( 2(^7 ) 



Dl'. VAN TjOon has also heen oii!L>agcd in determining the velocity 

 of the (ransConnalioii. An excess of liiiely powdered hydi'azol)enzene 

 was introduced into diliile alcohol, to which had l)een added acid of 

 a definite concentration, the niixlure being vigorously stirred. At 

 stated times certain (luantities of li(|uid wci-o wilhdra\vn from the 

 mixture and the amount of benzidine was (luamilatixely delei-mined. 



If (4 ii' called the concentration of the benzidine formed, Cnci 

 that of the hydrochloric acid at any moment, the equation 



— — = A t'lia 

 dt 



was found to represent the transformation ; in this t is the time (in 

 minutes) and K the reaction constant. No special figure is given for 

 the concentration of the h^drazobenzene as this may be taken as 

 constant in the modus operandi followed. 



The transformation is due to the hydrogen ions of the acid, for 

 on comparing the action of hydrochloric acid and dichloroacetic acid 

 the reaction constant was shown to be proportional to the degree of 

 ionisation of the acids employed. This caused Dr. van Loon to sug- 

 gest that during the transformation two H-ions are first linked to 

 liydrazobenzene forming 



0, H.NH. NHC, H. • 



" 11+ H+ 



and that then the repulsion of the two |)ositive charges causes the 

 molecule to break up l)etween the two nitrogen atoms, whereupoji 

 the two portions again unite in such a manner that the positive 

 charges are at a greater distance from each other. This representati(jn 

 accounts for the presence of C'^hci in the equation of velocity, as 

 according to this equation one mol. of liydrazobenzene reacts \vith 

 two H-ions. 



Cliem. Lab. Univ. Groningen, July 1903. 



Chemistry. — ^'llte transformntion of (Uplioujliiilrostnitlue into p.- 

 ji,/tro.so-(//j)heiif/Ia))nii(' ana' its' velocity." IJy II. Ivakkx. ((-om- 

 municated by Prof. V. A. Lobry de Bruyn as eouiuinnicaiioii 

 N". (5 on intramolecular rearrangements). 



(Commiinicalcd in Ihe mceling of Seplember 12(), 1003). 



In 1886 Otto Fiscukr discoxered the iiileresiing fact that under 

 the intlueiH'e of alcoholic hydrochloric acid the iiilroLi'cii-combiiied 

 nitro^ogroup of methylphenylnitrosamine changes place with flu; 

 pai'a-hyilrogen atom of the benzene nucleus ;ni<l is thus converted 

 into the isomeric nitrosobase. 



