Reaction of Starch with the Chlorosulfonic Acid-Formamide Reagent

Reactions of starch polysaccharides with sulfating agents have been carried out (1) for making heparinoids with blood anti coagulating properties (2-4), for obtaining products having anti ulcer action by inhibiting pepsin (5-7), to produce thickening agents for foods (8) and auxiliary substances in various techniques (9,10) and, generally to substitute for naturally occuring polysaccharide gums (11-13). The methods used for introducing sulfuric acid groups into the molecules of starch vary widely. There are (1) reactions in homogeneous nonaqeous or aqueous systems, (2) reactions in heterogeneous liquid systems, and (3) reaction in dry state. A summarizing survey on the most important methods and reagents used so far is given in Table 1. The properties of the resulting starch esters depend largely on these methods and reagents, and it is shown that reactions in homogeneous systems give products with low, medium and high degrees of substition (3,6,14-17). It is necessary, however, to