• Home
  • Search Results
  • NO(2)(+) nitration mechanism of aromatic compounds: electrophilic vs charge-transfer process

NO(2)(+) nitration mechanism of aromatic compounds: electrophilic vs charge-transfer process

The Journal of organic chemistry (2000-05-18)
Tanaka, Muro, Ando, Xu, Fujiwara, Souma, Yamaguchi

The nitration of methylnaphthalenes with NO(2)BF(4) and NOBF(4) was examined in order to shed light on the controversial aromatic nitration mechanism, electrophilic vs charge-transfer process. The NO(2)(+) nitration of 1,8-dimethylnaphthalene showed a drastic regioselectivity change depending on the reaction temperature, where ortho-regioselectivity at -78 degrees C and para-regioselectivity at 0 degrees C were considered to reflect the electrophilic and the direct or alternative charge-transfer process, respectively, because the NO(+) nitration through the same reaction intermediates as in the NO(2)(+) nitration via a charge-transfer process resulted in para-regioselectivity regardless of the reaction temperature. The NO(2)(+) nitration of redox potential methylnaphthalenes higher than 1,8-dimethylnaphthalene gave a similar ortho-regioselectivity enhancement to 1,8-dimethylnaphthalene at lower temperature, thus reflecting the electrophilic process. On the other hand, the NO(2)(+) nitration of redox potential methylnaphthalenes lower than 1,8-dimethylnaphthalene showed para-regioselectivity similar to the NO(+) nitration, indicating the direct or alternative charge-transfer process. In the presence of strong acids where the direct charge-transfer process will be suppressed by protonation, the ortho-regioselectivity enhancement was observed in the NO(2)(+) nitration of 1,8-dimethylnaphthalene, suggesting that the direct charge-transfer process could be the main process to show para-regioselectivity. These experimental results imply that the NO(2)(+) nitration proceeds via not only electrophilic but also direct charge-transfer processes, which has been considered to be unlikely because of the high energy demanding process of a bond coordination change between NO(2)(+) and NO(2). Theoretical studies at the MP2/6-31G(d) level predicted ortho- and para-regioselectivity for the NO(2)(+) nitration via electrophilic and charge-transfer processes, respectively, and the preference of the direct charge-transfer process over the alternative one, which support the experimental conclusion

Product Number
Product Description

1,8-Dimethylnaphthalene, 95%

Social Media

LinkedIn icon
Twitter icon
Facebook Icon
Instagram Icon


Research. Development. Production.

We are a leading supplier to the global Life Science industry with solutions and services for research, biotechnology development and production, and pharmaceutical drug therapy development and production.

© 2021 Merck KGaA, Darmstadt, Germany and/or its affiliates. All Rights Reserved.

Reproduction of any materials from the site is strictly forbidden without permission.