166 — 



CH 



h 8 cA 



C-CH 



H 2 Cl y 



C 



CH 2 



H 3 C • C • CH 3 



CH 



or 



H 2 C 

 H 2 C 



CCH 3 

 CH 



H 3 C • CH • CH 3 



On the strength of relationship between constitution and optical 

 behaviour set forth above, the authors *) proceed to deal with certain errors 

 which can be detected in chemical literature. Thus, for instance, the 

 formula laid down by Rupe and Liechtenhan 2 ) for methyl menthatriene, 

 which they obtained from carvone: — 



HC-CH 3 



HC 

 HC 



C-CH 3 

 CH 



CH 

 H 3 C • C : CH 2 

 is inaccurate, and the formulae I and II given below are more probably 

 correct: — 



C-CH 3 



HC^\C:CH 2 



H 2 C 



CH 2 



HC 

 H 2 C 



CCH 3 



JcH 



CH CH 



H 3 C • C : CH 2 H 3 C • C : CH 2 



I II 



Another instance is that of the hydrocarbon prepared by Rupe and 

 Emmerich 3 ) from pulegone and magnesium methyl iodide. In this case 

 Rupe and Emmerich's formula V is inaccurate, either No. Ill or IV being 

 the correct one: — 



CCH 3 



I 



H 2 C 



1CCH 3 



x Vh 2 



H 2 C 



. Jc:CH 



C 



H 3 CCCH 3 



III 



H 2 C^ 



CH 



H.cl^ 

 C 



CHCH 



H 3 C • C • CH 3 



IV 





I 



H 2 C 



1C( 



^H 3 

 CH 



H 2 C 



C 



CCH 



H 3 CCCH 3 





V 





J ) Berl. Berichte 43 (1910), 827. From a reprint kindly sent to us. 



2) Ibidem 39 (1906), lll9; 41 (1908), 1393, 1750, 2067; Report October 1906, 130, 131; 

 November 1908, 186. 



3 ) Berl. Berichte 41 (1908), 1750; Report November 1908, 186. 



