1921.] Recent Advances in Stereochemistry. 221 
has more than three times as high a rotation as phenylimino- 
cumphor : 
C=N ° 
G. Ma I <> [mM], 1750 
J 
and allowing for the two phenyliminocamphor residues in the 
jugated chain, which is twice as long in the former compound 
as in the latter. 
Hilditch (T. 1909, 95, 333) has also obtained compounds 
with high rotation constants by condensing camphor with 
aldehydes. The effect of breaking the conjugation in this series 
is also phenomenal : 
cy 
CeMig (| 
c=0 
[M]p 67°2° 
fA oe . = CH-CH=CH'C_H 
“ \¢=0 ee 
° 
[mM], 1020-3° [M},, 1397-8 
t 4 
: ‘ ¢ H-CHs CH=CH’C_H 
C,H iG CHa CoM, AEG! we 6's 
[mM], 248° (m], 179-1 
(c) The EFFECT OF Posir1on-ISOMERISM ON OPTICAL 
ACTIVITY. 
The relation between chemical constitution and rotatory 
power which is investigated most is that of pasition isomerism In 
the aromatic groups present in optically active co 
Frankland in 1896, as the result of his observations on the 
rotatory powers of dibenzoyl and ditoluoyl tartiates, found 
that the order of rotation in the case of position isomerides 
B 
side chain containing an optically active group in the following 
way :— 
The centre of gravity of the unsubstituted nucleus being 
at the centre of a regular hexagon that in the ortho derivative 
