Predictability of Chain Reactions

Abstract

The characteristic of a chain reaction is that the sum of the chain (or propagation) steps yields the overall reaction stoichiometry-the chain carriers canceling out in the addition. The closed reaction sequence involving the intermediates in a pyrolytic reaction is shown above (see Equation E). Reactant is consumed and products produced, but the concentration of intermediates which propagate the reaction is controlled only by distinct initiation and termination steps. The number of over-all reactions between the initiation and termination steps is called the chain length.In this article, pyrolytic and metathetical chain reactions are discussed in terms of our recently acquired knowledge of prototypes of their component steps-initiation, transfer, propagation, and termination.Predictability of products and product ratios is shown to be fairly good using Rice-Hertzfeld mechanisms and known data for radical reactions. Some semiquantitative generalizations concerning radical step reactions lead to about order-of-magnitude ability to predict overall chain rates.

Recoil Tritium Reactions with Ethyl Chloride1

“…The measurement of equilibrium constants of the iodine-catalyzed gas phase reactions of olefins and their parent hydrocarbons has been shown to be a very simple, direct, and valuable method to determine precise differences in the thermodynamic properties of the reactants. 23 Applied to the cis-trans isomerization of 1,3-pentadiene, the present paper reports an appreciable amount of side reactions and considerable difficulties in product separation. This result is in contrast to the clean-cut experiments on the isomerization of 2-butene, reported earlier.2…”

“…[20][21][22] However, C2H5C1* -> C2H4 + HCl (4) the kinetics of the pyrolysis of C2H5C1 can be accounted for through a chain mechanism starting with a C-Cl bond break, and reservations have still been expressed about the evidence for reaction 4. 23,24 These additional complexities of reaction provide advantageous opportunities for determining the basic principles underlying recoil tritium reactions and for further study of the analogies between pyrolytic and recoil tritium decomposition mechanisms.…”

Termólisis de Clorooxoacetato de Etilo en Fase Gas: Comparación con Oxoacetato de Etilo y Detalles del Sistema Estático para el Estudio Cinético

“…Efecto del inhibidor. Para impedir que la reacción siguiese un mecanismo por radicales libres en cadena [14][15][16][17][18] en lugar de la vía molecular, se utilizó tolueno como inhibidor de radicales [20][21][22][23][24][25] en diferentes proporciones. En la tabla 3 puede observarse cómo la invariabilidad del coeficiente de velocidad en presencia y ausencia de tolueno es indicio de que esta reacción en estudio no estuvo inhibida, lo que permite sugerir un mecanismo molecular.…”

Reactive symbol sequences for a model of hydrogen combustion

“…An important feature of combustion reactions is the chain length, L, the total number of reactions between initiation of a reactant and termination at products. 46 For all classical trajectories, we extract chemical symbol sequences with varying chain lengths, but only registering chemical species, or symbols, when a tracked atom transitions to another species; we also measure the simulation time at which the transition occurs and the waiting times between transitions. From each trajectory, there are roughly 169 hydrogen and 87 oxygen sequences (one per atom).…”