the bromine atoms. In these reactions, Wallach noted the following as the main points: — | 
1. Double-brominated cyclohexanones pass over comparatively easily into phenols" , 
by means of aqueous potash solutions under the conditions chosen in those cases, 
where the two bromine atoms had been added to a double-bond next to the carbony 
group and not separated from the latter by any substituting group. | 
2. In case the double-bond is vicinal to the carbonyl group, but separated ther % 
from by a substituting group, the ring is ruptured very easily on treatment with — 
alkalies, with formation of aliphatic ketoacids with equal number of carbon atom 
3. When the bromine atoms are distributed between nucleus and side-chain, or 
stand solely in the latter, the reaction can pass off in various ways. A mee ru e 
for these very varying possibilities cannot be established. a 
4. The most interesting results were obtained with those bromides, where. the 
bromine atoms must be assumed to be distributed in the nucleus, next to th 4 
carbonyl group. From these “hexacyclic bromides one can easily arrive, vid ‘inte : 
mediate products, to pentacyclic hydroxycarboxylic acids. | 
Active dihydrocarvone yields various dibromides, a liquid one, 3 pair 
menthanone-2, and a crystalline one, the structure of which is not yet settled. 
treating the dihydrocarvone dibromide with aqueous caustic potash, there re 
besides a little carvacrol and carvenone as by-products, as main product a hea’ 
brominated oil giving on reduction with zinc and caustic soda solution diby Atos 
is linked very Beanie The crystalline bromide of dihydrocarvone yen: on 
with aqueous potash a hydroxyketone CiolHieO2 with ony one double-bond, 
constitution of which is not yet quite ascenainee: ns 
1) Liebig’s Annalen 414 (1918), 271. 
