A Stable Sulfonated Catalyst Derived From Amino‐Functionalized MIL‐53‐NH ₂ for Efficient Fructose to 5‐Hydroxymethylfurfural

The development of stable, efficient catalysts for fructose conversion to 5‐hydroxymethylfurfural (5‐HMF) remains a challenge. While sulfonation enhances Brønsted acidity in metal–organic frameworks (MOFs), it often compromises their structural integrity. This work addresses the critical challenge by demonstrating that amino (–NH 2 ) functionalization in MIL‐53(Al) acts as a stabilizer, enabling the framework to withstand direct modification with chlorosulfonic acid and facilitating the introduction of sulfonic acid groups. The resulting sulfonated catalyst, MIL‐53‐N/S(1), achieves an outstanding 5‐HMF yield of 84.3% in a biphasic system (170°C, 6 h). This work underscores the dual role of amino functionalization in stabilizing MOFs and enabling efficient acid catalysis for biomass conversion.