— 139 — 



has been shown both by himself and also byKondakow and Skworzow 1 ), 

 but this conversion should not be utilised for the determination of the 

 constitution, as all terpenes of the menthane-series can be converted 

 in terpinene. No doubt the conversion of sabinene, or thujene, in 

 limonene hydrohalogen addition-products according to Kondakow and 

 Skworzow, and also according to Tschugaeff 2 ), could only be 

 explained from his (Semmler's) formulae by rearrangement, but a 

 rearrangement could in this case be readily explained, as glacial acetic 

 acid and hydrohalogen had been employed. Semmler considers that 

 the hydrohalogen addition-products cannot be utilised at all for constitution 

 determinations, and for this reason he also objects to the above -dis- 

 cussed work of Wallach on the conversion of sabinene and thujene 

 in terpinene dihydrochloride, the uniformity of which he doubts. The 

 whole process of this reaction appears to Semmler to be wanting in 

 lucidity, the more so as the terpinene dihydrochloride on treatment 

 with alkali, yielded the common terpin (1,8) as well as the other. 



The explanation of this behaviour is given by Wallach 3 ) in the 

 following manner: If the chloride melting at 52 has the formula 



C H„ v z C H — C H 9 \ /CI 

 3 \ c / 2 \c/ 



ci/ \ch 2 -ch/ \c 3 h 7 



it can on the one hand yield a new terpin by substituting OH for CI, 

 and on the other, by splitting off H CI and substitution of the second 

 chloride atom by OH, be converted among others in v. Baeyer's 

 7-terpineol, 



C H 3 v /C H 2 — C H 2 v 



>C< >C = C(CH 3 ) 2 



OH 7 X CH 2 -CH/ 



rendering subsequently ordinary terpin. 



As a matter of fact, Wallach was able to establish by experiment 

 the conversion of 7-terpineol in the common cis- and trans -terpins, 

 under the conditions determined for the conversion of terpinene dihydro- 

 chloride to terpinenol. The terpinene-terpin could now also be obtained 

 with great facility by treating the terpinenols with dilute sulphuric acid. 

 It melts at 137 to 13 8°, and boils at 250 with traces of decom- 

 position. It can be recrystallised from boiling water or dilute methyl 

 alcohol, and is inactive. When treated with hydrogen chloride, it 

 changes easily into terpinene dihydrochloride. 



x ) Journ. f. prakt. Chemie II. 69 (1904), 176; Report October 1904, 112; 

 Chem. Ztg. 26 (1902), 722. 



*) Berl. Berichte 37 (1904), 1483; Report October 1904, 113. 

 8 ) Berl. Berichte 40 (1907), 577. 



