Why are the methods mentioned earlier not applicable for the preparation of aryl halides, and what is the challenge associated with breaking the carbon-oxygen bond in phenols?

The methods mentioned earlier, such as nucleophilic substitution or elimination reactions, are not typically applicable for the preparation of aryl halides. Aryl halides are commonly prepared from aromatic compounds, and the aromaticity of the benzene ring makes it less reactive towards substitution or elimination reactions.
Breaking the carbon-oxygen bond in phenols poses a challenge due to the stability of the aromatic ring. Phenols have a resonance-stabilized phenoxide ion intermediate during nucleophilic substitution, making it energetically unfavorable to break the carbon-oxygen bond. The aromaticity of the benzene ring in phenols hinders straightforward reactions, requiring specific conditions or reagents to overcome this stability and introduce a halogen to the phenolic ring.