HO-PEG-CH2COOtBu

Alpha-(hydroxy)-omega-(tert-butyl-protected carboxymethyl) poly(ethylene glycol) (HO-PEG-CH2COOtBu) is a heterobifunctional precision PEG derivative with a defined chain length. The two ends bear hydroxyl and tert-butyl-ester-protected carboxymethyl groups, respectively. Discrete chain lengths with different degrees of polymerization are available. The terminal hydroxyl group can be further modified by esterification, etherification, or other functional-group transformations. The tert-butyl ester temporarily protects a carboxyl precursor. Appropriate acidic deprotection enables subsequent carboxyl activation and amide coupling. The two end groups can be coupled sequentially using compatible reactions and appropriate protection strategies, enabling surface immobilization, functional-molecule bridging, and directional spacer synthesis.

Customization available.