Consecutive Reactions

chemical processes in which the product of one reaction is the initial material for other reactions. Consecutive reactions include chemical processes such as polymerization and thermal cracking and chlorination of hydrocarbons. In cracking, the consecutive conversion of macro-molecular compounds into compounds of lower and lower molecular weight takes place at the same time as consecutive processes of formation of macromolecular hydrogen-poor compounds, such as coke. The compounds CH₃Cl, CH₂Cl₂, CHCl₃, and CCl₄ are formed consecutively upon chlorination of methane.

An example of a simple consecutive reaction is the consecutive occurrence of two irreversible first-order reactions A → B → C, where A, B, and C are certain substances. The change in concentration of the substances may be calculated by integrating a system of two kinetic equations. The calculation shows that the concentration of intermediate compound B at first increases to a maximum and then decreases.

A more complex description of consecutive reactions is obtained if the reversibility of the individual reactions and the participation of the various initial compounds in the reactions are considered.