Hydroformylation of vinyl acetate: A route to mixed propanediols

The Rh-catalyzed hydroformylation of vinyl acetate (VAM) was investigated as the selectivity-determining step in a reaction sequence toward 1,3-propanediol. Commercially available Rh precursors and phosphorus ligands were screened, identifying Xantphos and BiPhePhos as the most promising ligand systems. Time-resolved reaction profiles revealed that the attainable yield of 3-acetoxypropanal is determined not only by primary regioselectivity but also by secondary product decomposition accompanied by acetic acid formation. Solvent selection, temperature, and base additives strongly influenced the formation and stability of the linear aldehyde. In the Xantphos-based system, base addition delayed both the decrease in 3-acetoxypropanal and the formation of acetic acid, with N,N -dimethylaniline affording a maximum linear aldehyde yield of 24.4 % and an l/b ratio of 0.55. BiPhePhos afforded a maximum linear aldehyde yield of 18.5 % and an l/b ratio of 0.28, while acetic acid formation remained substantially less pronounced, indicating that the ligand environment also affects aldehyde stability. Finally, the hydroformylation products were converted to the corresponding propanediols by subsequent aldehyde reduction and hydrolysis. These results demonstrate that improved VAM hydroformylation requires simultaneous control of primary regioselectivity and secondary product stability.