Nitroacetic Acid Research Articles

An albumin unfolding and refolding cycle induced by a time-controlled pH jump.

Given the intimate connection between the structure and function of biological macromolecules, the ability to temporally control their unfolding-refolding process enables temporal regulation over specific functionalities, potentially applicable in innovative domains, including the construction of protein-based actuators or programmable catalysis and drug release in complex biotechnological processes. We show here how a temporally controlled protein unfolding-refolding cycle can be coupled in time with programmed pH sequences achieved through the spontaneous decomposition of an activated carboxylic acid. Specifically, we illustrate this process at the molecular level using albumin, the most prevalent protein found in plasma, for which a temporary shift from native to unfolded forms is promoted using nitroacetic acid, able to undergo base-catalysed decarboxylation when solubilized in water solution. As detected by small angle X-ray scattering and intrinsic tryptophan fluorescence, starting from the protein in its native form, the acid addition triggers unfolding to a partially denatured state and a subsequent time-tunable pH rise with gradual refolding that recapitulates the intermediate steps detected at the same pH values by static acidification, fitting within a framework of full reversibility of the structural changes as a function of the protein protonation state. At the end of the pH jump, the native structure is fully recovered, making this method a chemical tool to achieve a complete protein conformational sequence programmed in the timeframe of minutes without further intervention.

Synthesis of Indole‐2‐carboxylates via Condensation of Nitroacetic Esters and 2‐Dimethylbenzaldehydes

AbstractA new operationally simple single step method for synthesis indole‐2‐carboxylates from 2‐dimethylaminobenzaldehydes and nitroacetic acid esters in 22–59 % yields has been developed.

Theoretical insights into the linear relationship between [formula omitted] values and vibrational frequencies

A linear relationship between pKa values and vibrational frequencies has been derived in this work for hydrogen halides based on a statistical thermodynamic ansatz and successfully tested for a set of 24 aliphatic carboxylic acids, with predicted pKa values differing from measured values by less than 0.3 pKa units. Our work opens the door to reliably predicting pKa values for families of compounds often difficult to measure and paves the way for a natural extension of the derived relationship referring to local vibrational mode theory to treat systems with more delocalized A-H stretching vibrations, such as nitroacetic acid.

Dissipative operation of pH-responsive DNA-based nanodevices.

We demonstrate here the use of 2-(4-chlorophenyl)-2-cyanopropanoic acid (CPA) and nitroacetic acid (NAA) as convenient chemical fuels to drive the dissipative operation of DNA-based nanodevices. Addition of either of the fuel acids to a water solution initially causes a rapid transient pH decrease, which is then followed by a slower pH increase. We have employed such low-to-high pH cycles to control in a dissipative way the operation of two model DNA-based nanodevices: a DNA nanoswitch undergoing time-programmable open–close–open cycles of motion, and a DNA-based receptor able to release-uptake a DNA cargo strand. The kinetics of the transient operation of both systems can be easily modulated by varying the concentration of the acid fuel added to the solution and both acid fuels show an efficient reversibility which further supports their versatility.

Time-programmable pH: decarboxylation of nitroacetic acid allows the time-controlled rising of pH to a definite value.

In this report it is shown that nitroacetic acid 1 (O2NCH2CO2H) can be conveniently used to control the pH of a water solution over time. Time-programmable sequences of the kind pH1(high)–pH2(low)–pH3(high) can be achieved, where both the extent of the initial pH jump (pH1(high)–pH2(low)) and the time required for the subsequent pH rising (pH2(low)–pH3(high)) can be predictably controlled by a judicious choice of the absolute and relative concentrations of the reagents (acid 1 and NaOH). Successive pH1(high)–pH2(low)–pH3(high) sequences can be obtained by subsequent additions of acid 1. As a proof of concept, the method is applied to control over time the pH-dependent host–guest interaction between alpha-cyclodextrin and p-aminobenzoic acid.

A comprehensive study on the application of FeNi3@SiO2@ZnO magnetic nanocomposites as a novel photo-catalyst for degradation of tamoxifen in the presence of simulated sunlight

Pharmaceutical compounds at trace concentrations are found in the environment, especially in drinking water and food, posing significant negative effects on humans as well as on animals. This paper aimed to examine the diagnostic catalytic properties and efficacy of a novel synthesized photocatalyst, namely FeNi3@SiO2@ZnO magnetic nanocomposite, for the removal of tamoxifen (TMX) from wastewater under simulated sunlight. According to the results, it was found that TMX was completely degraded operating under optimized conditions (i.e. pH = 7, catalyst dose = 0.01 g/L, initial TMX concentration = 20 mg/L and reaction time = 60 min). The reaction kinetics of TMX degradation followed a pseudo-first order kinetics model. The final by-products from the TMX photodegradation were water, carbon dioxide, acetic acid, nitroacetic acid methyl ester, 2-methyl-2-pentenal, and 4-methyl-2-pentanol. In addition, the synthesized photocatalyst could successfully performed five consecutive photodegradation cycles. The obtained results revealed that the synthesized FeNi3@SiO2@ZnO magnetic nanocomposite holds a great potential to be applied as a photocatalyst for the degradation of TMX on an industrial scale.

INTEGRATED APPROACH TO NEUTRALIZATION OF WASTEWATER CONTAINING COPPER IONS AND EDTA LIGAND

An analysis of electrochemical degradation of organic compounds, in particular EDTA is presented. The influence of the nature of the anode and the nature of the oxidizing agent on the degradation of organic compounds is showed. Anode materials are classified based on their oxidizing power in an acidic environment. It is shown that direct oxidation of EDTA effectively occurs on the anodes Ti/PbO2 and Ti/SnO2. In the presence of NaCl EDTA is effectively oxidized on the anodes Ti/RuO2-TiO2 by the formation of hypochlorite. Examples of destruction of EDTA under the influence of ultraviolet radiation are given. Degradation products (nitro acetic acid, amino diacetic acid) form CO2, H2O, NO3-ions at full decomposition. It is noted that the neutralization of wastewater containing copper and EDTA is carried out in two stages: destruction of EDTA and the extraction of copper hydroxide. The extraction of copper ions from the system H2O-Cu2+-EDTA-electrolyte with different ratios of metal-ligand is investigated. The effect of EDTA concentration on the flotation process for extracting copper hydroxide is analyzed. The kinetics of flotation of copper extraction in the presence of two complexing agents - NH3 and EDTA is considered. The presented results allow to assess the degree of extraction of copper from solution copper-EDTA at different coal sorbents and resins. It is shown that the use of anion exchange resin Purolite A500 and anion exchange resin AB-17-8 is effective when the copper concentration is 25 mg/l. It is established that the sorption process is slow: stationary values are set for several hours. The degree of extraction of EDTA reaches 30-40%. When the ratio of copper-EDTA 1:1.0-1.5 it is possible to reach flotation copper extraction up to 80%. Under additional sorption treatment the extraction degree reaches to 99%. It is shown that the use of highly dispersed carbon materials (coal powders) allows extracting ligands from wastewater, increasing the efficiency of copper hydroxides electroflotation.

Safer, greener route to methyl nitroacetate

Methyl nitroacetate is a handy chemical building block. It can be used to produce α-amino acids, isoxazoles, and α,β-unsaturated compounds. It’s also a useful reactant in Michael additions, Mannich reactions, and cyclopropanations. But it’s expensive. One gram costs anywhere from $22 to $115, depending on the vendor. That’s probably because the process that has been used to make methyl nitroacetate for more than 40 years is dangerous. The 1976 procedure published in Organic Syntheses (DOI: 10.15227/orgsyn.055.0077) requires one to dry the highly explosive intermediate dipotassium salt of nitroacetic acid in a vacuum desiccator and then grind it with a mortar and pestle. The protocol also uses carcinogenic benzene as an extraction solvent and requires two distillations. Now, Pablo E. Guzmán, Jesse J. Sabatini, and coworkers at the U.S. Army Research Laboratory have developed a safer, more environmentally friendly way to make this ester (Org. Process Res. Dev. 2017, DOI: 10.1021/acs.oprd.7b00093).

A Convenient and “Greener” Synthesis of Methyl Nitroacetate

A new procedure for the synthesis and isolation of methyl nitroacetate is described. The previously published method required drying the explosive dipotassium salt of nitroacetic acid in a vacuum desiccator, followed by grinding this material into a fine powder with a mortar and pestle prior to esterification. To obtain the desired product, benzene was employed as the extraction solvent, sodium sulfate was used as the drying agent, and two distillations were required. The new procedure eliminates drying and grinding of the explosive dipotassium salt, employs ethyl acetate or dichloromethane as the extraction solvent, eliminates the need for a drying agent, and requires a single distillation to furnish the end product in high yield and purity.

Synthesis and structure of β-aryl-α-nitroacrylates

The method for preparation of ethyl α-nitrocinnamates by nitroacetic acid ester alkenylation with aromatic aldehydes in the presence of acetic acid and β-alanine has been modified. Structures of the prepared compounds have been proved by electronic, IR, 1H, and 13C-{1H} NMR spectroscopy (including heteronuclear correlation experiments 1H-13C HMQC and 1H-13C HMBC). In solution these compounds exist in the form of Z-isomer; the Z⇄E isomerization is observed in the case of the compound containing strong electron-donor group [N(CH3)2] at benzene ring.

Chiral Proton Catalysis: Enantioselective Broensted Acid Catalyzed Additions of Nitroacetic Acid Derivatives as Glycine Equivalents.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Chiral Proton Catalysis: Enantioselective Brønsted Acid Catalyzed Additions of Nitroacetic Acid Derivatives as Glycine Equivalents

An unsymmetrical, bifunctional chiral proton catalyst (2) has been developed to enable the highly diastereo- and enantioselective synthesis of epimerizable addition products from nitroacetic acid esters. The strategy is analogous to O'Donnell's glycine Schiff base alkylations that have been broadly applied to the synthesis of α-amino acids. In this regard, nitroacetic acid esters provide complementary products, namely, anti-α,β-diamino acids, derived from addition reactions. Products are obtained with high diastereoselection (generally 6−12:1) and enantioselection (generally >90% ee) using 5 mol% catalyst loading.

Preparation of β-nitroalanine using the Easton three-component coupling method

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.

Nitroketene Acetal Chemistry. Part 3. Facile Synthesis of Nitroacetic Acid Triarylmethyl Orthoesters from 1,1‐Di(methylsulfanyl)‐2‐nitroethylene.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Determination of acidity constants of enolisable compounds by capillary electrophoresis.

Research on the structure-activity relationships of molecules with acidic carbon atoms led us to undertake a feasibility study on the determination of their acidity constants by capillary electrophoresis (CE). The studied molecules had diverse structures and were tetronic acid, acetylacetone, diethylmalonate, Meldrum's acid, 3-methylrhodanine, nitroacetic acid ethyl ester, pyrimidine-2,4,6-trione, 3-oxo-3-phenylpropionic acid ethyl ester, 1-phenylbutan-1,3-dione, 5,5-dimethylcyclohexan-1,3-dione and homophthalic anhydride. The p Ka range explored by CE was therefore very large (from 3 to 12) and p Ka values near 12 were evaluated by mathematical extrapolations. The analyses were carried out in CZE mode using a fused silica capillary grafted (or not) with hexadimethrine. Owing to the electrophoretic behaviour of these compounds according to the pH, their acidity constants could be evaluated and appeared in perfect agreement with the literature data obtained, a few decades ago, by means of potentiometry, spectrometry or conductimetry. The p Ka of homophthalic anhydride and 3-methylrhodanine were evaluated for the first time.

Domino Processes as a Tool for Recovering Substandard Reactions. Synthesis and Use of Nitroacetic Acid Esters and Amides.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Domino processes as a tool for recovering substandard reactions. Synthesis and use of nitroacetic acid esters and amides.

[reaction: see text] Elusive nitroacetic acid esters and amides were obtained through a halogen exchange reaction of the corresponding bromoacetic acid derivatives with polymer-supported nitrite anion. The process is flawed by a side product catalyzed degradation of the products. Domino processes turned out to be a powerful tool for overcoming such drawbacks, converting a substandard reaction into an efficient multicomponent preparation of 4-hydroxy-4,5-dihydroisoxazoles.

Solution- and solid-phase synthesis of 4-hydroxy-4,5-dihydroisoxazole derivatives from enantiomerically pure N-tosyl-2,3-aziridine alcohols.

[reaction: see text] Enantiomerically pure N-tosyl-2,3-aziridine alcohols are directly converted into 4-hydroxy-4,5-dihydroisoxazole 2-oxides through oxidation to the corresponding aldehydes followed by in situ tandem nitroaldol-intramolecular cyclization. This study was concerned with (i) the selection of a suitable aziridine activation, (ii) the preparation of the target 4-hydroxy-4,5-dihydroisoxazole derivatives in solution, and (iii) the elaboration of a solid-phase process using hydroxy Merrifield-supported nitroacetic acid ester.

ChemInform Abstract: The Utility of Nitroacetic Acid and Its Derivatives in the Synthesis of Heterocycles

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

The Utility of Nitroacetic Acid and its Derivatives in the Synthesis of Heterocycles

Heterocycles, bearing nitro groups, are of interest as biologically active compounds (e.g., metronidazole, nitrazepam, nitroxolinum) or in connection with hydrogenation of nitro- to amino group. Methods of nitration are not always satisfactory because of low yields, mixture of isomers formation and potential hazard of nitrating reagents. The application of nitroacetic acid derivatives has been previously reviewed in part (1-5). The present review summarizes data reported after 1980 but older work is also cited when appropriate. Keywords: Nitroacetic Acid, tert-butyl esters, anti-histamine activity, Lawesson reagent, genuine amidines