YM ae ORE cama) OES BE a se Ot 
fe AK, Na eae: ; ee LE an erp hs oR “ash 
PRO 4 ee ae 
422, 
the alcohol split off water with foweaned of zsoamyl- dehydrophellandtn at 
of the tertiary isoamylcarveol with platinum and hydrogen in absolute-ethereal SO | 
led to the saturated alcohol C,;Hs00, tertiary isoamyltetrahydrocarveol. The seconda . 
wsoamyldihydrocarveol obtained by reduction of isoamyldihydrocarvone (oxime m. p. 10% 
yielded by reduction with the same means secondary isoamyltetrahydrocarveol. — 
Isoamyldihydrocarveol is obtained from tsoamyldihydrocarvone by reduction meres h 
sodium and alcohol. B. p. 150 to 155° (10 mm.); dy 0.8993; @)+1°; npn 1.47449, 
Its acetate boiled from 155 to 160° (14 mm.); doo 0.9227. ee 
\ 
A research on betulol has been dealt with on p. 9 of this Report. 
Aldehydes. 
In a communication on a new method for the preparation of aldehagtes K. W.. Rosen- ' 
mund”) draws attention to the fact, that, whereas the carboxylic acids, in general, are 
easily accessible, the formation of the aldehydes is far more difficult, bodies which 
are far more reactive and hence Of scientific and commercial importance. Many — 
attempts have been made to transform acids into aldehydes, but hardly any reactions — 
of general applicability have been found out. The most successful method, the distilla-_ 
tion of carboxylates with formiates, is restricted to those aldehydes which are distillable — 
without decomposition. Experiments to get at the aldehydes direct from the acid halides 
by reduction with hydrogen have hitherto not been successful. As Rosenmund, however, — 
has found, the reduction of acid chlorides by means of hydrogen in presence of a © 
catalyst can be successfully performed, it depends only upon correct disposition of 
the conditions upon which the reaction is carried out. Just those conditions which 
were chosen from the theoretical point of view proved to be unsuitable. The following, 
namely, seemed to be of importance: 1. low temperature, in order to obviate further 
reduction of the aldehyde formed; 2. working in closed apparatus, so as to measure 
the hydrogen consumed; 3. working without a solvent or in such a solvent which 
would not poison the catalyst or react with the acid chloride, as which solely ether 
would come into consideration; 4. removal of the hydrogen chloride formed. | 
Now, exactly those conditions led to good results which differed strongly from t 
above principles: working in open apparatus, use of benzene hydrocarbons as solve 
application of high temperature and disuse of absorbents for hydrogen chloride. Sin e 
the latter is nearly insoluble in benzene hydrocarbons it escapes immediately after its 
formation and does no harm to the catalyst. As such Rosenmund employed palladium 
precipitated on barium sulphate (content 5 per cent. Pd); nickel proved also to be effecti 
For the preparation of benzaldehyde from benzoyl chloride, Rosenmund procee 
as follows: 5 g. benzoyl chloride are dissolved in 25 cc. dry xylene, 2 g. of the cat: 
added and hydrogen is passed through the boiling mixture so long until the evolu 
of hydrogen chloride has come to an end. On shaking the xylene solution — 
concentrated bisulphite solution the double salt of bisulphite-benzaldehyde sepat 
off in nearly theoretical yield. Without a solvent the yield, decreases very str 
1) Berichte 50 (1917), 1838. — 2) Berichte 51 (1918), 585. 
