Mechanistic insight into formaldehyde hydroformylation catalyzed by rhodium complexes: A theoretical and experimental study

•Reaction mechanism of formaldehyde hydroformylation has been established using DFT calculation and experimental study.•The type of solvent determines the conversion pathway of formaldehyde: dissociation mechanism or anionic mechanism.•CH3OH, HCOOCH3 are preferentially produced via the CH3O-Rh route in the dissociation mechanism.•CH3OH, HOCH2CHO are preferentially produced via the HOCH2-Rh route in the anionic mechanism.•The calculations predict the strong electron-donating ligand serves to give rise to higher reactivity in the anion mechanism.