POSITION OF THE DOUBLE LINKAGE IN PIPERITONE, PART II. 39 
THE POSITION OF THE DOUBLE LINKAGE IN 
PIPERITONE, Part II, 
WITH NOTES ON SOME OF ITS DERIVATIVES. 
By A. R. PENFOLD, F.C.S. 
[Read before the Royal Society of N. S. Wales, June 7, 1922. ] 
In a Part I communication read before the Society on 3rd 
August 1921,* the writer submitted evidence which showed 
piperitone to possess the structure of a A\,-Menthenone-3, 
as diosphenol was one of the products resulting from its 
oxidation by means of potassium permanganate solution, 
As promised at the time, the examination of the acid bodies 
separated from the products of oxidation having since been 
completed, it was deemed advisable to publish the con- 
cluding evidence. As shown under “‘Experimental,’’ the 
results confirm the aforementioned structure for this 
ketone. 
Since the preliminary communication referred to above, 
two other papers have appeared bearing upon its structure, 
viz:—‘‘ Piperitone, Part I. The occurrence, isolation, and 
characterisation of Piperitone,’’ by John Read and Henry 
George Smith, Journal of the Chemical Society, June 1921, 
page 779, and “‘The Hssential Oil from Andropogon iwar- 
ancusa, Jones, and the Constitution of Piperitone,’’ by 
John Lionel Simonsen, October 1921, page 1644, 
The first named authors argue that the preparation of 
benzylidene-dl-piperitone is a convincing proof of the non- 
identity of piperitone with any of the menthenones hitherto 
described, whilst Simonsen shows that the Hssential oil of 
Andropogon iwarancusa contains about 80% piperitone, 

* This Journal, Vol. tv, 189, (1921). 
