119-26-6Relevant articles and documents
Doping-induced detection and determination of propellant grade hydrazines by a kinetic spectrophotometric method based on nano and conventional polyaniline using halide ion releasing additives
Subramanian, Selvakumar,Narayanasastri, Somanathan,Kami Reddy, Audisesha Reddy
, p. 27404 - 27413 (2014)
A kinetic spectrophotometric method is described for the detection and determination of propellant grade hydrazines and its derivatives based on their reaction with 1-chloro-2,4-dinitrobenzene (CDNB) incorporated in a solution matrix of polyaniline-Emaraldine Base (Pani-EB) to produce HCl. This strong acid protonates (dopes) Pani (EB-Blue) to form Pani Emeraldine salt (ES-Green). A kinetic study based on the gradual decrease in absorbance at 626 nm for both nano and conventional Pani-CDNB systems was carried out at 50 °C and 60°C under optimized conditions in the dynamic concentration range of 0.1-0.004 M. Initial rate and fixed time methods were adopted for constructing calibration curves. Hydrazines were determined based on the linear relationship between percent absorbance change at 30 min. and their concentration. R.S.D. for five replicate determinations of each one of these hydrazines using both systems is less than 1.5%. Minimum detectable limits for hydrazines were found for both systems. This method was successfully applied for determination of hydrazines in tap water with satisfactory analytical results.
PARTIAL REDUCTION OF DINITROARENES TO NITROANILINES WITH HYDRAZINE HYDRATE.
Avyyangar,Kalkote,Lugade,Nikrad,Sharma
, p. 3159 - 3164 (1983)
Dinitroarenes containing substituents such as hydroxyl and amine groups could be conveniently reduced with 3 molar equivalents of hydrazine hydrate in presence of Raney nickel catalyst in ethanol/1,2-dichloro-ethane solvent mixture to give a product wherein one of the two nitro groups was reduced to the amino group. The yields of the partial reduction products are good. Under similar conditions alkoxyl substitutes in the o,p-position to the nitro groups were displaced by the hydrazine to give 2,4-dinitrophenyl-hydrazine as the main product. The details of the reduction reaction are described.
Benzocrown Ether Hydrazones as Extractants for Alkali Metal Ions
Sakamoto, Hidefumi,Goto, Hiroki,Yokoshima, Makoto,Dobashi, Makoto,Ishikawa, Junichi,et al.
, p. 2907 - 2914 (1993)
Four types of benzo-15-crown-5 and benzo-18-crown-6 derivatives bearing a substituted hydrazone moiety as a proton-dissociable chromogenic group were synthesized and the solvent extraction behaviors of these compounds for alkali metal ions were evaluated spectrophotometrically.Benzo-15-crown-5 and -18-crown-6 hydrazones with 2,4-dinitro-6-(trifluoromethyl)phenyl or 2,6-dinitro-4-(trifluoromethyl)phenyl groups extracted alkali metal ions predominantly as 2:1 and 1:1 (crown ether:metal ion) complexes, respectively, from an aqueous alkaline solution into 1,2-dichloroethane and these ligands exhibited high K+-selectivity.The composition of the extracted species and the K+-selectivity depended on the polarity of the extraction solvent used.In particular, 2:2 complexes of several alkali metal ions with benzo-15-crown-5 and -18-crown-6 hydrazones bearing a 2,4-dinitro-6-(trifluoromethyl)phenyl group were readily extracted from an aqueous solution into chloroform.
Porphyrins as ITO photosensitizers: Substituents control photo-induced electron transfer direction
Furmansky, Yulia,Sasson, Hela,Liddell, Paul,Gust, Devens,Ashkenasy, Nurit,Visoly-Fisher, Iris
, p. 20334 - 20341 (2012)
Porphyrins have attracted much attention as dyes for photovoltaic applications due to their remarkable light harvesting properties and tunability of electronic behaviour. The photophysical and photochemical properties of porphyrins are influenced by electron-donating or electron-withdrawing substituents that can be attached at the perimeter of the porphyrin macrocycle. The current work shows that changing the porphyrin peripheral substituents can affect the direction of interfacial charge transfer at the interface of porphyrin and Indium tin oxide (ITO), a degenerate n-type semiconductor that is commonly used as a transparent conductive electrode in organic optoelectronic devices. Soret-band excitation resulted in electron injection from the molecular layer to the ITO in all porphyrin derivatives studied, suggesting that electron injection to ITO is faster than relaxation from the porphyrin upper excited state to the lower one. However, the direction of photo-induced electron transfer in the 500-650 nm spectral range (Q-bands excitation in porphyrins) was found to depend on the peripheral substituents. This is highly relevant for photovoltaic devices, as the solar spectrum peaks in this spectral range. The charge transfer behaviour was shown to depend on the composition of the interfacial adsorbed monolayer. Therefore, it is proposed that porphyrin derivatives can be used for modulating photo-induced interfacial transport at ITO/organic layer interfaces in a predefined, controllable way.
Preparation method of 2.4-dinitrophenylhydrazine
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Paragraph 0018; 0024; 0025; 0026; 0027; 0028, (2016/10/27)
The invention relates to a preparation method of 2.4-dinitrophenylhydrazine. The method includes the steps of: (1) dissolving 2.4-dinitrochlorobenzene and performing thermal filtration; (2) putting the filtrate into a reflux bottle, adding hydrazine hydrate accounting for 1/5-1/2 of the weight of 2.4-dinitrophenylhydrazine, conducting standing for 10min, maintaining a reflux state, performing calculation from the end of hydrazine hydrate adding, then conducting reflux again for 1h, precipitating red crystals, and stopping reflux; and (3) lowering the temperature, when the temperature drops to 50-55DEG C, filtering out crystals, performing washing with anhydrous ethanol 2-5 times, and conducting drying so as to obtain 2.4-dinitrophenylhydrazine. Starting from the raw material proportion, the method provided by the invention increases the dosage of hydrazine hydrate, enhances the yield of 2.4-dinitrophenylhydrazine, at the same time combines several process improvements, effectively increases the yield up to 98-100%.
Pd(OAc)2-catalyzed dinitration reaction of aromatic amines
Feng, Yi-Si,Mao, Long,Bu, Xiao-Song,Dai, Jian-Jun,Xu, Hua-Jian
, p. 3827 - 3832 (2015/06/02)
Taking advantage of Pd(OAc)2-catalyzed dinitration reactions with Bi(NO3)3·5H2O in trifluoroethanol (TFE) and trifluoroacetic acid (TFA), we have developed an efficient and practical method for the synthesis of secondary dinitro-aromatic amines. The products could be applied to the preparation of 5-amine-N-methyl-benzimidazolone, the azo-dyes, economic advantages. The method has also been expanded to the dinitration reaction of some tertiary aromatic amines.
The α-effect in SNar reaction of y-substituted-phenoxy-2, 4-dinitrobenzenes with amines: Reaction mechanism and origin of the α-effect
Cho, Hyo-Jin,Kim, Min-Young,Um, Ik-Hwan
, p. 2448 - 2452 (2014/09/17)
Second-order rate constants (kN) have been measured spectrophotometrically for SNAr reactions of Ysubstituted-phenoxy-2, 4-dinitrobenzenes (1a-1g) with hydrazine and glycylglycine in 80 mol % H 2O/20 mol % DMSO at 25.0 ± 0.1 °C. Hydrazine is 14.6-23.4 times more reactive than glycylglycine. The magnitude of the α-effect increases linearly as the substituent Y becomes a stronger electron-withdrawing group (EWG). The Bronsted-type plots for the reactions with hydrazine and glycylglycine are linear with βlg = -0.21 and -0.14, respectively, which is typical for reactions reported previously to proceed through a stepwise mechanism with expulsion of the leaving group occurring after rate-determining step (RDS). The Hammett plots correlated with so constants result in much better linear correlations than s- constants, indicating that expulsion of the leaving group is not advanced in the transition state (TS). The reaction of 1a-1g with hydrazine has been proposed to proceed through a five-membered cyclic intermediate (TIII), which is structurally not possible for the reaction with glycylglycine. Stabilization of the intermediate TIII through intramolecular H-bonding interaction has been suggested as an origin of the α-effect exhibited by hydrazine.
Application of screening experimental designs to assess chromatographic isotope effect upon isotope-coded derivatization for quantitative liquid chromatography-mass spectrometry
Szarka, Szabolcs,Prokai-Tatrai, Katalin,Prokai, Laszlo
, p. 7033 - 7040 (2014/08/05)
Isotope effect may cause partial chromatographic separation of labeled (heavy) and unlabeled (light) isotopologue pairs. Together with a simultaneous matrix effect, this could lead to unacceptable accuracy in quantitative liquid chromatography-mass spectrometry assays, especially when electrospray ionization is used. Four biologically relevant reactive aldehydes (acrolein, malondialdehyde, 4-hydroxy-2-nonenal, and 4-oxo-2-nonenal) were derivatized with light or heavy (d3-, 13C6-, 15N2-, or 15N4-labeled) 2,4-dinitrophenylhydrazine and used as model compounds to evaluate chromatographic isotope effects. For comprehensive assessment of retention time differences between light/heavy pairs under various gradient reversed-phase liquid chromatography conditions, major chromatographic parameters (stationary phase, mobile phase pH, temperature, organic solvent, and gradient slope) and different isotope labelings were addressed by multiple-factor screening using experimental designs that included both asymmetrical (Addelman) and Plackett-Burman schemes followed by statistical evaluations. Results confirmed that the most effective approach to avoid chromatographic isotope effect is the use of 15N or 13C labeling instead of deuterium labeling, while chromatographic parameters had no general influence. Comparison of the alternate isotope-coded derivatization assay (AIDA) using deuterium versus 15N labeling gave unacceptable differences (>15%) upon quantifying some of the model aldehydes from biological matrixes. On the basis of our results, we recommend the modification of the AIDA protocol by replacing d 3-2,4-dinitrophenylhydrazine with 15N- or 13C-labeled derivatizing reagent to avoid possible unfavorable consequences of chromatographic isotope effects.
Synthesis and antifungal activity of substituted 2,4,6-pyrimidinetrione carbaldehyde hydrazones
Neumann, Donna M.,Cammarata, Amy,Backes, Gregory,Palmer, Glen E.,Jursic, Branko S.
, p. 813 - 826 (2014/01/23)
Opportunistic fungal infections caused by the Candida spp. are the most common human fungal infections, often resulting in severe systemic infections - a significant cause of morbidity and mortality in at-risk populations. Azole antifungals remain the mainstay of antifungal treatment for candidiasis, however development of clinical resistance to azoles by Candida spp. limits the drugs' efficacy and highlights the need for discovery of novel therapeutics. Recently, it has been reported that simple hydrazone derivatives have the capability to potentiate antifungal activities in vitro. Similarly, pyrimidinetrione analogs have long been explored by medicinal chemists as potential therapeutics, with more recent focus being on the potential for pyrimidinetrione antimicrobial activity. In this work, we present the synthesis of a class of novel hydrazone-pyrimidinetrione analogs using novel synthetic procedures. In addition, structure-activity relationship studies focusing on fungal growth inhibition were also performed against two clinically significant fungal pathogens. A number of derivatives, including phenylhydrazones of 5-acylpyrimidinetrione exhibited potent growth inhibition at or below 10 μM with minimal mammalian cell toxicity. In addition, in vitro studies aimed at defining the mechanism of action of the most active analogs provide preliminary evidence that these compound decrease energy production and fungal cell respiration, making this class of analogs promising novel therapies, as they target pathways not targeted by currently available antifungals.
Specific nucleophile-electrophile interactions in nucleophilic aromatic substitutions
Ormazábal-Toledo, Rodrigo,Contreras, Renato,Tapia, Ricardo A.,Campodónico, Paola R.
supporting information, p. 2302 - 2309 (2013/04/10)
We herein report results obtained from an integrated experimental and theoretical study on aromatic nucleophilic substitution (SNAr) reactions of a series of amines towards 1-fluoro-2,4-dinitrobenzene in water. Specific nucleophile-electrophile interactions in the title reactions have been kinetically evaluated. The whole series undergoes SNAr reactions where the formation of the Meisenheimer complex is rate determining. Theoretical studies concerning specific interactions are discussed in detail. It is found that H-bonding effects along the intrinsic reaction coordinate profile promote the activation of both the electrophile and the nucleophile. Using these results, it is possible to establish a hierarchy of reactivity that is in agreement with the experimental data. Second order energy perturbation energy analysis highlights the strong interaction between the ortho-nitro group and the acidic hydrogen atom of the amine. The present study strongly suggests that any theoretical analysis must be performed at the activated transition state structure, because the static model developed around the reactant states hides most of the relevant specific interactions that characterize the aromatic substitution process.
