ON DYNAMIC ISOMERISM. 207 
iy : CH 
carbostyril (hydroxyquinoline), CoH | , and cyanuric acid, 
N=C.0H 
JN : COB) 
HO.C 
Nw.c(0H) 7 
and Hartley, Dobbie, and Lauder have shown that this is probably the 
ketonic form.! Cyanic and thiocyanic acids also yield isomeric esters, 
but are only known in one form, apparently the ketonic.? Lees and 
Shedden ? claim to have prepared the enolic form of acetyl-o-aminophenol, 
HO.C,;H,.N : CMe.OH, but the great stability of the substance, which 
does not appear to be convertible into the ketonic isomeride, is difficult to 
reconcile with the formula they propose. 
6. Witro- compounds.—These are influenced by substitution in a 
similar manner to the ketones. Even in aqueous solution the conversion 
of the pseudo into the normal form appears to be complete in the case 
of nitromethane, H.CH,.NO,, nitroethane, CH;.CH,.NO,, phenylnitro- 
methane, C,H;.CH,.NO,, and its p-bromo- and p-nitro- derivatives ; but 
dinitroethane, NO,.CH,.NO,, gives a mixture of the normal and pseude 
forms, and—in aqueous solution only (see p. 199)—acetylnitromethane 
CH;.CO.CH,.NO,, benzoylnitromethane, C,;,H,.CO.CH,.NO,, bromodi- 
nitromethane, NO,.CBrH.NO,, and trinitromethane, (NO,),CH.NO,, 
appear to exist almost exclusively in the pseudo- form.4 
Similar effects are produced in the camphor series, the nitro- com- 
pounds of which have been examined both in ionising and in non-ionising 
solvents. Nitrocamphane, 
N. In all these cases only one modification is known, 
CH, 
C,H 14 é | 
\CH.NO,, 
passes in solution completely from the pseudo- into the normal form.® 
Nitrocamphor, 
CH.NO, 
OC | 
gives a mixture, and in 3- and z-bromonitrocamphor, 
CH.NO, 
CH, Br | 
Noo, 
the influence of the keto- group is so far reinforced by the bromine that 
in the solid state the pseudo- is the stable form.® 
7. Nitroso- compounds and Oximes.—The group >CH.NO appears 
to be even more unstable than the pseudo-amide group —N : COH—. 
1 Trans. 1899, 75, 640. 2 Hartley, Proc. Chem. Soc. 1899, 15, 46. 
8 Trans. 1903, 88, 750-763. 
* Hantzsch, Ber. 1899, 32, 607. 5 Forster, Trans. 1900, 77, 260. 
6 The stability of the pseudo- form in the solid state is due to a decrease of solu- 
bility, and not to any marked increase in the proportion present in solution. 
