— no — 



Hydrocarbons. 



Pine ne. As long ago as 1877 Tilden pointed out that optically 

 strongly active pinene gives inferior yields in the production of nitroso- 

 chloride. As pinene nitrosochloride (as mentioned by v. Baeyer) is 

 bimolecular, Tilden 1 ) believes that the small yield of nitrosochloride 

 in the case of highly rotatory pinene must be attributed to the inversion 

 process of the one half of the hydrocarbon, but that, on the other 

 hand, with an inactive mixture of d- and 1-pinene the bimolecular 

 compound is only formed by the combination of the two semimole- 

 cules. Experiments have confirmed the correctness of this view- American 

 oil of turpentine with a rotatory power of -j~7° m a 2 °° mm - tu be, 

 yielded 31 to 32 per cent, nitrosochloride; 1-pinene («d — 57°48' in a 

 200 mm. tube) 2O°/ , and d-pinene (o D -J- 8o°4i' in a 200 mm. tube) 

 only 5,5 °/ . On the other hand, an inactive mixture of the two last- 

 named bodies yielded 55,6 °/ . The production of the nitrosochloride 

 was carried out as follows, contrary to the method hitherto in vogue: 

 pinene is diluted with two to three times its volume of petroleum 

 ether (boiling point 90 to ioo°), cooled to o°, and a solution of 

 nitrosylchloride saturated at o° in equal parts of petroleum ether and 

 chloroform (containing about 8°/ NO CI) added, whilst thoroughly 

 stirred. When the reaction is completed the mixture is diluted with 

 one and half times its volume of alcohol, and the crystalline pre- 

 cipitate filtered off after a short time. — In one experiment, when it 

 was attempted to produce the nitrosylchloride not separately, but by the 

 introduction of nitrous acid in concentrated hydrochloric acid, which 

 had been overlaid with pinene and petroleurh ether, the formation of 

 i-carvoxime hydrochloride (melting point 127 to 12 8°) was observed. — 

 The earlier statements as to the melting point of pinene nitrosochloride 

 are, according to Tilden, incorrect. The melting point of the com- 

 pound washed with alcohol and dried at 50 , lies at 109 to 111 ; 

 after recrystallisation from chloroform, when preferably only small quan- 

 tities are worked up at a time, as otherwise decomposition into nitroso- 

 pinene (melting point 129 ) occurs, the melting point lies at 115 . 

 If pure pinene nitrosochloride is dissolved in chloroform, and alcohol 

 is added, the solution acquires after some time an orange-red colour, 

 reduces F eh ling's solution, and contains clearly hydroxy lamine. — 

 Attempts to split up nitrosopinene and piny lamine into optical isomers, 

 gave negative results. For the regeneration of pinene from the nitroso- 

 chloride, methyl and dimethyl aniline, and dimethyl-p-toluidine are the 

 most suitable agents. From the regenerated pinene, 55% nitrosochloride 

 were obtained. The author has finally determined the molecular weights 



x ) Journ. Chem. Soc. 85 (1904), 759. 



