Metal-Free Fast Azidation Using Tetrabutylammonium Azide: Effective Synthesis of Alkyl Azides and Well-defined Azido-end Polymethacrylates.

Abstract

An effective method to synthesize azido-end polymethacrylates using tetrabutylammonium azide (BNN3) in a non-polar solvent (toluene) was developed. Several low-mass alkyl halides were reacted with BNN3 in toluene as model reactions and the rate constants of these reactions were determined, confirming fast BNN3-azidation for tertiary and secondary halides. The end-group transformation of halide-end polymethacrylates was effective and nearly quantitative. Notably, the combination of organocatalyzed living (or reversible deactivation) radical polymerization and BNN3-azidation enabled metal-free synthesis of azido-end polymethacrylates, including single-azido-end and multi-azido-end functional homopolymers and block copolymer. The rapid and quantitative reaction without using a large excess of BNN3 metal-free and polar-solvent-free nature, and broad polymer scope are attractive feature of this azidation.