Author
Home > Science > What is the Difference Between Addition and Substitution Reaction?

Guilherme Mazui

•3 minutes to read

What is the Difference Between Addition and Substitution Reaction?

🆚 Go to Comparative Table 🆚

The main difference between addition and substitution reactions lies in the process that occurs during the reaction:

  • Addition Reactions: These are chemical reactions in which a large molecule forms from two or more small molecules. In this process, the number of σ-bonds in the substrate molecule increases, usually at the expense of one or more π-bonds. Addition reactions are typically shown by unsaturated hydrocarbons, which contain double or triple bonds, and are used to convert unsaturated compounds into saturated compounds. An example of an addition reaction is the hydration reaction, where ethene reacts with water to form ethanol: $$C{H2} = C{H2} + {H2}O \to C{H3}C{H_2}OH$$.
  • Substitution Reactions: These are chemical reactions in which moieties of molecules replace the moieties of another molecule, resulting in different compounds. In this process, the replacement of an atom or group (Y) by another atom or group (Z) occurs. Substitution reactions are further divided into electrophilic substitution reactions and nucleophilic substitution reactions. Another category is radical substitution reactions. Aside from these groups, the number of bonds does not change during the reaction.

In summary, addition reactions involve the combination of small molecules to form a larger molecule, while substitution reactions involve the replacement of an atom or group within a molecule by another atom or group.

On this page
  • What is the Difference Between Addition and Substitution Reaction?
  • Comparative Table: Addition vs Substitution Reaction

    • Comparative Table: Addition vs Substitution Reaction

    Here is a table comparing addition and substitution reactions:

    Addition Reaction Substitution Reaction
    Occurs when two or more reactants combine to form a single product Occurs when an exchange of elements in the reactants takes place, resulting in a final product with different components
    General equation: $$\text{A} + \text{B} \to \text{C}$$ (no A or B remaining as a residue) General equation: $$\text{AB} + \text{CD} \to \text{AD} + \text{BC}$$
    Increases the number of σ-bonds in the substrate molecule, usually at the expense of one or more π-bonds Characterized by the replacement of an atom or group (Y) by another atom or group (Z), with no change in the number of bonds
    Examples include formation of haloalkanes: $$\text{CH}{4} + \text{Cl}{2} \to \text{CH}_{3}\text{Cl} + \text{HCl}$$ Examples include formation of alcohols: $$\text{CH}{4} + \text{OH}{2} \to \text{CH}{3}\text{OH} + \text{H}{2}\text{O}$$

    Addition reactions involve the combination of two or more reactants to form a single product, while substitution reactions involve the replacement of one atom or group with another in the reactants.

    Read more:

    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.