Berichte dcrBunsen-Gu\cll\ch;ifI 352 Buch besprechungenThe ratc of reduction is diffusion controlled for all donors except diphenylamine for which a rate constant of 2.5. 10' M ' s-I was obtained. The overall convcrsinn rate for fast catalytic reactions of gases in porous catalysts is controlled by pore diffusion. Since the molecular transport properties of the gases which take part in the reaction are usually different from one another, one has to calculate the conversion rate hy using the diffurion equations for rnulticomponent mixtures. It is shown, that these equations are not sufficient to determine the converqion rate, if the matcrinl transport within the catalyst is influenced by both g:is-ga\ and gas-wall collisions. In that case a calculation has to makc use of the diffusion equation and the integrated equation of motion. Although these equations are very complicated, a so-called system reduction will lead to simple relationships with which the posed problem can be treated in a relatively straightforward way. IJsing the example of diffusion controlled C 2 H + hydrogenation is i t shown experimentally, that the relationships mentioned are indeed very useful to calculate the conversion rates in narrow-pore catalysts.The The magnetic 'H-relalation rate in aqueous solutions of LiCI, NaCI, RbCI, CsCI, and K I was measured in order to cvaluate the nuclear magnetic proton-ion relaxation contribution using the isotopic dilution technique. Furthermore, the temperature dependence of these relaxation rates was cxamined. It turned out that for Rb', Cs+, and I the proton-ion relaxation rate consists of two parts: an intermolecular spin-rotation contribution and a magnetic dipole-dipole contribution. The first one increases and the second one decreases with increasing temperature.-From the dipole-dipole rate the proton ion distances were computed using suitable ion-proton model pair distribution functions.Kinetic Study of Chemically Activated 1, I-Dichlorocyclopropanes, I1 The reaction of dichlt)rocarhene with ethylenc produces chemically activated 1,l-dichlorocyclopropane which isomerises in a primary reaction to givc 2,3-dichloropropene. Dichlorocarbene is generated by the thermal decomposition of CCI,-SiX, (X = F, CI) at 531 K.
H . R U L L M A N N and H. H E Y D T MThe rate constants ( k , , , ) of isomerisation and decomposition of all chemically activated compounds reported in this work and the preceeding publication wcrc calculated by RRKM-theory and compared with the experimental results. Agreement was obtained if an excess energy Ei for CCl, wa5 introduced. Ei = 9 kJ!rnol for CCI,-SiCI, as CCI, source and E, = 22 kJ!inol for CCI, -SiF, :t'i CCl, wurce. CCI, was thermalized by addition or hclium and nitrogen: the collision efriciencics of these gases were determined.
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