4-chlorophenol is insoluble in water. Explain why 4-chlorophenol dissolves in 2.5M aqueous NaOH solution.
-Besides NaOH being a strong base and a great nucleophile is there any other reason ?
Phenols are acidic (the H of the OH attached to the ring) is labile so its the same as a neutralization reaction in inorganic chemistry.
acid + base = salt + water.
4-chlorophenol + NaOH ==>(4-chlorophenolate, Na salt) + H2O.
Yes, besides the strong basic nature of NaOH, there is another reason why 4-chlorophenol dissolves in a 2.5M aqueous NaOH solution.
The solubility of a compound in a particular solvent depends on the intermolecular forces between the compound's particles (molecules or ions) and the solvent. In the case of 4-chlorophenol, it is insoluble in water due to the presence of strong intermolecular hydrogen bonding within its molecules. The polar hydroxyl (-OH) group in 4-chlorophenol forms hydrogen bonds with other 4-chlorophenol molecules, leading to a tightly packed arrangement and making it difficult for water molecules to insert themselves into this structure.
However, when 4-chlorophenol is added to a 2.5M aqueous NaOH solution, a chemical reaction occurs. The hydroxide ions (OH-) from the NaOH solution react with the 4-chlorophenol molecules, forming sodium phenoxide (C6H5ONa) and water. This reaction breaks the intermolecular hydrogen bonding in 4-chlorophenol, disrupting its structure and allowing water molecules to solvate the resulting sodium phenoxide ions. Sodium phenoxide is highly soluble in water since it is an ionic compound that can readily interact with the polar water molecules through ion-dipole interactions.
Therefore, the combination of the strong basic nature of NaOH and the chemical reaction it undergoes with 4-chlorophenol plays a crucial role in the dissolution of 4-chlorophenol in a 2.5M aqueous NaOH solution.