202 REPORT—1904. 
is converted through its hydrochloride into camphene or camphor into 
carvenone.! 
In the hexachlorocycloketopentenes, studied by Kister,? the shifting 
of the double bond is accompanied by the transference of a halogen atom, 
and equilibrium is established fairly rapidly at 210°, the necessary catalyst 
being probably HCl, 
COL: CCL OCLC, 
*" CCl.CCl,”  CCLCCI,” 76) 
Included in this group are the stereoisomeric changes of unsaturated 
compounds. The conversion of maleic into fumaric acid, which takes 
place at ordinary temperatures in presence of HBr, is almost complete, 
H.C.CO,H _ CO,H.C.H 
Nl I 
H.C.00,2° > H.0.00,H. 
but the dibromotolanes which are convertible at 210° are almost equally 
stable and are present in approximately equal quantities in the melt.’ 
C,H;.C.Br C,H,.C.Br 
[48 9%] | Fs I [52%] 
C,H;.C.Br Br.C.C,H; 
In each case isomeric change may be due to association with HBr, though 
another explanation is available in the case of maleic acid (compare p. 211). 
Amongst nitrogen compounds similar equilibria are observed in the 
stereoisomeric oximes 4 and the syn- and anti-diazo- compounds.” 
3. Interchange of Radicles in Aromatic Compouwnds.—One of the most 
characteristic properties of aromatic compounds is the ease with which 
they undergo isomeric change, so that almost any radicle that can be 
attached to the nitrogen of aniline or the oxygen of phenol can be subse- 
quently interchanged with a hydrogen atom in the nucleus. In this way it 
is possible to transfer radicles as diverse as the halogens, NO,, OH, 8O3H, 
COPh, NHPh (semidine), PhNH, (benzidine), and (under somewhat forced 
conditions) CH;. The ring-substituted compounds are very stable, and 
the back action is usually slight, but as scarcely any attempt has yet been 
made to study these changes from the standpoint of equilibrium, it is 
impossible to say to what extent reversal occurs in any given case. Two 
ring-substituted compounds may exhibit a well-defined equilibrium, and 
such a case is found in the ethylxylenesulphide sulphonic acids,’ the 
stable proportions in the mixture being indicated by the equation 
CH, CH, 
SO,H/\ /\S803H 
[90-92 96] | | 2 | [10-8 94). 
\ZCHs3 \/ZCHs3 
SEt SEt 
1 Bredt, Annalen, 1901, 814, 369; compare Armstrong and Lowry, 7Zvans. 1902, 
81, 1469, and p. 214 of this report. 2 Zeit. phys. Chem. 1895, 18, 161. 
3 Wislicenus, Dekanatschrift, Leipzig, 1890. 
4 Cameron, J. phys. Chem. 1898, 2, 409; Carveth, ibid. 1899, 8, 437. 
5 See Dr. Morgan’s report, Belfast 1902, and Hantzsch, Die Diazoverbindungen, 
Ahren’s Sammlung, 1902. * Harker, Zhesis, London, 1903. 
