Presence Of Nitromethane Research Articles

A facile access to 1-substituted and unsubstituted 3-isoquinolinones via Mannich or Sn2 initiated cascade reactions under catalyst-free conditions.

Herein we report new cascade processes for the easy access to 1-substituted and C-unsubstituted 3-isoquinolinones. The Mannich initiated cascade reaction led to the synthesis of novel 1-substituted 3-isoquinolinones under catalyst-free conditions in the presence of nitromethane and dimethylmalonate as nucleophiles without the use of any solvent. The optimization of the synthesis of the starting material in a more environmentally benign manner, allowed the identification of a common intermediate useful for the synthesis of C-unsubstituted 3-isoquinolinones as well. The synthetic utility of 1-substituted 3-isoquinolinones was also demonstrated.

Anion Radical of Carbonyl Compounds as Electrochemically Generated Base in Henry Reactions: 1,2-Acenaphthenedione

Using 1,2-Acenaphthenedione as an example, cyclic voltammetry, chronoamperometry, coulometry, electrolysis and digital simulation were used to show that electroreduction of carbonyl compounds in the presence of nitromethane in 0.1 M Bu4NClO4/DMF proceeds via the ECE mechanism gives rise nitromethane anion initiating cyclic nitroaldol (Henry) process leading to β-nitroalcohols.

Fluorescence quenching of polycyclic aromatic hydrocarbons within deep eutectic solvents and their aqueous mixtures

Two common and popular deep eutectic solvents (DESs) composed of the salt choline chloride and H-bond donors glycerol and urea in 1:2mol ratio named glyceline and reline, respectively, are investigated for the analysis of polycyclic aromatic hydrocarbons (PAHs) using quenching of both steady-state and time-resolved fluorescence of ten different PAHs by nitromethane at 30°C. Based on their quenching efficiencies, the PAHs are divided into two groups – group 1 is constituted of the five PAHs whose fluorescence are quenched less effectively by nitromethane whereas the other five exhibiting high quenching efficiency are associated to group 2. Quenching of steady-state fluorescence of group 1 PAHs by nitromethane, albeit not very significant, follow a simple Stern-Volmer behavior. The excited-state emission intensity decay of these PAHs, in both absence and presence of nitromethane, fit best to a single exponential model with small but monotonic decrease in lifetimes. The decrease in lifetime also follows Stern-Volmer behavior, however, the quenching constants (KD) are lower than those obtained from steady-state fluorescence (KSV). This is ascribed to the possible formation of charge-transfer complex between the PAH and the nitromethane. Steady-state fluorescence quenching of group 2 PAHs exhibit distinct upward curvature from linear Stern-Volmer behavior implying highly efficient quenching. The intensity decay fits best to a double exponential decay model with longer of the decay times following simple Stern-Volmer behavior. Formation of a complex or the presence of nitromethane within the quenching sphere of action of the PAH having short decay time is proposed. Quenching behavior was found to be similar irrespective of the identity of the DES. A representative group 2 PAH, pyrene, is employed to investigate diffusion dynamics within aqueous mixtures of the two DESs. The bimolecular quenching rate constant (kq) is found to increase linearly with the mole fraction of water (xw) in aqueous mixtures of both the DESs. Stokes-Einstein relationship is not obeyed within the DES aqueous mixtures and is attributed to be due to the inherent heterogeneity of the mixtures. Diffusion dynamics of pyrene-nitromethane pair is compared with that of a tracer fluorescein isothiocyanate obtained using fluorescence correlation spectroscopy. Good correlation between the two highlights generality of diffusion dynamics with aqueous DES mixtures as far as solutes are concerned.

Point of care testing provides an accurate measurement of creatinine, anion gap, and osmolal gap in ex-vivo whole blood samples with nitromethane

Context. Nitromethane interferes with Jaffé measurements of creatinine, potentially mimicking acute kidney injury. Objectives. We determined the proportional contribution of nitromethane in blood samples to creatinine measured by the Jaffé colorimetric and the point-of-care (POC) reactions and determined whether the difference can reliably estimate the concentration of nitromethane. Additionally, we determined whether the presence of nitromethane interferes with anion/osmolal gaps and ascertained the stability of nitromethane in serum after 7 days. Methods. Nitromethane was added to whole blood from four healthy volunteers to achieve concentrations of 0, 0.25, 0.5, 1, and 2 mmol/L. The following tests were performed: creatinine (Jaffé and POC), electrolytes (associated with Jaffé and POC), osmolality and nitromethane concentration (gas chromatography [GC]). Remaining samples were refrigerated and reanalyzed using GC at 7 days. Anion and osmolal gaps were calculated. Proportional recovery and degradation of nitromethane were measured using GC. Data were analyzed for agreement with single-factor ANOVA (p = 0.05). Results. Mean creatinine for POC and Jaff methods were 0.93 vs. 0.76 mg/dL, respectively. Jaff creatinine concentrations increased linearly with increasing nitromethane concentrations (R2 = 1, p = 0.01): measured creatinine (mg/dL) = 7.1*nitromethane (mmol/L) = 0.79. POC creatinine remained unchanged across the range of nitromethane concentrations (p = 0.99). Anion and osmolal gaps also remained unchanged. Nitromethane was reliably identified in all sample concentrations using GC on Day 0. Detection of 0.25 mmol/L nitromethane was not consistently recovered on Day 7. Nitromethane degradation was most pronounced at 2 mmol/L concentrations (81% recovery). Conclusions. Nitromethane alters apparent concentration of creatinine using the Jaffé reaction in a linear fashion but not when using the POC reaction. Measured difference between Jaffé and POC creatinine may identify the presence and estimate concentration of nitromethane. Presence of nitromethane did not alter the anion or osmolal gap; thus it would not potentially interfere with the diagnosis of co-exposure to a toxic alcohol.

Theoretical and Experimental Studies on the Regioselectivity of Epoxide Ring Opening by Nucleophiles in Nitromethane without any Catalyst: Nucleophilic-Chain Attack Mechanism

We describe here a mild and efficient method for the nucleophilic ring-opening of epoxides with amines, alcohols and water in the presence of nitromethane as a polar solvent without using any catalyst. The reactions are highly regioselective and afford the products in excellent yields within a short period of time at room temperature. The regioselectivity for this ring opening has been investigated using experimental and theoretical 1H and 13C NMR studies together with activation energy calculations at the B3LYP/6-311+G(2d,p) level of theory. The mechanism of nucleophilic attack has been investigated in terms of a direct attack or a methanol chain attack.

Domino Reaction of Iodoglycosides: Synthesis of Carbohydrate‐Based Nitroalkenes

AbstractHerein we describe a tandem fragmentation/Henry reaction of iodoglycosides, which involves formation of a carbon–carbon double bond and a carbon–carbon single bond. If the fragmentation of methyl 5‐iodo‐D‐ribofuranoside is mediated by zinc/catalytic indium in the presence of bromonitromethane, a separable mixture of a 1‐nitro‐5‐hexene and a 1‐bromo‐1‐nitro‐5‐hexene is obtained in moderate yields with good diastereoselectivities. However, if the reaction is mediated by nBuLi in the presence of nitromethane, the corresponding 1‐nitro‐5‐hexene is obtained as the only product in excellent yield and stereoselectivity in a one‐pot synthetic protocol. This is a general methodology that can be applied to iodopyranoses and iodofuranoses with different protecting groups for the efficient preparation of highly functionalized 1‐nitro‐5‐hexenes or 1‐nitro‐6‐heptenes.

Structural Characterization of a Copper Nitrosyl Complex with a {CuNO}10 Configuration

The synthesis and characterization of a {CuNO}(10) complex, namely, [Cu(CH(3)NO(2))(5)(NO)][PF(6)](2), has been achieved by the addition of [NO][PF(6)] to copper metal powder in the presence of nitromethane. In the solid state, this complex exhibits a bent Cu-N-O moiety [Cu-N-O = 121.0(3)°] and a long Cu-N bond. This complex readily reacts with mesitylene to form [mesitylene, NO][PF(6)] and [Cu(η(2)-1,3,5-Me(3)C(6)H(3))(2)][PF(6)] by transfer of NO(+) to the mesitylene ring.

Fluorescent Properties of a Hybrid Cadmium Sulfide-Dendrimer Nanocomposite and its Quenching with Nitromethane

A fluorescent hybrid cadmium sulphide quantum dots (QDs) dendrimer nanocomposite (DAB-CdS) synthesised in water and stable in aqueous solution is described. The dendrimer, DAB-G5 dendrimer (polypropylenimine tetrahexacontaamine) generation 5, a diaminobutene core with 64 amine terminal primary groups. The maximum of the excitation and emission spectra, Stokes' shift and the emission full width of half maximum of this nanocomposite are, respectively: 351, 535, 204 and 212 nm. The fluorescence time decay was complex and a four component decay time model originated a good fit (chi = 1.20) with the following lifetimes: tau (1) = 657 ps; tau (2) = 10.0 ns; tau (3) = 59.42 ns; and tau (4) = 265 ns. The fluorescence intensity of the nanocomposite is markedly quenched by the presence of nitromethane with a dynamic Stern-Volmer constant of 25 M(-1). The quenching profiles show that about 81% of the CdS QDs are located in the external layer of the dendrimer accessible to the quencher. PARAFAC analysis of the excitation emission matrices (EEM) acquired as function of the nitromethane concentration showed a trilinear data structure with only one linearly independent component describing the quenching which allows robust estimation of the excitation and emission spectra and of the quenching profiles. This water soluble and fluorescent nanocomposite shows a set of favourable properties to its use in sensor applications.

Facile synthesis of vicinal diamines via oxidation of N-phenyltetrahydroisoquinolines with DDQ

The oxidation of N-phenyltetrahydroisoquinolines occurs rapidly with DDQ. Under ambient conditions and in the presence of nitromethane, the corresponding β-nitroamine derivatives are isolated in good to excellent yields. Variation in the electronic nature of the isoquinoline and the N-phenyl substituent showed that a broad range of substituents are tolerated, with electronic communication between the isoquinoline aromatic ring and the C1 carbon being stronger than with the N-aryl ring. Reduction of the β-nitroamines to the corresponding novel chiral vicinal diamines are straightforward. Examination of the reaction by 1H NMR spectroscopy suggested that the reaction proceeds via an iminium ion, which then reacts with nitromethane upon work-up. This information was used to shorten the required reaction time.

Rhodium(II) catalysed three-component coupling: a novel reaction of in situ generated iodonium ylides

Cyclic ethers are cleaved in the presence of nitromethane, a base, a hypervalent iodine compound and a Rh(II) catalyst to give nitromethoxy acetates in up to 71% isolated yields. The reaction is a three-component coupling of an ether with a nitromethane derived carbenoid and a carboxylate group originating from the hypervalent iodine compound.

Nitromethane as a scavenger of acrylonitrile in the deprotection of synthetic oligonucleotides

A novel deprotection procedure for synthetic oligonucleotides was developed to prevent nucleobase alkylation. Acrylonitrile, a side product of the deprotection of a 2-cyanoethyl phosphate protecting group and which causes nucleobase alkylation, was found to be trapped by the addition of some acidic compounds, which generate a carbanion species under the conventional deprotection conditions using aqueous NH 3. The 2-cyanoethylation of thymidine was inhibited effectively in the presence of nitromethane.

Classification of Select Aceanthrylenes, Acephenanthrylenes and Dicyclopentapyrenes as Alternant versus Nonalternant Polycyclic Aromatic Hydrocarbons on the Basis of Their Fluorescence Quenching Behavior in the Presence of Nitromethane and Cetylpyridinium Cation Selective Quenching Agents

Fluorescence behavior of dicyclopenta[cd, fg]pyrene, dicyclopenta[cd, jk]pyrene and dicyclopenta[cd, mn]pyrene is reported in the presence of nitromethane and cetylpyridinium (CPy+) cation quenching agents. Nitromethane and CPy+ are known to selectively quench fluorescence emission of alternant polycyclic aromatic hydrocarbons (PAHs). Emission intensities of nonalternant PAHs, with a few noted exceptions, are unaffected. Experimental measurements show that nitromethane and CPy+ effectively quenched fluorescence emission of the three dicyclopentapyrenes, thus suggesting that the perimeter C = C double bonds in the two cyclopenta-rings are alkenic, rather than aromatic in nature. Also reported are the fluorescence properties of 14 aceanthrylene and acephenanthrylene derivatives, as well as several structurally related compounds, to further document the cetylpyridinium cation's quenching selectivity.

A theoretical explanation of solvent effects in zeolite catalysis

In a previous study of solid acid catalysis (Nature (1998) 389, 832) we showed that the catalytic activity of zeolites could be increased by the coadsorption of “solvent” molecules, such as nitromethane. These coadsorbates do not participate directly in the reaction, but alter the environment within the zeolite such that reactivity is increased. In this work we provide further theoretical explanation of the increased reactivity observed upon coadsorption. We first use density functional theory (DFT) to study the proton affinity of acetone, and complexes of acetone with propane, bromomethane, nitromethane, nitroethane, nitropropane, and acetonitrile. We find that the proton affinity of acetone in the complexes is much higher than for acetone alone. Optimizations and frequency calculations at the B3LYP/6–311++G** level predict proton affinity increases that range from 0.9 kcal/mol for the acetone/propane complex to 12.8 kcal/mol for the acetone/acetonitrile complex. The increase in proton affinity due to the coadsorbed molecules is one of the causes of the increased reactivity observed experimentally. We also used DFT (B3LYP/DZVP2) to optimize the geometry of acetone and the acetone–nitromethane complex in contact with a cluster model of HZSM-5. There is greater proton transfer from the zeolite to acetone when nitromethane is present, as is reflected in the shorter distance between the acidic zeolite proton and the carbonyl carbon of acetone. Predictions of 1H and 13C NMR isotropic chemical shifts also indicate increased proton transfer to acetone in the presence of nitromethane. This further demonstrates how coadsorbates promote reactivity.

Surface functionalization of polymer networks. Sulfonation of the internal surface of macroporous styrene‐divinylbenzene copolymers

AbstractSurface functionalization of porous polymer networks was investigated using the sulfonation of macroporous styrene‐divinylbenzene (S‐DVB) copolymers as model reaction. Reaction conditions for the surface sulfonation were studied. Sulfonation with sulfuric acid in the presence of nitromethane was found to be a suitable method. Models and ideas of network structure are developed in order to estimate surface capacities and to show that surface‐sulfonated networks were obtained.

Radical reactions in aqueous solution: use of the aci-anion of nitromethane as a spin trap

The type of radical detected by esr when first-formed short-lived radicals are generated by photolytic, radiolytic, or flow techniques in the presence of nitromethane is shown to depend upon the nature and structure of the transient radical and on the pH. Thus electron-donating radicals may react with CH3NO2 itself under certain conditions to give rise to CH3NO2−• and the alkoxy nitroxides CH3N(OR)O•. At higher pH, a wide variety of radicals (X) react very readily with the aci-anion CH2:NO2− to give adducts XCH2NO2−• (and, from radicals capable of one-electron transfer, O2NCH2CH2NO2−•). Structural characteristics of adducts XCH2NO2−• are described and it is shown how radicals which are normally undetectable in fluid solution can be trapped and recognized in this way. Mechanistic pathways diagnosed with this trap (involving, e.g. alkoxyl radicals, aroyloxyl radicals, aromatic carboxylate cation-radicals) are exemplified.

Continuous photolysis at 253.7 nm of acetone in aqueous solution in the presence of nitromethane

Continuous photolysis at 253.7 nm of acetone in aqueous solution in the presence of nitromethane