1071 
chlorination of benzené with SnCl, (Sr.aror) and in the just mentioned 
research of Goipscumipt and Larsen in which, however, neither the 
progressive change of the reaction nor the role of the catalyst has 
been much elucidated. 
For this reason we have more closely studied the reaction between 
p-bromophenylsulphonchloride and benzene. 
It was first our intention to carry this out in a neutral solvent 
for which carbon disuphide was chosen; it appeared, however, 
that the reaction then took quite another course *) so that we were 
compelled to choose the hydrocarbon itself as the solvent. 
The p-bromosulphonchloride was prepared from bromobenzene by 
sulphonating this with fuming sulphuric acid, neutralising the mixture 
with lime and converting the calcium salt by means of sodium car- 
bonate into the sodium salt; the sodium p-bromosulphonate thus 
obtained was converted by PCI, into the chloride. This was freed 
from POCI, with cold water ,and recrystallised from ether. 
We had chosen the sulphonchloride as starting point because this 
is not decomposed by cold water, whereas it is rapidly decom- 
posed on warming with aqueous silver nitrate, so that the unat- 
tacked sulphonchloride could be freed, by means of cold water, from 
the AIC], and the HCl formed and afterwards be titrated with silver 
nitrate solution of known strength. 
The benzene hydrocarbons were dried carefully over AICI, and 
kept in stock with exclusion of moisture. 
The measurements were carried out by making (with exclusion 
of light and moisture) a solution of definite quantities of sulphon- 
chloride, aluminium chloride, and hydrocarbon ; from time to time a 
definite volume of this solution was withdrawn and analysed. 
For details we refer to the dissertation of Mr. Otvier which will 
appear shortly. 
We reprint therefrom a few series of analyses. 
The benzene required for this was treated before the reaction 
with AICI, and distilled; a thiophene-free benzene which had not 
thus been dried and distilled exhibited a ‘small initial value and a 
strong course of the constant. 
From table I we see that the reaction between 1 mol. of AICI, 
and 1 mol. of acid chloride is one of the first order; when, however, 
80°/, of the original quantity has been converted a serious retarda- 
1) It then proceeded according to the scheme: Br CgH,SO,Cl + AICI, + C,H, = 
Br C,H,SO,AICl, + C,H;Cl + HCl. 
70 
Proceedings Royal Acad. Amsterdam. Vol. XV, 
