170 R. S. HUGHESDON, H. G. SMITH AND J. READ. 
THE STEREOISOMERIO FORMS OF MENTHONHE. 
By REGINALD SLATER HUGHESDON,’ HENRY GEORGE SMITH, 
and JOHN READ. 
[Read before the Royal Society of N.S. Wales, November 1, 1922. ] 
FROM a stereochemical point of view the molecular con- 
stitution of menthone (p-menthan-3-one) is of particular 
interest, since it presents one of the best known examples. 
of a cyclic structure containing two dissimilar asymmetric 
carbon atoms (Nos. 1 and 4, Formula I): 
CH, Ch, 
| | 
CER ers. a aed C 
Ae a 
C6 CH H,C CH 
| | | | 
H,C; 3 CO H,C CO 
Aye aed 
Oa yee Rincemeutsan oD hey J CH / 
| att 
CH. CH 
ee \ i. \ 
CH, CH, CH, CH, 
(I) (11) 
Menthone. Piperitone. 
(p-menthan-3-one) (A *-p-menthen-3-one) 
The presence in the molecule of two such atoms should 
permit of the existence of four optically active forms of 
menthone. The two enantiomorphic spacial environments, 
and the corresponding right- and left-handed optical effects 
of carbon atom No. 1 may conveniently be indicated byjthe 
symbols d and 1, respectively, whilst the symbols D andiL 
may be used similarly for carbon atom No. 4. The four 
(* Science Research Scholar of the University of Sydney.) 
