Ecliancje IiCtkroyhe enti-e le CH,Br et le BrS0 (18 inn) issu de Transition IsomCrique R. COEKELBERGS, P. A. GOSSELAIN (*) et M. J. VAN DER VENNE (*) (Bruxelles)
SLIM-MARYExperiments conducted in Pyrex bulbs and with aluminium and gold coatings have shown that BrSo (18 mn) generated from gaseous CH,BrHo (4,s h) by isomeric transition, undergoes an heterogeneous exchange reaction with methyl bromide, the importance of which depends on temperature and nature of the wall, and resulting in the appearance of gaseous CH3BrBo (18 mn).A reaction scheme, involving a chemisorbed Br90 (18 mn) and a physically adsorbed CH3Br gives a rate ZI = y-'n," where n," is the BrSo (18 mn) adsorbed a t the wall, which agrees with the experimental facts between 22% and 1llOC. In that case, the heat of adsorption of CH3Br on Pyrex would be 5 Kcal, and the activation energy of the exchange process 16 Kcal. (1) D. DE VAULT et W. LIBBY, J. Am. Chem. SOC. 63, 3216 (1941). (2) R . COEKELBERGS, J.-L. DENAEYER et G. DOME, Cornpte-rendus _____ Nuclkaires. du X X V I I e Congrhs de Chimie Industrielle, I1 263. 1 . Preparation du CH,Brqo (4,5 h) 1 ,~ prinr-ipe dc caettc pr6p:~r:ttioii :t ktk cupo\c ailleurs ("). 0 1 1 it caeprrrclaiit souriiis iirie plils grsndc quaiitit6 de V6H6Hr (10 litres pcnd:rnt 15 lieure\) h I'actioii tl'une source tie neutrons tic 2 gr Ha-Br (*). I,cs ions nrforriidi par effet Sxilarcl-C'lialrner\ orit ktk extraits eoiiinie ~>rkcddenimcnt p o w prCparer, avec~ ('I130H, lc C€13Br radioactif. On retrouvait , soti\ foriiie cte ('H313r radioactif, erivirori 70 O,) de la radioactivitd totale clri Cb1l5T3r. ( I ) J . STRONG, Procedures in EJiperimenfnl Pliysii*s, pp. 168-177 Prentice-Hall New-York 1951.Li celles de Q*.Les resultats sont donnes dans le tableau 111.ECOLE ROYALE MILITA t i w , La borafoire tle Chimie Niccle'ciire.Comrrmuique i* la SociBe' Chimique de Belgique le 2 octobre 1955.
