— 171 — 



As terpinene may very easily be found in conjunction with ter- 

 pinolene, it was necessary to oxidise terpinolene under the same con- 

 ditions. Wallach 1 ) by his previous investigations, had already shown 

 that the erythritol could not be obtained from the ordinary terpinolene, 

 but owing to the importance of the question he regarded it as neces- 

 sary, with this end in view, once more to examine a terpinolene of 

 the greatest possible purity 2 ). As the methods hitherto employed for 

 preparing terpinolene did not yield a sufficiently uniform product, 

 Wallach employed ^-terpineol for preparing terpinolene, and converted 

 the former into the latter body by splitting-off water with anhydrous 

 formic acid: 



CH 2 CH 2 CH C H 2 



/ \ /H 8 ^ \ /CH 3 



CH-COH c=c< -> ch 3 — c c=c<; 



\ / X CH 3 \ / \CH 3 



CH 2 CH 2 CH 2 CH 2 



y-Terpineol Terpinolene 



The hydrocarbon thus obtained boiled at 181 to 185 and gave 

 a plentiful yield of terpinolene tetrabromide, m. p. 11 6°. With nitrous 

 acid it gave no reaction for a-terpinene. 



The hydrocarbon was oxidised in the familiar manner. No trace 

 was obtained of the erythritol melting at 23 7 , but an isomeric ery- 

 thritol was isolated. The compound crystallises with water of crystal- 

 lisation; it begins to fuse at as low a OH 

 temperature as oo° and melts over ioo° I 



irregularly with liberation of gas (up to ) v 2 CH 



about 130 ). This erythritol of ter- C H 3 — COH COH-c(oh 3 



pinolene (see formula above) is there- \ / ^ H 3 



fore entirely different from that obtained CH 2 CH 2 



from crude terpinene. When further oxidised with permanganate it 



of course produced no a, a'-dihydroxymethylzwpropyladipic acid. 



Terpinene. Several investigators have lately again turned their 

 attention to the composition of terpinene. Semmler 3 ) has published 

 an article dealing with the inversion-products of carvenene. The iso- 

 carvenene which was obtained from carvenene by the action of alcoholic 

 sulphuric acid proved to contain a high proportion of terpinolene, for 

 when treated with bromine 3 g. zlw-carvenene gave 0,5 g. tetrabromide, 

 m. p. 116 to 1 1 7 . This m. p. was not lowered in mixture with 

 terpinolene tetrabromide. It would thus appear that the inversion 

 tends towards terpinolene in a not inconsiderable measure. 



*) Liebig's Annalen 362 (1908), 285; Report November 1908, 174. 



2 ) Liebig's Annalen 368 (1909), 10. 



3 ) Berl. Berichte 42 (1909), 522; Report April 1909, 122. 



