Immobilizing an organic catalyst on a nylon fabric can simplify the production of chemical compounds, e.g., avoiding the need to dissolve and then recover the catalyst as now is required in some syntheses of pharmaceutical ingredients, report researchers at the Max-Plank-Institut für Kohlenforschung in Mülheim an der Ruhr, Germany. In addition, the textile provides greater surface area than other supports, and is flexible, safe, inexpensive and easy to transport, they say. "Our method enables the low-cost production of long-term functionalized textiles without causing any pollution," notes researcher Jiwoong Lee.
The immobilization process, developed in collaboration with scientists from the Deutsches Textilforschungszentrum in Krefeld, Germany, and Sungkyungkwan University, Suwon, South Korea, involves applying the catalyst to the fabric and then irradiating the textile with ultraviolet light for no more than five minutes (Figure 1).
The researchers used three organic catalysts: a base (dimethylaminopyridine), a sulfonic acid and one that functions both as an acid and a base. The latter catalyst currently is used in the pharmaceutical industry in dissolved form to promote production of a specific stereoisomer. All three catalysts converted around 90% of the feed materials into desired products; the dual-function catalyst's product contained 95% of the desired enantiomer.
Use of nylon does limit operating temperature to under 100°–150°C, notes Lee. However, other textiles could be used for higher temperature reactions, he says.
"Due to a capillary effect of the fabric, clogging can be a problem during a reaction but this can be easily solved by applying a continuous system, which is more efficient than a batch reactor," Lee explains. Otherwise, liquids or physical force can be used to clean the fabric, he notes.
"[The] next step of our research will be focused on the development of [a] more practical and efficient system of immobilization and its application in the real world, industry," declares Lee. A key challenge is to increase the catalyst loading per gram of textile material, he adds.
"From now [on], catalysts, reagents, ligands and even 'Merrifield's resin' can be immobilized on the textile permanently, and it's safe, flexible and cheap," concludes Lee.
Several research institutes and companies already have expressed interest in cooperating on the development and providing the catalyst on a large scale, Lee says.