We published a new preprint on the physics of active chemical reactions in phase separating fluids on arXiv. The main focus of this review is the thermodynamically consistent description of multicomponent fluids that can both phase separate and also undergo (driven) chemical reactions. In particular, we show how tightly connected these two physical processes are, essentially because they are both driven by chemical potential differences. Consequently, chemical reactions reduced the complexity of phase space in passive systems, but they can also lead to novel dynamics if they are kept away from equilibrium in active systems. We reveal how such reactions can control droplet size and location. The review provides an extensible framework for studying multi-component fluids and we discuss a range of possible extensions that will become relevant in the future.