Chemicals is a drink (although you shouldn’t really consume it) and can be used as crafting material for other uncommon items. You won’t be able to craft it, as there’s no recipe to create chemicals. You’ll need to traverse the map to locate chemicals. Garages and gas stations usually contain a few doses. You can also find blowtorches in similar locations. In the Yukon or Washington map, look for Scorpion-7 facilities.