Labile alkoxyamines: past, present, and future

Area of Science:

• Organic Chemistry
• Polymer Science
• Materials Science

Background:

• Alkoxyamines, derivatives of hydroxylamine, were discovered in 1974 and later recognized for their crucial role in nitroxide-mediated polymerization (NMP) starting in 1985.
• Their ability to undergo C-ON bond homolysis to generate persistent nitroxyl and transient alkyl radicals has driven extensive research.

Purpose of the Study:

• To survey and assess diverse applications of alkoxyamines, including tin-free radical chemistry, synthesis, and polymerization.
• To highlight recent findings on chemically triggered C-ON bond homolysis for controlled radical generation at room temperature.
• To explore new opportunities in smart materials, NMP initiators, and theranostic agents.

Main Methods:

• Review of existing literature on alkoxyamine applications in radical chemistry and polymerization.
• Description of recent experimental findings on the chemical triggering of C-ON bond homolysis.
• Exploration of potential applications based on radical generation properties.

Main Results:

• Alkoxyamines are versatile in tin-free radical chemistry, synthesis, and both thermal (NMP) and photochemical (NMP2) polymerization.
• Controlled generation of alkyl radicals from alkoxyamines at room temperature via chemical triggering has been achieved.
• The released nitroxyl and alkyl radicals offer potential for dynamic nuclear polarization (DNP) imaging and targeted therapy.

Conclusions:

• Alkoxyamines demonstrate broad utility across various chemical disciplines and material applications.
• Controlled radical generation at room temperature expands their potential as initiators and in smart materials.
• The dual radical-releasing nature positions alkoxyamines as promising candidates for theranostic agents.