( 512 ) 



Ghecaistry. — " 77/(' hrowhiation of toliiem'". B_v I'rof. A. F. 

 Hui.i.ivMAN and Di'. K. H. van dkh I.aan. 



(Coiiiinuiiicatecl in the ineetiug of OctobiT ^8, 1905). 



In till' ii'.iclion belwc'cn Inliicnc anil Inidnini- w i- have a sli'iUiii;f 

 c.xanijilc (if tlie inllnence exerted un I he ualme of liic |)r(>dncl of 

 reaction by exj)ei'iinenlal conditiüiis. Almnl this the fnllowiiiji' is 

 known: 



1. I II lliii-iici' (If' l.i'iii jurdliiri-. \\\ the dark and at a Inw icni|ii'fa- 

 tnre tliei'e is t'oi'ined a nnxlnre i)ï hrnniDlolncnes ; on tjie nlliei- hand 

 benzyl bromide is t'oi'ined at tiie boilini: iioini of toluene. 



'1. /ii/liit'iice ('/' /I1//1/. At a liiw Iein|ieralnri' benzv I lirmnide is 

 exeliisively fonned: the same takes plaee al the boiling;- temperat 11 re. 



3. Jnjiuciicc of ciifii/i/zi'rs. Tliroimh llieir aelinn the broinination 

 takes place exeiiisiveiy in the core, even in full dayli^lil and at 

 ail elevated temperature. 



If we make a closer slndy of the papers which lia\e a|)pearcd 

 a« to this reaction it strikes ns, as in so many other cases, that the 

 virtually known snlfers from much uncertainty owing tu an iiisiitli- 

 cient observance 01 liie quantitative proportions. When, for instance, 

 ScHKAMM states that on broinination in snnliü'ht l)en/.yl l>roniide is 

 e.xchisively formeil, a doubt arises as to the correctness of this view, 

 as the only proof he adduces is that tli(> boiliiii; point of his product 

 lies at 195^ — 205°; his boiüiifi' point limits are therefore s(j wide 

 apart that tlicv sn<i<iest rather the iirescnee than the total absence 

 of isomers. As rejiards the bioniolobieiies formed in the reticlioii, 

 it A\as known thai these are ortho- ami y/i//-'/-broinotoliieiie. Hiil the 

 (piestion, in \\ hat |n-oporlion those are formed under the inthieiice 

 of the three above factors, has only been niatle the subject of jxreatly 

 \aryinu,' conjectures and roiii^h estimates. Nuthinji' was known also 

 as to the naliire of the pi'odiicl> of reaction wiiich are formed in 

 the dark al temperaliire^ between the ordinar\ and the boilint; |ioinl 

 of toluene ( I 10 ,. 



There was, theiefori-, e\'ery reason to again study this interesting 

 reaction and to liy to soi\e the following cpiestions: 



In liow far is ili,' compo'-ition oi' the reaction-mixtni't' dependent 

 1. iiii the lemperaliire: '1. on the aclimi of light; !!. on the presence 

 of calaly/.i'i's. 



In m_\ laboral<'>ry , lirsl al ( ironingen. aflerwanl^ al .\ mslerdam. 

 Dr. VAN i)i''.u Laan has made a eontrilMiiiou lo ihe resobilion of these 

 (piestions by means of a careful expi'iiini'iiial n'^i-Hicii ; he rommenccMi 



