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Concentration‐Dependent Thermal Isomerization of Nitrile N ‐Oxide
Author(s) -
Bando Shiho,
Koyama Yasuhito,
Takata Toshikazu
Publication year - 2020
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.202000829
Subject(s) - isomerization , substituent , chemistry , nitrile , isocyanate , photochemistry , organic chemistry , catalysis , polyurethane
Kinetically stabilized nitrile N ‐oxides (NOs) have been regarded as viable tools for the postpolymerization functionalization of common polymers. However, thermal isomerization of NO to isocyanate restricts the applications of NO to industrial use. The reaction mechanism for the thermal isomerization has not been systematically evaluated. Herein, we report the concentration‐dependent isomerization of NOs for the first time. The time‐course plots suggest that the isomerization of NO would be driven by a very small amount of polymeric intermediate generated in situ in a substituent‐dependent equilibrium. The substituent effects of NO on the isomerization have been clarified with the kinetic parameters and the reaction order. It is indicated that an electron‐donating para ‐substituent facilitates both the intermediate‐forming reaction and the rearrangement reaction.