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Derivatives of ferrocenyl-substituted aziridinyl methanol (FAM) ligands were used with zinc metal for asymmetric aza-Henry (nitro-aldol) reaction of N-Boc protected imines with nitroalkanes. At optimized reaction conditions Zn-PFAM1 catalyst system with a variety of aromatic imines provided products in up to 77% ee and 88% yield. In addition, the reaction of N-Boc substituted imines with nitroethane also proceeded smoothly with moderate enantioselectivities and diastereoselectivities. [ABSTRACT FROM AUTHOR]

Ambient temperature static high pressure compression of liquid nitroethane has been performed using the diamond anvil technique. The first transition to a crystalline powder around 4.2 GPa did not return reliable indexing solutions and could be the result of a mixture of phases. Subsequent cycling of the pressure apparatus with the same sample triggered a solid-solid transition around 4.9-4.3 GPa on the downstroke. Indexing returned a monoclinic structure with spacegroup P21 or P21/m which is consistent with the lowest enthalpy solution predicted from density functional theory (DFT) calculations performed in this study, namely, P21. Attempts to reproduce the first anomalous mixture of phases with other samples were not successful; rather, the numerically preferred monoclinic structure manifests itself after a liquid-solid transition around 4.3-3.6 GPa, a value consistent with the results of a previous study. The transition typically occurs more readily on the downstroke. Incomplete Debye rings resulting from preferred orientation complicates any Rietveld refinement, though the DFT simulations predict 2 molecules per unit cell. Unit cell volumes during the upstroke were within 3% of that predicted by DFT calculations. This departure increases to about 9% below that from DFT predictions during the downstroke suggesting the presence of residual stresses due to non-hydrostatic conditions. Finally, a sudden relief in d-spacing values around 3.7-4.3 GPa during the downstroke is thought to be due to the influence of intermolecular hydrogen bonding. [ABSTRACT FROM AUTHOR]

Nitroethane is a potent methane-inhibitor for ruminants but little is known regarding simultaneous effects of repeated administration on pre- and post-gastric methane-producing activity and potential absorption and systemic accumulation of nitroethane in ruminants. Intraruminal administration of 120 mg nitroethane/kg body weight per day to Holstein cows (n = 2) over a 4-day period transiently reduced (P < 0.05) methane-producing activity of rumen fluid as much as 3.6-fold while concomitantly increasing (P < 0.05) methane-producing activity of feces by as much as 8.8-fold when compared to pre-treatment measurements. These observations suggest a bacteriostatic effect of nitroethane on ruminal methanogen populations resulting in increased passage of viable methanogens to the lower bovine gut. Ruminal VFA concentrations were also transiently affected by nitroethane administration (P < 0.05) reflecting adaptive changes in the rumen microbial populations. Mean (± SD) nitroethane concentrations in plasma of feedlot steers (n = 6/treatment) administered 80 or 160 mg nitroethane/kg body weight per day over a 7-day period were 0.12 ± 0.1 and 0.41 ± 0.1 μmol/mL 8 h after the initial administration indicating rapid absorption of nitroethane, with concentrations peaking 1 day after initiation of the 80 or 160 mg nitroethane/kg body weight per day treatments (0.38 ± 0.1 and 1.14 ± 0.1 μmol/mL, respectively). Plasma nitroethane concentrations declined thereafter to 0.25 ± 0.1 and 0.78 ± 0.3 and to 0.18 ± 0.1 and 0.44 ± 0.3 μmol/mL on days 2 and 7 for the 80 or 160 mg nitroethane/kg body weight per day treatment groups, respectively, indicating decreased absorption due to increased ruminal nitroethane degradation or to more rapid excretion of the compound.

In previous work, a novel pathway for the synthesis of ephedrine/pseudoephedrine and methamphetamine using the precursors benzaldehyde, nitroethane and dimethyl carbonate was investigated, and an impurity profile presented. This paper presents chiral and stable isotope ratios of ephedrine/pseudoephedrine and methamphetamine synthesised by this pathway. Based on the chiral profile and the more negative δ 13C (avg. –33.2‰) and more positive δ 2H values, it is possible to distinguish ephedrine/pseudoephedrine and methamphetamine prepared from this pathway from those of "fully synthetic", "semi-synthetic" or "natural" origin. The more positive δ 2H values of methamphetamine from this pathway allowed for differentiation from methamphetamine produced from phenyl-2-propanone. It was noted, however, that the use of stable isotope profiling would likely be limited when a benzaldehyde source having a negative δ 2H value was used as a precursor. Furthermore, the stable isotope values alone could not be used to differentiate from methamphetamine prepared by the Akabori-Momotani reaction, highlighting the need for combination with impurity profiling. [ABSTRACT FROM AUTHOR]

Electrophilic amination of methyl N-(hydroxyphenyl)carbamates and methyl N-(4-methoxyphenyl)carbamate with sodium azide in 86% polyphosphoric acid (PPA) at 55–60°C regioselectively afforded methyl N-(3-amino-2-hydroxyphenyl)-, N-(4-amino-3-hydroxyphenyl)-, N-(3-amino-4-hydroxyphenyl)-, and N-(3-amino-4-methoxyphenyl)carbamates, i.e., the amino group entered the ortho position with respect to the hydroxy or methoxy group. The reactions of methyl N-(4-methoxyphenyl)carbamate with nitromethane and nitroethane in 80% PPA at 95–110°C gave methyl N-(3-carbamoyl-4-methoxyphenyl)carbamate and methyl N-(3-acetamido-4-methoxyphenyl)carbamate, respectively. Methyl N-[4-(N′-hydroxyethanimidamido)phenyl]carbamate was obtained by reaction of 4-[(methoxycarbonyl)amino]benzoic acid with excess nitroethane in 86% PPA at 125°C. [ABSTRACT FROM AUTHOR]

Nitroethane is a representative nitro-containing energetic molecule, and is considered to be a potential propellant and a fuel additive. Thus, understanding its combustion characteristics and chemistry is critical in the development of hierarchical kinetic models of nitro-containing energetic materials. Herein, we investigate the high-temperature ignition kinetics of nitroethane via experimental measurements and kinetic modeling. Ignition delay times of nitroethane are measured using a high-pressure shock tube in the temperature range 900–1150 K, at pressures of 5 and 10 bar, for equivalence ratios of 0.5, 1.0 and 2.0 in diluted air. A detailed kinetic mechanism of nitroethane is updated by incorporating new reaction rate coefficients for hydrogen abstraction reactions that are studied using quantum chemistry calculations at the G4//M06–2X/6–311++ G (d, p) level of theory and transition state theory. The kinetic model simulations using the updated mechanism are in good agreement with the experimental results at all conditions. Reaction path and sensitivity analyses were conducted to understand the ignition kinetics of nitroethane, and the results reveal that abstraction reactions play a critical role in the oxidation of nitroethane in addition to the C–N bond dissociation and HONO elimination reactions. [ABSTRACT FROM AUTHOR]

Nitromethylation of nitrones occurred efficiently in CH3NO2 in the presence of tetramethylammonium fluoride or triazabicyclodecene as promoters. The obtained adducts might be conveniently transformed into vicinal diamines. The process was extended to nitroethane and nitropropane affording mixtures of syn and anti stereoisomers with low diastereoselectivity. Comprehensive study of the addition of nitroalkanes to nitrones was conducted. The reaction proved efficient with TMAF or TBD as bases, in the presence of a large excess of R–NO2. Phase‐transfer catalysis gave also acceptable yields. Nitroethane or nitropropane afforded mixtures of isomerisable diastereomers. The reaction was applied to the synthesis of biologically relevant compounds. [ABSTRACT FROM AUTHOR]

A sustainable route for the Henry reaction of isatins with nitromethane or nitroethane to afford 3‐hydroxy‐3‐(nitroalkyl)indolin‐2‐ones was developed by the catalysis of 1‐butyl‐3‐methyl imidazolium hydroxide (BMIm[OH]) ionic liquid in water‐SDS system. Incorporation of SDS in the reaction medium enhances the reaction rate by suppressing the solubility issues for different substrates particularly for N‐alkylated isatins. This method provides high yield of the condensation product in a shorter reaction time under a very mild condition and in a multi‐gram scale reaction. Moreover, recyclability of the catalyst ionic liquid as well as reaction medium including surfactant makes the present protocol environmentally benign. [ABSTRACT FROM AUTHOR]

Nitroalkane oxidase (NAO) and nitronate monooxygenase (NMO) are two different types of nitroalkane oxidizing flavoenzymes identified in nature. A previous study suggested that the hypothetical protein PA4202 from Pseudomonas aeruginosa PAO1 is NMO and utilizes only anionic nitronates. However, the structural similarity between the PA4202 protein and Streptomyces ansochromogenes NAO has motivated investigation for what features of the two enzymes differentiate between the NAO and NMO activities. Herein, we report the crystal structure of PA4202 in a ternary complex with a neutral nitroethane (NE) and flavin mononucleotide (FMN) cofactor to elucidate the substrate recognition mechanism using a site-directed mutagenesis. The ternary complex structure indicates that the NE is bound with an orientation, which is poised for the proton transfer to H183 (which is the essential first catalytic step with nitroalkanes), and subsequent reactions with FMN. Moreover, a kinetic study reveals that the catalytic reactions of the wild type and H183 mutants PA4202s with nitroalkane substrates may yield the products of hydrogen peroxide and nitrite that are specified to NAO, although they show a low catalytic efficiency. Our results provide the first structure-based molecular insight into the substrate binding property of the hypothetical protein PA4202, including the interactions with neutral nitroalkanes as the substrate. [ABSTRACT FROM AUTHOR]

Methanogenic substrate loss is reported to be a major bottleneck in microbial fuel cell (MFC), which significantly reduces the power production capacity and coulombic efficiency (CE) of this system. Nitroethane is found to be a potent inhibitor of hydrogenotrophic methanogens in rumen fermentation process. Influence of nitroethane pre-treated sewage sludge inoculum on suppressing the methanogenic activity and enhancing the electrogenesis in MFC was evaluated. MFC inoculated with nitroethane pre-treated anodic inoculum demonstrated a maximum operating voltage of 541 mV, with CE and maximum volumetric power density of 39.85% and 20.5 W/m3, respectively. Linear sweep voltammetry indicated a higher electron discharge on the anode surface due to enhancement of electrogenic activity while suppressing methanogenic activity. A 63% reduction in specific methanogenic activity was observed in anaerobic sludge pre-treated with nitroethane, emphasizing the significance of this pre-treatment for suppressing methanogenesis and its utility for enhancing electricity generation in MFC. [ABSTRACT FROM AUTHOR]

A class of aliphatic short chain nitrocompounds have been reported as being capable of CH4 reduction both in vitro and in vivo. However, the laboratory evidence associated with the metabolic fate of nitrocompounds in the rumen has not been well documented. The present study was conducted to compare in vitro degradation and metabolism of nitroethane (NE), 2-nitroethanol (NEOH), and 2-nitro-1-propanol (NPOH) incubated with mixed rumen microorganisms of dairy cows. After 10 mM supplementation of nitrocompounds, a serious of batch cultures were carried out for 120 h under the presence of two substrates differing in the ratio of maize meal to alfalfa hay (HF, 1:4; LF, 4:1). Compared to the control, methane production was reduced by 59% in NPOH and by >97% in both NE and NEOH, and such antimethanogenic effects were more pronounced in the LF than the HF group. Although NE, NEOH, and NPOH addition did not alter total VFA production, the rumen fermentation pattern shifted toward increasing propionate and butyrate and decreasing acetate production. The kinetic disappearance of each nitrocompound was well fitted to the one-compartment model, and the disappearance rate (k, %/h) of NE was 2.6 to 5.2 times greater than those of NEOH and NPOH. Higher intermediates of nitrite occurred in NEOH in comparison with NPOH and NE while ammonia N production was lowest in NEOH. Consequently, a stepwise accumulation of bacterial crude protein (BCP) in response to the nitrocompound addition was observed in both the HF and LF group. In brief, both NE and NEOH in comparison with NPOH presented greater antimethanogenic activity via the shift of rumen fermentation. In addition, the present study provided the first direct evidence that rumen microbes were able to cleave these nitrocompounds into nitrite, and the subsequent metabolism of nitrite into ammonia N may enhance the growth of rumen microbes or promote microbial activities.

The explosion hazards characterizing vapor-liquid mixtures (mists) are commonly overlooked, resulting in significant damage within processing industries that use these mixtures. This article presents new experimental data that enable the quantitative evaluation of the effects of vapor-liquid mixtures of nitroethane/air on various explosion parameters. A series of experiments was conducted as follows: First, at mean Sauter mean diameter (SMD, D32=6Vp/Ap, where Ap and Vp are the surface area and volume of the particle, respectively) values of 19.33 and 33.75 μm, two sets of vapor-liquid mixtures of nitroethane/air at various concentrations were obtained. Subsequently, experiments were conducted, and the explosion pressure and temperature of the two sets of vapor-liquid mixtures of nitroethane/air at various concentrations were analyzed. The flame temperatures and explosion pressures, maximum rate of pressure rise [dP/dt]max, maximum rate of temperature rise [dT/dt]max, flame propagation delay time, and lower explosion limit (LEL) were analyzed. At both mean SMD values (19.64 and 34.40 μm), the peak pressure of the vapor-liquid mixtures of nitroethane/air increased as the total concentration was increased, within the flammable range. However, the total concentration of the maximum peak temperature at a mean SMD of 19.64 μm was less than that at a mean SMD of 34.40 μm, with values of 418.38 and 631.20 g m−3, respectively. For a similar concentration of the gaseous-phase or vapor-liquid mixture of nitroethane/air, the [dP/dt]max of the vapor-liquid mixtures of nitroethane/air was significantly larger than that of the gaseous-phase nitroethane/air mixtures. [ABSTRACT FROM AUTHOR]

A simple model for binary liquid-liquid equilibrium data correlation is explored. The model describes liquid-liquid equilibrium in terms of Henry's law and unsymmetrically normalized activity coefficients in each phase. A procedure for parameter estimation including an approach to initial guesses, uncertainty analysis of regression results, obtained parameters, and predicted mole fractions has been formulated. The procedure is applied to three cases: hydrocarbons + water, ionic liquids + water, and nitroethane + hydrocarbons. The model has four parameters in the most basic formulation. Depending upon the available data, this number can be extended in a systematic fashion. We compare results of correlation to results obtained with a four-parameter nonrandom two-liquid (NRTL) equation and COSMO-SAC. In general, the new model does nearly as well as NRTL. Advantages of the presented model are a simple form and a parameter set that can be extended in a systematic fashion with an interpretation in terms of thermodynamic properties. The model may be developed further for validation of experimental data. [ABSTRACT FROM AUTHOR]

Australian clandestine drug laboratories are constantly utilising alternative methods to produce methamphetamine, in part as restrictions are placed by Government on, for example, chemicals such as phenyl-2-propanone (P2P) (in the early 1980s), or on pseudoephedrine-containing pharmaceuticals, from the mid-2000s. This paper discusses the nitro-aldol reaction occurring between nitroethane and benzaldehyde, which can be utilised in a number of differing routes, in the presence of different bases. The resulting products, namely phenyl-2-nitropropene (P2P pathway) and 2-nitro-1-phenyl-1-propanol (ephedrine pathway) are directly dependant on which base is used; as such, the base may be used to provide an indication of a possible manufacture pathway of methamphetamine at a clandestine laboratory. [ABSTRACT FROM PUBLISHER]

In a continuation from a previous work, experimental densities, speeds of sound, and refractive indices data, for eight binary liquid mixtures of nitroethane with 1,1,2,2-tetrachloroethane, 1,1,1-trichloroethane, trichloromethane, 1,2-dichloroethane, 1,3-dichloropropane, 1,4-dichlorobutane, 1-chlorobutane and 1-chloropentane were measured in the temperature range of (298.15–318.15) K and at atmospheric pressure. From the measured data the derived properties, such as the excess molar volumes, the isentropic compressibility, the deviations in isentropic compressibility, the deviations in refractive indices, the molar refractions and the deviations in molar refractions data have been calculated. The excess properties of the binary mixtures were correlated by the Redlich–Kister type polynomials using a robust regression along the gnostic influence function. Speed of sound and isentropic compressibility data have been compared with calculated values from Jacobson free length theory (FLT), Nomoto's relation (NR), Zhang Junjie's relation (JR), Van Deal's ideal mixing relation (IMR), Impedance dependence relation (IDR) and Schaaff's collision factor theory (CFT). The ability of different theoretical ( n , ρ ) mixing rules (Lorentz–Lorenz, Gladstone–Dale, Arago–Biot, Edwards and Eykman) to predict the refractive indices was evaluated. The experimental and calculated results are discussed in terms of molecular interactions and structural effects between components of mixtures. [ABSTRACT FROM AUTHOR]

The three phase separation due to contact between binodals was observed for the ternary system nitroethane(NE) + methylcyclohexane(MCH) + polystyrene(PS) with the molecular weight (M w = 9.64 × 10 4 g/mol). A phase equilibrium experiment was made to determine binodals and three phase triangles on a composition triangle. With decreasing temperature a binodal spreads out from the MCH-PS side of a composition triangle at 48.4 °C and reaches the NE-MCH side at 23.6 °C. Another binodal spreads out from the NE-PS side at 43.6 °C and makes contact with the binodal running between the MCH-PS and NE-MCH sides at 3.3 °C. Simultaneously with the contact the three phase separation appears. The contact occurs at the critical point of the former binodal and at a noncritical point of the latter. The three phase separation usually occurs due to projection of a new binodal from the two phase region. [ABSTRACT FROM AUTHOR]

In this paper, heart-cutting two-dimensional GC/MS (GC–GC/MS) method in combination with a simple sample collection procedure was developed for the determination of 6 nitroalkanes in mainstream cigarette smoke. The method could remove large amounts of impurities on-line in the first polar column by heart-cuts and separate from the left interferences in a second mid-polar column. And the target compounds could be focused at the inlet of the second column by cryo-concentration. Compared to conventional GC/MS, GC–GC/MS achieved a lower noise level and sensitivity at least an order of magnitude higher. Furthermore, the GC–GC/MS method could avoid the false negative and false positive results that appeared in the compared conventional GC/MS analysis. By trapping the vapor phase of 20 cigarettes smoke, the LODs and LOQs of the nitroalkanes were 1.3 to 9.8 and 4.3 to 32.6 ng/cigarette, respectively, and all linear correlation efficiencies were larger than 0.999. The validation results also indicate that the method has high accuracy (spiked recoveries between 84% and 102%) and good repeatability (RSD between 7.2% and 9.4%). The developed method was applied to analyze 1 Kentucky reference cigarette (3R4F) and 10 Chinese commercial brands of cigarettes. The research results indicated that nitromethane, nitroethane, 2-nitropropane and 1-nitro- n -pentane were detected in mainstream cigarette smoke, but 1-nitro- n -butane and 2-nitropropane, which were reported by one previous study, were not detected in all cigarette samples. [ABSTRACT FROM AUTHOR]

The article discusses the development of the synthetic method of 1,3,4-trisubstituted benzenes from Morita-Baylis-Hillman (MBH) adducts. Topics covered include the construction of functionalized benzene ring in a regioselective way, the introduction of nitroethane at the primary position of the MBH adduct and the assessment of primary nitroalkanes under the same reaction conditions.

A density functional theory (DFT) study was performed to elucidate the mechanism for the [5 + 1] benzannulation of nitroethane and α-alkenoyl ketene-( S,S)-acetals. The calculation results are consistent with experimental findings, showing that the reaction proceeds via deprotonation of nitroethane, nucleophilic addition, intramolecular cyclization, elimination of HNO2, and the keto-enol tautomerization sequence. It was disclosed that N,N-dimethylformamide (DMF) and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) act as not only solvent and nonnucleophilic base, respectively, but also catalysts in the reaction by stabilizing the transition states (TSs) and intermediates via intermolecular hydrogen bonds and electrostatic interactions. Besides, the effective orbital interaction of the reaction site in TS also contributes to the intramolecular cyclization step. The new mechanistic insights obtained by DFT calculations highlight that the hydrogen bonds and electrostatic interactions are key factors for the [5 + 1] benzannulation of nitroethane and α-alkenoyl ketene-( S,S)-acetals. © 2015 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Two complexes [KLa(HL1)2{(CH3)2NCHO}2(H2O)3] (1) and [Sm(H2O)9](E-H2L2)3·2H2O (2) were synthesized by the reaction of lanthanum(iii) and samarium(iii) nitrates with potassium 3-(2-(2,4-dioxopentan-3-ylidene)hydrazinyl)-2-hydroxy-5-nitrobenzenesulfonate (KH2L1) and potassium (E,Z)-5-chloro-3-(2-(1,3-dioxo-1-phenylbutan-2-ylidene)hydrazinyl)-2-hydroxybenzenesulfonate (KH2L2), respectively. Both complexes were fully characterized by elemental analysis, IR, 1H and 13C NMR spectroscopy, ESI-MS and single-crystal X-ray diffraction. Cooperative E,Z→E isomerization of KH2L2, induced by resonance assisted hydrogen bonding and ionic interactions, occurs upon the interaction with Sm(iii). Catalytic activities of KH2L1,2 and their lanthanide derivatives were evaluated in the Henry reaction of nitroethane with a variety of aromatic and aliphatic aldehydes. Good yields (up to 91%) and diastereoselectivities (syn/anti 3 : 1) were observed in the reactions catalyzed by 1 in water. [ABSTRACT FROM AUTHOR]

The intermolecular complex with aCHN hydrogen bond formed by 1,1-dinitroethane(DNE) and 2,4,6-trimethylpyridine (collidine) dissolved in CD2Cl2was studied experimentally by 1HNMR spectroscopy at 180–300 K. Equilibrium between the molecularCH···N form and the zwitterionic C–/HN+form was detected in the slow exchange regime inthe NMR time scale. No sign of a direct C–···HN+bond was observed; the ion pair is likely to be held by Coulombinteractions. Moreover, there are indications that the protonatedbase is involved in the formation of homoconjugated (NHN)+collidine–collidinium hydrogen bonded complexes. The reactionpathway of proton transfer in the DNE–pyiridine complex ina vacuum was studied computationally at the B3LYP/6-31++G(d,p) levelof theory. NMR chemical shifts and coupling constants were calculatedfor a series of snapshots along the proton transfer coordinate. Whilethe central carbon atom has a pyramidal (sp3) configurationin DNE, it is flat (sp2) in the DNE carbanion. As a result,the most indicative computed NMR parameter reflecting hybridizationof a carbon atom appeared to be 1JCC, which starts to change rapidly as soon as a structure witha quasi-symmetric C··H··N bond is reached. Couplingswithin the hydrogen bridge, 1JCH, 1hJHN, and 2JCN, can serve as good indicators of the degreeof proton transfer. [ABSTRACT FROM AUTHOR]

Dihydroxylammonium 5,5′-bistetrazole-1,1′-diolate (TKX-50) emerged as a novel energetic material with low sensitivity and excellent calculated detonation performance. The compatibility of TKX-50 with nitrocellulose (NC), an NC/NG (nitroglycerine) mixture (mass rate: 1.25:1), 2,4-dinitroanisole (DNAN), 2,4,6-trinitrotoluene (TNT), cyclotrimethylenetrinitramine (RDX), ammonium perchlorate (AP), hexanitroethane (HNE), cyclotetramethylenetetranitramine (HMX), hexanitrohexazaisowurtzitane (CL-20), glycidyl azide polymer (GAP), hydroxyl-terminated polybutadiene (HTPB), aluminum powder (Al), boron powder, and centralite was studied by differential scanning calorimetry (DSC). The results show that TKX-50/HNE possesses good compatibility, TKX-50 and HMX have moderate compatibility, and the compatibility of TKX-50 with TNT, CL-20, centralite, NC, AP, Al, and GAP is poor; in addition, TKX-50/RDX, TKX-50/NC + NG, TKX-50/B, and TKX-50/HTPB have poor compatibility. [ABSTRACT FROM AUTHOR]

Polydentate ligands 1 and 2, which incorporate a terminal pyridyl moiety and an oxygen-rich oxalate dihydrizide/malonic dihydrizide spacer moiety, as well as their binuclear metal complexes [Cu212] and [Cu222], which adopt a 1:1 metal/ligand ratio, were synthesized and characterized. Both complexes were screened for their catalytic activity in the nitroaldol reaction, in which [Cu212] worked efficiently as catalyst for both substituted benzaldehyde and pyridinecarboxaldehyde, whereas [Cu222] is highly substrate specific and showed activity towards nitro-substituted aldehydes and pyridinecarboxaldehyde. Furthermore, as helicates are intrinsically chiral, the stereochemical architecture in the binuclear double-stranded Cu2 helicates as catalyst favored the diastereoselective syn product with nitroethane and nitropropane and their respective diastereoselectivities were determined by using ¹H NMR spectroscopy. [ABSTRACT FROM AUTHOR]

The reactivity of 2-alkylthio(2-alkoxy)-substituted 3-aryl(hetaryl)propenals in a one-pot, three-component reaction with primary amines and nitroethane has been studied. A method for the synthesis of highly functionalized pyrroles (in 36–80% yield) from 2-alkylthiopropenals has been developed on the basis of this reaction. It is found that the reaction proceeds via formation of the intermediate imine of the starting enal, which undergoes 1,2-addition by nitroethane to give kinetically controlled 2-alkylthio-3-alkylamino-1-aryl(hetaryl)-4-nitropentene. When left to stand, upon heating or under microwave assistance, this adduct can be transformed into the thermodynamically controlled 1,4-adduct. The latter undergoes intramolecular cyclization to afford the target pyrrole. A possibility of such isomerization of addition products of nitroalkane to 2-functionalized α,β-unsaturated imines is revealed for the first time. Scope of the reaction depending upon its conditions as well as structure of the starting substrates and amines has been studied. [ABSTRACT FROM AUTHOR]

New podands containing pyrrole or pyrazoline fragments have been synthesized. A hypothesis was proposed that closure of the pyrrole ring in the presence of alumina nanoparticles may proceed through 1,4-addition of nitroethane to the chalcone podand to give the Michael adduct rather than through an iminium intermediate usually observed in the reactions of α,β-unsaturated ketones (chalcones) in the presence of Lewis acids. Moderate tuberculostatic activity was found for the starting chalcone podands. Much greater such activity was found upon subsequent modification of the chalcone fragment to give a five-membered heterocycle. Pyrrole derivatives displayed greatest activity among the hetaryl podands obtained. [ABSTRACT FROM AUTHOR]

The asymmetric Michael reaction of nitroalkanes and β,β-disubstituted α,β-unsaturated aldehydes was catalyzed by diphenylprolinol silyl ether to afford 1,4-addition products with an all-carbon quaternary stereogenic center with excellent enantioselectivity. The reaction is general for β-substituents such as β-aryl and β-alkyl groups, and both nitromethane and nitroethane can be employed. The addition of nitroethane is considered a synthetic equivalent of the asymmetric Michael reaction of ethyl and acetyl substituents by means of radical denitration and Nef reaction, respectively. The short asymmetric synthesis of (S)-ethosuximide with a quaternary carbon center was accomplished by using the present asymmetric Michael reaction as the key step. The reaction mechanism that involves the E/Z isomerization of α,β-unsaturated aldehydes, the retro-Michael reaction, and the different reactivity between nitromethane and nitroethane is discussed. [ABSTRACT FROM AUTHOR]

In present work the effects of nitromethane (NM) and nitroethane (NE) as nitrogenated additives on physical properties, combustion performance, and emission of diesel fuel, were studied. Nitrogenated additives have high oxygen content and are considered as oxygenated additives. These additives were blended with diesel fuel, in 1/9 volume ratio. The experimental study was carried out on ECE R-96 8-modes cycle. The result showed that the use of additives reduces viscosity but increases cetane index. In addition, nitrogenated additives increased brake thermal efficiency (BTE) while reduced certain exhaust emissions. Results of AVL SPC 472_MCE97 analysis showed that the addition of NE can reduce the overall smoke value by 44%. The smoke emission decreased at the maximum torque speed (1500 rpm) rather than at the rated power speed (2200 rpm). [ABSTRACT FROM AUTHOR]