— 177 — 



has a penetrating and most unpleasant odour: b. p. 141 to 143° (100 mm.). 

 By using 1-menthylamine the author succeeded in splitting up the acid 

 into its optical components. The d-modification gave Hd + 33,1°, and 

 the 1-antipode [«] D — 30,9°. The latter, therefore, was not yet quite free 

 from d-acid. 



By treating with magnesium methyliodide by the method usual for the 

 preparation of tertiary alcohols, i-l-methyl-zl 5 -c?/dohexene-3-carboxylic ethyl- 

 ester yielded i-zl 5 -m-menthenol-8. This body is a refractory, colourless 

 liquid, with a strong odour of terpineol and peppermint oil. By boiling 

 the alcohol with 6°/ oxalic acid, a hydrocarbon, i-zJ 5,8(9) -menthadiene, b. p. 

 175 to 176°, with a lemon-like odour, was obtained. Perkin is of opinion 

 that this body is not pure zl 5,8(9) -menthadiene, but is probably contaminated 

 with zd 5,3(8) -m-menthadiene. By the same method as described for the in- 

 active compound, d-l-methyl-zP-q/cfohexene-3-carboxylic ethylester gave 

 rise to d-zl 5 -m-menthenol-8 ([«] D + 36,7°) and to d-zl 5,8f9) -menthadiene, 

 (Md + 29,6°) while the corresponding laevorotatory ester yielded l-^ 5 -m- 

 menthenol-8 ([«] D — 32,6°) and l-J 5 - 8(9) -m-menthadiene ([«] D — 25,3°). 



By oxidising d- and l-J 5 -m-menthenol-8 with highly dilute solution of 

 permanganate of potassium by the cold method, Perkin obtained the lactones 

 of ds- and £rafts-a-methyl-/-hydroxyisopropyladipic acid. The m. p. of the 

 cislactone was 102°, and of the £mwslactone 136°. 



By the same method as described above for zl 5 -m-menthenol-8, Perkin 

 prepared from i-l-methyl-J 4 -cyc/ohexene-3-carboxylic acid; b. p. 143 to 146° 

 (20 mm.); b. p. of the ethylester 142 to 144° (100 mm.); i-z4 4 -m-menthenol-8. 

 This alcohol likewise constitutes a refractory oil with an odour of terpineol 

 and menthol (b. p. 115 to 117° at 30 mm.) from which, when heated with 

 dilute oxalic acid, i-# ,8(9) -m-menthadiene (b.p. 175 to 177° at 755 mm.) results. 



l-Methyl-zl 3 -c?/dohexene-3-carboxylic acid, which had been prepared by 

 Perkin and Tattersall 1 ) from zl 3 -menthenol-8 a few years ago, has now been 

 obtained by another and easier method by Perkin in collaboration with 

 B. D. W. Luff 2 ). The authors first prepare l-methyl-ci/cZohexane-4-one-3- 

 carboxylic acid 3 ) from 1 -methyl -ci/cfohexanone-4 with sodium amide, and 

 from this, by reducing with sodium amalgam, they obtain \ -methyl- cyclo- 

 hexane-4-ol-3-carboxylic acid. From the last-named acid they derived an 

 almost quantitave yield of l-methyl-zl 3 -c?/cfohexene<-3-carboxylic acid. A s -m- 

 menthenol-8, which is prepared by the usual method from the ethylester 

 of this acid, constitutes a liquid of pleasant odour, b.p. 102° (14mm.) 

 with the following constants: d§§ 0,9268, n D 1,4798, mol. refr. 47,10, calc. 

 47,16. Its phenylurethane melts at 130°. The zl 3 ' 8(9) -m-menthadiene obtained 

 from this alcohol boiled at 181 to 182° (760 mm.): d 20 o 0,8609, n D 1,4975. 



i) journ. chem. Soc. 87 (1905), 1087; Report October 1905, 93. 

 2 ) Journ. chem. Soc. 97 (1910), 2147. 

 >') Comp. Report October 1910, 202. 



12 



