Chemoselective hydrogenation of α, β-unsaturated aldehyde over Rh nanoclusters confined in metal-organic framework
Selective hydrogenation of α, β-unsaturated aldehyde to achieve high selectivity towards a desirable product is still a great challenge, mainly because of the complex conjugate system. Herein, Rh nanoclusters encapsulated in MIL-101 (Cr), synthesized by double solvents method, are able to selectively hydrogenate C=C of α, β-unsaturated aldehyde cinnamaldehyde and achieve over 98% selectivity with conversion of 98% to saturated aldehyde in mild condition. The Fourier transform infrared spectroscopy confirms that MIL-101 acts as aldehyde protector to suppress the reactivity of C=O, and the X-ray photoelectron spectroscopy (XPS) data indicates that the electropositive Rh, owing to the electron transfer from Rh to MIL-101, preferentially absorbs C=C rather than C=O leading to improvement of the selectivity of saturated aldehyde. In addition, Rh@MIL-101 can also efficiently hydrodefluorinate of aryl fluoride with good stability. This work gives out a basic strategy to develop other selective heterogeneous catalysts via structure modulation for synergetic catalysis.