144 Report of Schimmel § Co. April /October 1917. 



Enklaar assumes on the strength of the results of these and former investigations 

 the following formula for allooclmene: — 



H H H H 



H 3 C-C:C-C:C-C:C-CH 3 . 



CH 3 CHa 



However, he is not inclined to regard this formula as final till larger quantities 

 of the ozonide have been examined. 



On this basis ocimene would apparently have the following formula: — 



H2 H 2 H H 

 H 2 C : C • C • C • C : C • C : CH 2 



CH 3 CH 3 



It is just possible also that ocimene and allooclmene are mixtures like the citronellals. 

 The formula for allooclmene which Enklaar suggests is the same Auwers and Eisen 

 lohr 1 ) formerly proposed. 



Enklaar prepared methyl-5-heptatriene-i ; «5,5 (octatriene) and methyl-5-octatriene-i,3 ; 5 

 (nonatriene) for synthetical purposes. In order to obtain methyl-5-heptatriene-i,3 ; 5 he 

 produced tiglinaldehyde according to Grignard's and Abelmann's 2 ) method and let the 

 mixture of tiglinaldehyde and allyl bromide react in a solution of ether with zinc. 

 Hereby methyl-5-hepatriene-2, 5-ol-4 was obtained, a compound having a refreshing 

 odour, reminding rather of menthol. By heating the former with pulverized potassium 

 bisulphate on a sandbath at a pressure of 70 to 100 mm. in a current of carbon dioxide, 

 the desired octatriene is formed, an unstable substance which very easily resinifies 

 and polymerizes. It turned out to be impossible to hydrogenize octatriene by the aid 

 of sodium and alcohol, as it became resinous immediately. When, however, this 

 hydrocarbon was heated with sodium without a solvent a compound resulted which 

 closely resembled artificial rubber. 



In order to produce methyl-5-octatriene-i,3 ; 5, Enklaar started from a^-m ethyl ethyl 

 acrolein, prepared according to Grignard's and Abelman's above-mentioned method, 

 and allowed it to react in the same manner as tiglinaldehyde. The resulting methyl-5- 

 octatriene-i,5-oZ-4 was then transformed into nonatriene in the same manner as indicated 

 concerning octatriene; the former polymerizes easily and smells rather of aniseed. 



Enklaar supplies the refractrometrical figures for aZZoocimene again because those 

 he mentioned formerly were miscalculated. He also reports those of ocimene and of 

 decane which is made from the former, besides those of a few other saturated hydro- 

 carbons. 



Finally, he refers to the difficulties he met in performing the combustion of the 

 above-mentioned compounds, recommending the use of lead chromate in order to 

 obviate them. 



On the qualities of pure d-camphene, vide page 147. 



G. Komppa and R. H. Roschier 3 ) have confirmed by means of a complete synthesis 

 of a-fenchene the formula Wallach had advanced for it*). They began with rac. «-fencho- 

 camphorone (I) which they treated with methylmagnesiumiodide in dry ether.— 



!) Journ. f. prakt. Chem. II. 84 (1911), 41. — 2 ) Bull. Soc. c/rim. IV. 7 (1910), '639. — 3 ) Ann. Acad. 

 Scient. Fennicae, Series A, vol. X. 3 (1916), 3; Chem. Zentralbl. 1917, I. 751. — *) Comp. K. Auwers, Liebigs 

 Annalen 387 (1912), 240; Report April 1912, 168. 



