Ultrafine Copper Oxide Particles Dispersed on Nitrogen-Doped Hollow Carbon Nanospheres for Oxidative Esterification of Biomass-Derived 5-Hydroxymethylfurfural.

One-pot synthesis of furan-2,5-dimethylcarboxylate (FDMC) from 5-hydroxymethylfurfural (HMF) is highly demanding for the commercial production of polyethylene furanoate (PEF). Herein, a direct synthesis of FDMC is reported from oxidative esterification of HMF using ultrafine CuO particles dispersed on nitrogen-doped hollow carbon nanospheres (CuO/N-C-HNSs) as a catalyst and tert-butyl hydroperoxide (TBHP) as an oxidizing and methylating reagent. The CuO/N-C-HNSs was prepared through a template protection-sacrifice strategy using SiO2 as a sacrificial template and histidine as the precursor for N and C. N-doping facilitated a strong interaction between the support and copper species, affording formation of CuO nanoparticles of less than 10 nm in size. By virtue of the highly dispersed CuO nanoparticles and a high BET surface area 373 m2 /g, the CuO/N-C-HNSsshows excellent catalytic performance in the selective conversion of HMF into FDMC affording 93 % yield of the desired product with a TON value of 49. Furthermore, the oxidative esterification involving SP3 C-H bond functionalization is also demonstrated using the same catalyst.