Dextran chloroacetic acid

Another approach uses reactive alkyl halogen compounds containing a terminal carboxylate group on the other end to form spacer arms off the dextran polymer from each available hydroxyl. In this manner, Brunswick et al. (1988) used chloroacetic acid to modify the hydroxyl groups to form the carboxymethyl derivative. The carboxylates then were aminated with ethylene diamine to create an amine-terminal derivative (Inman, 1985). Finally, the amines were modified with iodoacetate to form a sulfhydryl-reactive polymer (Figure 25.14). 

Figure 25.14 An amine derivative of dextran may be prepared through a two-step process involving the reac-tion of chloroacetic acid with the hydroxyl groups of the polymer to create carboxylates. Next, ethylene diamine is coupled in excess using a carbodiimide-mediated reaction to give the primary amine functional groups.

Protocol for the Modification of Dextran with Chloroacetic Acid... 

Trichloroacetic acid is said to give better results with glycoproteins than either sulfuric acid or ion-exchange resins,51 and the solvent properties of 50% chloroacetic acid have been utilized in the hydrolysis of a p-toluenesulfonylated dextran.52... 

The following protocol illustrates the modification of a dextran polymer with chloroacetic acid. 

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