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The Critical Phenomena in the Dynamics _new_


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									                       The Critical Phenomena in the Dynamics
                       of the Homogeneous Catalytic Processes
                             S. N. Gorodsky, L. G. Bruk*, O. N. Temkin

                    Lomonosov State Academy of Fine Chemical Technology.
                86, prospect Vernadskogo, 119571, Moscow, Russian Federation

   By the study of catalytic reaction kinetics in increasing frequency nontrivial dynamic
behaviour of reacting systems is observed - occurrence of intermediates, products and reactions
rates self-oscillations, multiple steady states, hysteresis, chaotic behaviour [1]. Reactions, in
which the critical phenomena are found out in homogeneous isothermal conditions, in general
concern to organic substrates oxidation processes by strong oxidants, catalyzed by metals ions of
variable valency.
   Participants of our team discovered the critical phenomena in typical reactions of the
organometallic catalysis by metals complexes in which no substrates destruction, but synthesis of
complex molecules occurs. So, in acetylene carbalkoxylation reaction in the system PdBr2 – KBr
– HBr – butanol-1 – dimethylsulphoxide, in alkynes oxidative carbonylation reaction in the
system PdI2 - KI – MeOH [2, 3], and in reaction of maleic anhydride synthesis from acetylene
and CO the various nonlinear phenomena was discovered. The analysis of the information about
findings allow us to formulate the features of homogeneous catalytic reactions mechanisms
which can become the reason of nontrivial dynamic behaviour:
   1) Presence of nonlinear stages in the process mechanism (reaction between intermediates,
presence of one or more catalysts); 2) Participation of active particles formation and destruction
stages, i.e. chain mechanisms of the catalytic process; 3) Presence in the mechanism schema the
positive (autocatalysis) and negative (autoinhibition) feedbacks.
   Work is executed at financial support of the Russian Foundation for Basic Research (Projects
№№ 00-03-32037 and 05-03-33151)
   [1] R. J. Field, M. Burger, Oscillations and Travelling Waves in Chemical Systems, Wiley,
       New York, 1985.
   [2] S. N. Gorodskii, A. N. Zakharov. A. V. Kulik, Bruk, O. N. Temkin, Kinetics and
       Catalysis, 2001, 42, 2, 280 – 291.
   [3] S. N. Gorodskii, E. S. Kalenova, L. G. Bruk, O. N. Temkin, Russ. Chem. Bull., 2003, 52,
       7, 1534 - 1543.

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