Is there a way to convert aniline to phenol without diazotizing it?
Benzenediazonium salt is so versatile that it can be used to make many compounds. That's why, diazotization reaction is so popular and useful. The reaction conditions is not that harsh and is easily achievable. Coming to the reaction, diazotization is a straight one-way procedure to achieve aniline to phenol conversion. If you talk about other ways of converting aniline to phenol, the reaction conditions for such ways are generally harsh and hence not done practically to obtain phenol. In addition, there are so many steps, that the conversion is practically not feasible.
One of the ways of converting aniline to phenol without diazotizing is to convert aniline to acetanilide and then hydrogenolyze it to make benzene which can be then used to make phenol.

Step 1



Step 2


The reaction is taken from a paper1. The paper discussed the use of $\ce{NiMo}$ based catalyst along with novel neo-microporous composite material HSM/ZSM-5 as support. The reaction result is compared with other supports like $\ce{\gamma-Al2O3}$ and lone ZSM-5 and HSM system.

Step 3


Reference

Sajedeh Jafarian, Ahmad Tavasoli, Hasan Nikkhah, &quot;Catalytic hydrotreating of pyro-oil derived from green microalgae spirulina the (Arthrospira) plantensis over $\ce{NiMo}$ catalysts impregnated over a novel hybrid support,&quot; International Journal of Hydrogen Energy 2019, 44(36), 19855-19867 (https://doi.org/10.1016/j.ijhydene.2019.05.182) 44. 10.1016/j.ijhydene.2019.05.182(PDF).