Search

Nitroalkanes such as nitromethane, nitroethane, 1-nitropropane (1NP), and 2-nitropropane (2NP), derived from anthropogenic activities, are hazardous environmental pollutants due to their toxicity and carcinogenic activity. In nature, 3-nitropropionate (3NPA) and its derivatives are produced as a defense mechanism by many groups of organisms, including bacteria, fungi, insects, and plants. 3NPA is highly toxic as its conjugate base, propionate-3-nitronate (P3N), is a potent inhibitor of mitochondrial succinate dehydrogenase, essential to the tricarboxylic acid cycle, and can inhibit isocitrate lyase, a critical enzyme of the glyoxylate cycle. In response to these toxic compounds, several organisms on the phylogenetic scale express genes that code for enzymes involved in the catabolism of nitroalkanes: nitroalkane oxidases (NAOs) and nitronate monooxygenases (NMOs) (previously classified as nitropropane dioxygenases, NPDs). Two types of NMOs have been identified: class I and class II, which differ in structure, catalytic efficiency, and preferred substrates. This review focuses on the biochemical properties, structure, classification, and physiological functions of NMOs, and offers perspectives for their in vivo and in vitro applications. • Nitronate monooxygenases (NMOs) are key enzymes in nitroalkane catabolism. • NMO enzymes are involved in defense mechanisms in different organisms. • NMO applications include organic synthesis, biocatalysts, and bioremediation.

A nitrile N-oxide-functionalized polypeptide was synthesized by a two-step method involving the combination of ring-opening polymerization of an α-amino acid N-carboxyanhydride monomer using a primary amine initiator containing a nitroalkane group and a subsequent terminal conversion. The catalyst-free grafting reaction of the formed functionalized peptide with rubbers containing double bonds was achieved with high efficiency. A nitrile N-oxide-functionalized polypeptide was synthesized by a two-step method involving the combination of ring-opening polymerization of an amino acid N-carboxyanhydride (NCA) monomer using a primary amine initiator containing a nitroalkane group and a subsequent terminal conversion. The formed peptide was fully characterized by NMR, FT-IR, and MALDI-TOF MS measurements. The catalyst-free grafting reaction of the formed functionalized peptide with rubbers containing double bonds was achieved with high efficiency via an environmentally benign process. These results surely contributed to the development of novel peptide-grafted polymers.

A facile one-pot, three component reaction has been developed using aldehydes, nitroalkane and sodium azide with zinc oxide nanocatalyst for the synthesis of 4-aryl-NH-1,2,3-triazoles. ZnO nanoparticles with controlled size (15–25 nm) and morphology were prepared using a sonochemical strategy. Structural and morphological study revealed the growth of well crystalline particles along the c axis i.e. [0001] direction due to higher surface energy. The catalysis protocol used in this work offers an efficient and highly economical alternative to the existing methods since the reactions proceed smoothly in green solvent polyethyleneglycol (PEG) 400 under aerobic condition. The reaction has a broad substrate scope resulting in excellent yields of the desired products. The catalyst recovery part was tricky at the initial stages; however an alternative route was successfully introduced to recover the former and reused it for the next cycles of catalytic reaction with excellent retentivity in the catalytic activity. The observed high catalytic efficacy with no significant activity loss using recovered catalyst is mainly due to the retention of morphology and crystal structure of ZnO nanoparticles after many catalytic reactions.

Synthetic control over chirality and function is the crowning achievement for metal-organic frameworks, but the same level of control has not been achieved for covalent organic frameworks (COFs). Here we demonstrate chiral COFs (CCOFs) can be crystallized from achiral organic precursors by chiral catalytic induction. A total of nine two-dimensional CCOFs are solvothermally prepared by imine condensations of the C3-symmetric 1,3,5-triformylphloroglucinol (Tp) with diamine or triamine linkers in the presence of catalytic amount of (R)- or (S)-1-phenylethylamine. Homochirality of these CCOFs results from chiral catalyst-induced immobilization of threefold-symmetric tris(N-salicylideneamine) cores with a propeller-like conformation of one single handedness during crystallization. The CCOF-TpTab showed high enantioselectivity toward chiral carbohydrates in fluorescence quenching and, after postsynthetic modification of enaminone groups located in chiral channels with Cu(II) ions, it can also be utilized as a heterogeneous catalyst for the asymmetric Henry reaction of nitroalkane with aldehydes., Controlling chirality and function in metal organic frameworks has been an achievement, but very difficult to carry out in covalent organic frameworks. Here the authors show chiral covalent organic frameworks that are crystallized from achiral precursors by chiral catalytic induction.

Excess enthalpies, HE, at 298.15 K and atmospheric pressure determined for 12 binary liquid mixtures containing nitromethane or nitroethane+1-chlorobutane, +1-chloropentane, +1-chlorohexane, +1,2-dichloroethane, +1,3-dichloropropane, and +1,4-dichlorobutane by means of a flow 2277-LKB microcalorimeter, are reported on over composition range. The experimental results, along with the literature data on vapor–liquid equilibrium (VLE), excess Gibbs energies, GE, and activity coefficients at infinite dilution, \( \gamma_{\text{i}}^{\infty } \), are interpreted in terms of DISQUAC group contribution model. The systems are characterized by three types of contact surface: nitro (NO2), chlorine (Cl), and alkyl (CH3, CH2). The interchange energy parameters of the alkyl/NO2 and alkyl/Cl contacts were determined independently from the study of alkane+nitroalkane and alkane+chloroalkane systems. The structure-dependent interchange parameters of the NO2/Cl contact are reported in this work. The model provides a fairly consistent description of the VLE and of thermodynamic functions GE, HE, \( \gamma_{\text{i}}^{\infty } \), for all investigated mixtures.

The versatility of nitroaliphatics is demonstrated by using it in the syntheses of artemisinin derived dimers. A few novel artemisinin derived dimer and monomer have been synthesized using nitroalkane as linker.

Based on the experimentally determined values and published data, the enthalpies of formation of nitroalkanes C4–C7 in the standard state and in the gas phase were recommended. The dissociation energies of bonds in these compounds were determined taking into account the enthalpies of atomization and the energies of nonvalent interactions of nitro groups with one another. The calculated values were compared with the available thermal decomposition kinetic data. The dissociation energies of bonds in C4–C7 nitroalkane radicals were also calculated using the enthalpies of atomization and the energies of nonvalent interactions of nitro groups. Regularities of changes in the bond dissociation energies of nitroalkanes C1–C7 and their radicals are established.

The equilibrium geometric parameters, enthalpies of formation of molecular and radical species, and dissociation energies of the C-N bond at 0 and 298 K were determined by the B3LYP density functional method for nitroethane, fluoronitroethanes, chloronitroethanes, and mixed fluorochloronitroethanes. Trends in variation of the geometric and electronic parameters of the molecules, enthalpies of formation, and dissociation energies were discussed.

Physical studies such as Powder X-ray,FT-IR, UV, 1H and 13C NMR clearly identifya 1 : 1 inclusion complex formed betweenβ-cyclodextrin and nitroolefins such asβ-nitrostyrene, 1-nitrocyclohexene in thesolid state as well as in solution. The olefins lieshallow inside the cavity leaving the nitro groupoutside the torus. It has been found that the complexis capable of reacting with aα-phenyl-N-p-methylphenyl nitrone ina 1,3-dipolar cycloaddition with excellent rateacceleration and regioselection. The NaBH4reduction of the complex in the solid state leads tothe corresponding nitroalkane.

A simple one-step preparation of beta-nitroalanine has been developed using the Easton three-component coupling method. To date one limitation of this method has been that use of nitromethane as the nitroalkane component does not yield beta-nitroalanine. We report that use of the dipotassium salt of nitroacetic acid in the Easton three-component coupling gives beta-nitroalanine in high yield, presumably via facile decarboxylation of a beta-nitroaspartate intermediate.

By means of ESR, under conditions of eletrochemical generation of particles, the formation of four types of secondary free radicals has been confirmed in the process of electrochemical reduction of molecules of N-unsubstituted derivatives of 3-nitro-1,4-dihydropyridine in dimthylformamide — specifically, a dianion radical of the molecule of the original compound; an anion radical of the corresponding isomeric 4,5-dihydropyridine; a radical of the nitroalkane type; and in addition, for the compound substituted with a nitrobenzene group; a free radical with the nitrobenzene structure. Methods for synthesis of the individual compounds are described, and a scheme is presented for the mechanism of their electrochemical conversion.

We have studied the reactions of salts of nitroalkanes with tropylium and 2,6-diphenylpyrylium salts leading to products of C-tropylation and C-pyrylation of the corresponding anions. The only exception is the salt of cyanodinitromethane, which is not tropylated. Splitting off of a HNO2 molecule from the products of tropylation of nitroalkane anions to prepare nitroheptafulvenes was unsuccessful.

1. Depending on the number and position of alkyl groups, whenα-,β-, andγ-alkyl derivatives of N-nitropyridinium salts react with nitroalkane salts, they form products of nitration and nitrosation of the nitro-alkane anions, aγ-nitroalkylation product of N-nitropyridinium, or a mixture of these products. 2. β-Alkyl derivatives of N-nitropyridinium salts with a 2,2-dinitroethane anion form onlyγ-dinitroethylation products of N-nitropyridinium.

1. Reduction of nitroacetonitrile and 2-cyano-2-nitropropane proceeds through attack at the nitrogroup N-O bond. 2. The details of the structure of the anion formed through C-N bond rupture will determine whether nitroalkane reduction, will proceed through the C-N or N-O bonds.

The present work has led to certain basic rules applying to the electrochemical reduction of CH acids in the polynitroalkane series. 1. Reduction of the un-ionized form of the polynitro compound is initiated by C-N bond rupture, rather than by breaking the N-O bond of the nitro group. 2. Rupture of the C-N bond is followed by chemical reactions involving the product anion; three different processes are possible at this point, a Nef reaction, protonation, and nitrosation. The ratio of the rates of these three reactions determines the polarographic behavior of the un-ionized polynitro compound, the ratio itself depending on the acidity of the solution and the nature of the intermediate nitroalkane anion. 3. Succession effects appear in the reduction of the un-ionized forms of the polynitroalkanes the waves for the intermediate reduction products on the polarograms of the un-ionized forms differing from the waves of the individual compound as recorded for comparison.

When alkynes are reacted with strong inorganic acids in a nitroparaffin medium a new reaction is observed, representing the “conjugated” addition of a proton and the nitroalkane moiety to the triple bond, with the formation ofα-substituted functional derivatives of ketones.

The 1,2,4-triazolylhydrazones of the corresponding nitro aldehydes were obtained by the reaction of the anions of nitromethane, nitroethane, and 1-nitropropane with diazo-1,2,4-triazoles. 2-Nitropropane, 1,1-dinitroethane, 1,1-dinitropropane, and trinitromethane form 1,2,4-triazolylazonitro compounds.

1. Measurements have been made of electroosmotic transport of aqueous phosphate nitroalkane solutions through oxidized and unoxidized high-purity graphite diaphragms. 2. The variation of the electroosmotic transport with the molecular weight of the adsorbed compound is such as to indicate that the nitroalkane molecule is preferentially normally oriented with respect to the oxidized surface, and preferentially tangentially oriented with respect to the unoxidized surface.

Δ2-Isoxazolines were obtained from the reaction of alkenes with nitrile N-oxides, generatedin situ from primary nitroalkane salts in presence of toluenesulfonyl chloride.

1. The PMR spectra of a number of nitro compounds were studied. As in the case of other electronegative groups, the introduction of fluorine atoms into a nitroalkane molecule leads to a shift in the PMR signal of theα-hydrogen toward weaker fields. 2. Except in the case of the introduction of fluorine atoms, the change in the chemical shift of theα-hydrogen in the PMR spectra of nitroalkanes on introduction of electronegative substituents is related symbatically to the change in the ionization constants of these compounds. 3. The introduction of fluorine atoms in theβ-position relative to the nitro group increases the chemical shift of theα-hydrogen in the PMR spectrum and simultaneously increases the ionization constant of the nitro compound. The introduction of fluorine in theα-position leads to increase in the chemical shift of theα-hydrogen and lowering of the ionization constant.

1. In the case of acetaldol and nitromethane, nitroethane, and 2-nitropropane it was shown that in presence of barium hydroxide condensation of acetaldol and nitroalkane takes place, the corresponding mononitrodiol being formed, dehydration of which leads to the corresponding mononitrodienes. 2. By condensing acetaldol with 1,1-dinitroethane, 2,2-dinitrodecanetetrol-3,5,7,9 is formed.

1. Fluorolysis occurs with fluorination of the dipotassium salt of tetranitroethane in the solid phase, and the reaction products are 1,2-difluorotetranitroethane; 1,1,2-trifluorotrinitroethane; and 1,1,2,2,-tetrafluorodinitroethane. 2. The dipotassium salt of tetranitroethane is the first example of a nitroalkane fluorinated in water. In this case fluorolysis did not occur. The principal and practically the sole product was 1,2-difluorotetranitroethane.