250. 
eraction of an entering molecule with group X, then one could 
immediately trace the influence on this reaction velocity of the 
situation and of the nature of different groups in the benzene nucleus. 
If e.g. a group X directs substituents to the para- and ortho-place, 
it is to be expected that the rate of reaction mentioned above will 
be the most modified by groups already present in the ortho- or 
para-position and less by groups in the meta-position. 
If on the other hand we had a group X directing to the meta 
place, then the reverse would have to be expected if for the rest 
the acting molecule and the circumstances are the same. 
To this end we have in the first place selected the diazotisation 
reaction, viz. the rate of reaction of the NH, group with HNO,, 
partly as the NH, group directs to para and ortho in a very pronounced 
way, partly because HNO, will show a great similarity in its nature 
with HNO,, the reagent examined most fully by HorurmaN and 
his pupils. 
In this case one will have to take into consideration that the 
velocity of the diazotisation may also depend on the basicity of the 
“amine. For instance it is not at all out of the question that the 
reaction exclusively takes place between the free amine and free 
nitrous acid. Then this reaction will be the quickest with the weakest 
bases because their salts are hydrolysed in the highest degree. Now 
if the meta substituted amines are stronger bases than the para- 
and ortho-substituted ones, then the first mentioned would show a 
smaller rate of diazotisation than the last. As however the basicity 
can be deduced from data independent of the rate of diazotisation, 
its influence can be brought into account. 
2. About the rate of diazotisation of different substituted amines 
we meet with but a few investigations. 
The first studies go back to the research of Hanrzscn and SCHUMANN’). 
They estimated after different periods the quantity of unchanged 
nitrite by the reaction of Trommsporr (with zine iodide-amylum 
solution). As will appear later on, this method is too liable to errors 
to use it for determining the rates of diazotisation. Hanrzscx operated 
as follows: 
He mixed at 0° 500c.c. of a solution of the amine (*/,,, N. amine 
hydrochloride + '/,,, N. HCl) with 500 ec. */,,. N. nitrite solution; 
after 30 minutes he made the first determination. 5 cylinders each 
with 3¢.c. zine iodide-amylum solution and 1 e.e. H,SO, were filled 
1) Ber. 32, 1691 (1899). 
