GAS-PHASE ION-MOLECULE NITRATION CHEMISTRY: THE NITRATION OF AROMATIC RADICAL CATIONS BY NITROGEN DIOXIDE.

Article abstract of DOI:10.1021/ja00316a017

The authors have observed in gas-phase work at 10 torr that aromatic cations (ArH** plus multiplied by (times) )readily react with NO//2 to give the sigma -bonded ArH-NO//2** plus . Under the same conditions the reactions of nitronium ion (NO//2** plus ) with neutral ArH yield only ArH** plus multiplied by (times) and ArH-O** plus multiplied by (times) , products of electron or oxygen transfer. The radical cations giving the sigma intermediate were those from benzene, methylbenzenes up to mesitylene and 1,2,4-trimethylbenzene, phenol, and several fluorobenzenes up to 1,2,4-trifluorobenzene. In contrast tetrafluorobenzenes, furan, and pyridine did not yield the sigma intermediate. Naphthalene reacted to give the sigma -bonded C//1//0H//8-NO//2** plus , but surprisingly slowly. The parallels to condensed-phase nitration are yet to be fully demonstrated, but it is clear that the odd-electron system NO//2 plus ArH** plus multiplied by (times) yields the sigma -bonded intermediate leading to nitration.