Here are the essential concepts you must grasp in order to answer the question correctly.
Solubility and Reaction Dynamics
The solubility of reactants in a solvent significantly influences the reaction dynamics. In this case, potassium iodide is soluble in acetone, allowing it to dissociate into potassium and iodide ions, which can readily participate in the nucleophilic substitution reaction. Conversely, potassium chloride is not soluble in acetone, which limits its presence in the reaction mixture and thus favors the formation of alkyl iodide.
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Nucleophilic Substitution Reactions
Nucleophilic substitution reactions involve the replacement of a leaving group (like chloride) by a nucleophile (like iodide). The efficiency of this reaction can be enhanced by using a solvent that stabilizes the nucleophile and the transition state. In acetone, the iodide ion is better able to attack the alkyl chloride, leading to a higher yield of alkyl iodide.
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Polar Aprotic Solvents
Acetone is classified as a polar aprotic solvent, which means it has a significant dipole moment but does not have hydrogen atoms bonded to electronegative atoms that can participate in hydrogen bonding. This property allows polar aprotic solvents to solvate cations effectively while leaving anions like iodide free to act as nucleophiles. This enhances the nucleophilicity of iodide, promoting the formation of alkyl iodide in the reaction.
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