— 143 — 



Treatment of the alcohol with phthalic anhydride yielded the same 

 acid phthalate, m. p. 120°; oxidation with chromic acid gave rise to a 

 ketone, of which the semicarbazone possessed the following constants: 

 m. p. 174 to 175°, « D of a solution of 1,0816 g. substance in 100 cc. absolute 

 alcohol, + 4°46' in a 2 dm.-tube; from which [«] D +200° was calculated. 



M e n t h e n o 1. B. D. W. Luff and Perkin 1 ), after overcoming serious experi- 

 mental difficulties, have succeeded in resolving into its optical components 

 d,Z-l -methyl-/! 3 -q/cZohexene-3-carboxylic acid 2 ) by repeated crystallisation of 

 its brucine and Z-menthylamine salts. It is still doubtful whether the 

 active modifications have been obtained in a chemically pure state, the 

 yields being rather small. £Z-l-methyl-zl 3 -c2/cZohexene-3-carboxylic acid melts 

 at 62 to 64°; [«] D + 40,1° (3,6 °/o solution in ethyl acetate). The ethyl 

 ester boils at 150 to 151° (100 mm.); [«] D + 32,5°. The dibromo-derivative 

 of the free acid (m. p. 165°; [«] D + 28,5°) when treated with potassium 

 hydroxide does not give off hydrobromic acid but only bromine, the 

 original acid with the same optical deviation being recovered in the 

 process. When magnesium methyl iodide is allowed to act upon 

 ethyl cZ-l-methyl-J 3 -cycfohexene-3-carboxylate, the result is d-A 3 -m-men- 

 thenol-8 (b. p. 107 to 108° at 25 mm.; dgg 0,9235; [«] D + 20,9 o in 3,6% so- 

 lution in ethyl acetate; n D 1,4791); this substance, when heated with oxalic 

 acid, yields d-d 3:8(9) -w-menthadiene: b. p. 179° (730 mm.), [«] D + 17,5 

 (3,5°/o solution in ethyl acetate), n D 1,4975. 



Z-l-methyl-zl 3 -ci/cZ0hexene-3-carboxylic acid gave [«] D — 35,8° (3,7 °/o so- 

 lution in ethyl acetate); its ethyl ester boiled at 148 to 150° (100 mm.): 

 Wd — 28,9°. The constants of Z-J 3 -m-menthenol-8 were as follow: b. p. 102 

 to 103° (14 mm.), [«] D — 18,5° (4°/o solution in ethyl acetate). It yielded 

 Z-zJ 3:8C9) -m-menthadiene: b. p. 181 to 182° (760 mm.), [«] D — 12,9° (4°/o so- 

 lution in ethyl acetate), n D 1,4969. 



Perkin, in collaboration with Tsan Quo Chou 3 ) also describes a dextro- 

 rotatory modification of the J 3 -p-menthenol-8 4 ) and zJ 3:8(9) -j9-menthadiene 

 described by Perkin and Wallach. The authors started from d-1-methyl- 

 q/cZohexane-3-one, which was allowed to react with sodium amide and 

 carbonic acid. The product of reaction, d-l-methylq/cZohexane-3-one-4-car- 

 boxylic acid, when reduced with sodium amalgam yielded d- 1 -methyl - 

 q/cZohexane-3-ol-4-carboxylic acid, which when treated with phosphorus 

 trichloride gave rise to d-1 -methyl-^ 3 -q/cZohexene-4-carboxylic acid. For 

 the purpose of preparing cZ-zl 3 -p-menthenol-8 the ethyl ester of d-1-methyl- 

 J 3 -q/cZohexene-4-carboxylic acid iwas allowed to react with magnesium 

 methyl iodide. The] alcohol possessed the following properties: b. p. 105° 



x ) Journ. chem. Soc. 99 (1911), 518. 



2 ) Comp. Report April 1911, 175. 



3 ) journ. chem. Soc. 99 (1911), 526. 

 *) Comp. Report October 1910, 190. 



