Thermodynamic characteristics of protolytic equilibria of ethylenediamine-<Emphasis Type="Italic">N,N</Emphasis>′-diacetic-<Emphasis Type="Italic">N,N</Emphasis>′-dipropionic acid

Heat effects of protonation and neutralization of ethylenediamine-N,N′-diacetic-N,N′-dipropionic acid at 298.15 K and ion force values of 0.1, 0.5, and 1.0 (KNO₃) were measured by the direct calorimetric method. Combined use of the results of thermochemical and potentiometric measurements carried out under the identical experimental conditions permitted to evaluate standard thermodynamic characteristics of the equilibria under study. The results obtained were compared with the corresponding data for related compounds considering the specific features of structure of the diamine complexones.     

3,3,3-Trifluoro-<Emphasis Type="Italic">N</Emphasis>′-(3-trifluoromethylphenyl)-1,2-propanediamine and its <Emphasis Type="Italic">N</Emphasis>-mono-and <Emphasis Type="Italic">N,N</Emphasis>-dicarboxyethyl derivatives: synthesis,protolytic and complexation properties

3,3,3-Trifluoro-N′-(3-trifluoromethylphenyl)-1,2-propanediamine (5) was synthesized by the reaction of 2-diazo-1,1,1-trifluoro-3-nitropropane or 3,3,3-trifluoro-1-nitropropene with 3-aminobenzotrifluoride followed by the reduction of the nitro group. The Michael 1,4-addition of diamine 5 to acrylic acid occurs only at the N(1) atom and affords N-mono-or N,N-dicarboxyethyl derivatives 6 and 7, depending on the reactant ratio. Protolytic equilibria 5–7 in aqueous solutions were studied by pH-potentiometry and UV spectroscopy. Only the aliphatic amino group can be protonated in an aqueous solution, while the aromatic amino group remains unprotonated even in 12 M HCl. The stability constants of transition metal (Cu²⁺, Ni²⁺, Zn²⁺) complexes with ligands 5–7 were determined by pH-potentiometric titration. The stability of the complexes and selectivity of the ligands toward Cu²⁺ ions increase with an increase in the number of N-carboxyethyl groups. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2465–2469, November, 2005.     

Reaction sites of <Emphasis Type="Italic">N,N′</Emphasis>-substituted <Emphasis Type="Italic">p</Emphasis>-phenylenediamine antioxidants

The geometries of N,N′-diphenylbenzene-1,4-diamine (DPPD), N-phenyl-N′-(1-phenylethyl)benzene-1,4-diamine (SPPD), N-(4-methylpentan-2-yl)-N′-phenylbenzene-1,4-diamine (6PPD), N-propan-2-yl-N′-phenylbenzene-1,4-diamine (IPPD), N-(2-methoxybenzyl)-N′-phenylbenzene-1,4-diamine (MBPPD), and N-phenyl-N′-(2-phenylpropan-2-yl)benzene-1,4-diamine (CPPD) as well as of their dehydrogenation products were optimized by the semiempirical AM1 method. The results support the idea of stable N_B=C_X structures formation during the consecutive dehydrogenation of SPPD, 6PPD, IPPD, and MBPPD antioxidants. The biradicals formed during the second step of dehydrogenation of substituted phenylenediamines might be important for their antioxidant effectiveness. Dedicated to Professor Vladimír Kvasnička, DrSc., in honour of his 65th birthday     

Intermolecular interactions in orthophosphoric acid-<Emphasis Type="Italic">N,N</Emphasis>-dimethylformamide system according to viscometric data

The viscosity of an orthophosphoric acid—N,N-dimethylformamide system was measured in the whole region of compositions at 298–338 K. An excess viscosity of the system was analyzed by the data obtained using different model concepts. Calculations suggested that strong intermolecular interactions and the formation of complexes (H₃PO₄)₂·DMF occur in the system. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2252–2256, October, 2005.     

RuO<Subscript>4</Subscript>-mediated oxidation of<Emphasis Type="Italic">N</Emphasis>-benzylated tertiary amines. Are amine<Emphasis Type="Italic">N</Emphasis>-oxides and iminium cations reaction intermediates?

N-Benzylmorpholine,-piperidine, and-pyrrolidine (1A-C, resp.) are oxidised by RuO₄ (generated in situ) at both endocyclic and exocyclic (benzylic) N—α-methylene positions to afford lactams (and dioxo-derivatives) and benzaldehyde (and benzoyl derivatives), respectively. The N-oxides of 1A-C, formed by a minor side reaction, are not involved as intermediates. Control experiments showed the transient formation of endo- and exocyclic iminium cations trapped with NaCN as the corresponding nitriles. The proposed course of the RuO₄-mediated oxidation of 1A-C involves the consecutive steps 1⇒iminium cations+cyclic enamine⇒oxidation products. The endocyclic/exocyclic regioselectivity of the oxidation reaction lies between 0.8 (for 1A) and 2.1 (for 1B). The amine cation radical and the N-α-C· carbon-centered radical seem not to be involved.     

Syntheses,spectroscopic study and crystal structures of some new <Emphasis Type="Italic">N</Emphasis>-benzoylphosphoric triamides

The reaction of N-benzoylphosphoramidic dichloride with amines afforded some new N-benzoylphos-phoric triamides with formula C₆H₅C(O)NHP(O)(X)₂, X=NH–CH(CH₃)₂ (1), NH–CH₂–CH(CH₃)₂ (2), NH–CH₂–CH(OCH₃)₂ (3), N(CH₃)[CH₂CH(OCH₃)₂] (4) and N(CH₃)(C₆H₁₁) (5) that were characterized by ¹H,¹³C,³¹P NMR, IR spectroscopy and elemental analysis. The structures have been determined for compounds 4 and 5 by X-ray crystallography. These compounds contain one amidic hydrogen atom and form centrosymmetric dimmers via intermolecular –P–O⋯H–N–hydrogen bonds besides weak C–H⋯O hydrogen bonds that lead to three-dimensional polymeric clusters in the crystalline lattice.     

Synthesis and structure of <Emphasis Type="Italic">N</Emphasis>-substituted (1-ferrocenylethyl)amine derivatives

N-Acetyl-(1-ferrocenylethyl)amine (8) was synthesized by N-acylation of (1-ferrocenylethyl)amine (7) in 84% yield. Reaction of N-acetyl-[1-(1′-bromo-ferrocenyl)ethyl]amine (4) (which was prepared by multistep sequence starting from bromoferrocene) with n-BuLi/ClCOOEt gave 77% of N-acetyl-N-ethoxycarbonyl-(1-ferrocenylethyl)amine (6) instead of the expected ethyl 1′-[1-(acetamido)ethyl]ferrocene-1-carboxylate (5). Both structures were undoubtedly confirmed by (HR)MS spectroscopy and single crystal X-ray structure analysis.     

UV/Vis Spectroscopic Properties of <Emphasis Type="Italic">N</Emphasis>-(2′-Hydroxy-4′-<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-dimethyl-aminobenzylidene)-4-nitroaniline in Various Solvents and Solid Environments

Summary.  N-(2′-Hydroxy-4′-N,N-dimethylaminobenzylidene)-4-nitroaniline [HDBN] has been used as a model for investigating intra- and intermolecular D–A (donor–acceptor) interactions in various environments by means of UV/Vis spectroscopy. UV/Vis spectra of HDBN have been measured in various solvents, ethanolic solutions of different pH, adsorbed on silica, and in the solid state. A bathochromic shift of ν_max is observed with increasing the dipolarity/polarizability and HBD (hydrogen bond donor) capacity of the solvent, which is described by means of a multiple LSE (linear solvation energy) relationship in terms of the empirical Kamlet-Taft solvent polarity parameters. The adsorption of HDBN on Aerosil^? 300-silica particles in non-HBA (hydrogen bond acceptor) solvents is explained in the same sense. Mobile protons and sol–gel entrapping cause a hypsochromic shift due to protonation of the lone electron pair of the 4′-N,N-dimethylamino group. Hydroxide ions attack the 2′-hydroxy group which causes a bathochromic shift. A strong intramolecular hydrogen bond between the 2′-hydroxyl hydrogen and the imine nitrogen atom is present in the solid-state structure causing an unprecedented bathochromic shift. Corresponding author. E-mail: stefan.spange@chemie.tu-chemnitz.de Received July 8, 2002; accepted (revised) September 30, 2002     

Mass spectrometric study of the overheated vapor over nickel(II), Copper(II), and Zinc(II) <Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>′-Ethylenebis(salicylaldiminato) complexes

A mass spectrometric study of the overheated vapor over the nickel(II), copper(II), and zinc(II) N,N′-ethylenebis(salicylaldiminato) complexes between 300 and 865°C has been carried out. Throughout this temperature range, the overheated vapor over all of the complexes contains no ions heavier than the molecular ion [MO₂N₂C₁₆H₁₄]⁺. At ∼600°C, Cu(salen) and Zn(salen) interact with the structural material of the double-chamber two-temperature effusion cell (Kh18N10T steel). The complexes are thermally very stable. The fragmentation pattern of the chelates under electron-impact ionization is metal-dependent.     

Crystal structures of [Hg(<Emphasis Type="Italic">N</Emphasis>-ethylthiourea)<Subscript>2</Subscript>(CN)<Subscript>2</Subscript>] and [Hg(<Emphasis Type="Italic">N</Emphasis>-propylthiourea)<Subscript>2</Subscript>(CN)<Subscript>2</Subscript>]

Two mercury(II) cyanide complexes of N-ethylthiourea (Ettu) and N-propylthiourea (Prtu) ligands, [Hg(Ettu)₂(CN)₂] (1) and [Hg(Prtu)₂(CN)₂] (2), were prepared and their crystal structures were determined by X-ray crystallography. In both structures, the mercury atom is coordinated to two sulfur atoms of thioureas and two cyanide carbon atoms in a pseudo-tetrahedral mode with the bond angles in the range of 90.52(11)–162.2(3)°. The structures are stabilized by N-H—S, N-H—N, and C-H—N intramolecular and intermolecular hydrogen bonds.     

<Emphasis Type="Italic">N</Emphasis>-benzyl derivatives of valine esters

The reactions of methyl and ethyl esters of valine with m-bromobenzaldehyde and p-chlorobenzaldehyde in absolute methanol in the presence of magnesium sulfate yielded the corresponding azomethines (CH₃)₂CHCH(COOR¹)N=CHR² (R¹ = CH₃, C₂H₅; R² = 3-BrC₆H₄, 4-ClC₆H₄); their reduction with sodium borohydride gave N-benzyl derivatives of valine esters, (CH₃)₂CHCH(COOR¹)NHCH₂R².Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 11, 2004, pp. 1855–1857.Original Russian Text Copyright © 2004 by Yakubovich, Zhavnerko, Shirokii, Knizhnikov.This revised version was published online in April 2005 with a corrected cover date.     

X-ray structures of iron(III) and cobalt(III) complexes containing 2-<Emphasis Type="Italic">S</Emphasis>-methyl-6-methyl-4-formylpyrimidine-<Emphasis Type="Italic">N</Emphasis>(4)-ethylthiosemicarbazone

Iron(III) and cobalt(III) complexes of types [Fe(LEt)₂]ClO₄·3/2C₆H₆ (1) and [Co(LEt)₂]ClO₄·2CH₂Cl₂ (2) with a new pyrimidine-derived thiosemicarbazone ligand, 2-S-methyl-6-methyl-4-formylpyrimidine-N(4)-ethylt-hiosemicarbazone (HLEt), having N, N, S donor centers have been synthesized and characterized by X-ray crystallography. The structural study shows distorted octahedral geometry for both 1 and 2 with MN₄S₂ chromophores. The space group of 1 is C2/c (monoclinic) and that of 2 is P2₁2₁2₁ (orthorhombic). The electrochemical electron transfer study in MeCN solutions shows a one-electron reductive response presumably due to a metal(III)–metal(II) couple.     

Facile synthesis and biological evaluation of novel fluorine-containing <Emphasis Type="Italic">N</Emphasis>-nitro-<Emphasis Type="Italic">N</Emphasis>′-substituted phenylurea

Twenty-two novel N-nitro-N′-substituted phenyl-N-(2,6-dibromo-4-fluorophenyl)urea derivatives were designed and synthesized via a simple and convenient BTC ‘one-pot’ procedure using DMAP as the catalyst. The structures of all newly synthesized compounds were confirmed by IR, ¹H NMR, and elemental analysis, and a part has been identified by ¹³C NMR. The preliminary bioassay indicates that the target compounds possesses moderate herbicidal activity against Sorghum sudanense. However, some of the title compounds presented high plant growth regulating activity against rape.     

<Emphasis Type="Italic">N,N,N′,N′</Emphasis>-tetramethylmethanediamine,efficient reagent for thioles aminomethylation

Efficient method was developed for thiols aminomethylation using N,N,N′,N′-tetra-methylmethanediamine in the presence of Sm and Fe salts. Aminosulfides were obtained in high yields and selectivity.     

Reaction of iodo(trimethyl)silane with <Emphasis Type="Italic">N,N</Emphasis>-dimethyl carboxylic acid amides

The reactions of iodo(trimethyl)silane with N,N-dimethylformamide and N,N-dimethylacetamide Me₂NCOR (R = H, Me) at a molar ratio of 1: 2 involved mainly cleavage of the N-C(=O) bond with formation of up to 80% of N,N-dimethyltrimethylsilylamine Me₃SiNMe₂ and the corresponding acyl iodide RCOI. In the reaction with N,N-dimethylformamide, formyl iodide HCOI was detected for the first time by gas chromatography-mass spectrometry. The contribution of Me-N bond cleavage, leading to N-methyl-N-trimethylsilyl derivative Me(Me₃Si)NCOR and methyl iodide was considerably smaller. Another by-product was the corresponding N-methyl imide MeN(COR)₂ formed by reaction of the initial amide with acyl iodide. The primary intermediate in the reaction of iodo(trimethyl)silane with DMF and DMA is quaternary ammonium salt [Me₂(Me₃Si)N⁺COR] I⁻ which decomposes via dissociation of the N-CO and N-Me bonds.     

The products of phosphorylation of <Emphasis Type="Italic">N,N</Emphasis>-dialkylureas and dialkylcyanamides with phosphorus pentachloride. NMR spectroscopy study

The study by ¹H and ³¹P NMR spectroscopy has shown that phosphorylation of N,N-dimethylurea and diethylcyanamide with phosphorus pentachloride results in the formation of N′-(N,N-dialkylchloroformamidino) trichlorophosphonium hexachlorophosphorates where the positive charge of the organyltrichlorophosphonium cation is delocalized over the system of the multiple bonds with participation of the lone electron pair of the nitrogen atom. Bis-N′-(N,N-dialkylchloroformamidino)dichlorophosphonium hexachlorophosphorates, dichlorides of N,N-dialkylchloroformamidinophosphonic and thiophosphonic acids are synthesized where the conjugation of the phosphorus-containing substituent with the chloroformamidinium part of the molecules is retained. Organyltetrachlorophosphoranes based on N,N-dimethylurea and diethylcyanamide exist in polar and nonpolar solvents as orhanyltrichlorophosphonium chlorides.     

Standard molar enthalpies of formation and sublimation of <Emphasis Type="Italic">N</Emphasis>-phenylphthalimide

The standard (p ⁰=0.1 MPa) molar enthalpy of formation, Δ_f H ⁰ _m, for crystalline N-phenylphthalimide was derived from its standard molar enthalpy of combustion, in oxygen, at the temperature 298.15 K, measured by static bomb-combustion calorimetry, as –206.0±3.4 kJ mol^–1. The standard molar enthalpy of sublimation, Δ^g _cr H ⁰ _m , at T=298.15 K, was derived, from high temperature Calvet microcalorimetry, as 121.3±1.0 kJ mol^–1. The derived standard molar enthalpy of formation, in the gaseous state, is analysed in terms of enthalpic increments and interpreted in terms of molecular structure.     

Antioxidant flavonoids from <Emphasis Type="Italic">Tamus communis</Emphasis> ssp. <Emphasis Type="Italic">cretica</Emphasis>

A new flavonoid, kaempferol-3,4′-di-O-α-L-rhamnopyranoside (1), and three known flavonoids (2–4) were isolated from the aerial parts of T. communis L. The structure of the new compound was elucidated on the basis of spectroscopic data. Compounds 1 and 2 showed significant antioxidant activity (IC₅₀ 187.151 ± 0.821 μM, and 92.079±0.513 μM, respectively), whereas compounds 3 and 4 showed moderate activity in DPPH free radical scavenging assays. Published in Khimiya Prirodnykh Soedinenii, No. 3, pp. 295–297, May–June, 2009.     

Synthesis,structure, and magnetic properties of the cobalt(<Emphasis Type="SmallCaps">II</Emphasis>) 1,3,5-benzenetricarboxylate layered coordination polymer

The reaction of Co(NO₃)₂·6H₂O with 1,3,5-benzenetricarboxylic acid (H₃btc, trimesic acid) in DMF at 100 °C afforded the coordination polymer [Co₃(dmf)₆(btc)(Hbtc)(H₂btc)]··9H₂O (1) (dmf is N,N′-dimethylformamide, DMF). According to the X-ray diffraction study, the metal-organic coordination polymer is composed of planar honeycomb (6,3) networks, in which the organic benzenetricarboxylate anions and the inorganic Co²⁺ cations play a role of three-connected nodes. Disordered water molecules are intercalated between the layers. A study of the magnetic properties showed the presence of a weak antiferromagnetic coupling between the Co²⁺ ions (S = 3/2). Dedicated to Academician G. A. Abakumov on the occasion of his 70th birthday. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1719–1723, September, 2007.     

Ellagic acid glycosides from the stem bark of <Emphasis Type="Italic">Aphananthe aspera</Emphasis>

Five ellagic acid glycosides were isolated from Aphananthe aspera and their structures were identified as 3-O-methylellagic acid-4′-O-α-L-rhamnopyranoside (1), 3-O-methylellagic acid-4′-O-β-D-xylopyranoside (2), 3,3′-di-O-methylellagic acid-4′-O-β-D-xylopyranoside (3), 3,3′, 4-tri-O-methylellagic acid-4′-O-β-D-glucopyranoside (4), and 3,3′-di-O-methylellagic acid-4′-O-α-L-rhamnopyranoside (5) on the basis of spectroscopic analysis. Compound 1 is new, and all the compounds were isolated for the first time from the title plant. Published in Khimiya Prirodnykh Soedinenii, No. 5, pp. 458–459, September–October, 2007.