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Identify Electrophile Chlorination Benzene
The identification of electrophilic reagents in the chlorination of benzene is an important matter in chemistry. To understand the mechanism of this reaction, the first thing to do is to identify its electrophilic reagents.
Benzene is an aromatic cyclic hydrocarbon. Its π electron cloud is distributed above and below the ring, and its electron-rich properties are significant. The chlorination reaction is a typical electrophilic substitution.
In the chlorination process of benzene, the reagent used is usually chlorine ($Cl_2 $), but chlorine itself is not a direct electrophilic reagent. A catalyst is required, such as the commonly used ferric chloride ($FeCl_3 $). Chlorine gas meets ferric chloride, and the chlorine atom of chlorine gas interacts with the iron atom of ferric chloride. The electron cloud of the chlorine atom is biased towards the iron atom, causing the chlorine atom to have a partial positive charge, and the activated chlorine-chlorine bond is broken.
Among them, the positively charged chlorine atom ($Cl ^ + $) is an electrophilic reagent. Because of its electron deficiency, it is easily attracted by the electron-rich π electron cloud of the benzene ring. The π electron cloud of the benzene ring attacks the electrophilic reagent $Cl ^ + $, forming an unstable intermediate. Then the intermediate loses a proton, restoring the aromaticity of the benzene ring and completing the chlorination reaction.
Therefore, in the chlorination reaction of benzene, the electrophilic reagent is a positively charged chlorine atom ($Cl ^ + $), which is the key to understanding the reaction mechanism.
Benzene is an aromatic cyclic hydrocarbon. Its π electron cloud is distributed above and below the ring, and its electron-rich properties are significant. The chlorination reaction is a typical electrophilic substitution.
In the chlorination process of benzene, the reagent used is usually chlorine ($Cl_2 $), but chlorine itself is not a direct electrophilic reagent. A catalyst is required, such as the commonly used ferric chloride ($FeCl_3 $). Chlorine gas meets ferric chloride, and the chlorine atom of chlorine gas interacts with the iron atom of ferric chloride. The electron cloud of the chlorine atom is biased towards the iron atom, causing the chlorine atom to have a partial positive charge, and the activated chlorine-chlorine bond is broken.
Among them, the positively charged chlorine atom ($Cl ^ + $) is an electrophilic reagent. Because of its electron deficiency, it is easily attracted by the electron-rich π electron cloud of the benzene ring. The π electron cloud of the benzene ring attacks the electrophilic reagent $Cl ^ + $, forming an unstable intermediate. Then the intermediate loses a proton, restoring the aromaticity of the benzene ring and completing the chlorination reaction.
Therefore, in the chlorination reaction of benzene, the electrophilic reagent is a positively charged chlorine atom ($Cl ^ + $), which is the key to understanding the reaction mechanism.
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