Solvent effect on mechanistic pathways in Rh-catalyzed hydroformylation of formaldehyde

•Correlation of solvent descriptors with the hydroformylation activity established.•The net electron-giving ability of solvent is essential to the selectivity of glycolaldehyde.•Polar aprotic solvents influence the dissociation of Rh-H to form the anionic Rh species.•Generating MeOH is relatively easier in non-polar solvents.•HCHO activation requires a cooperation of anionic Rh species and protonated solvent molecule.