— ■ 120 — 



Pinene. By oxidation of d-and 1-pinene of high rotatory power, 

 Ph. Barbier and V. Grignard 1 ) obtained the optically active forms 

 of pinonic and pinic acids. 1-Pinene from French turpentine oil (b.p. 155 

 to 157 , «d — 37> 2 °; x 57 to 160 , «d — 3 2 >3°) was oxidised with 

 permanganate. From the product of oxidation, which (after elimination 

 of the volatile acids and of nopinic acid) boiled at 189 to 195 under 

 18 mm. press., 1-pinonic acid separated out in long crystalline needles, 

 which, after nitration by the suction pump and re-crystallisation from 

 a mixture of ether and petroleum ether, melted from 67 to 69 . The 

 acid was easily soluble in water and ether, fairly soluble in chloro- 

 form, and almost insoluble in ligroin. Its specific power of rotation 

 was determined to be Mp — 90,5° in chloroform solution. Oximation 

 produced two oximes; one laevogyre, m. p. 1-2 8°; and the other dextrogyre, 

 m. p. 189 to 19 1°, corresponding to the /?- and y-pinonic acid oximes 

 described by v. Baeyer 2 ), which this investigator obtained from oily 

 pinonic acid. By oxidising 1-pinonic acid with hypobromite, active 

 pinic acid, C 9 H 14 4 , was produced. This possessed the following cha- 

 racteristics : b.p. 225 at 17mm. press., m. p. 135 to 136 , Md -f"~7> IO ° 

 in acetone solution. The oily parts filtered off from 1-pinonic acid 

 proved to be a mixture of this acid with racemic pinonic acid, the 



latter melting at 104 to 105 . 



14.0 

 d-Pinene from myrtle oil (b.p. 155^158°; d^- 0,8635; n D 1,46977; 



[a] D _|- 39,4°) yielded upon oxidation a mixture of racemic and d- 

 pinonic acids. The latter melted at 67 to 68° and showed the same 

 properties as the acid described above, except as regards its specific 

 rotatory power, which was found to be Md -J- 89,0°. By mixing the 

 two active pinonic acids the inactive form, m. p. 104 , was obtained. 

 Oximation produced the two oximes corresponding to the above. A 

 preparation obtained by Tie man n from a-dihydroxy dihydrocampholenic 

 acid by means of distillation, and described as 1-pinonic acid (m. p. 98 

 to 99 ; oxime m. p. 147 ) possibly represents, according to Barbier 

 and Grignard, a stereo-isomeric acid. 



With reference to the foregoing we wish to point out that research 

 upon the same subject has been in progress in our laboratory. We 

 were the first to obtain 1-pinonic acid by oxidation of 1-pinocamphone 

 from oil of hyssop, and described it briefly in a preliminary com- 

 munication 3 ). 



We had reserved further investigation of the compound to ourselves. 

 In order to place beyond a doubt the characteristics of our acid by 

 comparing it with the dextrorotatory acid, and inspired by the same con- 



x ) Compt. rend. 147 (Oct. 5, 1908), p. 597. 



2 ) Berl. Berichte 29 (1896), 2786. 



8 ) Report April 1908, 58. Chem. Zentralbl. 1908, I. 1840. May 20. 



