Location: Plant Polymer ResearchTitle: Metal chloride-catalyzed acetylation of starch: Synthesis and characterization
|FURTADO, ROSELAYNE - Embrapa|
|ALVES, CARLUCIO - Universidade Estadual Do Ceara|
Submitted to: International Journal of Polymer Analysis and Characterization
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/10/2018
Publication Date: 9/17/2018
Citation: Biswas, A., Kim, S., Furtado, R.F., Alves, C.R., Buttrum, M., Boddu, V.M., Cheng, H.N. 2018. Metal chloride-catalyzed acetylation of starch: Synthesis and characterization. International Journal of Polymer Analysis and Characterization. 23(6):577-589.
Interpretive Summary: Acetylated starch is a useful product, and its improved synthesis is desirable, especially if we can minimize the chemical hazards by not using strong mineral acids. In this work we have shown that the metal halides in general can be employed as catalysts for starch acetylation. This work could enable the industrial chemical starch ester manufacturers to minimize the chemical hazards by replacing hazardous acids with metal halide catalysts.
Technical 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 satifactory 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 13C NMR, FTIR, thermogravimetric analysis and size exclusion chromatography.