Amberlyst 35 resin is widely used as a solid acid catalyst in various industrial and laboratory processes. Its primary application is in esterification reactions, where it promotes the formation of esters from carboxylic acids and alcohols, commonly used in the production of plasticizers, flavors, and fragrances. It is also effective in transesterification, enabling biodiesel synthesis by converting triglycerides into fatty acid methyl esters. The resin is employed in etherification processes, such as the production of methyl tert-butyl ether (MTBE) and other fuel additives, due to its high acid strength and thermal stability. In fine chemical synthesis, Amberlyst 35 facilitates dehydration, hydrolysis, and condensation reactions, offering advantages over liquid acids by simplifying product separation and reducing corrosion and waste. Because it is a heterogeneous catalyst, it can be easily filtered from the reaction mixture and reused, making processes more efficient and environmentally friendly. It is also used in continuous flow systems and fixed-bed reactors for large-scale operations. Additionally, Amberlyst 35 finds use in analytical chemistry for sample preparation, such as the derivatization of acids and alcohols prior to chromatographic analysis.