Nitronium cation

Electrostatic potential map for nitronium cation shows most positively-charged regions (in blue) as likely electrophilic sites. 

The latter is involved in the intramolecular alkylation of one of the nitro groups accompanied by elimination of the nitronium cation. It was not rigorously established whether the reaction afforded six-membered cyclic nitronate (35 d) or... 

Nitrous acid catalysis also takes place in the nitration of such compounds (naphthalene) that are unable to undergo nitrosation on the given conditions or whose nitrosation proceeds slower than nitration. As accepted, the nitrosonium ion is formed from HNOj in acid media. The nitrosonium ion oxidizes an aromatic substrate into a cation-radical and transforms into nitric oxide. The latter reduces nitronium cation to nitrogen dioxide that gives a a-complex with the aromatic cation-radical ... 

Having in mind the mentioned importance of gas-phase aromatic nitration, it should be useful to arrange benzene derivatives as electron donor with respect to nitronium ion, using IPs. These potentials have been measured in the gaseous phase and can be extracted from NIST Chemistry WebBook (Lindstrom and Mallard, 2003). The data provide an indication for the thermodynamic feasibility of their one-electron oxidation by nitronium cation. 

A process known as alkene nitrofluorination has been extensively used for the synthesis of /3-nitroalkyl fluorides. Reagents used generate the nitronium cation in the presence of... 

Mixed acid or anhydrous nitric acid has been used for the nitration of em-nitronitronate salts to the corresponding 1,1,1-trinitromethyl compounds. A convenient route to hexan-itroethane (75) involves treating the dipotassium salt of 1,1,2,2-tetranitroethane (74) with mixed acid the nitration proceeding via electrophilic addition of the nitronium cation to the bis-nitronitronate ion. ... 

Tetranitromethane is an electrophilic source of nitronium cation and has been used in alkaline solution for the nitration of 1,1-dinitropropane to 1,1,1-trinitropropane (32%), and for nitration of l-phenyl-3-nitropropane to l-phenyl-3,3-dinitropropane (32 %) and its further nitration to l-phenyl-3,3,3-trinitropropane (33%). ... 

Our basic knowledge of electrophilic nitration of aromatic hydrocarbons results from the work of Ingold,24 who established that the nitronium cation is the true reactive electrophile in these reactions.64-67 In the traditional nitration process with the mixed acid the nitronium cation is generated according to Eqs. (10.4) and (10.5) ... 

The nitronium cation, NO, with a structure resembling that of carbon dioxide (linear, N—O = 1.154 A), was discovered by spectroscopic methods.26 Its linear configuration has been verified for NO2CIO4 by spectroscopic methods28 and for NO NO (crystalline dinitrogen pentoxide) by x-ray diffraction,27 and also for several other crystals.28... 

On the other hand, some of these species are stable enough to be isolated as salts. Nitronium cation N02 exists in equilibrium with nitric acid at ambient temperature however, more than 15 crystalline nitronium salts with a variety of counter ions have been isolated and characterized [ 1 ]. The most widely used salt N02+BF4- is made by the reaction of HN03 and BF3 in anhydrous hydrogen fluoride [41] ... 

Acetic acid, protonated acetic, diprotonated acetic acid (89), acetyl cation, and the protioacteyl cation (46) were calculated at the MP2/6-31G //GIAO-MP2/tzp/dz level of theory nitric acid, nitronium cation, and the protionitronium cation (3) were calculated at the HF/6-31G // II//6-31G level of theory hydronium ion and the tetrahydridooxonium ion (90) were calculated at the MP2/6—31 G //GIAO-MP2/tzp/dz level of theory. 

When nitronium tetrafluoroborate was attempted to react with the trityl cation in CH2CI2 or sulfolane, no nitration occurred due to the deactivating effects of the carbenium ion center in 215. Nitration of deactivated substrates is also readily accomplished by reaction with NO2CI with three mole excess AICI3 suggesting Lewis acidic electrophilic solvation of the nitronium cation (217, eq 62).105... 

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