3463-36-3Relevant articles and documents
HNO3/HFIP: A Nitrating System for Arenes with Direct Observation of π-Complex Intermediates
Lu, Le,Liu, Huixin,Hua, Ruimao
supporting information, p. 3197 - 3201 (2018/06/11)
This report describes an efficient nitrating system for the nitration of arenes at room temperature by using an equivalent of nitric acid in HFIP (1,1,1,3,3,3-hexafluoroisopropanol). The π-complex intermediate of an arene with a nitronium ion stabilized by HFIP can be directly observed by UV-vis spectra and is supported by theoretical calculations.
Photochemical nitration by tetranitromethane. Part XXXIII. Adduct formation in the photochemical reactions of 1,2,4,5- and 1,2,3,5-tetramethylbenzene
Butts, Craig P.,Eberson, Lennart,Fulton, Karen L.,Hartshorn, Michael P.,Robinson, Ward T.,Timmerman-Vaughan, David J.
, p. 991 - 1008 (2007/10/03)
The photolysis of the charge-transfer complex of tetranitromethane and 1,2,4,5-tetramethylbenzene in dichloromethane or acetonitrile gives the epimeric 1,3,4,6-tetramethyl-3-nitro-6-trinitromethylcyclohexa-1,4-dienes 8 and 9, in addition to products of nuclear nitration 12 and side-chain modification 10, 11, and 13-18. Similar reactions of 1,2,3,5-tetramethylbenzene gave trans-1,3,5,6-tetramethyl-6-nitro-3-trinitromethylcyclohexa-1,4-diene 30 and two isomeric 'double' adducts 31 and 32, in addition to products of nuclear nitration 27 and side-chain modification 26, 28 and 29. The eliminative rearrangements of adducts 8 and 30 to give re-aromatized products in acetonitrile or [2H3] acetonitrile and in [2H] chloroform are reported. The photolysis of the charge-transfer complexes of tetranitromethane with either 1,2,4,5-tetramethylbenzene or 1,2,3,5-tetramethylbenzene in 1,1,1,3,3,3-hexafluoropropan-2-ol (HFP) gives a marked increase in the yields of ring-nitration products 12 or 27, respectively, reactions presumed to proceed via a nitrosation-oxidation sequence. Reaction of 1,2,4,5-tetramethylbenzene with excess nitrogen dioxide in HFP also results in extensive ring nitration to give 12 and 2,3,5,6-tetramethyl-1,4-dinitrobenzene (25); the latter compound is seen as arising via the 2,3,5,6-tetramethyl-1,4-dinitrosobenzene (34). Similar reaction of 1,2,3,5-tetramethylbenzene gives ring-nitration product 27 as the major product. X-Ray crystal structures are reported for 2,4,6-trimethyl-1-(2′,2′,2′-trinitroethyl)benzene (26) and trans-1,3,5,6-tetramethyl-6-nitro-3-trinitromethyl-cyclohexa-1,4-diene (30). Acta Chemica Scandinavica 1996.
Thermal and Photochemical Nitration of Aromatic Hydrocarbons with Nitrogen Dioxide
Bosch, E.,Kochi, J. K.
, p. 3314 - 3325 (2007/10/02)
Aromatic hydrocarbons (ArH) are readily nitrated by nitrogen dioxide (NO2) in dichloromethane at room temperature and below (in the dark).The red colors, transiently observed, arise from the metastable precursor complex NO3(1-), which is formed in the prior disproportionation of nitrogen dioxide induced by the aromatic donor (eq 7).The deliberate irradiation of the diagnostic (red) charge-transfer absorption band (hνCT) of NO3(1-) at low temperatures results directly in aromatic nitration, even at -78 deg C, where the thermal nitration is too slow to complete.The mechanism of the photochemical (charge-transfer) nitration is established by time-resolved laser spectroscopy to proceed via the aromatic cation radical (ArH.+) formed spontaneously upon the charge-transfer excitation of NO3(1-) in Scheme 1.The related thermal activation of NO3(1-) derives from the adiabatic electron transfer that produces the same radical pair as the reactive intermediate in Scheme 3.The close relationship between the thermal/photochemical nitrations with nitrogen dioxide and those conventionally carried out with nitric acid (in the presence of nitrous acid) is delineated by Scheme 4.