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Developing efficient catalytic processes for obtaining biobased monomers for plastics can significantly contribute to a more sustainable economy. The biomass‐derived and chemical platform 5‐hydroxymethylfurfural (HMF) can be converted to various key intermediates, which is often hampered by side reactions due to the reactive nature of the formyl group in HMF. Here, we present a stepwise approach involving a protecting agent to obtain dimethyl furan‐2,5‐dicarboxylate (MFDC), which is a monomer for polyalkylene furanoates, a new class of biobased polyesters. Methanol is used as a solvent, reactant, and protecting agent for HMF's formyl group. In the first step, the oxidative esterification of the hydroxymethyl group to methyl carboxylate in HMF‐dimethylacetal catalyzed by Au/CeO2 affords methyl 5‐formylfuran‐2‐carboxylate dimethylacetal (MFFC‐acetal) in high yields (>90 %) from concentrated methanolic solutions (~20 wt %). Without protecting agent, a mixture of methyl‐5‐hydroxymethylfuran‐2‐carboxylate (MHMFC), MFDC, and humin byproduct was obtained. The deprotection of MFFC‐acetal in the second step proceeded efficiently in acetone with Amberlyst‐15, affording MFFC in a >90 % yield. In the final step, oxidative esterification of MFFC in methanol (10 wt %) afforded MFDC in a 93 % yield using Au/CeO2. The acetal protection strategy with methanol offers an efficient route toward MFDC in two oxidative esterification steps. [ABSTRACT FROM AUTHOR]

Hierarchical zeolites can offer substantial benefits over bulk zeolites in catalysis. A drawback towards practical implementation is their lengthy synthesis, often requiring complex organic templates. This work describes an accelerated synthesis of nanolayered MWW zeolite based on the combination of interzeolite transformation (IZT) with a dual‐templating strategy. FAU zeolite, hexamethyleneimine (HMI), and cetyltrimethylammonium bromide (CTAB) were respectively employed as Al source and primary zeolite, structure directing agent, and exfoliating agent. This approach allowed to reduce the synthesis of nanolayered MWW to 48 h, which is a considerable advance over the state of the art. Tracking structural, textural, morphological, and chemical properties during crystallization showed that 4‐membered‐ring (4MR) units derived from the FAU precursor are involved in the faster formation of MWW in comparison to a synthesis procedure from amorphous precursor. CTAB restricts the growth of the zeolite in the c‐direction, resulting in nanolayered MWW. Moreover, we show that this approach can speed up the synthesis of nanolayered FER. The merits of nanolayered MWW zeolites are demonstrated in terms of improved catalytic performance in the Diels‐Alder cycloaddition of 2,5‐dimethylfuran and ethylene to p‐xylene compared to bulk reference MWW sample. [ABSTRACT FROM AUTHOR]

The role of Lewis and Brønsted acid sites in the Diels‐Alder cycloaddition (DAC) of ethylene to 2,5‐dimethylfuran (2,5‐DMF) to p‐xylene was investigated. Amorphous silica catalysts containing Al3+ (ASA), Ga3+ (ASG), and In3+ (ASI) were prepared via homogeneous deposition‐precipitation. Silica modified with Zr4+ (ASZ) was prepared by impregnation. Their acidic properties were characterized by various IR and NMR spectroscopic techniques. Measurements using pyridine as a probe molecule highlighted the presence of mostly Lewis acid sites (LAS) in all materials. Using CO as a probe, in contrast, demonstrated the existence of Brønsted acid sites (BAS) in ASA and ASG, which were nearly absent in ASI and ASZ. Differences in basic strength can explain the contrast in results observed between the two probe molecules. The highest p‐xylene yield (~20 %) in the DAC reaction, could be achieved with ASA and ASG. The lack of BAS in ASI and ASZ resulted in inferior performance in the DAC, with p‐xylene yields below 5 %. These results indicate the importance of BAS for the DAC reaction. Several other heterogeneous and homogeneous catalysts were explored for the DAC reaction to show the generality of our conclusion that BAS play a critical role in obtaining p‐xylene from 2,5‐DMF and ethylene. [ABSTRACT FROM AUTHOR]