— 140 — 



The priority claimed by Semmler 1 ) with regard to the inversion 

 of sabinene to terpinene, is objected to by Wallach 2 ), as Semmler 

 had only given theoretical speculations, but not supplied experimental 

 proofs. He also considers Semmler wrong in his opinion that the 

 intermediate products occurring in this process cannot be separated. 

 Wallach proves this by isolating the products obtained by shaking 

 sabinene with dilute sulphuric acid, particularly terpinenol and terpinene- 

 terpin, during which not a trace of the common terpins occurs. The 

 last-named fact may serve as a proof that sabinene, — contrary to 

 the opinion represented by Semmler — has little inclination when 

 in contact with acids to pass over into compounds of the limonene 

 series. The terpinenol obtained from sabinene is chemically and 

 physically identical with that from the oils of cardamom and sweet 

 marjoram (see p. 135), and is the optically active modification of the 

 one obtained from terpinene dihydrochloride and alkali. 



Some time ago Wallach 3 ) had already called attention to the 

 abnormally high molecular refraction of sabinene, and on that occasion 

 corrected the figures calculated by Semmler, which agreed with those 

 found by experiment. In face of the reply by Semmler 4 ) who 

 holds out a prospect of further communications regarding the high 

 dispersion of sabinene, Wallach 5 ) maintains the abnormal refraction 

 of sabinene. 



By treating sabinene with glacial acetic acid alone, or with glacial 

 acetic and sulphuric acids, Semmler 6 ) obtained an acetate in ad- 

 dition to a mixture of hydrocarbons. When shaking sabinene with 

 aqueous hydrochloric acid, there were obtained besides a dichloride 

 (m. p. 5 2°), monochlorides which Semmler considers partly as semi- 

 cyclic, whilst on introducing hydrochloric acid in the solution of 

 sabinene in absolute ether at — 18 , a dichloride of the m. p. 53 to 

 54 was formed, in addition to the terpinene dichloride (m. p. 51 to 

 52 °) of Wallach, and monochlorides which appear to be semicyclic. 

 The action of glacial acetic acid and hydrochloric acid, on the other 

 hand, yielded a dichloride (m. p. 52 ) besides semicyclic monochlorides. 

 Semmler concludes from the formation of semicyclic bodies that the 

 hydrochloric acid is absorbed more difficultly by the semicyclic double 

 linking than by the double linkings in the nucleus or in the side-chain. 



These observations of Semmler agree only in part with Wallach's 

 results, who, however, considers Semmler's dihydrochloride of the 



x ) Berl. Berichte 39 (1906), 4418. 



2 ) Berl. Berichte 40 (1907), 592. 



8 ) Liebig's Annalen 347 (1906), 319. 



4 ) loc. cit. 



5 ) Berl. Berichte 40 (1907), 585. 



6 ) Berl. Berichte 39 (1906), 4419. 



