Solvents of the Hydroformylation Reaction

Suitable solvents, or diluents, in the hydroformylation reaction are aliphatic, cycloaliphatic and aromatic hydrocarbons, aliphatic, cyclic and aromatic ethers, aliphatic alcohols, nitriles, anhydrides, ketones, esters, lactones, lactams, orthoesters and water. 

In many cases the reaction products themselves, or recycled high boiling residues, are used as diluents. In technical operations the reaction is generally run without diluents and solvents are used only for charging the catalyst. 

The solvent influence on the reaction velocity of the hydroformylation was studied in detail [199-201]. The influence varies, depending on the unsaturated starting material. 

While I. Wender et al, [199] in the case of cyclohexene observed differences in the reaction velocity only up to a factor of 1.5 with different solvents, Iwanaga et aL [200] and also Wakamatsu et al. [201] stated a 6 times higher reaction velocity in the conversion of acrylonitrile with methanol as solvent compared to ben2ene. 

In case of acrylates even differences of a factor of 7 were observed with various solvents (see table 6). 

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