種々の酸塩基反応や酸化還元反応の固体触媒として機能するシアノ架橋配位高分子（[MN(H2O)x]y[MC(CN)6]）の活性点は、水分子が脱離することでMN上に生成する配位不飽和サイトである。本研究では、CN配位子の一部を単座配位子（L）に置換した配位高分子（[MN(H2O)x]y[MC(CN)5(L)、L = NH3 or H2O）を合成した。この配位高分子では、Lの脱離によりMC上にも配位不飽和サイトが生じる。本配位高分子を利用し、エステル加水分解反応や芳香族化合物の酸化反応におけるMCの寄与やMNとMCの協働作用を評価した。
Aerobic oxidation of 5-hydroxymethylfurfural (HMF), protected as a six-membered ring acetal with 1,3-propanediol (PDO), was examined using a nitrogen-doped carbon-supported cobalt catalyst in a stepwise approach. Usage of acetal-protected HMF (HMF-acetal) enabled the production of 5-formylfuran-2-carboxylic acid in its acetal form (FFCA-acetal) in 97% yield even in a 20 wt% solution with Ca(OH)2. The protective PDO was recovered in 94% through acid-catalyzed hydrolysis of FFCA-acetal using HCl in the second step. FFCA in 10 wt% could then be oxidized to 2,5-furan dicarboxylic acid in 96% yield under conditions optimized for this step, enabled through the flexibility of the stepwise approach.
The reductive amination of 5-formylfuran-2-carboxylic acid (FFCA) and its dimethylacetal form (FFCA-acetal) was studied with a cobalt phosphide nanorod catalyst to yield 5-aminomethylfuran carboxylic acid (AMFCA) which can be potentially used as a monomer for biobased polyamides. Under optimized conditions, i.e. 0.5 mmol of FFCA-acetal, 5 mmol of NH4OAc, substrate to catalyst ratio of 10 mol/mol, under 5 bar H2 at 393 K for 3 hours in methanol/water 2/1 (v/v), AMFCA was obtained in 91% yield. Kinetic studies suggests that the reaction route via the hemiacetal form of FFCA-acetal is the key for efficient AMFCA formation.
Dehydration of glucose produces HMF, an important key intermediate for biorefinery processes. Crystalline and thermally stable mixed metal oxide YNbO4 showed to possess Lewis acid and base sites able to catalyse HMF; however, a too pronounced basic character has a negative impact in HMF selectivity. In this work we investigate the role of the secondary A3+ metal in controlling the acid-base properties of the material. After a screening of several elements in the lanthanide series, YbNbO4 was found to be the most selective to HMF (60% after phosphorylation). Several parameters of the material synthesis were studied; calcination temperature was found to greatly impact the properties of material.