Synthesis and characterization of Sodium salt of partially carboxymethylated starch

Sodium salt of partially carboxymethylated starch (Na-PCMS) was prepared in a completely heterogeneous process in an isopropyl water slurry and the influence of the reaction conditions on the degree of substitution (DS) was checked. The concentration of aqueous sodium hydroxide solution, which was used to activate the starch, was varied in the range from 8 to 30% Wt, reaction time from 2 to 6 hr at 55°C. The reaction with sodium monochloroacetate leads to the highest degree of substitution of 1.24 at a NaOH concentration of 15% and 5 hr reaction time. Using a lye concentration of 30% no influence of the reaction time between 2 hr and 6 hr was found. From FTIR spectroscopical studies it was concluded that all the samples were Na-PCMS.