Background:

Iodo-PEG3-Azide contains a highly reactive iodide functional group which can alkylate a variety of C-, O-, N-, S-centered and other nucleophiles.

Organic iodides are roughly an order of magnitude more active than bromides, and four orders of magnitude more active than chlorides in S_N2 reactions. This means that the same alkylation will take 10x less time with iodide than with bromide. Therefore, this molecule helps to effect very fast alkylation.

PEG3 is a moderately long hydrophilic linker. The azide group participates in Click chemistry reactions. It is also easily reduced to an amine group.