Ethylene imine, hydrolysis

FIGURE 3.16 Monomer synthesis and cationic pol5mierization of oxazolines (Nu"=nucleophile, e.g., amine) followed by acid hydrolysis toward linear poly-(ethylene imine) for R=Me, Et. 

A number of alkylating agents yield derivatives which are stable under the conditions for acidic hydrolysis of proteins. The reaction with ethylene imine giving an S-aminoethyl derivative and, hence, an additional linkage position in the protein for hydrolysis by trypsin, was mentioned in Section 1.4.1.3. lodoacetic acid, depending on the pH, can react with cysteine, methionine, lysine and histidine residues ... 

Besides the synthetic aspects of the preparation of (functional) poly(2-oxazoline)s, it is noteworthy to mention that poly(2-oxazoHne)s are weU-known precursors for the preparation of linear poly(ethylene imine)s upon hydrolysis under either alkaline [147] or acidic [148] conditions (Scheme 6.21). Detailed kinetic investigations on the acidic deacetylation of poly(2-oxazoline)s have revealed that both partial and full deacetylation can be achieved by varying the stoichiometry between the acid and the cleavable groups [149]. Furthermore, partial cleavage of the side chains can be controlled by selective acidic hydrolysis based on the easier hydrolysis of poly(2-ethyl-2-oxazoline) compared to poly(2-[4-tert-butylphenyl]-2-oxazoline) [150]. 

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