TRANSACTIONS. OF SECTION B. 519 
remained undecided whether every difference in the groups attached to the nitrogen 
atom was sufficient to cause activity. Contrary to expectation, I have been unable 
to obtain optically active forms of the asymmetric salts of the above-mentioned 
paratoluidine series. The failure was probably due to unfavourable solubility 
conditions, and also to a tendency to autoracemisation. The latter phenomenon 
was observed by Pope and by myself in the case of the active a-phenylmethyl- 
allylbenzylammonium iodide. 
This phenomenon was formerly explained by assuming the dissociation of the 
salt into benzyl iodide and allylmethylaniline, according to the equation :— 
(C,H) (C;H,). (CH,)N (C,H,)I @ C,H, (C,;H;) (CH,)N + C,H, I. 
That is to say, by the easy passage, under certain conditions, of pentavalent into 
bivalent nitrogen, and the consequent destruction of space asymmetry, and, therefore, 
also of optical activity. Asa matter of fact, the iodide is largely dissociated in 
boiling chloroform solution. Whether this is also the case in chloroform solution 
at ordinary temperature could not then be decided. H.O. Jones, however, by 
using Barger’s microscopic method for determining molecular weights, was able to 
show that such salts possess normal molecular weights in chloroform solution at 
ordinary temperature. The explanation of the mechanism of autoracemisation in 
the case of the active asymmetric ammonium salts becomes, therefore, as difficult 
as that of the spontaneous racemisation of the active esters of brom-fatty acids, 
unless it is assumed that the degree of dissociation at any instant is at ordinary 
temperatures so small as to escape measurement by the methods employed. This 
small amount of dissociated material would on recombination form the racemic 
salt. In the next instant another small quantity of the active salt would be dis- 
sociated and racemised, and so on until the whole mass was racemised. It is 
evident that, in spite of this process, an approximately normal molecular weight 
might be found. The velocity of the change—that is to say, the amount of active 
salt dissociated in the unit of time—depends upon the strength and duration of the 
light falling on the solution, and also on the temperature. I am at present engaged 
in the measurement of the velocity of autoracemisation under various conditions, in 
the hope of elucidating this problem. 
The important question whether all asymmetric ammonium salts, independent 
of difference in groups, could be obtained in active forms has at last beeu answered. 
Jones, after failing to obtain ammonium salts of the type N.a.a.b.c.X., and also 
cyclic salts in active forms, succeeded in resolving the phenylethylmethylbenzyl- 
ammonium base at almost the same time. I prepared the iodide and the dextro- 
camphorsulphonate of the same base, and succeeded in resolving the latter by 
a single recrystallisation from methyl formate ([m{, of the dextro-phenylbenzyl- 
ethylmethy] d-camphorsulphonate= +69°). By employing the same useful solvent 
I have also recently been able to resolve the homologous propylphenylbenzyl- 
methylammoniumhydroxide. The d-camphorsulphonate of the dextro base forms 
transparent rhombohedra, which attain a diameter of one or more centimetres. 
The highest rotatory power hitherto observed is [M] p= +62°. The iodide pre- 
pared from the camphorsulphonate was active. Activity did not result when 
acetone or acetic ether was employed. I am at present working on the resolution 
of the homologous isobutyl base. 
The problem of resolving salts containing two asymmetric nitrogen atoms 
appeared particularly interesting.' For this purpose I have converted ethylene 
dikairolinium iodide * into the di-dextro-camphorsulphonate. 
CH,—CH, 
CH,—CH, / 
>C.H, x 
H, N OS HG, Pat hee el ope. 
| 
CH, SO,.C,,H,,0 OH, SO,.C,,H,,0: 
1 O. Aschan, Zeitachr. f. physikal. Chemie, 46, 312 ff. 
2 BE. Wedekind, Ber. d. deutsch. Chem. Ges. 36, 3796. 
