Selective transformation of furfural to cyclopentanone

An entirely new route for highly selective preparation of cyclopentanone from furfural is described. It has been found that furfural dissolved in water is converted to cyclopentanone with very high selectivity at temperatures above 140 °C and hydrogen pressures > 30 bar. The selectivity of this reaction is strongly influenced by the heterogeneous catalyst and depends on the reaction conditions. Prolongation of the reaction time leads to the hydrogenation of cyclopentanone to cyclopentanol. If instead of water other solvents are used, the main products of reaction are well known hydrogenated derivatives of furfural, i.e. furfuryl alcohol, tetrahydrofurfuryl alcohol, 2-methylfuran and 2-methyltetrahydrofuran. In the presence of 5% Pt/C catalyst, 76.50 mol% yield of cyclopentanone (81.32 mol% comprehensive yield of cyclopentanone and cyclopentanol) is obtained after 30 min of reaction at 160 °C and a hydrogen pressure of 80 bar.

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► Only in water furfural is selectively converted to cyclopentanone.
► The selectivity depends on heterogeneous catalyst and reaction conditions.
► In other solvents products arise from hydrogenation of the C=O group and furan ring.
► Mass-transfer effects are not the reason for the furan ring rearrangement.