— 123 — 



hours with 2 5°/ alcoholic sulphuric acid, it yielded a hydrocarbon 

 which Semmler calls isocarvenene, and which he regards as zJ 1>4 -di- 

 hydrocymene. Among its constants (b. p. 59 to 62 ° at 10 mm. press.; 

 ^20° 0*845; "d 1,480, exaltation about 0,4), the value of the refraction 

 especially differs from that observed in the case of carvenene. In 

 addition to the product described above, a diterpene had been formed, 

 which has been called dicarvenene and which possessed the following 

 constants: b. p. 170 to 1 73 at 10 mm. press., d2o° 0,928, n D I ?5 I 75> 

 molec. refr. found 88,8, calculated for C 20 H 32 /2~ 87,07, for C 20 H 32 /3~" 

 88,77. I* 1S somewhat remarkable that the isocarvenene also ap- 

 peared to yield terpinene nitrosite, and no satisfactory explanation of this 

 occurrence is given. As a combination with two adjacent double linkings, 

 carvenene passed over, on treatment with sodium in amyl alcoholic 

 solution, (although only slowly), into zf 2 -tetrahydrocymene. For the 

 last-named body the following constants were found: b. p. 55 to 5 6° 

 at 12 mm. press., d2o° 0,824, u D 1,461. The ozonide of carvenene, 

 when decomposed with water, yielded dimethyl acetonyl acetone, 

 (b. p. 82 to 86° at 10 mm. press., d2o<> 0,95, % 1,433) °f which 

 the dioxime had a melting-point of 130 . The terpinene preparation 

 obtained by the familiar methods, on the other hand, yielded only 

 very little of this diketone. In the terpinene which was obtained from 

 terpinene dihydrochorate by splitting-off hydrogen chloride Semmler 

 was, moreover, able to prove the existence of a large quantity of 

 terpinolene by means of the bromide, melting at 117 . 



Isocarvestrene. In a manner similar to that in which, some 

 time ago, Per kin and Tattersall 1 ) carried out the synthesis of car- 

 vestrene, W. H. Perkin jun. and K. Fisher 2 ) have now succeeded in 

 preparing an isocarvestrene (J 6 > 8 ( 9 )-m-menthadiene). 



i-Methylcyclohexane-6-one 3-carboxylic acid (m. p.94 to 96 ; oxime, 

 m. p. 1 7 2 ; semicarbazone, m. p. 200 ) yielded by reduction with so- 

 dium amalgam a mixture of cis- and trans- i-methylcyclohexane-6-ol 

 3-carboxylic acid. The cis-acid had m. p. 14 1°, it yielded a lactone of 

 m. p. 4 6° and when treated with hydrogen bromide was converted into 

 cis-6-bromo 1 -methylcyclohexane 3-carboxylic acid (m. p. 53 ). The 

 trans-hydroxy-acid melted at 115 to 117 and yielded an oily bromi- 

 nated acid. The mixture of the two bromo acids was esterified, where- 

 upon hydrogen bromide was split off by means of diethyl aniline, 

 resulting in the formation of the ester of 1 -methyl zl 6 -cyclohexene 

 3-carboxylic acid, boiling at 146 under 100 mm. press. The b. p. of 

 the free acid under the same pressure was about 1 84 . Upon treat- 

 ment of the ester with magnesium methyl iodide, dihydro isocarvestrenol 



*) Journ. chem. Soc. 91 (1907); Report April 1907, 145; October 1907, 146. 

 2 ) Journ. chem. Soc. 93 (1Q08), 1876. 



