1610-26-0Relevant articles and documents
Nucleophilicities of nitroalkyl anions
Bug, Thorsten,Lemek, Tadeusz,Mayr, Herbert
, p. 7565 - 7576 (2004)
The kinetics of the reactions of eight nitroalkyl anions (nitronate anions) with benzhydrylium ions and quinone methides in DMSO and water were investigated photometrically. The second-order rate constants were found to follow a Ritchie constant selectivi
Kinetic study of the proton transfer reaction between 1-nitro-1-(4-nitrophenyl)alkanes and P1-t-Bu phosphazene base in THF solvent
Wis?ocka, Zaneta,Nowak, Iwona,Jarczewski, Arnold
, p. 152 - 158 (2006)
The rates of proton transfer reactions between C-acids of the series of nitroalkanes with increasing bulk of R=H, Me, Et, i-Pr substituents as 4-nitro-phenylnitromethane (1), 1-(4-nitrophenyl)-1-nitroethane (2), 1-(4-nitrophenyl)-1-nitropropane (3), 2-methyl-1-(4-nitrophenyl)-1-nitropropane (4) and the P1-t-Bu phosphazene have been measured in THF at pseudo-first-order conditions. The product of the proton transfer reaction with P1-t-Bu is associated into ion pair. The equilibrium constants decrease along with growing bulk of alkyl substituent in the reacting C-acid: >100 000, 1170, 590, and 11.8 for 1, 2, 3, 4, respectively. The second order rate constants (k2H) for this very strong base and C-acids are rapidly declining: 9357, 2.31, 0.66, 0.09 dm3 mol-1 s-1 for 1, 2, 3, 4, respectively, and could not be accounted for the small values of the enthalpies of activation Δ HH≠ = 6.1, 18.0, 20.7 and 11.1 kJ mol- 1. The appropriate values of the entropies of activation were all negative and relatively large Δ SH≠ = - 149.7, - 176.5, - 178.7, - 227.8 J mol- 1 deg- 1 indicating an importance of steric and ordering effects in forming the transition state. The primary deuterium kinetic isotope effects are large showing tendency of reverse relation towards steric hindrance of the reacting C-acids, kH/kD=15.8, 13.6, 13.2 for 1, 2, and 3, respectively. The explanation of the unusual slow proton transfer abstraction caused by this extremely strong base is undertaken.
Scalable, easy synthesis, and efficient isolation of arylnitromethanes: a revival of the Victor Meyer reaction
Alaime, Thibaud,Delots, Audrey,Pasquinet, Eric,Suzenet, Franck,Guillaumet, Gérald
, p. 1337 - 1341 (2017/01/21)
A modified approach to synthesize and isolate arylnitromethanes is described. The method takes advantage of the significant difference in acidity between the arylnitromethane and the major impurity of the reaction, the nitrite ester. The arylnitromethanes resulting from this process are obtained in high yields and are analytically pure, i.e., they do not require distillation or further purification, which is a comfortable improvement of the ancestral Victor Meyer reaction.
Reactions of substituted phenylnitromethane carbanions with aromatic nitro compounds in methanol: Carbanion reactivity, kinetic, and equilibrium studies
Asghar, Basim H.
, p. 477 - 488 (2014/07/08)
The feasibility of carrying out nucleophilic addition from electron-deficient heteroaromatics has been addressed through a detailed investigation of the interaction of a two 7-substituted-nitrobenzofurazan (R = OMe 2a; R = Cl 2b) with a series of substituted-nitroaryl anions (X = 4-NO 2 1a; X = 3-NO2 1b; X = 4-CN 1c; X = 4-Br 1d), all reactions first lead to the quantitative formation of the σ-adducts 3a-d and 4a-d arising from covalent addition of the nucleophile to the C-5 carbon. The rate and equilibrium constants for the formation of σ-adducts 3a-d and 4a-d (k5, K5) together with the rate constants for their decomposition (k-5) have been determined in methanol at 25C, allowing a determination of intrinsic rate constants, k0 = 0.03, the lower k0 value reflects the very strong salvation by methanol of the negative charge on the nitro group. The discovery of a linear correlation between the E and pKaMeOH parameters allows a calibration of the electrophilicity power of 2a and 2b, E = -11.67 and -10.29, respectively. Applying the general approach to nucleophilicity/electrophilicity recently developed by Mayr et al. through the relationship log k = s(E + N), a successful ranking of our nitroaryl anions 1a-d on the general nucleophilicity scale (N) has been carried out. The N values of 1a-d are found to cover a range from 15.78 to 16.69. The results are compared with previously reported data in water and DMSO.
Minimizing the amount of nitromethane in palladium-catalyzed cross-coupling with aryl halides
Walvoord, Ryan R.,Kozlowski, Marisa C.
, p. 8859 - 8864 (2013/09/24)
A method for the formation of arylnitromethanes is described that employs readily available aryl halides or triflates and small amounts of nitromethane in a dioxane solvent, thereby reducing the hazards associated with this reagent. Specifically, 2-10 equiv (1-5% v/v) of nitromethane can be employed in comparison to prior work that used nitromethane as solvent (185 equiv). The present transformation provides high yields at relatively low temperatures and tolerates an array of functionality, including heterocycles and substantial steric encumbrance.
Kinetic study of proton-transfer reactions of phenylnitromethanes. Implication for the origin of nitroalkane anomaly
Ando, Kenichi,Shimazu, Yu,Seki, Natsuko,Yamataka, Hiroshi
experimental part, p. 3937 - 3945 (2011/07/08)
Measurements of rate constants and substituent effects for three important elementary steps of proton-transfer reactions of phenylnitromethane were reported. The Hammett ? values for the deprotonation of ArCH2NO 2 with OH-
Synthesis of unsymmetrical 3,4-diaryl-3-pyrrolin-2-ones utilizing pyrrole weinreb amides
Greger, Jessica G.,Yoon-Miller, Sarah J. P.,Bechtold, Nathan R.,Flewelling, Scott A.,MacDonald, Jacob P.,Downey, Catherine R.,Cohen, Eric A.,Pelkey, Erin T.
supporting information; experimental part, p. 8203 - 8214 (2011/12/04)
A regiocontrolled synthesis of unsymmetrical 3,4-diaryl-3-pyrrolin-2-ones has been achieved in three steps from 1,2-diaryl-1-nitroethenes with pyrrole-2-carboxamides (pyrrole Weinreb amides) serving as the key linchpin intermediates. Two different methods for the preparation of the requisite nitroalkenes were investigated: (1) modified Henry reaction between arylnitromethanes and arylimines; and (2) Suzuki-Miyaura cross-coupling reaction of 2-aryl-1-bromo-1-nitroethenes with arylboronic acids. Some difficulty was encountered in the preparation of arylnitromethanes, thus leading to the exploration of a cross-coupling strategy that proved more useful. A Barton-Zard pyrrole cyclocondensation reaction between 1,2-diaryl-1-nitroethenes and N-methoxy-N-methyl-2-isocyanoacetamide gave the corresponding pyrrole Weinreb amides, which were then converted into the desired 3-pyrrolin-2-ones in two steps. Overall, this method allowed for the construction of 3,4-diaryl-3- pyrrolin-2-ones with complete regiocontrol of the substituents with respect to the lactam carbonyl. The utility of this synthetic methodology was demonstrated by the preparation of eight unsymmetrical and symmetrical 3,4-diaryl-3-pyrrolin- 2-ones including the N-H lactam analogue of the selective COX-II inhibitor, rofecoxib.
Oxidation of azides by the HOF·CH3CN: A novel synthesis of nitro compounds
Carmeli, Mira,Rozen, Shlomo
, p. 4585 - 4589 (2007/10/03)
The HOF·CH3CN complex, readily prepared by passing F 2 through aqueous acetonitrile, is an exceptionally efficient oxygen transfer agent. It is unique in its capacity to oxidize various azides into the corresponding nitro derivatives. This method requires short reactions times and room temperature or below, and the desired nitro compounds were usually isolated in very good yields. The respective nitroso derivatives are believed to be the intermediates in this reaction. Functional groups such as aromatic rings, ketones, nitriles, halides, alcohols, and esters are tolerated. Sulfides react with HOF·CH3CN usually at the same rate as azides. Amines and olefins, however, react faster, so they have to be protected first. Nitro derivatives with various oxygen isotopes can be made using the labeled H 18OF·CH3CN. In the case of chiral azides the stereochemistry around the nitrogen-bonded carbons is retained.
The Kinetics and Mechanism of Proton Transfer from 4- Nitrophenylnitromethane to Triethylamine
Volkov,Afanas'ev
, p. 1937 - 1941 (2007/10/03)
The rate constants for the forward and back proton transfer reactions between 4-nitropehenylnitromethane and triethylamine in aprotic solvents, whose permittivities varied in a wide range, were determined by the stopped flow method. A quantum-chemical stu
Solvent Effects on Proton Transfer Reactions: Benzoate Ion Promoted Deprotonation Reactions of Arylnitromethanes in Methanol Solution
Gandler, Joseph R.,Saunders, Oliver L.,Barbosa, Ronald
, p. 4677 - 4682 (2007/10/03)
Second-order rate constants and equilibrium constants have been determined for the benzoate ion promoted deprotonation reactions of (m-nitrophenyl)nitromethane, (p-nitrophenyl)nitromethane, and (3,5-dinitrophenyl)nitromethane in methanol solution. The pK
