Effective Activation of Strong C−Cl Bonds for Highly Selective Photosynthesis of Bibenzyl via Homo‐Coupling

Abstract

Carbon‐carbon coupling of organic halides as an important process in organic synthesis has been successfully achieved in homogeneous catalysis, while the dependence on rare noble metals, complicated metal‐complex and poor catalyst stability and recyclability, need to be tackled. The past few years have witnessed heterogeneous photocatalysis as green and novel methods for organic synthesis processes. However, the study on C–C coupling of chloride substrates is very limited due to the extremely high bond energy of C–Cl bond (327 kJ mol‐1). Here, we report a robust heterogeneous photocatalyst (Cu/ZnO) to drive the homo‐coupling of benzyl chloride with high efficiency, which achieves an unprecedented high selectivity of bibenzyl (93%) and yield rate of 92% at room temperature. Moreover, this photocatalytic process can be applied to 10 benzyl chlorides with high yields. With detailed characterisation (XPS, EPR, TPD) and DFT calculation, the high selectivity is attributed to the enhanced adsorption of reactants, stabilisation of intermediates (benzyl radicals) for the selective coupling by the Cu loading and the moderate oxidation ability of ZnO support, besides the promoted charge separation and transfer by Cu species. Therefore, this work offers a new route to highly selective synthesise bibenzyl from chloride substrates by a stable heterogeneous system.

Bioinspired Photoactive Cu–Halide Coordination Polymers for Reduction Activation and Oxygen Conversion

“…The X-ray photoelectron spectroscopy (XPS) analysis of Cu-bbmz-1/Cu-bbmz-2 with NHP ester 1a upon irradiation gave overlapped peaks of Cu­(II) and Cu­(I) species with the binding energies of Cu 2 p 3/2 and Cu 2 p 1/2 at 932 and 952 eV, respectively (Figures S32–S35). , These results demonstrated the effective photoinduced electron transfer from the excited Cu catalysts to the NHP ester and the potential conversion of Cu­(I) to Cu­(II) states.…”

Variable-valence element doping mediated photogenerated electron trapping for selective oxidation reactions

“…The peak observed at around 933.7 eV can be attributed to Cu 2+ , and the peak observed at around 932.2 eV is assigned to Cu 0 /Cu + . 32 It is interesting that the concentration of Cu 0 /Cu + in Cu–Bi 2 WO 6 increased from 73.3% to 83.7% after light irradiation, which could be understood as the photogenerated electron accumulation on the Cu 2+ species, beneficial for the hole generation. Besides, the Bi 4f and W 4f in situ XPS spectra of Cu–Bi 2 WO 6 exhibit tailing in the low binding energy direction under light irradiation (Fig.…”

Coupling Cu Coordination Polymers with CdS Forming an S-Scheme Heterojunction for Rapid Charge Separation and High Photocatalytic Activity

“…8 At the same time, it provides an environmentally friendly and sustainable method for the organic synthesis of the chemical industry. 9 A substantial number of semiconductor photocatalysts have been produced, including metal oxides (ZnO, SnO 2 , TiO 2 , etc. ), 10−12 transition metal sulfides (TMSs: CdS, MoS 2 , etc.…”

“…This technology directly utilizes sunlight to drive the reaction, and the catalysts have shown excellent stability . At the same time, it provides an environmentally friendly and sustainable method for the organic synthesis of the chemical industry . A substantial number of semiconductor photocatalysts have been produced, including metal oxides (ZnO, SnO 2 , TiO 2 , etc.…”