I believe that from previous crafting reveals alchemy was split between potions and poisons. To me that feels like a pretty shallow difference with potions being clearly superior as only possibly melee characters could benefit from poisons but everyone likes potions.
I would split Alchemist into Transmuter and Creator. The transmuter focuses on changing one type of material into another. They primarily change raw materials into a specialized version of the raw material needed for customized crafting of items. The Creator on the other hand creates reagents and unique materials that are required for many other classes combines.
I come up with Hermetics as a specilization. This means the specialist can imbue items with a kind of magic that is within the physical world (natural elements, mitigation, disease or mitigation against it).
To me this falls in line with the posion and potion making of the alchemist.
NOT to be confused with a scribe that can imbue/augment items with a kind of magic that is beyond the physical world. As they lean more towards spells and incantations.
@Trasak I see transmuter as a general trade for all tradesmen, at least the way you explain it here.
The Creator sounds very much like an expert alchemist. So yeah I like that one very much. Again this specialization could be linked to the perception skill.