60367-99-9Relevant articles and documents
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.
Aromatic Iodination: Evidence of Reaction Intermediate and of the ?-Complex Character of the Transition State
Galli, Carlo
, p. 3238 - 3245 (2007/10/02)
The reactivity of the four different procedures of aromatic iodination is compared under the same experimental conditions, and their selectivity toward two substrates in competition, i. e., mesitylene (1,3,5-trimethylbenzene, MES) and durene (1,2,4,5-tetramethylbenzene, DUR), is evaluated.Two of these procedures, namely, S2O82-/I2 and Ce(IV)/I2, present strong oxidizing capacity.Since the same MES/DUR relative reactivity is obtained from the four procedures, it becomes possible to state that a common reactive intermediate, most likely the I+ ion, is generated.The use of the MES/DUR mechanistic probe allows one to describe the reactivity picture of the iodination reaction as one of electrophilic substitution at the aromatic nucleous, with a transition state properly represented in terms of a ?-complex.The radical cation of durene also forms when the iodination is carried out by means of oxidizing agents, but it is solely responsible for the formation of side-chain substitution products and is not involved in the nuclear substitution process.
