AUTHOR=Zhao Xiaotian , Xu Wen , Chen Xi , Lin Shibo , Li Xuanhao , He Lihui , Liao Xu , Ye Guodong 

TITLE=A comparison of hydrogen abstraction reaction between allyl-type monomers with thioxanthone-based photoinitiators without amine synergists

JOURNAL=Frontiers in Chemistry

VOLUME=Volume 10 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2022.967836

DOI=10.3389/fchem.2022.967836

ISSN=2296-2646

ABSTRACT=The photodriven radical-mediated [3+2] cyclization reaction was found to yield polymers efficiently without being hindered by degradative chain transfer. The first reaction is a hydrogen abstraction process which one hydrogen atom migrates from α-methylene group of an allyl monomer to triplet state (or fragments) of photoinitiator, thus yields primary allyl radicals as primary radicals, and then begin chain propagation via 3+2 cyclization reaction. Allyl ether monomers were found to be significantly higher than other allyl monomers even with absence of amine-like synergists. In order to clarify the procedure of hydrogen abstraction mechanism, we used four allyl-type monomers as hydrogen donors and three thioxanthone photoinitiators as hydrogen acceptors by quantum chemistry method in terms of geometry and energy. The results were interpreted with transition-state theory and the interaction/deformation model. Then, the tunneling factors of hydrogen abstraction reactions were also investigated by Eckart’s correction. The results show allyl ether systems are more reactive than other allyl systems and it would be provide us new insights into these hydrogen abstractions.