Problem This Addresses

Any proper chemistry mod will always have more possible compounds than the actual recipes of usable items.

Description

There's a way to encourage the player to develop a proper chemical lab that can be repurposed for all sorts of compounds: add a villager/trader that will "order" random obscure chemicals and reward that well.

By random I mean generated on the fly (some more common chemicals are pre-coded into tables, but the trades pay less). Payment is probably done not in emeralds, but in valuable crafting components of vanilla/Create, important ingredients that are unavailable in survival (as long as the mod is in development, that's probably gonna happen) or just some destroycoins (lame).

Pre-generated compounds pay a little, auto-generated compounds that are available in survival pay better; if the compound explicitly uses a "creative" ingredient it pays even more, as you must have obtained it from the Chemist. A good and timely chemistry job might pay you a full netherite set or so, idk about balance.

Outside of chemical RNG, the trader should probably sell you some useful catalysts at a uninteresting price, just like Wandering Traders sell you random (not even rare!) stuff from other biomes.

Minecraft Username
zaafonin

Something like this (an NPC which requests randomly generated molecules) is already planned. Therefore it must be a good suggestion.