NitreRat - 3-6-2016 at 19:55
While most aliphatic alcohols can easily be converted to the corosponding alkyl halide with a the apropriate halogenating agent such as
PBr3 then easily substituted with other nucleophiles, it seems phenol cannot. I'm not really sure why this is. I think it's because the
stability of the phenoxide ion and the instability of a phenyl cation make phenol much more difficult to protonate compared to other alcohols and
carboxylic acids. Can anyone confirm whether this is the case?
If phenol cannot be halogenated by conventional reagents, is the same true when more extreme leaving groups are attached such as a mesylate, tosylate
or triflate group?
DraconicAcid - 3-6-2016 at 22:06
Phenyl halides simply don't undergo nucleophilic substitution unless they have strongly electron-withdrawing groups on them. Same with phenyl esters
of halophosphonic acids (the expected intermediate in the reaction with phosphorus trihalides).