— 127 — 



(m. p. 94°), is identical with fencholic acid amide 1 ). When heated with 

 hydrochloric acid in a sealed tube the amide yielded dihydro-/?-fencholenic 

 acid, which is identical with fencholic acid. Dihydro-«-fencholenic acid 

 boils at 259 to 260°. 



Dihydrothujaketone, to which a brief reference was made in our 

 previous Report 2 ), boils between 183 and 185°. When reduced with sodium 

 in alcoholic solution it yields dihydrothujaketol (b. p. 191,5 to 192,5°). 

 When treated with methyl magnesium iodide, dihydrothujaketone yields a 

 tertiary alcohol with an agreeable rose-like odour, b. p. 192 to 194°. 



The reduction of tanacetophorone gave rise to isopr opy \-i-cyclo- 

 pentanone-3. 



The reaction of hexahydro-p-acetyltoluene 3 ) with methyl magnesium 

 iodide yielded p-menthanol-8 (b. p. 209 to 211,5°; d 19 o 0,9090; n D16D 1,4640). 



Hydrocarbons. 



Is op r en e. According to H. Staudinger and H. W. Klever 4 ), a sub- 

 stantial yield of isoprene, an olefinic hydrocarbon which occurs as a de- 

 composition-product of turpentine oil and caoutchouc, may be obtained by 

 heating dipentene- or limonene-vapour in the rarified state at high tem- 

 peratures. The rarification may be attained either by evacuation or by 

 mixing with indifferent gases. The heating is best done by means of 

 glowing metallic wire. Yields up to 60% have been obtained by this 

 method. The vapour of turpentine oil yields but little isoprene; terpinolene 

 and terpinene are not easy to decompose. Camphene and pinene yield 

 none, or only a small proportion of isoprene. 



For the purpose of decomposing certain terpene-bodies, in particular 

 limonene, by means of red-hot metal wires, Harries and Gottlob 5 ) have 

 constructed what they term an isoprene-lamp. This apparatus consists of 

 a flask or bulb in which is placed a platinum wire 120 cm. long which, 

 at an average red-hot temperature, has a resistance of 9 £, and requires 

 about 5 amperes at 220 volts. The flask is connected with a vertical 

 condenser at the top of which is a delivery-tube for the isoprene-vapour. 

 The non-decomposed terpene drops down the condenser and the isoprene 

 is collected in a receiver which has been cooled down by a freezing 

 mixture. Pinene only gave about 1 % of isoprene, but commercial carvene, 

 according to its limonene-content, yielded up to nearly 50% of almost 

 pure isoprene. 



*) Comp. Report April 1911, 185. 



2 ) Ibidem 165. 



3 ) Ibidem 165. 



4 ) Berl. Berichte 44 (1911), 2212. 



5 ) Liebigs Anna! en 383 (1911), 228. 



