192 REPORT—1904. 
alkyl and acidic radicals in both the possible positions gives rise to a 
mixture of optical antimers. 
The isomerism observed by Wedekind in the diquinolinium compounds 
if established by further work is readily accounted for, since it would be 
expected that mobility would be diminished in these cases. Two exter- 
nally compensated compounds ought to be produced, but since the pro- 
duct was apparently homogeneous, the two compounds must either be 
extremely similar or one of them must be formed in extremely small 
quantities, as in the case of the mannose cyanhydrins. 
The existence and properties of the isomeric ethylene-trimethylene 
dipiperidinium dibromides discovered by Aschan are readily accounted for 
by any one of the proposed configurations, though Aschan himself says : ! 
‘Das von van’t Hoff mit dem gewohnten Scharfsinn dieses Gelehrten 
vorgeschlagene Modell fiir den pentavalenten Stickstoff ist die einzige mir 
bekannte, welche die Existenz und Inaktivitaét der beiden untersuchten 
Dipiperidid-Dibromide erkliren kann.’ 
With the aid of the pyramidal configuration these isomerides would 
be represented thus : 
Fie. 17. 
Formed by the addition of trimethylene dibromide to ethylene dipiperidide : 
Fig. 18. 
Formed by the addition of ethylene dibromide to trimethylene dipiperidide : 
oan CH 
eG CH> 
CH2s__ , CHa 
CH3-~-.> 
CHa Che As 
CH3-"" _-°CHo 
Che 
“CH 
Interchange of positions between the bromine atom and one of the 
chains forming the central ring is not possible without almost complete 
disintegration of the molecule, and is improbable for other reasons, so 
that each bromine atom occupies a position at the base of the pyramid. 
The planes of the piperidine rings are in each case represented as 
perpendicular to the plane of the paper ; each compound has thus a plane 
of symmetry in the plane of the paper and would be optically inactive. 
Hence, the ‘ pyramidal’ configuration of Bischoff, with the assumptions 
made as to the mode of formation of ammonium compounds from amines, 
1 Toe. cit., 318. 
