112 



pound by means of GrignarcTs reaction, A. Hesse 1 ) gives some 

 interesting information on the relations between pinene hydrochloride 

 and camphene hydrochloride. Both can be converted by means 

 of a new method, with a yield of 70 to 8o°/ , into a magnesium 

 compound. When decomposed with water both magnesium compounds 

 supply the same camphane of the m. p. 153 in a very good yield. 

 It is therefore proved that the two terpene hydrochlorides possess 

 the same carbon skeleton. Pinene hydrochloride magnesium, when 

 exposed to the air, briskly absorbs oxygen, and the decomposition of 

 the oxidised magnesium compound by water takes place less briskly 

 than that of the n on -oxidised compound, when at the same time 

 abundant quantities of borneol are formed. The experiments also 

 served for elucidating the relationship between borneol and iso- 

 borneol and the relation in which the two alcohols stand to the 

 above-mentioned hydrochlorides. According to the well-known patents, 

 isoborneol in benzene solution is converted into camphor by oxidation 

 with aqueous dilute permaganate, with ozone, with hot air, or by the 

 introduction of chlorine or nitrous vapours. In the case of isoborneol, 

 the reaction is in many oxidation-methods accomplished more readily 

 than in the case of borneol. But as all endeavours to detect an 

 isomeric camphor in the oxidation-products were unsuccessful, Hesse 

 believes that borneol and isoborneol are stereo-isomeric, in support of 

 which may be mentioned the conversion of isoborneol in xylene solution, 

 by sodium, into borneol, and for which H esse himself supplies fresh proofs. 

 His method for the production of organo-magnesium compounds is 

 chiefly based upon this, that the solution of hydrochlorides is added 

 to the magnesium whilst a primarily initiated reaction of the 

 magnesium with briskly reacting alkyl halogenides is still proceeding. 

 By this method Hesse converts 80 to 85 °/ of the pinene hydro- 

 chloride into the magnesium compound C 10 H 17 MgCl, whilst 10 to 

 I 5% react m tne well-known manner according to the equation: — 

 2 C 10 H 17 CI + Mg = MgCl, + (C i0 H 17 ) 2 



and the remainder of the reaction-product is formed of small quantities 

 of camphene and camphane. The final product of the reaction is 

 generally free from chlorine. Hesse concludes from his experiments 

 that in this Grignard's reaction not the alkyl halogenides, but 

 the alkylmagnesium halogenides formed during the prim- 

 ary reaction, initiate the reaction. This process was also 

 accomplished without difficulties with camphene hydrochloride; about 

 6o°/ reacted with the magnesium, with formation of C ]0 H 17 MgCl; 

 2O°/ formed (C 10 H i7 ) 2 ; and the general properties of this hydrocarbon 

 point to its identity with the one obtained from pinene hydrochloride. 



i) Berl. Berichte 39 (1906), 1127. 



