Starch imidazolides

Starch esters have been obtained by reactions of starch and carboxylic or sulfonic acid imidazolides in aqueous NaOH or nonaqueous solutions, as described in reference [226]. The esterification of dextran with butyric or palmitic acid using CDI in DMSO or formamide is discussed in reference [174]. 

In the context of synthesis and exchange reactions of biodegradable drug-binding matrices, starch trisuccinic acid was loaded via imidazolides with amines such as n-butylamine, morpholine, 4-aminobenzoic acid, or 3,4-dihydroxyphenylalanine to prepare the respective amides in high yields [160] an example is presented below. 

Although CDI was applied as early as 1972 as reagent for the esterification of starch and dextran, it has only scarcely been used up to now. Its renaissance during the last few years may be due to the fact that it became an affordable commercially available product. Among the first attempts for the esterification of polysaccharides via CDI is the binding of amino acids onto dextran. Besides CDI, -(thiocarbony diimidazole can be utilised to obtain the corresponding imidazolide [198]. The amino acids bound via this path are glycine, L-leucine, L-phenylalanine, L-histidine and L-alanyl-L-histidine. They are protected with N-trifluoroacetyl, N-benzyloxycarbonyl... 

Starch carbonate diesters were formed by reaction of starch with alkylene carbonates under diminished pressure at 100-140 °C 2002 The products were proposed as surgical dusting powders. Another method involved dimethyl sulfoxide as the reaction medium, triethylamine as the catalyst, and trans-carbonates of glycosides as the acylating agents. Thionocarbonates were used similarly. The degree of substitution was O.4.2003 Another method involves 1-acyl I, I -carbodiirnidazole or dicarboxylic acid imidazolides at pH 8.O.2004... 

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See also in sourсe #XX -- [ , ]

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