Metal chloride-catalyzed acetylation of starch: Synthesis and characterization

Abstract

Acylation of polysaccharides is a commercially important reaction and is usually performed in a process involving the polysaccharide, an acid anhydride, and an inorganic acid. As an alternative to inorganic acid, many catalysts, including some metal chlorides, have been previously reported as catalysts. In this work, we took a more comprehensive look at several metal chlorides to observe trends and reactivities among them, particularly relating to reaction temperature, time, and amount of acetic anhydride used. Iodine was also included for comparison. Almost all the metal chlorides studied were found to be active as catalysts for the acetylation of starch under suitable reaction conditions. However, each metal chloride had a somewhat different reactivity with a different optimal temperature needed for satisfactory reactions to take place. The molecular weight of the starch acetate products decreased in all cases observed. The reactivity trends among the metal halides seemed to correlate both with the ease of complexation between the halide and the substrate and with the acidity of the metal chloride. Characterization was achieved through 13 C NMR, FT-IR, thermogravimetric analysis and size exclusion chromatography.

A Simple and Cost-Effective FeCl3-Catalyzed Functionalization of Cellulose Nanofibrils: Toward Adhesive Nanocomposite Materials for Medical Implants

“…Metal chlorides have found application in the catalytic modification of polysaccharides . However, there is a lack of catalytic procedures for the grafting of amine-containing molecules onto polysaccharides in general and specifically onto CNFs.…”

“…Metal chlorides have found application in the catalytic modification of polysaccharides. 47 However, there is a lack of catalytic procedures for the grafting of amine-containing molecules onto polysaccharides in general and specifically onto CNFs. In this work, we have optimized a catalytic chemical procedure using a commercially available and cheap iron (FeCl 3 ) salt ( Scheme 1 ).…”