Oxidation of 5-Chloromethylfurfural (CMF) to 2,5-Diformylfuran (DFF).

2,5-Diformylfuran (DFF) is an important biorenewable building block, namely for the manufacture of new polymers that may replace existing materials derived from limited fossil fuel resources. The current reported methods for the preparation of DFF are mainly derived from the oxidation of 5-hydroxymethylfurfural (HMF) and, to a lesser extent, directly from fructose. 5-Chloromethylfurfural (CMF) has been considered an alternative to HMF as an intermediate building block due to its advantages regarding stability, polarity, and availability from glucose and cellulose. The only reported method for the transformation of CMF to DFF is restricted to the use of DMSO as the solvent and oxidant. We envisioned that the transformation could be performed using more attractive conditions. To that end, we explored the oxidation of CMF to DFF by screening several oxidants such as H2O2, oxone, and pyridine N-oxide (PNO); different heating methods, namely thermal and microwave irradiation (MWI); and also flow conditions. The combination of PNO (4 equiv.) and Cu(OTf)2 (0.5 equiv.) in acetonitrile was identified as the best system, which lead to the formation of DFF in 54% yield under MWI for 5 min at 160 °C. Consequently, a range of different heterogeneous copper catalysts were tested, which allowed for catalyst reuse. Similar results were also observed under flow conditions using copper immobilized on silica under thermal heating at 160 °C for a residence time of 2.7 min. Finally, HMF and 5,5'-oxybis(5-methylene-2-furaldehyde) (OBMF) were the only byproducts identified under the reaction conditions studied.

Carboxylic modified spherical mesoporous silicas аs drug delivery carriers.

The present study deals with the development and functionalization of mesoporous silica nanoparticles as drug delivery platforms. Spherical MCM-41 and SBA-15 silicas with different pore sizes (2.7 nm and 5.5 nm, respectively) were post-synthesis modified applying a new, two step process. The initial step was the modification with 3-amino-propyltriethoxysilane, and the next was the reaction with succinic anhydride in toluene in order to obtain carboxylic modified mesoporous carriers. The carboxylic-functionalized mesoporous materials were characterized by XRD, nitrogen physisorption, TEM, ATR FT-IR spectroscopy. The successful carboxylic functionalization was proved by the changes of the zeta potential of the mesoporous materials before and after modification. The parent and the carboxylic-modified MCM-41 and SBA-15 materials showed high adsorption capacity (approximately 50 wt.%, except for non-functionalized MCM-41) for sulfadiazine that possesses amino functional groups. Mesoporous structure peculiarities lead to different adsorption capacities on the carriers. In vitro release studies showed slower release rate of sulfadiazine from carboxylic modified MCM-41 and SBA-15 mesoporous particles compared to the non modified ones. Both non loaded and drug-loaded silica materials demonstrated no cytotoxicity on Caco-2 cell line. The functionalized mesoporous systems are appropriate drug delivery platforms due to their biocompatibility and the possibility to modify drug release.