Cyclopalladation of N,N,N′,N′-tetramethylisophthalthioamide

Summary N,N,N,N-Tetramethylisophthalthioamide (Hmpt) was cyclopalladated with PdCl₂ in hot dimethylsulphoxide to give [PdCl(mpt)]. The structure was determined by X-ray analysis. The thioamide is metallated at C(2) to act as an S528-01C528-02S tridentate anionic ligand. There is appreciable steric repulsion between the benzene ring H(4, 6) and the dimethylamino groups. The hydrogens and the methyl groups mutually deviate from the coordination plane in opposite directions. The stability of the fused 5,5-membered chelate ring formed by the S528-03C528-04S ligand seems to overcome the steric hindrance. Derivatives were prepared by replacement of the chloride ion with iodide, diethyldithiocarbamate, 4-tert-butylpyridine, or tri-n-butylphosphine, and characterized spectroscopically. The S528-05C528-06S-fused chelate ring was maintained in these derivatives.     

Synthesis of N′-phosphinatodiazene N-oxides

We have developed a regiospecific method for synthesis of N-phosphinatodiazene N-oxides, a previously unknown type of azoxy compounds in which the diazene oxide fragment is directly connected with the phosphinate group. The method involves reaction of amidoesters of alkyl- and arylphosphonic acids with nitroso compounds in the presence of dibromoisocyanurate.N. D. Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, 117913 Moscow. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 11, pp. 2648–2656, November, 1992.     

GC-MS determination and optimization of extraction of N,N′-dimethyl-N,N′-diphenylcarbamide from building materials

N,N’-dimethyl-N,N’-diphenylcarbamide (centralite) extracted from building materials was quantitated using ion trap GC-MS detection technique. Both linearity and standard deviation of the calibration curve were dependent on the conditions of the mass spectral detection. The most precise calibration has been achieved by quantification of a mass ion not participating in secondary reactions and which is produced via single fragmentation. The best recovery of centralite was obtained after either 30 min of normal extraction with toluene at 60 °C or 10 min of ultrasonic extraction with chloroform at room temperature. Using the latter method resorption processes might cause decrease in efficiency of the recovery at longer extraction time. Received: 3 July 1998 / Revised: 5 November 1998 / Accepted: 26 January 1999     

Synthesis of hydrogels from a polymeric N,N′-diallyl-N,N′-dimethylammonium salt

Feasibility in principle has been demonstrated for obtaining hydrogels with controlled parameters of the three-dimensional network by copolymerization of N,N-methylenebisacrylamine with macromolecules of poly-N,N-diallyl-N,N-dimethylammonium chloride containing terminal double bonds, i.e., with macromonomers of N,N-diallyl-N,N-dimethylammonium chloride. The hydrogels that are obtained have high anion-exchange capacities.A. V. Topchiev Institute of Petrochemical Synthesis, Academy of Sciences of the USSR, Moscow 117912. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 4, pp. 851–854, April, 1992.     

The step dissociation constants of ethylenediamine-N,N′-diacetic-N,N′-dipropionic and ethylenediamine-N,N,N′,N′-tetrapropionic acids

The step dissociation constants of ethylenediamine-N,N′-diacetic-N,N′-dipropionic and ethylenediamine-N,N,N′,N′-tetrapropionic acids at 298.15 K and ionic strengths of 0.1, 0.5, and 1.0 (KNO₃) were determined potentiometrically. The results were extrapolated to zero ionic strength by the equation with one individual parameter. The thermodynamic constants of dissociation were calculated. The results are compared with the corresponding data on related compounds.     

Mononuclear palladacycles of N,N′-diaryl-2-iminoisoindolines

Reaction of acetato-bridged dinuclear palladacycles, [Pd(iminoisoindoline)(μ-OAc)]₂, with stoichiometric amounts of PR₃ (where R = Ph or Cy) resulted in formation of the corresponding mononuclear phosphine-ligated, six-membered palladacycles with the general formula [Pd(iminoisoindoline)(OAc)PR₃]. The analogous chloride complexes were synthesized by reaction of [Pd(iminoisoindoline)(μ-OAc)]₂ with LiCl in acetone followed by addition of phosphine to afford the monomeric derivatives [Pd(iminoisoindoline)(Cl)PR₃]. Representative crystal structures of both types of mononuclear palladacycles confirmed the mononuclear nature of the complexes and showed a trans-arrangement of the phosphine ligand to the heterocyclic imine-nitrogen of the palladacycles.     

Thermochemistry of 2,2′-dipyridil N-oxide and 2,2′-dipyridil N,N′-dioxide. The dissociation enthalpies of the N−O bonds

In this paper, the first, second and mean (N?O) bond dissociation enthalpies (BDEs) were derived from the standard (p° = 0.1 MPa) molar enthalpies of formation, in the gaseous phase, ${\mathrm{\Delta }}_{\text{f}}{H}_{\text{m}}^{°}(\text{g})$, at T = 298.15 K, of 2,2′-dipyridil N-oxide and 2,2′-dipyridil N,N′-dioxide. These values were calculated from experimental thermodynamic parameters, namely from the standard (p° = 0.1 MPa) molar enthalpies of formation, in the crystalline phase, ${\mathrm{\Delta }}_{\text{f}}{H}_{\text{m}}^{°}(\text{cr})$, at T = 298.15 K, obtained from the standard molar enthalpies of combustion, ${\mathrm{\Delta }}_{\text{c}}{H}_{\text{m}}^{°}$, measured by static bomb combustion calorimetry, and from the standard molar enthalpies of sublimation, at T = 298.15 K, determined from Knudsen mass-loss effusion method.     

FT-IR study of the conformation and proton acceptor ability of N-tertiobutoxycarbonylsarcosine N′-methylamide and N-tertiobutoxycarbonylsarcosine N′,N′-dimethylacetamide

Two model dipeptides, N-tertiobutoxycarbonylsarcosine N′-methylamide (BSMA) and N-tertiobutoxycarbonylsarcosine N′,N′-dimethylamide (BSDA) are investigated by FT-IR spectrometry. The conformation of BSMA is very sensitive to the environment. In solvents of weak polarity (carbon tetrachloride, cyclohexane), BSMA accomodates the extended and seven-membered ring conformation, but in 1,2-dichloroethane, the C₇ conformers are greatly destabilized. Hydrogen bonding between BSMA or BSDA and phenols is studied in carbon tetrachloride. The thermodynamic data (equilibrium constants and enthalpies of complex formation) show that the BSMA complexes are stronger than the BSDA complexes. The spectroscopic data suggest that for BSMA, complex formation occurs at the O atom of the amide function while for BSDA about 50% of the complexes are formed on the O atom of the urethane group. The differences between the two sarcosine dipeptides are discussed in terms of cooperative and steric effects. It can be concluded that the global polarity of the medium exerts a greater influence on the conformation of the C₇ dipeptides than the specific interactions taking place on a given site of the molecule.     

Synthesis and Crystal Structure of Complexes of Lanthanide Picrates With N,N ′-Dimethyl-N,N ′-Diphenyl-1,2-PhenylenediOxydiacetamide

Lanthanide picrate complexes with the ligand N,N'-dimethyl-N,N'-diphenyl-1,2-phenylenedioxydiacetamide (L) [Ln(Pic)₃L] (Ln=La,Gd,Er,Y) have been prepared in nonaqueous medium and characterized by elemental analysis, IR and ¹H spectra. The Gd(III) complex [Gd(Pic)₃L]·3CH₃CN is triclinic, space group P&1macr;, with a=14.292(1), b=14.967(2), c=16.571(2)Å, α=97.855(9), γ=113.070(9)°, ν=28706(6)ų, D _c=1.584g/cm³ for Z=2. The structure was refined to R=0.0318 based on 8409 observed reflections.     

A calorimetric study of N,N-diethyl-N′-furoylthiourea and N,N-diisobutyl-N′-furoylthiourea

The standard ( p^o =  0.1 MPa) molar enthalpies of combustion in oxygen, at T =  298.15 K, were measured by rotative bomb calorimetry for crystalline N, N -diethyl- N^′-furoylthiourea, (2-C₄H₃O)CONHCSN(C₂H₅)₂, HFET, and N, N -diisobutyl- N^′-furoylthiourea, (2-C₄H₃O)CONHCSN(iso-C₄H₉)₂, HFIB. The standard molar enthalpies of sublimation of both HFET and HFIB were measured by high-temperature Calvet microcalorimetry. These values were used to derive the standard molar enthalpies of formation of the compounds, in their crystalline and gaseous phases.     

Networks based on aromatic glycidylamines: 1. Effect of curing conditions on the crosslinking of N,N-diglycidylaniline with 4,4′-diaminodiphenylmethane and of N,N,N′,N′-tetraglycidyl-4,4′-diaminodiphenylmethane with 4,4′-diaminodiphenylmethane

The effect of time and temperature of curing on the conversion of epoxy groups, on the relative change of some other functional groups (–OH, –NH₂, RNH), glass transition temperatureT _g , and equilibrium modulusG _e was investigated for epoxy networks having various initial ratios of N,N-diglycidylaniline to 4,4-diaminodiphenylmethane (DDM) and of networks with various ratio of N,N,N,N-tetraglycidyl-4,4-diaminodiphenylmethane and DDM. Curing conditions were found under which the conversion of minority groups is maximal at the minimal extent of degradation reactions for networks prepared both in the excess of amine and in the excess of epoxide. For networks prepared in the excess of epoxide the degree of the etherification reaction was found to depend on time and temperature.     

Thermodynamic characteristics of protolytic equilibria of hexamethylenediamine-N,N,N′,N′-tetraacetic acid

The heats of dissociation of betaine groups of hexamethylenediamine-N,N,N′,N′-tetraacetic acid (H₄L) at 298.15 K and the ionic strengths of 0.1, 0.5, and 1.0 (KNO₃) were determined by direct calorimetry. The standard thermodynamic characteristics of the ptotolytic equilidria of H₄L were calculated using the results from thermochemical and potentiometric measurements made under identical test conditions.     

Organocatalytic Enantioselective Synthesis of Axially Chiral N,N′-Bisindoles

This study establishes the first organocatalytic enantioselective synthesis of axially chiral N,N′-bisindoles via chiral phosphoric acid-catalyzed formal (3+2) cycloadditions of indole-based enaminones as novel platform molecules with 2,3-diketoesters, where de novo indole-ring formation is involved. Using this new strategy, various axially chiral N,N′-bisindoles were synthesized in good yields and with excellent enantioselectivities (up to 87 % yield and 96 % ee). More importantly, this class of axially chiral N,N′-bisindoles exhibited some degree of cytotoxicity toward cancer cells and was derived into axially chiral phosphine ligands with high catalytic activity. This study provides a new strategy for enantioselective synthesis of axially chiral N,N′-bisindoles using asymmetric organocatalysis and is the first to realize the applications of such scaffolds in medicinal chemistry and asymmetric catalysis.     

Thermal and FTIR spectral studies of N,N′-diphenylguanidine

Thermal decomposition of N,N??-diphenylguanidine (DPG) was investigated by simultaneous TG/DSC-FTIR techniques under nonisothermal conditions. Online FTIR measurements illustrate that aniline is a major product of DPG decomposition. The observation that the activation energy depends on the extent of conversion indicates that the DPG decomposition kinetics features multiple processes. The initial elimination of aniline from DPG involves two pathways because of the isomerization of DPG. Mass spectrometry and thin film chromatography suggest that there are two major intermediate products with the major one of C₂₁N₃H₁₇. The most probable kinetic model deduced through multivariate nonlinear regression method agrees well with the experimental data with a correlation coefficient of 0.9998. The temperature-independent function of conversion f(??), activation energy E and the pre-exponential factor A of DPG decomposition was also established through model-fitting method in this research.     

A Facile Synthesis of N′-Benzoyl Thiophosphoryluras

Twelve title compounds 3a-l were synthesized by nuclophilic addition of thiophosphoramide 1 to benzoylisocyanate 2. The yield of compounds 3a-f and 3g-l is 72–83% and 18–33%.     

Preparation and Characterization of N,N′-Dialkyl-1,3-propanedialdiminium Chlorides,N,N′-Dialkyl-1,3-propanedialdimines,and Lithium N,N′-Dialkyl-1,3-propanedialdiminates

We describe convenient preparations of N,N′-dialkyl-1,3-propanedialdiminium chlorides, N,N′-dialkyl-1,3-propanedialdimines, and lithium N,N′-dialkyl-1,3-propanedialdiminates in which the alkyl groups are methyl, ethyl, isopropyl, or tert-butyl. For the dialdiminium salts, the N₂C₃ backbone is always in the trans-s-trans configuration. Three isomers are present in solution except for the tert-butyl compound, for which only two isomers are present; increasing the steric bulk of the N-alkyl substituents shifts the equilibrium away from the (Z,Z) isomer in favor of the (E,Z), and (E,E) isomers. For the neutral dialdimines, crystal structures show that the methyl and isopropyl compounds adopt the (E,Z) form, whereas the tert-butyl compound is in the (E,E) form. In aprotic solvents all four dialdimines (as well as the lithium dialdiminate salts) adopt cis-s-cis conformations in which there presumably is either an intramolecular hydrogen bond (or a lithium cation) between the two nitrogen atoms.     

Copper-mediated synthesis of N,N′-diarylhydrazines from boronic acids

N,N＇-Diarylhydrazines have been prepared via the reaction of N-Boc-aryl hydrazines with boronic acids mediated by copper acetate. This mild reaction condition tolerates the presence of a variety of functional groups.     

Sensitive Spectrophotometric Determination of Benzoylperoxide with N,N,N′,N′-Tetramethyl-p-phenylenediamine

Abstract

A highly sensitive spectrophotometric determination of benzoylperoxide (BPO) based on the color developing reaction between N,N,N′,N′-tetramethyl-p-phenylenediamine (TMPD) and BPO in the presence of cerium(IV) in weakly acidic media is proposed. The calibration graph is linear in the range 0–6000 ng BPO per 10 ml with an apparent molar absorptivity of 4.73 × 10⁵ 1 mol^?1 cm-1 at 612 nm. The proposed method is about 50-fold more sensitive than N-ethyl-2-naphthylamine (NENA), and application to assays of flour is described.     

Physicochemical studies of the structure of N,N′-dinitrourea and its salts

The properties and behavior of dinitrourea and its potassium and dipotassium salts in different solvents have been studied by IR and UV spectroscopy. In different media, dinitrourea can exist in several tautomeric forms. An XRD study of the potassium and dipotassium salts of dinitrourea revealed a tendency toward equalization of the bond lengths of the C-N⁻-NO₂ fragments compared with those of C-NH-NO₂, which agrees with the results of quantum-chemical calculations.