1921.] Recent Advances in Stereochemistry. 225 
croup. Fourthly, the nature of the solvent is sufficient to bring 
about an alteration in the order of rotatory power, as is seen 
in the case of tolyl and bromphenyl derivatives in chloroform 
and methyl alcohol solutions. 
Cohen’s Rule is also not obeyed as it is the meta compound 
in the case of bromphenyliminocamphor and the para deriva- 
tive in the case of methoxyphenyliminocamphor which differ 
most in rotatory power from the constants of the unsubstituted 
compound and not the ortho. 
The resulis obtained by the writer in the case of deriva- 
tives of phenylaminocamphor equally go against the above 
rules as the following points show :— 
M)< Chloroform solution phenyl- 
(M)a aminocamphor =309°. 
fects Sr ene a NE ee 
Derivatives of phenylamino- CH Br 
camphor. ao 
ortho i ae 179° 235° 
meta .. i itt 361 277°6 
para .. Ss ae 265 2889 
o<p<un¢cm; o<m<cp<un. 
M Methy] alcohol solution phenyl- 
(M)a aminocaw phor=229°81. 
Derivatives of phenylamino- CHe Br 
camphor, 
ortho : 174° 230-2° 
eta.. «se 198 207°9 
para .. : “ 158 2096 
p<o<m<un; m <pcun <0. 
(i) The order of rotatory powers as laid down by Frank- 
land is not followed once in the above four cases. 
(ii) The difference in rotatory powers of o—and p—tolyl 
d is 1} timesas large as that in the case of 
Bromphenyl derivatives in chlorofrom ~ solution, 
although Bromine is a heavier group than the - 
methyl radical. ; 
(iii) In no case has the para compound the maximum rota- 
tion; whereas the ortho, meta, and the unsub- 
stituted compound each has had the maximum 
rotatory power, 
(iv) The effect of solvent on the order of rotatory power 
of position isomerides is remarkable; the ortho 
bromphenyl compound has the lowest value in 
s 
methyl! alcohol. : 
(v) Cohen’s Rule is followed in chloroform solution, but 
not in methyl! alcohol. 
