Statement 1 Phenol reacts with \(\mathrm{PCl}_{5}\) to give only a small amount of chlorobenzene, the main product is triphenyl phosphate \(\left(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{O}\right)_{3} \mathrm{P}=\mathrm{O}\) or \(\left(\mathrm{C}_{6} \mathrm{H}_{5}\right)_{3} \mathrm{PO}_{4}\) and Statement 2 \(\mathrm{C}-\mathrm{O}\) bond in phenol has partial double bond character.

Understanding the structure and resonance of phenol is crucial when studying its chemical behavior, especially its interactions with other substances like phosphorus pentachloride (PCl₅). Phenol consists of a benzene ring with a hydroxyl (OH) group—exhibiting a unique relationship between the oxygen and the aromatic ring. Due to the aromatic nature of the benzene ring, the electrons are delocalized over the entire system, which introduces resonance. This causes the phenolic C-O bond to exhibit partial double bond characteristics, making it stronger and less reactive than a typical single bond. The implications of this are seen in chemical reactions where the participation of the C-O bond is required.

• Increased bond strength due to resonance
• Decreased likelihood of the OH bond being replaced in reactions

These properties are fundamental to understanding why phenol reacts with PCl₅ in a particular way, and why certain products are more favored than others. Resonance in aromatic systems often plays a significant role in dictating reaction pathways and outcomes.

Triphenyl phosphate synthesis involves the reaction of phenol with phosphorus pentachloride (PCl₅). This chemical reaction is an example of how functional groups can significantly alter the behavior of a compound during chemical reactions. Triphenyl phosphate, (C₆H₅O)₃P=O, is the product of this reaction, containing three phenyl groups attached to a phosphorus atom with a double bonded oxygen. The synthesis begins with the nucleophilic attack of phenol's oxygen onto the phosphorus atom, followed by stepwise replacement of chloride ions from the PCl₅, resulting in the distinctive triphenyl structure.

Reaction Mechanism Stages

• Initial nucleophilic attack of phenol on PCl₅
• Subsequent displacement of three chloride ions
• Formation of the triphenyl phosphate compound

The outcome of this synthesis underscores the complexity of organic reactions, where multiple products can form, but the stability of intermediates and the reactivity of functional groups help determine the major product.

The difficulty in forming chlorobenzene from phenol's reaction with PCl₅ is inherent in the nature of the C-O bond within phenol. Typically, chlorobenzene would form through a reaction where the OH group is replaced by a chlorine atom. However, due to the resonance stabilization of the phenolic C-O bond, the energy required to break this bond is significantly higher. This makes the substitution process energetically unfavorable and less likely to occur as a primary route. Consequently, triphenyl phosphate forms as the major product rather than chlorobenzene.

• Resonance stabilization increases the bond dissociation energy
• Higher activation energy required for substitution

The formation of chlorobenzene can still occur, but it is a minor product because of the greater stability provided by resonance in the molecular structure of phenol. Highlighting the difficulty in forming chlorobenzene showcases the importance of considering resonance effects and bond strengths when predicting the outcomes of organic reactions.