Reaction Of Nitromethane Research Articles

Reaction of Nitromethane with Phenylacetylene in Superbasic Medium

Reaction of Nitromethane with Phenylacetylene in Superbasic Medium

Phonon anharmonicity and the pressure dependence of phonon lifetime for solid nitromethane by ab initio calculations

Phonon anharmonicity is important for energy transfer in energetic materials. Here we have investigated the vibrational anharmonicity including phonon lifetime, mode Grüneisen parameters and lattice thermal conductivity of solid nitromethane using first-principles calculations combining Boltzmann transport equation theory. The calculated structural and vibrational properties of solid nitromethane agree well with experimental results. It’s found that the CN stretching mode among all phonons has the longest lifetime with 99.3 ps at ambient condition. It’s worth noting that this would allow the vibrational energy to reside in this mode for a long time, leading to the formation of “hot” chemical bond and further its rapture. This is consistent with the previous report that the breakage of CN bond may be the initial reaction in nitromethane. The results also show the lifetimes of internal modes are generally higher than those of lattice modes. And the mode Grüneisen parameters indicate that the lattice modes are much more sensitive to the volume change than internal modes. Moreover, the lattice thermal conductivity of solid nitromethane shows obvious anisotropy. Finally, the influence of hydrostatic pressure on the phonon lifetime of solid nitromethane was also calculated and discussed.

1,2‐Diamine‐Derived (thio)Phosphoramide Organocatalysts in Asymmetric Michael Additions

AbstractPhosphoramides and thiophosphoramides were prepared from optically pure C2‐symmetric 1,2‐diamines and were used as chiral organocatalysts in the asymmetric Michael additions of aldehydes and ketones to N‐substituted maleimides. The 1,2‐diphenylethane‐1,2‐diamine derived thiophosphoramide, which could be prepared in good yield in a one‐step procedure, was found to be more active and selective catalyst in the addition of aldehydes to various maleimide derivatives, when compared to sulfonamides having the same backbone. Products resulted in reactions of ketones with maleimides were also obtained in high yields and enantioselectivities.The thiophosphoramide derivative was also efficient in the asymmetric conjugate addition of carbonyl compounds to β‐nitrostyrene and in the reaction of nitromethane with α,β‐unsaturated ketones.Based on results obtained with (thio)phosphoramides in asymmetric additions to maleimides it was suggested that a weaker, more flexible hydrogen‐bonding of the rigid electrophile to the catalyst is responsible for the improved performance of these bifunctional organocatalysts, as compared with sulfonamides.magnified image

Free energy profile and microkinetic modeling of base-catalyzed conjugate addition reaction of nitroalkanes to α,β-unsaturated ketones in polar and apolar solvents

Michael reactions involving nitroalkanes and enones are important carbon-carbon bond formation reactions. These reactions are base-catalyzed, and during the past 15years, the asymmetric version using bifunctional amino-thiourea organocatalyst has been developed. In this work, the reaction of nitromethane and 4-phenyl-3-buten-2-one, catalyzed by the methoxide ion and piperidine as bases, was investigated by theoretical calculations. We obtained the theoretical free energy profile and did a microkinetic analysis of the catalytic cycle. The direct reaction of the CH2NO2- ion and the enone is very favorable, with a free energy of activation of 21.1kcalmol-1 in methanol solvent. However, the generated MS2 product works like an inhibitor of the catalysis, and the effective barrier in the catalytic cycle becomes 25.5kcalmol-1, leading to slow kinetics at room temperature. In the case of the reaction in apolar solvent (toluene), we found a pathway involving isomerization from the CH3NO2 reactant to the CH2NO2H species, and the latter makes a nucleophilic attack on the enone. Piperidine works like a bifunctional catalyst. In this case, the barrier is very high (32.5kcalmol-1), indicating the importance of the polar environment to accelerate the reaction in the catalytic cycle. Graphical abstract Base-catalyzed conjugate addition reaction of nitroalkanes to α,β-unsaturated ketones.

Hybrid‐Type Squaramide‐Fused Amino Alcohol Organocatalysts for Enantioselective Nitro‐Aldol Reaction of Nitromethane with Isatins

A series of hybrid‐type squaramide‐fused amino alcohol (SFAA) catalysts were synthesized, and their catalytic efficiency in the enantioselective nitro‐aldol reaction of various isatins with nitromethane has been described. This transformation afforded chiral 3‐substituted 3‐hydroxyoxindoles in excellent chemical yields (up to 99 %) with high enantioselectivities (up to 95 % ee). The resulting chiral 3‐hydroxyoxindoles can be further used as synthetic precursors for the synthesis of several natural products that have a broad spectrum of fascinating biological activities.

ChemInform Abstract: Synthesis and Applications in Henry Reactions of Novel Chiral Thiazoline Tridentate Ligands.

Several novel chiral tridentate ligands containing thiazoline were efficiently synthesized from commercially available l=cysteine in high yield. These ligands were subsequently applied to the asymmetric Henry reaction of nitromethane and various aldehydes. It was found that the structures of the thiazoline ligands had a significant influence on the enantioselectivity. It was shown that the optimal catalyst for this reaction was a ligand complexed with CuCl, which was formed from chiral thiazoline with chiral aminoalcohol. At −20°C, with 10 mol% of this ligand, a product with (S)-configuration was isolated in 93% yield and 98% enantiomeric excess. Copyright © 2015 John Wiley & Sons, Ltd.

Reactions of stabilized aliphatic carbanions with esters of formic acid in the gas phase.

The reactions of nitromethane, acetonitrile, and ethyl acetate carbanions with formic acid esters were investigated in the gas phase by mass spectrometry and quantum chemical calculations. It was found that the carbanion of nitromethane practically does not react with formic acid esters and only traces of the Claisen- type addition-elimination reaction product were observed. In the case of the deprotonated acetonitrile, the Claisen-type condensation that yielded the carbanion of cyanoacetaldehyde proceeded almost quantitatively for all the studied formates. Other products, like the Riveros reaction product, were observed in minor amounts. The ethyl acetate carbanion reacts with formates in a much more complex way because it decomposes in a collision cell, yielding the deprotonated ketene anion, which also can react with formic acid esters. Consequently, the Claisen condensation reaction products of both anions were observed as well as the products of other reactions. All the proposed reaction pathways were confirmed by quantum chemical calculations, including the transition-state energies.

ChemInform Abstract: Asymmetric Henry Reactions Catalyzed by Copper(II) Complexes of Chiral 1,2,4‐Triazine‐oxazoline Ligands: The Impact of Substitution in the Oxazoline Ring on Ligand Activity.

Abstract An enantiomerically pure 1,2,4-triazine-oxazoline ligand with an indanol-derived substituent in the oxazoline ring has been synthesized using Buchwald–Hartwig amination of 3-bromo-1,2,4-triazine. The catalytic efficiency of the ligand was estimated in the asymmetric nitroaldol (Henry) reaction of nitromethane with several aromatic and aliphatic aldehydes. The appropriate nitroaldol products were formed in good yields (up to 91%) and with up to 92% ee. In order to investigate the influence of the conformational rigidity and the additional stereocenter in the oxazoline ring on the catalytic activity of the ligand, a 1,2,4-triazine-oxazoline ligand with two phenyl substituents in the oxazoline ring was synthesized and tested in the asymmetric nitroaldol reaction.

ChemInform Abstract: An Efficient One‐Pot Synthesis of 1,4‐Oxathiane and 1,4‐Thiomorpholine Derivatives.

AbstractAttempts to prepare the spirocyclic product (XI) fail.

Reaction of Nitromethane with Cinnamoyl Derivatives of Cyclic β-dicarbonyl Compounds. Application to the Synthesis of 2(3)-(4-aryl-pyrrolidin-2-ylidene)-1,3(2,4)-diones*

We have shown that reaction of nitromethane with cinnamoyl derivatives of five- and six-membered carbo- and heterocylic β-dicarbonyl compounds in the presence of 1,1,3,3-tetramethylguanidine proceeds according to the mechanism of 1,4-conjugate addition to the enone fragment of cinnamoyl moiety to give 2(3)-( 3-aryl-4-nitrobutanoyl)-substituted cyclic 1,3- or 2,4-diones in good to excellent yields. Chemoselective reduction of nitro function of the latter leads to synthetically useful and biologically interesting 2(3)-(4-arylpyrrolidin-2-ylidene) derivatives.

Asymmetric Henry reactions catalyzed by copper(II) complexes of chiral 1,2,4-triazine-oxazoline ligands: the impact of substitution in the oxazoline ring on ligand activity

An enantiomerically pure 1,2,4-triazine-oxazoline ligand with an indanol-derived substituent in the oxazoline ring has been synthesized using Buchwald–Hartwig amination of 3-bromo-1,2,4-triazine. The catalytic efficiency of the ligand was estimated in the asymmetric nitroaldol (Henry) reaction of nitromethane with several aromatic and aliphatic aldehydes. The appropriate nitroaldol products were formed in good yields (up to 91%) and with up to 92% ee. In order to investigate the influence of the conformational rigidity and the additional stereocenter in the oxazoline ring on the catalytic activity of the ligand, a 1,2,4-triazine-oxazoline ligand with two phenyl substituents in the oxazoline ring was synthesized and tested in the asymmetric nitroaldol reaction.

Ultrafast Chemical Reactions in Shocked Nitromethane Probed with Dynamic Ellipsometry and Transient Absorption Spectroscopy

Initiation of the shock driven chemical reactions and detonation of nitromethane (NM) can be sensitized by the addition of a weak base; however, the chemical mechanism by which sensitization occurs remains unclear. We investigated the shock driven chemical reaction in NM and in NM sensitized with diethylenetriamine (DETA), using a sustained 300 ps shock driven by a chirped Ti:sapphire laser. We measured the solutions' visible transient absorption spectra and measured interface particle and shock velocities of the nitromethane solutions using ultrafast dynamic ellipsometry. We found there to be a volume-increasing reaction that takes place around interface particle velocity up = 2.4 km/s and up = 2.2 km/s for neat NM and NM with 5% DETA, respectively. The rate at which transient absorption increases is similar in all mixtures, but with decreasing induction times for solutions with increasing DETA concentrations. This result supports the hypothesis that the chemical reaction mechanisms for shocked NM and NM with DETA are the same. Data from shocked NM are compared to literature experimental and theoretical data.

Electron transfer reactions of nitromethane, acetaldehyde and benzaldehyde with (H2O)n−, CO2[rad]−(H2O)n, and O2−(H2O)n, n < 110, in the gas phase

The reactions of nitromethane, acetaldehyde and benzaldehyde with hydrated electrons (H2O)n− and the hydrated radical anions CO2−(H2O)n, O2−(H2O)n, with n<110, were studied by Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry. Electron transfer reactions, with the newly formed radical anion staying in the water cluster, were found to take place for (H2O)n− and CO2−(H2O)n, while O2−(H2O)n were unreactive. The reaction rates for the electron transfer processes were derived assuming pseudo first order kinetics. Thermochemistry was analyzed in the framework of nanocalorimetry. Reaction dynamics governs the measured rates, with benzaldehyde reacting least efficiently. Electron transfer from CO2−(H2O)n is probably associated with a barrier. Hydration seems to stabilize a valence-bound state of CH3CHO(H2O)n−.

Novel catalysts for the enantioselective Henry reaction

Two novel catalytic systems based on the CuII complexes with N-(3,5-dibromo-2-hydroxybenzyl)- and N-(2-hydroxy-3-nitrobenzyl)-(S)-α,α-diphenylprolinols were developed. These systems catalyze the condensation of 4-nitrobenzaldehyde with nitromethane to produce S-nitroaldol with maximum enantiomeric excess of >90% (99% yield). The reactions of nitromethane with aliphatic aldehydes give the corresponding products in the yields above 80% and ee > 90%.

The Henry Reaction in [Bmim][PF6]-based Microemulsions Promoted by Acylase

An environmentally-friendly, enzyme-promoted procedure for the Henry reaction was first studied using water-in-[Bmim][PF6] microemulsions as reaction medium. The Amano acylase from Aspergillus oryzae showed better catalytic activity for the addition reactions of nitromethane with a series of aromatic aldehydes, and a highest yield of 90% was obtained.

Multicomponent reactions for the synthesis of functionalized 1,4-oxathiane-3-thiones under microwave irradiation in water

Abstract A series of substituted 1,4-oxathiane-3-thione derivatives were synthesized via one-pot multicomponent reactions of nitromethane, carbon disulfide and oxiranes in the presence of Et 3 N in water as the solvent under microwave irradiation. Particularly valuable features of this method include high yields of products, broad substrate scope, short reaction time and straightforward procedure.

Regio- and Enantioselective Palladium-Catalyzed Allylic Alkylation of Nitromethane with Monosubstituted Allyl Substrates: Synthesis of (R)-Rolipram and (R)-Baclofen

The Pd-catalyzed asymmetric allylic alkylation (AAA) reaction of nitromethane with monosubstituted allyl substrates was realized for the first time to provide corresponding products in high yields with excellent regio- and enantioselectivities. The protocol was applied to the enantioselective synthesis of (R)-baclofen and (R)-rolipram.

Sc(OTf)3-catalyzed diastereoselective Friedel–Crafts reactions of arenes and hetarenes with 3-phenylglycidates

Five different para-substituted 3-phenylglycidates (3-phenyloxirane-2-carboxylates) were prepared and subjected to reactions with arenes and hetarenes under Lewis acid catalysis. Sc(OTf)(3) was found to effectively (5 mol%) promote a Friedel-Crafts reaction in nitromethane as the solvent. The reaction was shown to proceed stereoconvergently, which makes the intermediacy of a benzylic cation likely. The diastereoselectivities varied depending on the choice of the nucleophile and 3-arylglycidate. Best results were obtained with tert-butyl 3-anisylglycidate, which delivered the respective products with high syn-preference in diastereomeric ratios (d.r.) between 82 : 18 and >95 : 5. The observed selectivity can be explained by a model, according to which the intermediate benzylic cations adopt a preferred conformation, which allows for diastereoface-differentiation by the adjacent stereogenic center.

ChemInform Abstract: Sequential Nitromethane Conjugate Addition/Elimination-Pd-Catalyzed Allylation of β-Trifloxy Acrylates. Application to Carbapenem Synthesis.

Sequential reactions of nitromethane via conjugate addition−elimination to β-trifloxy acrylates followed by Pd-catalyzed substitution of the resulting allyl nitro compounds with nucleophiles afforded homologation products at the β-position. 2-Naphthosultammethyl carbapenem, an anti-MRS carbapenem intermediate, was prepared in one pot from the corresponding 2-trifloxy compound. The scope and limitation of the one-pot method were investigated using several cyclic unsaturated esters and nucleophiles.

Interaction of Dichloride Iron(II) Clathrochelate with Dimercaptomaleodinitrile: Synthesis of the Precursor Monoribbed-Functionalized Phthalocyaninoclathrochelates and the Unexpected Formation of a New Thiophene-Containing Heterocyclic System in the Ribbed Chelate Fragment of the Clathrochelate Framework

Clathrochelate iron(II) FeBd 2(S2C2(CN)2Gm)(BF)2 tris-dioximate with a ribbed vic-dinitrile fragment was synthesized as a precursor of the monoribbed-functionalized hybrid phthalocyaninoclathrochelates by nucleophilic substitution of the vic-dichloride FeBd2(Cl2Gm)(BF)2 clathrochelate (1) with the potassium salt of dimercaptomaleodinitrile. Reaction of nitromethane with this salt was followed by the condensation of the reaction products with 1 to yield the clathrochelate with an annulated previously unknown thiazinothiophene heterocyclic system in the ribbed fragment. Both complexes were characterized on the basis of elemental analysis; MALDI-TOF mass spectrometry; IR, UV-vis, (57)Fe Mössbauer, and NMR spectroscopies; and X-ray crystallography.