- 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
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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.
- Subramanian, Selvakumar,Narayanasastri, Somanathan,Kami Reddy, Audisesha Reddy
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- PARTIAL REDUCTION OF DINITROARENES TO NITROANILINES WITH HYDRAZINE HYDRATE.
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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.
- Avyyangar,Kalkote,Lugade,Nikrad,Sharma
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- Benzocrown Ether Hydrazones as Extractants for Alkali Metal Ions
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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.
- Sakamoto, Hidefumi,Goto, Hiroki,Yokoshima, Makoto,Dobashi, Makoto,Ishikawa, Junichi,et al.
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- Porphyrins as ITO photosensitizers: Substituents control photo-induced electron transfer direction
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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.
- Furmansky, Yulia,Sasson, Hela,Liddell, Paul,Gust, Devens,Ashkenasy, Nurit,Visoly-Fisher, Iris
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- Preparation method of 2.4-dinitrophenylhydrazine
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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%.
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Paragraph 0018; 0024; 0025; 0026; 0027; 0028
(2016/10/27)
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- Pd(OAc)2-catalyzed dinitration reaction of aromatic amines
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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.
- Feng, Yi-Si,Mao, Long,Bu, Xiao-Song,Dai, Jian-Jun,Xu, Hua-Jian
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p. 3827 - 3832
(2015/06/02)
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- The α-effect in SNar reaction of y-substituted-phenoxy-2, 4-dinitrobenzenes with amines: Reaction mechanism and origin of the α-effect
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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.
- Cho, Hyo-Jin,Kim, Min-Young,Um, Ik-Hwan
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p. 2448 - 2452
(2014/09/17)
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- Application of screening experimental designs to assess chromatographic isotope effect upon isotope-coded derivatization for quantitative liquid chromatography-mass spectrometry
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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.
- Szarka, Szabolcs,Prokai-Tatrai, Katalin,Prokai, Laszlo
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p. 7033 - 7040
(2014/08/05)
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- Synthesis and antifungal activity of substituted 2,4,6-pyrimidinetrione carbaldehyde hydrazones
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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.
- Neumann, Donna M.,Cammarata, Amy,Backes, Gregory,Palmer, Glen E.,Jursic, Branko S.
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p. 813 - 826
(2014/01/23)
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- Specific nucleophile-electrophile interactions in nucleophilic aromatic substitutions
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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.
- Ormazábal-Toledo, Rodrigo,Contreras, Renato,Tapia, Ricardo A.,Campodónico, Paola R.
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supporting information
p. 2302 - 2309
(2013/04/10)
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- Synthesis and biological activity of pyrazolidine-3,5-dione substituted benzimidazole derivatives
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Condensation of o-phenylene diamine with chloro acetic acid gave 2-chloromethyl benzimdazole, which undergoes halide replacement with phenylhydrazines to give the corresponding N,N'-disubstituted hydrazines. Later these compounds were treated with diethyl malonate in presence of acetic acid to get the pyrazolidine-3,5-dione substituted benzimidazole derivatives. The synthesized compounds were subjected to microbiological screening and in vitro antiinflammatory activity.
- Tiwari, Abhishek,Tiwari, Varsha,Venkataramana,Madhavan
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experimental part
p. 1179 - 1182
(2012/01/05)
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- Reaction of bis(2,4-dinitrophenyl) phosphate with hydrazine and hydrogen peroxide. Comparison of O- and N- phosphorylation
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Nonionic hydrazine reacts with anionic bis(2,4-dinitrophenyl) phosphate (BDNPP), giving 2,4-dinitrophenyl hydrazine and dianionic 2,4-dinitrophenyl phosphate by an SN2(Ar) reaction, and at the phosphoryl center, giving 2,4-dinitrophenoxide ion and a transient phosphorylated hydrazine that rearranges intramolecularly to N-(2,4-dinitrophenyl)-N-phosphonohydrazine. Approximately 58% of the reaction at pD = 10 occurs by N-phosphorylation, as shown by 31P NMR spectroscopy. Reaction of HO2- is wholly at phosphorus, and the intermediate peroxophosphate reacts intramolecularly, displacing a second 2,4-dinitrophenoxide ion, or with H 2O2, giving 2,4-dinitrophenyl phosphate and O2. Rate constants of O- and N-phosphorylation in reactions at phosphorus of NH2-NH2, HO2-, and NH2OH and its methyl derivatives follow Broensted relationships with similar slopes, but plots differ for oxygen and nitrogen nucleophiles. The reaction with NH2NH2 has been probed by using both NMR spectroscopy and electrospray ionization mass and tandem mass spectrometry, with the novel interception of key reaction intermediates in the course of reaction.
- Domingos, Josiel B.,Longhinotti, Elisane,Brandao, Tiago A. S.,Santos, Leonardo S.,Eberlin, Marcos N.,Bunton, Clifford A.,Nome, Faruk
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p. 7898 - 7905
(2007/10/03)
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- SULFUR INHIBITORS OF PHOSPHOLIPASE A-Z
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Phospholipase A2 inhibitors having the formula wherein R" is a C2-C20 alkyl group, R1" is a C1-C4 alkyl group, y is an integer from 2 to 10, and J- is a pharmaceutically acceptable anion, are described
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- Kinetics and mechanism of acid catalyzed hydrolysis of 2,4-dinitrophenylhydrazones of 2-, 3-, and 4-hydroxy-benzaldehydes
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Kinetics of hydrolysis of 2,4-dinitrophenylhydrazones (I-IV) derived from benzaldehyde, and 2-, 3- and 4-hydroxybenzaldehydes, respectively have been studied in 50percent (v/v) aqueous acetone at different hydrochloric acid concentrations.The observed hydrolysis rates are first order in .The first-order rate coefficients increase with the increase in .The substituent on the aldehyde moiety has a considerable effect on the rates of hydrolysis reactions.A high negative p-value (-2.4 +/- 0.4) is obtained for the series.Activation parameters for the reactions have also been determined.A mechanism consistent with the observed results is proposed
- Awwal, A.,Miah, A. S.,Kabir, M.
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p. 753 - 756
(2007/10/02)
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- Reaction of o-nitrophenylhydrazines with 2,5-dimethoxytetrahydrofuran
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Reactions of 2-nitrophenylhydrazine and 2,4-dinitrophenylhydrazine with 2,5-dimethoxytetrahydrofuran yield the bis-hydrazones (1a) and (1b) respectively.On further heating with acid, they yield the pyrroles (2a) and (2b) respectively.Excess of 2,5-dimethoxytetrahydrofuran leads to the indoles (3a) and (3b) and the carbazoles (4a) and (4b) respectively.
- Viswanathan, N.,Sidheye, A. R.,Gawad, D. H.
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p. 182 - 183
(2007/10/02)
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- A STUDY OF NUCLEOPHILICITY IN SELECTED SYSTEMS
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Kinetic studies have been carried out of the reactions of 15 nucleophiles with 2,4-dinitrophenyl acetate and 14 nucleophiles with 2,4-dinitrofluorobenzene in 52percent (w/w) methanol at 25 deg C.The rate constant values obtained and literature data have been treated by the factor analysis.It has been found that the description of nucleophilicity at least needs two factors.The nucleophiles studied are divided into two groups (ionic and nitrogen-containing ones).In each group, the nucleophilic properties are affected by linear combination of both factors.
- Zima, Vitezslav,Pytela, Oldrich,Vecera, Miroslav
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p. 814 - 821
(2007/10/02)
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- Antihypertensive phosphate derivatives
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Antihypertensive phosphate derivatives having the following formula are described: STR1 wherein X is selected from one or more of: (a) C1 -C24 branched or straight chain alkyl; (b) C1 -C24 branched or straight chain alkoxy; (c) STR2 wherein n and m are integers from 0 to 25 and the sum of n and m is less than or equal to 25; phenyl; substituted phenyl wherein the substituents are selected from the group consisting of C1 -C20 branched or straight chain alkyl, C1 -C20 branched or straight chain alkoxy, halogen, trifluoromethyl, phenyl, and substituted phenyl, phenoxy; and substituted phenoxy, wherein the substituents are selected from the group consisting of C1 -C20 branched or straight chain alkyl, halogen, trifluoromethyl, phenyl and substituted phenyl; Q is selected from the group consisting of: STR3 wherein R1 is selected from the group consisting of hydrogen, C1 -C4 branched or straight chain alkyl, C1 -C4 branched or straight chain alkoxy and C1 -C4 branched or straight chain alkylamino and wherein R3 is C1 -C4 alkyl, with the proviso that when Q is STR4 then R1 is C1 -C4 branched or straight chain alkyl; T is a bivalent radical selected from the group consisting of --(CHR)p -- and STR5 wherein p is an integer from 1 to 15, the moiety --(CHR)p -- represents an alkylene chain substituted at any position with one or more C1 -C10 alkyl groups or phenyl groups, and the moiety STR6 is bound with the oxygen atom attached directly to the aromatic ring; and Z is STR7 wherein R2 is hydrogen or C1 -C4 branched or straight chain alkyl and q is an interger from 4 to 7; in either the racemic or optically active forms.
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- BICYCLIC GUANIDINES
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The invention relates to bicyclic derivatives which are histamine H-2 antagonists and which inhibit gastric acid secretion. According to the invention there is provided a guanidine derivative of the formula I: STR1 in which R 1 and R 2, same or different, are hydrogen or 1-10C alkyl, 3-8C cycloalkyl or 4-14C cycloalkylalkyl, each alkyl, cycloalkyl or cycloalkylalkyl optionally carrying one or more F, Cl or Br atoms, provided that one of R 1 and R 2 is halogen substituted, or R 2 is hydrogen and R 1 is R 3-E-W in which W is 2-6C alkylene optionally substituted by 1 or 2 1-4C alkyls, E is O, S, SO, SO. sub.2 or NR 4 in which R. sup.4 is H or 1-6C alkyl, R 3 is H or 1-6C alkyl optionally substituted by 1 or 2 1-4C alkyls, or R. sup.3 and R. sup.4 are joined to form a pyrrolidine, piperidine, morpholine, piperazine or N-methylpiperazine ring, or R 2 is H and R. sup.1 is H, 1-10C alkyl, 3-8C cycloalkyl, 4-14C cycloalkylalkyl, 3-6C alkenyl, 3-6C alkynyl, 1-6C alkanoyl, 6-10C aryl, 7-11C aralkyl or 7-11C aroyl; ring X is a heterocyclic ring as defined in the specification; A is phenylene or 5-7C cycloalkylene, or a 1-8 C alkylene into which is optionally inserted one or two groups; ring Y is a heterocyclic ring described in the specification: and the pharmaceutically-acceptable acid-addition salts thereof. Manufacturing processes and pharmaceutical compositions are also described.
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- Biphenyl compounds and method of preparing same
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The present invention relates to novel biphenyl compounds of the formula STR1 wherein one of R1 and R2 is hydrogen and the other is --CH3-m Xm wherein X is chloro or bromo and m is an integer one or two, and the cyclic moiety A is a -2,5-; -2,3-; or -3,4-di-OR-1-phenyl moiety wherein R is a hydroxy-protecting group and to a method of preparing same. The biphenyl compounds are useful as intermediates in preparing redox compounds containing a phenylhydroquinone or phenylcatechol moiety.
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