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Guilherme Mazui

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What is the Difference Between Concerted and Stepwise Reactions?

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The key difference between concerted and stepwise reactions lies in the number of steps involved in the reaction mechanism.

  • Concerted reactions are single-step reactions, where all bond-breaking and bond-forming reactions occur simultaneously to form the products. These reactions do not involve any intermediate steps or substrates. An example of a concerted reaction is the cycloaddition reaction.
  • Stepwise reactions, on the other hand, are multistep reactions, where the mechanism includes two or more steps. In these reactions, the slowest elementary reaction is the rate-determining step. Stepwise reactions may involve intermediates, which are transient substances formed during the course of the reaction.

In summary, concerted reactions involve a single step, while stepwise reactions involve multiple steps in their reaction mechanisms.

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  • What is the Difference Between Concerted and Stepwise Reactions?
  • Comparative Table: Concerted vs Stepwise Reactions

    • Comparative Table: Concerted vs Stepwise Reactions

    The main difference between concerted and stepwise reactions lies in the number of steps involved in the chemical process. Here is a comparison table highlighting the key differences between the two types of reactions:

    Feature Concerted Reactions Stepwise Reactions
    Number of Steps Single-step reactions Multiple-step reactions
    Bond Breaking and Forming Occur simultaneously Occur in sequence, with specific bonds breaking and forming in each step
    Reactive Intermediates None or minimal One or more highly reactive intermediates
    Solvent Polarity Dependence Generally do not depend on solvent polarity May depend on solvent polarity
    Reaction Rate Often faster, as the reaction occurs in a single step Generally slower, due to the cumulative effect of multiple individual steps, each with its own energy barrier
    Examples Pericyclic reactions, SN2 reactions, and some rearrangement reactions like Claisen rearrangement SN1 reaction (Substitution Nucleophilic Unimolecular) and some rearrangement reactions

    Concerted reactions occur in a single coordinated step, where all the necessary bond-breaking and bond-forming processes happen simultaneously, without forming distinct intermediates. On the other hand, stepwise reactions involve a sequence of individual, distinct intermediate steps, where molecules undergo changes in a step-by-step manner.

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    Guilherme Mazui

    Guilherme Mazui is graduated in journalism from the Federal University of Minas Gerais (UFMG) and a master's degree in Communication from the University of São Paulo (USP). In addition, he has experience in advertising writing and has worked as a content editor in several companies.