DYNAMIC ISOMERISM. 271 
addition of either acids or alkalis; the isomeric change thus appeared to 
be due to a direct interaction between the sugar and the water of low 
conductivity which formed the solvent. In the case of nitrocamphor 
dissolved in chloroform it has been found possible to check the mutarota- 
tion by the addition of N/100 acetic acid, and to stop it altogether 
during a period of three weeks by the addition of N/1,000 trichloracetic 
acid. The experiments therefore afford valuable confirmation of the 
view already arrived at! that the isomeric change which usually takes 
place when nitrocamphor is dissolved in chloroform or benzene does not 
occur spontaneously, but is conditioned by the presence of minute traces 
of alkaline impurities. 
Experiments were made to determine quantitatively the effects pro- 
duced by these impurities. Sodium ethoxide, added to an alcoholic 
solution of nitrocamphor, was found to produce an acceleration very 
similar to that which results from the addition of caustic potash to an 
aqueous solution of glucose ; the mutarotation in presence of N/1,000 
NaOHKt was complete in about a quarter of an hour, with N/10,000 NaOKt 
in about three hours, and a slight acceleration could be detected in 
presence of N/100,000 NaOEt. Thenormal period of the isomeric change 
in absolute alcohol at 20° C. is about six hours, but the change is greatly 
accelerated by the addition of a little water. The velocity of change in 
alcohol containing 1 per cent. of water was exactly equal to that in a 
sample of 99-8 per cent. alcohol to which sodium ethoxide had been added 
in a concentration of N /10,000. 
Extraordinary effects were produced by the addition of piperidine to 
solutions of nitrocamphor in benzene. In presence of N/1,000 piperidine 
the mutarotation was complete in two minutes, and even when working 
as rapidly as possible only two readings of the polarimeter could be 
obtained before the final value was reached. With N /10,000 piperidine 
the change was complete in about six minutes, with N / 100,000 in an 
hour, and with N/1,000,000 in about ten hours. With N/10,000,000 
piperidine the acceleration of the isomeric change was comparable with 
that due to the trace of impurity normally present in the purified 
materials, and no definite observations could be made. 
In the case of the N/100,000 solution the molecules are present in 
the proportion— 
piperidine ; nitrocamphor : benzene=1 : 25,000 : 1,000,000— 
and about 2 per cent. of the nitrocamphor undergoes change in each 
minute. It therefore follows that if each molecule of piperidine is able 
to invert only one molecule of nitrocamphor at a time, it must accomplish 
500 such inversions per minute, and unless selectively guided to the nitro- 
camphor must come in contact also with some 20,000 molecules of benzene. 
_ In view of the remarkable effects produced by the addition of 
piperidine, it is noteworthy that the addition of aniline is almost without 
effect. In presence of N/1,000 aniline the velocity of isomeric change 
in a solution of nitrocamphor in benzene was slower than in presence of 
N/10,000,000 piperidine—a result that was confirmed by a second series 
of observations ; the blank experiment, with benzene only, showed a 
still slower change, but this result was only achieved by very careful 
purification of the materials, 
The experiments now described are a importance as indicating the- 
conditions under which isomeric change may in general take place. Tt 
 Trans., 1899, 75, 221; Report, 1904, p. 196. 
