the boiling point of diphenyl ether is 259 degrees C. It dissolves many nonpolar compounds but it is a poor solvent for crystallization.Why?
Diphenyl ether (C12H10O) has a boiling point of 259 degrees Celsius and exhibits some unique properties as a solvent. While it is soluble in many nonpolar compounds, it is considered a poor solvent for crystallization.
The reason behind its poor solvent properties for crystallization lies in its molecular structure and intermolecular interactions. In order to understand this, we can look at the concept of solubility and the factors that influence it.
Solubility refers to the ability of a solute (the substance being dissolved) to dissolve in a solvent (the dissolving medium) to form a homogeneous mixture. For crystallization to occur, the solute molecules need to come together and form an organized, repeating crystal lattice structure.
In diphenyl ether, its molecular structure consists of carbon (C) and hydrogen (H) atoms, with an oxygen (O) atom bridging the two benzene rings. This structure gives the molecule a nonpolar nature. Nonpolar molecules lack a significant difference in electronegativity between their atoms, resulting in weaker intermolecular forces.
In order to dissolve a solute for crystallization, the solvent-solute interaction should be stronger than the solute-solute interaction. Crystals form when the solvent-solute interactions are stronger than the solute-solute interactions, allowing the solute molecules to separate from each other and interact with the solvent molecules.
However, diphenyl ether's nonpolar nature limits its ability to form strong solvent-solute interactions with many polar or ionic solutes. Most crystalline compounds, especially those with polar or ionic characteristics, require a polar solvent for effective solubility and crystallization.
Polar solvents have molecules that possess an uneven distribution of electrical charge, leading to stronger intermolecular forces such as dipole-dipole interactions or hydrogen bonding. These strong intermolecular forces facilitate the dissolution of polar solutes and allow for efficient crystallization.
In contrast, diphenyl ether's nonpolar nature and weak intermolecular forces make it less effective in dissolving polar or ionic compounds. The relatively weak interaction between diphenyl ether molecules and solute molecules results in a poor solvent-solute interaction, making it less suitable for crystallization.
In summary, diphenyl ether's poor solvent properties for crystallization stem from its nonpolar character and weak intermolecular forces. Its ability to dissolve nonpolar compounds is due to the compatibility between their nonpolar structures. However, when it comes to crystallization, most crystalline compounds require a polar solvent with stronger intermolecular forces to effectively dissolve and facilitate the formation of organized crystal structures.