Usually, a free radical is marked by a dot beside the symbol which represents an odd electron exists on the species. This odd electron makes the intermediate very reactive. For example, the oxygen, chlorine and ethyl radicals are represented by and respectively. The radicals can be formed by the homolytic photodissociation reaction: Lecture123: Mechanism of Chain Reactions 1: The elementary steps used for mechanisms of chain reactions can be grouped into the following categories: Initiation step Chain propagation steps branching steps Chain inhibition steps Chain termination steps For example, the chlorination of ethane is a reaction, and its mechanism is explained in the following way. If we mix chlorine, Cl2, and ethane, CH3CH3, together at room temperature, there is no detectable reaction. However, when the mixture is exposed to the reaction suddenly initiates, and explodes. To explain this, the following mechanism is proposed. Initiation Step: Light (hν) can often be used to initiate chain reactions since they can generate free radical intermediates via a photodissociation reaction. as: The initiation step can be written
Usually, a free radical is marked by a dot beside the symbol which represents an odd electron exists on the species. This odd electron makes the intermediate very reactive. For example, the oxygen, chlorine and ethyl radicals are represented by and respectively. The radicals can be formed by the homolytic photodissociation reaction: Lecture123: Mechanism of Chain Reactions 1: The elementary steps used for mechanisms of chain reactions can be grouped into the following categories: Initiation step Chain propagation steps branching steps Chain inhibition steps Chain termination steps For example, the chlorination of ethane is a reaction, and its mechanism is explained in the following way. If we mix chlorine, Cl2, and ethane, CH3CH3, together at room temperature, there is no detectable reaction. However, when the mixture is exposed to the reaction suddenly initiates, and explodes. To explain this, the following mechanism is proposed. Initiation Step: Light (hν) can often be used to initiate chain reactions since they can generate free radical intermediates via a photodissociation reaction. The initiation step can be written as:
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