- Establishment of heterolytic and homolytic Y-NO2 bond dissociation energy scales of nitro-containing compounds in acetonitrile: Chemical origin of NO2 release and capture
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(Chemical Equation Presented) The first heterolytic and homolytic N(O)-NO2 bond dissociation energy scales of three types Y-nitro (Y = N, O) compounds and corresponding radical anions in acetonitrile were established by using titration calorimetry combined with relevant electrochemical data through proper thermodynamic cycles.
- Li, Xin,Zhu, Xiao-Qing,Zhang, Fan,Wang, Xiao-Xiao,Cheng, Jin-Pei
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p. 2428 - 2431
(2008/09/20)
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- Reaction of N-Aryl- and N-Alkyl-benzimidoyl Chlorides with Silver Nitrate
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N-Arylbenzimidoyl chlorides, in which the N-aryl group is unsubstituted at the ortho- and para-positions, react with AgNO3 to yield N-(nitroaryl)benzamides, in which the NO2 group resides in the ortho- or para-position.N-Arylbenzimidoyl chlorides, in which the N-aryl ring is 2,4,6-trisubstituted, react with AgNO3 to yield the corresponding N-aryl-N-nitrobenzamides.The formation of both types of product can be explained by the intermediacy of an O-nitro imidate.Spectroscopic and chemical evidence is presented for the formation of this intermediate in the reaction of N-(2,4,6-trisubstituted phenyl)benzimidoyl chlorides with AgNO3.Rearrangement of the O-nitro imidate is unimolecular and intramolecular.The rate of rearrangement is independent of the substituent in the C-aryl ring, but increases with the electon-withdrawing ability of the substituents in the N-aryl ring.A mechanism is proposed in which the imidoyl chloride reacts with AgNO3 to produce first a nitrilium ion which goes on to form an O-nitro imidate that subsequently rearranges via a homolytic cleavage of the O-NO2 bond.The ortho:para ratios of N-(nitroaryl)benzamides obtained in the present work indicate that O-nitro imidates are not responsible for the high 1/2ortho:para ratios sometimes observed in the nitration of anilides.N-Alkylbenzimidoyl chlorides react with AgNO3 to form the corresponding N-nitro- and N-nitrosobenzamides.The mechanism of formation of the N-alkyl-N-nitrobenzamide arises from a pathway analogous to that for N-aryl-N-nitrobenzamides, involving a nitrilium ion that gives rise to an O-nitro imidate.The evidence for the formation of the N-nitrosobenzamide points to an alternative reaction of the imidoyl chloride with AgNO3.One possible mechanism for this reaction is described.
- Iley, Jim,Carvalho, Emilia,Norberto, Fatima,Rosa, Eduarda
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p. 281 - 290
(2007/10/02)
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- Improved Methods for the N-Nitration of Amides
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The reactivity of several nitrating mixtures with amides has been compared.Ammonium nitrate/ trifluoroacetic anhydride, morpholinium nitrate/ trifluoroacetic anhydride, and morpholinium nitrate/ heptafluorobutyric anhydride are the reagents of choice sinc
- Romea, Pedro,Aragones, Montse,Garcia, Jordi,Vilarrasa, Jaume
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p. 7038 - 7042
(2007/10/02)
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- Reaction of N-Nitroso- and N-Nitro-N-alkylamides with Amines
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Several N-nitroso- and N-nitrocarboxamides have been characterized by 1H and 13C NMR spectroscopy.These compounds react with ammonia and aliphatic amines to afford mainly carboxamides of general formula RCONH2, RCONHR', or RCONR'R''.N-Nitrosocarboxamides and aromatic amines give poor yields of RCONHAr; by contrast, N-nitrocarboxamides and aromatic amines lead to RCONHAr in good yields.The higher thermal stability of the N-nitroamides as compared to N-nitrosoamides is advantageous in this connection; nevertheless, the principal advantage of the NNO2 group appears to be that it activates the nucleophilic attack to the carbonyl of the amide function more than the NNO group, as has been demonstrated by competitive experiments.The reaction of N-nitroso- and N-nitro-N-methylsulfonamides with ammonia and diethylamine has been studied as well; whereas N-methyl-N-nitro-p-toluenesulfonamide reacts as N-nitrocarboxamides, transnitration is predominant with N-methyl-N-nitroso-p-toluenesulfonamide.
- Garcia, Jordi,Gonzalez, Javier,Segura, Ramon,Urpi, Felix,Vilarrasa, Jaume
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p. 3322 - 3327
(2007/10/02)
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