— 101 — 



The resemblance of the constitution of zl 1 -menthenone to that of car- 

 venone on the one hand and that of pulegone on the other induced us 

 to test the behaviour of the ketone towards phosphorus pentachloride. 

 In analogy with the carvenone-reaction, «-terpinene, or at least a hydro- 

 carbon rich in that body, was expected to be obtained from primarily 

 produced terpinene monochloride. 



For the preparation of the terpinene monochloride we followed the 

 indications given by Wages and Kraith 1 ) as well as by Semmler. We 

 used for each reaction 30 g. ketone, which was dissolved in ten times 

 that quantity of low boiling light petroleum. At ordinary temperature 

 at least one day was required to complete the reaction. Only a little 

 hydrochloric acid was split off, the bulk of this body only being eliminated 

 when the light petroleum was distilled off. The product of chlorination 

 consisted mainly of terpinene monochloride, together with which dichloride, 

 and unattacked ketone also occurred. By careful fractionation, however, 

 we were very successful in obtaining in every experiment fractions con- 

 sisting almost wholly of monochloride. 



I. B. p. 92 to 93° (12 mm.), d 20 o 0,9850, n D20O 1,50001, mol. refr. found 50,91. 

 II. B. p. 88 to 89° (9 mm.), d 20 o 0,9852, n D20O 1,50001, mol. refr. found 50,90. 

 0,1285 g. subst: 0,3289 g. C0 2 , 0,0974 g. H 2 0. 

 Found Calc. for Ci Hi 5 Cl 



C 69,81 °/o 70,35 °/o 



H 8,43 °/o 8,87 °/o. 



The close agreement between the constants of these two preparations, 

 the result of separate processes, is worthy of note. The molecular re- 

 fractions also correspond very nearly; as compared with the value 

 calculated (for Ci Hi 5 Clf2 55,18) they show a difference of 0,72, which is 

 due to the conjugated position of the double bonds. 



The chloride was reduced with sodium and absolute alcohol. At 

 40° the reaction proceeded very imperfectly, but at higher temperatures 

 (80 to 90°) chlorine-free products were obtained very readily. We pre- 

 ferred, however, to work at the lower temperature, in consideration of the 

 fact that at a higher temperature the hydrocarbon which was formed pri- 

 marily might perhaps have been reduced still further. The hydrocarbon, 

 when purified by fractionation and repeated distillation over sodium, 

 possessed the following constants: b. p. 176° (751 mm.), di 5 o 0,8469, « D i0, 

 n D i50 1,48441, mol. refr. found 45,98, calculated for C 10 H 16 /145,24. Proof of 

 the fact that the resulting hydrocarbon contained at least «-terpinene was 

 afforded by the preparation of the nitrosite and of «, «'-dihydroxy-methyl- 

 isopropyladipic acid. The terpinene nitrosite melted at 155°, the acid at 

 187 to 189°. 



It has thus been shown that by the action of phosphorus pentachloride 

 and the reduction of the terpinene monochloride, z^-menthenone, like car- 



l ) Berl. Berichte 32 (1899), 2558. 



