180 ; REPORT— 1904. 
Wedekind ! compared the rate of formation of quaternary compounds 
from dimethylaniline and similar tertiary amines and various alkyl iodides. 
In all cases methyl, benzyl], and allyl iodides react much more rapidly than 
any others ; the order of their rapidity, however, depends on the amine 
used. 
This kind of effect is often attributed to ‘stereochemical obstruction ’ 
or ‘space filling,’ in the same way as the phenomena observed in the 
esterification of diortho substituted benzoic acids by V. Meyer. There is 
certainly an effect of this sort. Thus, for example, tribenzylamine, 
(C,H,);N, is capable of reacting with methyl iodide ; dibenzylaniline (C,H) 
(C,H;CH,)N is not ; and triphenylamine will not even react with hydro- 
chloric acid. Again, the halides of normal alkyl groups invariably react 
more rapidly than those of the corresponding iso groups. All the facts 
cannot, however, be accounted for in this way. On such a view iodides 
should react less rapidly than chlorides. Also Menschutkin ? finds that, 
whereas substitution of an alkyl group in the a position in pyridine, 
piperidine, or quinoline diminishes the velocity of reaction with alkyl 
bromides, the introduction of the same group in the / or y position 
increases the velocity. 
Much more work of a systematic kind is needed before any general 
conclusions on the subject can be drawn ; all that we can at present say 
is that the rate of formation of an ammonium compound depends both on 
the alkyl radicals already present in the amine, and also on that which is 
to be added on to it. 
(ii) Compounds of the Type Na,bX. 
The first experiments made on compounds having three radicals 
identical and one different were those of Meyer and Lecco already 
mentioned : a very large number of similar experiments have failed to 
produce isomerides of this type. 
Le Bel* found that the chloroplatinate of benzyl-triethylammonium 
hydroxide was the same whether produced from triethylamine and benzyl 
chloride or from benzyl-diethylamine and ethyl iodide, and similarly with 
that of trimethyl-propyl ammonium hydroxide or tripropylmethyl- ammo- 
nium hydroxide, whereas that of trimethyl iso-butylammonium hydroxide 
was found to exist in two different crystalline modifications, the one 
being anisotropic needles which readily changed into octahedra; the 
chloride of the same base also exhibits differences of a similar kind. 
Similar differences were observed by Le Bel* in the chloroplatinate of 
dimethylamine, and by Arzruni and others® in ethylamine hydrochloride, 
tetramethyl ammonium chloride, m-xylidine hydrochloride, tropidine 
chloroplatinate, and several other similar salts, Although the evidence is 
insufficient to show that these differences are not due to isomerism, it is 
highly probable that they are merely due to dimorphism. 
Messrs. Schryver and Collie® found that only one chloroplatinate of 
trimethyl-ethyl ammonium hydroxide, dimethyl] diethyl ammonium hydrox- 
ide, and methyl-triethyl ammonium hydroxide could be prepared. 
1 Stereochemie des fiinf. Stickstoffes, 1899, 18. 
2 Jour. russ. phys. Chem. Gies., 1902, 34, 411. 
3 Compt. rend., 1890, 110, 145; 1891, 112, 725; Bull. Soc. Chem., 1890 [3], 4, 104. 
+ Compt. rend., 1893, 116, 513. 
5 Cf, Lehmann, Molecular Physik, vol. i. pp. 177, 539, 599; Zeit. Kryst., vol. iii. 
16. 6 Proc. Chem. Soc., 1891, vii. 39. 
