Physico-chemical properties of the first metal compound of di-2-pyridylketone p-nitrophenoxyacetic acid hydrazone (dpknxh), fac-Re(CO)3(κ2-Npy,Npy-dpknxh)Cl

Abstract

Di-2-pyridyl ketone p-nitrophenoxyacetic acid hydrazone (1), obtained from acid-catalyzed condensation of di-2-pyridyl ketone (dpk) with p-nitrophenoxyacetic acid hydrazide, reacts with Re(CO)₅Cl in refluxing toluene to form fac-Re(CO)₃(κ²-N_py,N_py-dpknxh)Cl (2). 1 and 2 were identified from the results of their elemental analyses, spectroscopic and electrochemical properties. X-ray structural analysis on single crystals of 1 and 2 grown from CH₃CN solutions and fac-Re(CO)₃(κ²-N_py,N_py-dpknxh)Cl·DMSO (3) grown from a DMSO solution of 2 confirmed their identities. Spectrophotometric titrations of protophilic solutions of 2 with protophilic solutions of NaBX₄ (X?=?H or F) divulged inter-conversion between the high- and low-energy ILCT transitions of 2 and its solvated complex. Substrates in low concentrations can be detected and determined using protophilic solutions of 2. Electrochemical measurements on 1 and 2 disclosed irreversible redox transformations leading to decomposition of 1 and 2 following the first electron transfer.     

Kinetics of isotope exchange between [3-(iodophenyl)methyl]guanidine (mIBG) and [131I]-iodide

The reaction of isotope exchange between [3-(iodophenyl)methyl]guanidine, mIBG, and [¹³¹]-iodide in relatively concentrated solutions, in the presence of different ammonium salts, in a closed system, over the temperature range from 130 to 150°C, has been investigated. The reaction occurs either with (NH₄)₂SO₄ or CH₃COOH, which indicates that the reaction goes through some intermediate stages. Kinetic studies show the influence of the additives. The activation energies for the reaction with (NH₄)₂SO₄/H₂O, (NH₄)₂SO₄/CH₃COOH and CH₃COOH are 121.1, 115.1 and 84.5 kJ·mol^–1, respectively.     

Solvent extraction studies of radioisotopic exchange of36Cl with Chloramine-B in strong acid medium

Exchange studies with³⁶Cl and Chloramine-B in strong acid medium revealed that the extent of exchange is less than that occurs at pH 3.3 indicating the formation of a new species of Chloramine-B which is not participating in the exchange reaction and this has been confirmed by conductometric titration of Chloramine-B with dilute solutions of H₂SO₄, HCl, HClO₄ and CH₃COOH.     

Carbonylation of aliphatic and cyclic alcohols by carbon monoxide in the presence of complexes of BF3 with acetic,propionic, or monochloroacetic acid

Conclusions The complexes BF₃-2CH₃CH₂COOH and BF₃·2CH₃COOH and the system 3BF₃·2CH₂ClCOOH-BF₃·2CH₃-COOH are active and stable catalysts of the carbonylation reaction (80–100°, p_CO=100 atm) of tertiary and secondary alcohols of aliphatic and cyclic structure with formation of carboxylic acids in high yields and can be used repeatedly without a decrease in the initial activity.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 817–825, April, 1977.Deceased.     

Beiträge zur Chemie der Alkylverbindungen von Übergangsmetallen. XXVII. Darstellung von Titanacetaten aus Tetramethyl- und Tetrabenzyltitan

Contributions to the Chemistry of Transition Metal Alkyl Compounds. XXVII. Preparation of Titanium Acetates from Tetramethyl and Tetrabenzyl Titanium (CH₃)₄Ti reacts with CH₃COOH at deep temperature to the colourless Ti(OCOCH₃)₄. Using ClCH₂COOH slight violet Ti(OCOCH₂Cl)₄ is formed containing small amounts of reduction products. A complete reduction occurs in the analogous reaction with CF₃COOH yielding dark green Ti(OCOCF₃)₃. From (C₆H₅CH₂) 4 Ti and CH₃COOH a green titanium(III,IV) acetat of the formula 4 Ti(OCOCH₃) · Ti(OCOCH₃)₄ was obtained. – The isolated titanium acetates were characterized by elementary analyses, magnetic moments and i.r. spectra.     

Methane Carboxylation Using Electrochemically Activated Carbon Dioxide

Direct synthesis of CH₃COOH from CH₄ and CO₂ is an appealing approach for the utilization of two potent greenhouse gases that are notoriously difficult to activate. In this Communication, we report an integrated route to enable this reaction. Recognizing the thermodynamic stability of CO₂, our strategy sought to first activate CO₂ to produce CO (through electrochemical CO₂ reduction) and O₂ (through water oxidation), followed by oxidative CH₄ carbonylation catalyzed by Rh single atom catalysts supported on zeolite. The net result was CH₄ carboxylation with 100 % atom economy. CH₃COOH was obtained at a high selectivity (>80 %) and good yield (ca. 3.2 mmol g⁻¹_cat in 3 h). Isotope labelling experiments confirmed that CH₃COOH is produced through the coupling of CH₄ and CO₂. This work represents the first successful integration of CO/O₂ production with oxidative carbonylation reaction. The result is expected to inspire more carboxylation reactions utilizing preactivated CO₂ that take advantage of both products from the reduction and oxidation processes, thus achieving high atom efficiency in the synthesis.     

Radiation stability of trivalent antimony in the presence of organic acids

The gamma ray induced oxidation of Sb(III) in sulfuric acid solutions was studied. A simplified method depending on selective extraction of the different valency states and radiometric counting was elaborated for oxidation yield determination. The effect of increasing amounts of HCOOH, CH₃COOH, NH₂CH₂COOH, CH₃CHOH COOH and H₂C₂O₄ on G[-Sb(III)] was examined. The study enabled a determination of rate constant values for reactions of the used additives with the OH radical in the working solutions.     

Copper(II) Complexes with N‐(9‐anthracenyl)‐N′‐(3‐pyridyl)urea (L) and a Derivative of L: Synthesis,Structure, and Fluorescent Properties

Three copper(II) complexes, [Cu₂(OAc)₄L₂] · 2CH₃OH ( 1 ), [CuBr₂L′₂(CH₃OH)] · CH₃OH ( 2a ), and [CuBr₂L′₂(DMSO)] · 0.5CH₃OH ( 2b ) {L = N‐(9‐anthracenyl)‐N′‐(3‐pyridyl)urea and L′ = N‐[10‐(10‐methoxy‐anthronyl)]‐N′‐(3‐pyridyl)urea} have been synthesized by the reaction of L with the corresponding copper(II) salts. Complex 1 shows a dinuclear structure with a conventional “paddlewheel” motif, in which four acetate units bridge the two Cu^II ions. In complexes 2a and 2b , the anthracenyl ligand L has been converted to an anthronyl derivative L′, and the central metal ion exhibits a distorted square pyramidal arrangement, with two pyridyl nitrogen atoms and two bromide ions defining the basal plane and the apical position is occupied by a solvent molecule (CH₃OH in 2a and DMSO in 2b ).     

Extraction of Lanthanide Nitrates in Multicomponent Aqueous-Organic Two-Phase Systems with D2EHPA

Lanthanum nitrate distribution in three-component aqueous-organic systems with D2EHPA from acetate or acetic acid–acetate solutions has been studied, it has been shown that variation in sodium acetate concentration or composition of CH₃COONa–CH₃COOH mixture can affect metal distribution ratios. It has been found that extraction in three-component mixture of 1: 1: 1 composition (aqueous solution Ln(NO₃)₃ + CH₃COONa + CH₃COOH–D2EHPA in hexane–isopropyl alcohol) can provide lanthanide separation, which is dependent on the ratio of sodium acetate and acetic acid in aqueous phase and on D2EHPA concentration in organic phase. Lanthanide–lanthanum separation factors have been calculated for the extraction of lanthanide nitrates from acetic acid–acetate solutions.     

Lactam acetals and acid amides. 31. Synthesis,protonation, and basicities of some heterocyclic enamino ketones

The protonation of cyclic enamino ketones of the pyrrolidine, piperidine, and hexahydroazepine series, as well as their noncyclic analogs, was studied by PMR spectroscopy. It is shown that the presence of a CH₂ or CH₃ group in the “enamine” position leads to C protonation (in CF₃COOH). In the case of enamino ketones that do not contain substituents in the “enamine” α position N-and O-protonated forms are observed in CF₃COOH. The measured pK_a values (in 10% alcohol) and the ΔpK_a values (in nitromethane) of the enamino ketones show that the compounds for which C protonation is characteristic are two to three orders of magnitude more basic than in the case of compounds that do not contain substituents in the “enamine” α position; this is explained by the different character of protonation. See [1] for communication 30. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 344–348, March, 1980     

The protonated betaine/ammonia complex: how stable is the gas-phase zwitterion structure?

The ammonium ion stabilizes a betaine zwitterion in the gas phase forming a salt-bridge structure, [(CH₃)₃N⁺CH₂COO^–NH₄⁺] that is 3.7 kcal/mol less stable than the ion/molecule complex between protonated betaine and neutral ammonia, (CH₃)₃N⁺CH₂COOH/NH₃. DFT calculations have reversed the previously determined relative stability based on PM3 calculations and are in agreement with black-body infrared radiative dissociation experiments. A double-well potential energy surface is formed with a rather low central barrier separating the two complexes. This is conducive to efficient hydrogen/deuterium exchange in agreement with experiment. It prevents the existence of the salt-bridge complex as a distinct species under thermal conditions.     

Computational design of BC3N2 based single atom catalyst for dramatic activation of inert CO2 and CH4 gasses into CH3COOH with ultralow CH4 dissociation barrier

The production of CH₃COOH from CO₂ and CH₄ has stimulated much interest due to the high energy density of C2 species. Various kinds of catalysts have been developed while the high dissociation barrier of CH₄ and low selectivity still hinders the efficiency of the reaction. We have herein proposed a novel catalyst with single metals loaded on 2D BC₃N₂ substrate (M@2D-BC₃N₂) based on density functional theory. Among numerous candidates, Pt@2D-BC₃N₂ possesses the most favorable reactivity with an ultralow barrier of CH₄ splitting (0.26 eV), which is due to the efficient capture ability of CH₄ on Pt site. Besides, the selectivity for CH₃COOH is also very high, which mainly stems from the unique electronic properties of molecules and substrate: The degenerated states, including s, p_x, p_y and p_z, in CO₂ reflects the existence of delocalized π bonds between C and O. This can interact with states of Pt(s), Pt(p_z), Pt(d_xz), Pt(d_yz),and Pt(z²) in Pt@2D-BC₃N₂. The kinetics model also proves that our system can promote CH₃COOH production via simply increasing the temperature or the coverage of CH₄ and CO₂. Our results provide a reasonable illustration in clarifying mechanism and propose promising candidates with high reactivity for further study.     

Bestimmung von freier Essigs?ure neben Metallsalzen durch automatische Acidimetrie

Zusammenfassung Bei Verwendung einer automatisch arbeitenden potentiometrischen Apparatur (Titrator TTT 1c + Titrigraph SBR 2c, Radiometer) kann freie Essigsäure in Anwesenheit von Metallsalzen mit ausreichender Genauigkeit zur Untersuchung von Essigsäuresolvaten, wie z. B. NiCl₂·0,5 CH₃COOH, CuCl₂·0,5 CH₃COOH, PbCl(CH₃COO)·CH₃COOH, bestimmt werden.

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Summary Using an automatically working potentiometric apparatus (Titrator TTT 1c + Titrigraph SBR 2c, Radiometer) free acetic acid can be determined in presence of metal salts with sufficient exactness to analyze acetic acid solvates, i.e. NiCl₂·0.5 CH₃COOH, CuCl₂·0.5 CH₃COOH, PbCl(CH₃COO)·CH₃COOH.

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Die Verfasser danken der Deutschen Forschungsgemeinschaft und der Wissenschaftlichen Gesellschaft des Saarlandes e.V. für die Förderung dieser Untersuchungen durch Sachmittel.     

Synthesis and physicochemical properties of fac-[Re(CO)3(κ2-N,N-dpkfah)Cl], dpkfah=di-2-pyridyl ketone 2-furoic acid hydrazone: the molecular structure of fac-[Re(CO)3(κ2-N,N-dpkfah)Cl] · acetone

Reaction between [Re(CO)₅Cl] and di-2-pyridyl ketone 2-furoic acid hydrazone (dpkfah) (1) in refluxing toluene gave fac-[Re(CO)₃(κ²-N,N-dpkfah)Cl] (2). Spectroscopic and electrochemical measurements disclosed sensitivity of 2 to its surroundings. ¹H-NMR measurements showed that the amide proton exchanged with solvent protons, and its chemical shift is solvent and temperature dependent, while the chemical shifts of aromatic protons are solvent and temperature independent. Electronic absorption spectra of 2 divulged two intra-ligand charge transfer transitions (ILCT) in protophilic solvents and a single ILCT transition in non-protophilic solvents. Optical measurements on protophilic solutions of 2 established an equilibrium between 2 and its conjugate base, fac-[Re(CO)₃(κ²-N,N-dpkfah-H)Cl]^? (3). Thermo-optical measurements confirmed that the interconversion between 2 and 3 and gave ΔG ^ø values of ?26.48 and 22.99?kJ?mol^?1, respectively, for the protonation of DMF and DMSO by 2. Optosensing measurements showed that [MCl₂] (M?=?Zn, Cd, or Hg) in concentrations as low as 1.00?×?10^?7?mol?L^?1 can be detected and determined using protophilic solutions of 2. Electrochemical measurements showed 2 to be more stable in CH₃CN than DMF. Single-crystal X-ray structural analysis on fac-[Re(CO)₃(κ²-N,N-dpkfah)Cl]?·?acetone (4) obtained from an acetone solution of 2 confirmed the solvent–complex interaction and revealed two symmetry-independent molecules in the asymmetric unit. The extended structure of 4 disclosed parallel stacks connected via a network of classic and non-classic hydrogen bonds.     

Synthesis and inhibiting activity of functional derivatives of 2,6-di-tert-butylphenol

Conclusions Methods were developed for the synthesis of 2,6-di-tert-butylphenols that are substituted in the 4 position by HOCH₂CH₂CH₂ and XCH₂CH₂ groups, where X = OH, COOH, CONH₂, CONHR, CONR₂, CONHNH₂, and HOCH₂CH₂O.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1174–1177, May, 1976.     

Effect of nitric acid on radiation stability and radiolysis product of N,N-Diethylhydroxylamine

This paper reports the effect of HNO₃ on radiation stability and radiolysis product of N,N-Diethylhydroxylamine (DEHA), which is used as a reducer in the reprocessing of spent fuel. Results show that with the addition of HNO₃, radiation stability of DEHA is weakened obviously, the volume fraction of H₂, CH₄ and C₂H₄ decreases but the concentration of CH₃COOH increases. As to 1.0 and 2.0 M HNO₃, the concentration of CH₃CHO increases, but it decreases when HNO₃ is 3.0 M.     

Molecular Dynamics Simulation of the Binding Interaction between Hormone Glucagon Protein and Self-Assembled Monolayer Molecules

Restrained molecular dynamics simulations were performed to study the binding affinity of the peptide with alkanethiols of different tail-groups, S（CH2）7CH3, S（CH2）7OH and S（CH2）7COOH, which self-assembled on Au（111） surface in the presence of water molecules. The curves of binding affinity were calculated by fixing the center of mass of the peptide at various distances from the assembling surface. Simulation results show that the binding affin- ity is in the order as COOH-SAMs〉OH-SAMs〉CH3-SAMs, while 100% COOH-SAMs〉5% COOH-SAMS in concentration. The effects on binding affinity by different tail-groups were also studied. Results show that the binding affinity between COOH-SAMs and the peptide is bigger than those of the others and increasing the acidity of COOH-SAMs will result in stronger attractive power.     

Reactions of perfluorobenzocycloalkenes with ethyl cyanoacetate and methyllithium and some transformations of the products

Reactions of perfluorobenzocycloalkenes (Ar_FF) with methyllithium and ethyl cyanoacetate involved replacement of fluorine atoms in positions 3 and 4 of perfluorocyclobutabenzene, position 5 of perfluoroindan, and position 6 of perfluorotetralin by CH₃ and CH(CN)COOEt groups. Hydrolysis of the resulting esters Ar_FCH(CN)COOEt gave the corresponding perfluoroarylacetic acids Ar_FCH₂COOH which were converted into dichloroacetyl chlorides Ar_FCCl₂COCl by treatment with PCl₅. The reaction of Ar_FCCl₂COCl with SbF₅ produced trifluoromethyl derivatives Ar_FCF₃. Decarboxylation of Ar_FCCl₂COOH in DMF afforded dichloromethyl derivatives Ar_FCCl₂H which reacted with CsF on heating to form difluoromethyl analogs Ar_FCF₂H.     

Formate dehydrogenase–viologen-immobilized electrode for CO2 conversion,for development of an artificial photosynthesis system

Formate dehydrogenase (FDH)–viologen with a long alkyl chain (CH₃V(CH₂) _n COOH) immobilized on an indium–tin oxide (ITO) electrode, with the function of reduction of CO₂ to formic acid, was investigated as an artificial photosynthesis device based on CO₂ reduction. The amount of formic acid produced by use of FDH–CH₃V(CH₂) _n COOH immobilized on ITO in CO₂-saturated buffer solution, on application of a potential, as a result of one-electron reduction of viologen, depends on the carbon chain length of CH₃V(CH₂) _n COOH. When a CH₃V(CH₂)₉COOH–FDH/ITO electrode was used, production of formic acid was estimated to be 23 μmol after 3 h.     

Electrophilic hydrogen-deuterium exchange of some deactivated pyrroles

The rate coefficients and partial rate factors for the hydrogen-deuterium exchange of some 1-substituted pyrroles (1-substituents = -COCH₃, - COC₆H₅, -SO₂CH₃, -SO₂CF₃, -N(CH₃)₃, -NH(CH₃)₂, -SO₂C₆H₅) in deuterated trifluoroacetic acid have been determined. In all cases the rate of exchange is faster at the 2-position. Similarly, the hydrogen-deuterium exchange of some pyrroles with electron withdrawing substituents in the 2-position indicate a relative reactivity of 4→ 5→ 3-position with the selectivity being greatest for the more electron withdrawing groups. A nitro group in the 3-position of pyrrole shows a relative reactivity of 5→2→4-position for the hydrogen-deuterium exchange in deuterated trifluoroacetic acid. A linear correlation is observed for the log of the rate coefficient of the hydrogen-deuterium exchange at the 4-position of some 2-substituted pyrroles and the difference in the calculated energy of formation of the pyrrole and the corresponding 4-deuterated cation.