H 2 C CH C(CH 8 ) 2 



Notes on scientific research. 137 



Camphene. — The body m. p. 157° known generally in literature as camphene hydro- 

 chloride resulting from the treatment of camphene with an excess of gaseous hydrogen 

 chloride should be termed appropriately isobornyl chloride, as we learn from a patent 

 application by the firm of Schering 1 ), since it is a stereoisomeride of pinene hydro- 

 chloride, or bornyl chloride. The true camphene hydrochloride (hitherto unknown), i.e., 

 the primary addition product of hydrogen chloride to 

 camphene, is easily obtained by the action of hydrogen 

 chloride on a solution of camphene, when care is taken qj-j 



to avoid any excess of the acid. | j /CH 3 



Camphene hydrochloride occurs in snow-white crys- H 2 C -CH ~^\ 



tals (m. p. 125 to 127°) and shows a strong odour of _ • .< 



r Camphene hydrochloride. 



menthol differing enterely from that of pinene hydro- 

 chloride or isobornyl chloride. The compound splits off HC1 soon after its preparation, 

 and readily passes over into isobornyl chloride, so it is stable only for a short time. 

 Camphene hydrochloride, on shaking with water, or preferably on treatment with 

 alkalies, is transformed nearly quantitatively into camphene hydrate. 



J. Schindelmeiser 2 ) reports on attempts to split off hydrogen chloride from pinene 

 monohydrochloride by means of Reychler's reaction (with potassium phenate) with the 

 object of obtaining camphene and camphor. Anhydrous potassium phenate (2 mol.) 

 prepared with an excess of potassium hydroxide was mixed thoroughly with pinene 

 hydrochloride (1 mol.) and the mixture distilled immediately. After removing the 

 phenols the author was able to prove, in the distillate, the presence of camphene 

 (in shape of isobornyl acetate after heating with glacial acetic acid in a sealed tube; 

 isoborneol, m. p. 212°; from the latter, camphene, m. p. 50°, a D + 0) and of bornylene, 

 besides some terpinene and diphenyl oxide (m. p. 28°, b. p. 246°). Since, however, 

 this process allows but 25 per cent, of the pinene to be transformed into camphor, 

 it is of no interest from a commercial standpoint. The oil of Abies sibirica, Ledeb. 

 offers a more advantageous crude material, as it contains 35 to 50 per cent, of hornyl 

 acetate. Schindelmeiser was able to split off the acetic acid readily and quantitatively 

 by a very cheap process; the borneol obtained was successfully transformed into 

 camphor on commercial scale by electrical processes. A Franco-Japanese company 

 intends, as per Schindelmeiser, to obtain camphor on a large scale in Siberia from 

 the oil of the Siberian pine. 



On a- and ^-pinene, from French turpentine oil, compare p. 74 of this Report. 



Limonene. — A process for obtaining limonene and pinene nitrosochlorides, worked 

 out years ago by K. Loffl 3 ), is published by H. Rupe 4 ). It gives far better yields than 

 the usual method (with ethyl or amyl nitrite) and consists in introducing a mixture 

 of nitrous gases and hydrogen chloride into a solution of the hydrocarbon. The gases 

 must be mixed in the correct proportion and must react at a temperature as low as 

 possible. If hydrogen chloride is in excess only a green oil results with but very 

 little crystalline nitrosochloride, the amount of which otherwise reaches 90 per cent, 

 of that calculated 5 ). 



!) Germ. pat. appl. C 29517, Sept. 25, 1921. — *) Pharmacia 1921, N° 1 (Reval). As per a copy kindly 

 forwarded to us. — 3 ) Uber Reduktionen in der Reihe der cyclischen Oxirne und Nitrosochloride. Dissertation, 

 Basle 1915. -- *) Hefoet. chifn, acta 4 (1921), 149. — 5 ) According to Wallach {Terpene und Gampher, 2 nd ed., 

 p. 69) the preparation of nitrosochlorides by Tilden's process (introducing vapours of nitroxyl chloride into the 

 chloroform solution of the terpenes at —10°) is troublesome. Wallach's method (treatment with amyl nitrite 

 and concentrated hydrochloric acid), however, works quickly and satisfactorily. 



