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ARS Home » Midwest Area » Peoria, Illinois » National Center for Agricultural Utilization Research » Plant Polymer Research » Research » Publications at this Location » Publication #213953
Title: SCANDIUM TRIFLATE CATALYZED ACETYLATION OF STARCH UNDER MILD CONDITIONS

Author
item Shogren, Randal

Submitted to: Carbohydrate Polymers
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/11/2007
Publication Date: 5/16/2008
Citation: Shogren, R.L. 2008. Scandium triflate catalyzed acetylation of starch under mild conditions. Carbohydrate Polymers. 72(3):439-443.

Interpretive Summary: There is increasing interest in discovering new biobased materials to replace petroleum-based polymers. Corn starch, in particular, has potential applications in biodegradable packaging, adhesives, coatings, dispersants, etc. but usually needs to be chemically modified. New methods of chemical modifying corn starch are needed to improve the properties of starch for these applications. It was found that a novel catalyst called scandium triflate was able to cause starch to react with acetic acid at fairly low temperatures. This is the first time that such a reaction has been reported and may allow new types of chemically modified starch esters to be prepared. A novel starch having acetic groups on the surface of the starch particles only was prepared. These findings should be useful to other academic, government and industrial scientists studying ways to prepare new starch esters under mild "green" conditions.

Technical Abstract: Scandium (III) trifluoromethan sulfonate (Sc(OTf)3) was investigated as a catalyst for the acetylation of starch in order to determine the potential for preparing new types of starch esters under mild conditions. At room temperature, dry granular corn starch reacts with acetic anhydride in the presence of Sc(OTf)3 for form starches highly acetylated on the granular surface only. At high temperatures (80 deg C), starch acetates of degree of substitution (DS) 1.2 and 0.40 were obtained by reaction of granular starch with acetic anhydride or acetic acid, respectively. When starch was gelantinized in acetic acid prior to reaction, acetylation with acetic anhydride was much more rapid with DS reaching 3 after 1 h at 80 deg C. Acetylation was rapid at levels of Sc(OTf)3 down to 0.1 mole %. These data suggest that powerful Lewis acid catalysts such as Sc(OTf)3 may be useful in preparing novel starch esters using either carboxylic acids or anhydrides.