POSITION OF THE DOUBLE LINKAGE IN PIPERITONE. 141 



of the linkage being in a similar position in the molecule 

 of piperitone, as if it were at 4, it could not yield diosphenol 

 on oxidation. This decisive evidence is thus recorded in 

 this note merely as a preliminary, thereby leaving the 

 account of the other interesting acid products of oxidation 

 for a Part II communication. 



Experimental. 



104 ccs. of piperitone possessing the following characters: 

 Boiling point at 760 mm. ... 235° C. (corrected) 



Specific gravity at 15° 0. ... 0'9383 



Optical rotation ... ... —0*4° 



Refractive Index at 20° C. ... 1*4837 



were oxidised at 18° O. with 2% aqueous solution potassium 

 permanganate. On completion of the reaction and separa- 

 tion of the solution from the manganese sludge, steam was 

 blown through it, when 7 grams of a white crystalline 

 body were obtained. This material was purified by sub- 

 limation, when it was obtained in monoclinic needles 

 possessing a mixed odour of mint and menthol. (See Plate 

 VII.) 



The crystals melted at 82° C, and were insoluble in water 

 but soluble in a cold 5% aqueous solution sodium hydroxide. 

 From the latter they were liberated again on addition of 

 dilute acid. They gave a green colouration with ferric 

 chloride in alcoholic solution, restored the colour to SchiftV 

 solution, reduced both ammoniacal silver nitrate and 

 Fehling's solutions, behaviour characteristic of diosphenol. 

 It was confirmed by the preparation of the oxime, m. pt. 

 125° C, and phenylurethane, m. pt. 41° O. 



On combustion it gave results in accord with the formula 

 CioHi602. The crystals having been proved to be diosphenol, 

 piperitone must necessarily possess the following struc- 

 ture: — 



