- neutralization), which wields nearly pure Tircistonphotenh ea ‘ode don 
8-compounds obtained from menthone dibromide, may be regarded as -unsa irate 
hydroxyketones; most probably, they are stereoisomerides of the same comp 
The «a-isomeride is identical with buchu camphor (= diosphenol). - Cusmano%), 
had found that on shaking menthone dibromide with potash lye buchu camphor re 
Hence, the constitution of the menthone dibromide used is 2, 4-dibromomenthanon 
On brominating inactive menthone, such as is easily accessible by reducing sf 
natural 4+-menthenone-3 according to Paal and Skita?), a liquid inactive dibromide 
obtained which on treatment with aqueous potash leads to the same products as 
obtained from the active dibromide of the m.p.79 to 80°. When active crystalli 
methoxide, a mixture is obtained containing a body CioHi6O., probably an oxide. . 
In order to prepare tetrahydrocarvone (carvomenthone), one starts from acti i 
dihydrocarvone — easily accessible from carvone by the old reduction process —, and . 
from carvenone, for obtaining the inactive preparation. Both of these ketones with 
one double-linking may be reduced most readily and completely under ordinary presst 
_by Paal’s and Skita’s method. The dibromides of tetrahydrocarvone melting at 80 to 8! 
and 66 to 67° respectively must be considered as the active or inactive forms 
dibromo-/, 3-menthanone-2.. The active dibromide has formerly been described — 
Cusmano and Poccianti’). 
Monobromotetrahydrocarvone’), on abstracting hydrogen bromide Ay means of ead 
acetate in glacial acetic acid solution, yields carvotanacetone. As alluded to abo 
- tetrahydrocarvone is the most convenient crude material for the preparation of active a 
inactive carvotanacetone. On shaking with aqueous potash monobromotetrahydracarv 
gives rise to a hydroxyketone. Equally, Kétz and Steinhorst arrived at a hydroxyket 
when treating monochlorotetrahydrocarvone with potassium carbonate solution. — 
The behaviour of the afore- mentioned a- and 6-modifications of the ah oe 
of the bromides the mixture may ie used which is abtared on tncatine ae me 
dibromide with potash lye. The results obtained Py Wales on brominati 
statements. When bromine acts on buchu camphor, the properties of. ‘eo 
employed and the temperature observed influence the result elioee si Bs 
x 
1) Atti R. Accad. dei Lincei (5) 22, Il (1913), 569; Chem. Zentralbl. 1914, I. 976; ee Ap 
*) Liebig’s Annalen 397 (1913), 217; Report October 1918, 146. — %) Atti R. Accad. det Lincet 
347; Chem. Zentralbl. 1914, Il. 481; Report April 1918, 104. — “4 Comp. Kotz and Ste’ hors 
379 (1911) 25; Report April 1911, 182. — 5) Wachir. K. Ges. Wiss., Gottingen, mecting of oO. 
8) Berichte 39 (1900), 1158; Report October 1906, 140. — "Chem. oi istics alte 1s i Rep 
