— 39 — 



and having the appearance of dipentene tetrabromide, which melted 

 after recry stall isation at 125 . In the meantime the rotation of the 

 oil had also changed from -j- 1,7° to — 1,6°; after a further five 

 or six days, it had increased to — 9,8°, after another month to 

 — 34,5°, a proof that a considerable alteration was proceeding 

 spontaneously in the oil. After three more weeks the oil was distilled 

 with steam; the distillate showed after drying «D3oo — 3 8°, and the 

 conversion had consequently probably come to an end. The tetra- 

 bromide produced in various solvents melted after one recrystallisation 

 at 120 to 1 2 3 , without becoming brown; after further purification 

 at 1 2 5 . Phellandrene could no longer be detected by the nitrite- 

 reaction, probably owing to the presence of a large quantity of dipentene. 

 In Clover's opinion the almost pure terpinolene present in the original 

 oil, (which had a particularly low boiling point), had consequently 

 been converted by standing for several weeks, into dipentene, a small 

 quantity of d -phellandrene, and an unknown laevorotatory terpene. 



The high-boiling oil-portions from the individual species of 

 resin had mostly a feeble laevorotation, and their specific gravities 

 fluctuated between 0,9 and 1,03; they were chiefly mixtures of 

 sesquiterpenes and oxygenated bodies. From an oil with the rotation 

 a D30° -f- 7i>6°, a solid substance of the formula C 15 H 26 could be 

 isolated, which, however, during recrystallisation separated off in liquid form. 

 In two species of resin, tests for the presence of amyrin had negative results. 



With the individual terpenes isolated from the oils, Clover has 

 made a series of experiments, for details of which we must refer 

 to the original work. With d-limonene he was able to state that heating 

 to 180 to 220 has but a slight influence on the rotation, and that 

 after heating to 250 to 270 , the isomerisation into dipentene proceeds 

 very slowly. If the temperature is carried higher, to 380 , the formation 

 of dipentene subsides before the polymerisation of limonene. 



In the case of phellandrene, Clover observed that always the a-modif- 

 ication of this terpene occurs in elemi oil. The rotation of the phellandrene 

 diminished slowly already if left standing at ordinary temperature. With 

 dry hydrochloric acid gas there was obtained an addition product which 

 could not be distilled in vacuo without decomposition. A crystalline 

 dibromide was not obtained even from the purest phellandrene which 

 absorbed only 2 atoms bromine. When the phellandrene was left 

 standing, crystals separated off on the glass walls of the bottle, the 

 formation of which must be attributed to autoxidation of the phellandrene; 

 after purification from hot acetic ester they melted at 164,5 to I0 5,5°, 

 and had a composition corresponding to the formula C 10 H 18 O 2 . 



The terpinene of elemi oil yielded, on oxidation with 4 per cent, 

 permanganate solution, considerable quantities of a crystallised acid 

 which apparently represented a mixture. 



