Phenol and PCl5 Reactivity
Phenol, being a weakly acidic compound, does not react with PCl5 due to several reasons:

Lack of Strongly Acidic Hydrogen
- Phenol does not have a strongly acidic hydrogen atom that can be easily replaced by chlorine from PCl5.
- The hydrogen in phenol is not as acidic as that in alcohols or carboxylic acids, which are more reactive towards PCl5.

Stability of Phenoxide Ion
- When phenol reacts with a strong base, it forms a stable phenoxide ion due to resonance stabilization.
- This stability makes it difficult for PCl5 to displace the hydroxyl group in phenol and replace it with a chlorine atom.

Reactivity of PCl5
- PCl5 is a strong electrophile that typically reacts with compounds containing strongly acidic hydrogen atoms.
- Since phenol lacks such a hydrogen, the reaction with PCl5 does not occur easily.

Conclusion
In conclusion, the lack of a strongly acidic hydrogen in phenol, the stability of the phenoxide ion, and the reactivity of PCl5 as an electrophile all contribute to the lack of reactivity between phenol and PCl5. This explains why phenol does not readily react with PCl5.