Showing papers in "Monatshefte Fur Chemie in 1977"
TL;DR: In this paper, a monomer-dimer equilibrium for pyrromethenones was deduced by means of absorption and fluorescence spectroscopy and measurement of a colligative property.
Abstract: Depending on solvent polarity and concentration a monomer—dimer equilibrium for pyrromethenones was deduced by means of absorption and fluorescence spectroscopy and measurement of a colligative property. The monomer could be characterized as asyn-(Z) form with a dihedral angle at the methine single bond of about fourty degrees using the lanthanide shift technique and nuclearOverhauser effect studies. Two types of dimer geometry with differing bond strengths were found by comparingPPP calculation results with the measured absorption spectra and the liquid crystal induced circular dichroism. The (Z) isomers can be transformed to the corresponding (E) isomers by means of a photoreaction. The latter is thermally stable but rather sensitive against oxygen, light and protons, an effect which varies strongly with the substitution pattern of the pyrrole fragment thus enabling isolation in certain cases only.
59 citations
TL;DR: In this paper, the unit cell parameters of AlVO4 have been determined from powder diagrams and the infrared spectra of the system has been recorded and discussed using a series of solid solutions in the system.
Abstract: The unit cell parameters of AlVO4 have been determined from powder diagrams. The compound pertains to the triclinic system and is isostructural wi7h FeVO4. The infrared spectra of AlVO4 and FeVO4 and of a series of solid solutions in the system AlVO4/FeVO4 has also been recorded and discussed.
54 citations
TL;DR: In this paper, the acceptor numbers for binary mixtures of water with acetonitrile (AN), dioxane, acetone (AC), pyridine (PY), N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), hexamethylphosphoramide (HMPA), methanol, ethanol andi-propyl alcohol were determined both by selective solvation and specific solvent-solvent interactions.
Abstract: Acceptor numbers have been determined for binary mixtures of water with acetonitrile (AN), dioxane, acetone (AC), pyridine (PY), N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), hexamethylphosphoramide (HMPA), methanol, ethanol andi-propyl alcohol. The electrophilic properties of binary aqueous-non aqueous solvent mixtures are determined both by selective solvation and specific solvent-solvent interactions. The variation of the acceptor number as a function of solvent composition is interpreted in terms of the previously determined nucleophilic and electrophilic properties of the pure components and their specific solvent structure.
54 citations
TL;DR: The low temperature form of Ag8GeS6 (synthetic argyrodite) was determined from 2-circle diffractometer data by means of direct methods and refined toR=0.081 for 3431 intensities.
Abstract: The low temperature form of Ag8GeS6 (synthetic argyrodite) is orthorhombic, space group Pna21, witha=15.149 (1),b=7.476 (2),c=10.589 (1), andZ=4. The crystal structure has been determined from 2-circle diffractometer data by means of direct methods and refined toR=0.081 for 3431 intensities. The structure consists of slightly distorted isolated GeS4 tetrahedra (mean Ge−S bond length 2.212 A) and two further sulphur atoms without bonds to the germanium atoms. The GeS4 tetrahedra and the S atoms are connected by the Ag atoms to form a three-dimensional framework. Three types of Ag coordination by S atoms are encountered. Three Ag positions have a strongly distorted tetrahedral environment, four Ag positions an approximately planar threefold coordination, while one Ag atom is almost linearly coordinated by two S atoms. The Ag−S distances are 2.56–2.94 A, 2.49–2.76 A, and 2.42–2.44 A, resp. All Ag atoms have at least one near Ag neighbour between 2.93 and 3.11 A.
46 citations
TL;DR: In this article, the chiroptical properties of disubstituted ferrocenes are recorded, and preliminary tests using a shortened Ansatz revealed large discrepancies between calculated (χ) and found [M]D-values.
Abstract: Starting from optically active methylferrocene-α- and-β-carboxylic acids (1 a and1 b) of known absolute configuration and enantiomeric purity about 15 chiral ferrocenes (of each isomeric series—α and β) were obtained by suitable ligand transformations. Thereby (almost) all possible chiral combinations of the ligands CH3, COOH (COO−), COOCH3, C≡N and NH2 (NH3+) were accessible which are necessary for a potential test of approximations of chirality functions for compounds with basic symmetry C5v. The chiroptical properties of these disubstituted ferrocenes are recorded.Preliminary tests using a shortened Ansatz revealed large discrepancies between calculated (χ) and found [M]D-values. Possible reasons for this failure are discussed.
23 citations
TL;DR: In this article, the synthesis of α-aminopyridines can be carried out as one step reactions starting with malononitrile and orthoformate, and the latter can easily be cyclised to 2-amino-6-chloro-3,5-dicyano-(4-alkyl and aryl, resp.)-pyridine.
Abstract: Malononitrile reacts with triethyl orthoformate,-orthoacetate,-orthopropionate and-orthobenzoate, resp., in the presence of different amounts of pyridine to ethoxymethylene-malononitriles and pyridinium 1,1,3,3-tetracyano-propenides, resp. The latter can easily be cyclised to 2-amino-6-chloro-3,5-dicyano-(4-alkyl and aryl, resp.)-pyridines. The synthesis of the α-aminopyridines can be carried out as one step reactions starting with malononitrile and orthoformate.
22 citations
TL;DR: In this article, a new classification of the variety of η-phases is presented, considering the different modes of filling the voids, a new class of κ-oxides: {Zr, Zr, Hf}9Os4O4O3 and new η -oxides, {Ti, ZR, HF, Zn3O, Hf4Os2O≈0.75] were prepared.
Abstract: New κ-oxides: {Zr, Hf}9Os4O3 and new η-oxides: {Ti, Zr, Hf}3Zn3O
x
and Hf4Os2O≈0.75 were prepared. Considering the different modes of filling the voids, a new classification of the variety of η-phases is presented.
22 citations
TL;DR: In this paper, an intramolecular hydrogen bond characteristic of this bile pigment partial structure was found to be coplanar (in solution) in contrast to pyrromethenones and arylmethylidenepyrrolinones which have a twisted conformation at the methine single bond.
Abstract: By investigation of model systems related to 5-[5-methylidene-(5H-pyrrolyl-2-methylidene)]-3-pyrrolin-2-one by means of pK- and Lanthanide induced shift measurements (usingPDIGM-calculations),1H-NMR-, IR-, and UV-spectroscopy andPPP-calculations an intramolecular hydrogen bond has been shown to be characteristic of this bile pigment partial structure. As a consequence of this bond the system is coplanar (in solution) in contrast to the recently studied pyrromethenones and arylmethylidenepyrrolinones which have a twisted conformation at the methine single bond.
21 citations
TL;DR: In this paper, the synthesis of 5-arylpyrromethenes and their biological activities related to metacycloprodigiosin were described, and the syntheses of some 5-yrlpyrrhromethens were described.
Abstract: The syntheses of some 5-arylpyrromethenes are described, and their biological activities related to that of metacycloprodigiosin.
20 citations
TL;DR: Condensation reactions of alkyl and cycloalkylenaminoketones, resp. with cyanoacetamide, malononitrile and 2-amino-1-propene-1,1,3-tricarbonitrile (2) are investigated as mentioned in this paper.
Abstract: Condensation reactions of alkyl-and cycloalkylenaminoketones, resp. with cyanoacetamide, malononitrile and 2-amino-1-propene-1,1,3-tricarbonitrile (2) are investigated. Hydrolysis of dicyanomethylene substituted alkyl-dihydropyridines3 leads to 1,6-naphthyridines4 and5. With 2-morpholino-1-cyclohexenyl-1-ethanone (6) isoquinolines8 and9 are obtained. Condensation of 2-morpholinomethylene-cycloalkanones11 yields cycloalkanepyridines12 and13. 2-Morpholinomethylene-1,3-cyclohexanediones18 with malononitrile give the quinolinones20.
20 citations
TL;DR: In this article, the transanular double bond participation of N-bromosuccinimide (NBS) and water on (Z,Z)-1,5-cyclononadiene (1) was shown to give 1βbromo-3a α,4α,5,6,7,7a α-hexahydroindan-4-ol (2 a) and 2β,6β-dibromo -10-oxabicyclo[5.2.1]decane (3
Abstract: The action of N-bromosuccinimide (NBS) and water on (Z,Z)-1,5-cyclononadiene (1) results in transanular reactions to give 1β-bromo-3a α,4α,5,6,7,7a α-hexahydroindan-4-ol (2 a) and 2β,6β-dibromo-10-oxabicyclo[5.2.1]decane (3). The formation of2 a is a result of transanular double bond participation.3 is considered to be produced from intermediary (Z)-2β-bromo-5-cyclononen-1α-ol (6)via transanular participation of the hydroxyl group. The reaction of1 withNBS and methanol similarly produces 1β-bromo-4-methoxy-3aα,4α,5,6,7,7a α-hexahydroindan (2 b) and3.
TL;DR: In this paper, the system TiC−HfC−MoC was investigated by means of melting point, differentiothermoanalytical, X-ray diffraction and metallographic techniques on hotpressed as well as melted alloy specimens.
Abstract: The system TiC−HfC−“MoC” was investigated by means of melting point, differentiothermoanalytical, X-ray diffraction and metallographic techniques on hotpressed as well as melted alloy specimens A constitutional diagram from 1500°C through the melting range was established
TL;DR: In this article, the structure of 2.5-Diamino-1,3,4-thiadiazole and 2.6-aryl (alkyl)-imidazo was shown to form easilySchiff bases.
Abstract: 2,5-Diamino-1,3,4-thiadiazole (1) reacts with α-halogencarbonyl compounds to 2-imino-3-phenacyl(acetonyl)-5-amino-1,3,4-thiadiazolines (3) which easily can be cyclised to 2-amino-6-aryl (alkyl)-imidazo[2,1-b]-1,3,4-thiadiazoles (4), the structure of which was proofed. On the basis of the amino function in position 2 these substances were able to form easilySchiff bases (5, 6, 7). Their semicyclic amidine system did not allow as yet to integraet it in a third ring system.
TL;DR: In this paper, a synthetic approach to 2-alkoxycarbonyl-3-indolealkanoic acids via partial saponification of the corresponding diesters is presented.
Abstract: A synthetic approach to 2-alkoxycarbonyl-3-indolealkanoic acidsvia partial saponification of the corresponding diesters is presented. 2-Ethoxycarbonyl-3-indoleacetic acid as well as the homologous propionic and butyric acids may conveniently be prepared by this method. A different synthesis of 3-indoleacetic acids functionalized at position 2 can be accomplished by decomposition of ethyl diazoacetate in the presence of the indole derivative at elevated temperature. Cyclization of 2-hydroxymethyl-3-indoleacetic acid, thus prepared, yields the corresponding δ-valerolactone. With 1-acyl-indoles and ethyl diazoacetate addition of the carbene to the C-2=C-3 double bond prevails, resulting in the formation of cyclopropanecarboxylic esters.
TL;DR: By means of vapor pressure measurements using theTorker method (Torsion-Knudsen Effusion Recoil) as well as the Knudsen tanspiration technique in connection with a mass spectrometer, the heats of formation of the following compounds were found to be −6.5±0.6
Abstract: By means of vapor pressure measurements using theTorker method (Torsion-Knudsen Effusion Recoil) as well as theKnudsen tanspiration technique in connection with a mass spectrometer, the heats of formation of the following compounds were found to be −6.5±0.7 kcal/g atom (Mn0.366Si0.634), −7.8±0.6 kcal/g atom (Mn0.50Si0.50), −7.3±0.6 kcal/g atom (Mn0.625Si0.375), and −6.6±0.6 kcal/g atom (Mn0.75Si0.25).
TL;DR: In this article, the standard free energies of transfer from the reference solvent acetonitrile to various protic and aprotic solvents have been calculated based on the assumption of negligible diffusion potentials in certain galvanic cells.
Abstract: Standard free energies of transfer from the reference solvent acetonitrile to various protic and aprotic solvents have been calculated based on the assumption of negligible diffusion potentials in certain galvanic cells. The standard free energies of transfer of Cl−, Br−, and I− are linearly related to the acceptor numbers of unstructured solvents. Similarly, linear relationships were found to exist between the donor numbers of unstructured solvents and the standard free energies of transfer of K+ and in part Ag+. Deviations from linearity occuring in protic solvents like water, methanol, ethanol or trifluoroethanol are interpreted in terms of changes in solvent structure.
TL;DR: A solubility cell which can be operated continuously over the temperature range 5 −95 °C has been developed in this article, where the authors investigated at fixed partial pressures of H2S at 50.7 °C.
Abstract: A solubility cell which can be operated continuously over the temperature range 5–95 °C has been developed. The solubility of Fe0.88S (monoclinic pyrrhotite) in solutions
$$S_0 = ([H^ + ]) = H{\text{ }}m,{\text{ }}[Na^ + ] = (1.00---H) m,{\text{ }}[ClO_{4^ - } ] = 1.00 m)$$
at fixed partial pressures of H2S has been investigated at 50.7 °C. The hydrogen ion concentration and the total concentration of iron(II) ion in equilibrium with the solid phase was determined by e.m.f. and analytical methods respectively. The data were consistent with
$$\log ^* K_{pso} = \log \frac{{[Fe^{2 + } ]pH_2 S}}{{[H^ + ]^2 }} = 3.80 \pm {\text{ }}0.10{\text{ }}[50.7^\circ C,{\text{ }}1 m(Na)ClO_4 ]$$
according to the overall reaction
$$1.14{\text{ }}Fe_{0.88} S_{(s)} {\text{ }} + {\text{ }}2H_{(I = 1m)}^ + {\text{ }} \rightleftharpoons {\text{ }}Fe_{(I = 1m)}^{2 + } {\text{ }} + {\text{ H}}_{\text{2}} S_{(g)} {\text{ }} + {\text{ }}0.14{\text{ }}S_{(s)} $$
TL;DR: In this paper, the volume susceptibilities of various solvents were determined by means of NMR-spectroscopy, and the results showed that the susceptibilities varied with the temperature.
Abstract: By means of NMR-spectroscopy the volume susceptibilities of various solvents have been determined.
TL;DR: In this paper, the X-ray powder patterns of the resulting superstructures are determined by comparison of calculated and observed reflections of the unit cell with the same unit cell in all three dimensions.
Abstract: The described procedure is based on the choice of a basic unit cell. The parameters of this unit cell are variably combined in all three dimensions and X-ray powder patterns of the resulting superstructures are determinated. The correct superstructure unit cell is found by comparison of calculated and observed reflections.
TL;DR: In this paper, the IR spectrum of hydrohematite was studied and it was shown that the molecules of water responsible for these two bands confer high resistance on the hematite lattice.
Abstract: The hydrothermal method may lead to “structurally pure” hydrohematite when traces of aluminium ions are added during the precipitation of iron(III)-hydroxide. The concentration needed to eliminate the goethite phase increases with increasing alkalinity of the solution. The best results, preserving hydrohematite in an excellent crystalline state without any contamination by another phase are obtained at pH 9 in the presence of 0.01 mole Al3+ pro one mole Fe3+. Due to complete elimination of the goethite phase from hydrohematite, it was possible to study the IR spectrum of the latter, and to prove its individual character by absorption bands at 960 cm−1 and 660 cm−1. In this way may be distinguished the roentgenographically indistinguishable hydrohematite from hematite. The molecules of water responsible for these two bands confer high resistance on the hematite lattice.
TL;DR: For example, Dibromoisocyanuric acid (DBI) has proved to be a particularly powerful brominating agent, which can be easily handled in the laboratory as discussed by the authors.
Abstract: Of the bromo derivatives of isocyanuric acid, unknown until 1967, dibromoisocyanuric acid (DBI) has proved to be a particularly powerful brominating agent, which can be easily handled in the laboratory.
TL;DR: In this article, the structure of β-Sn[(OC2H4)2NC2H 4OH]2 was solved by the heavy atom technique (571 observed reflections, R1=5.9%).
Abstract: β-Sn[(OC2H4)2NC2H4OH]2 crystallizes with space group Pccn and cell dimensionsa=16.35 (2),b=7.26 (1),c=12.82 (1) A andZ=4. The structure was solved by the heavy atom technique (571 observed reflections, R1=5.9%). Tin is octahedrally coordinated by four oxygen and two nitrogen atoms (Sn−O 2.01; 2.04 A, Sn−N 2.33 A) of the triethanolamine molecules. The complexes possess a crystallographic two-fold axis of rotation. They are linked by hydrogen bonds, thus forming infinite chains parallel to the twofold axis.
TL;DR: In this article, NMR spectroscopy was used to obtain equilibria of cyclic hydroxylamine and hydroxynitrone forms2 resp.1, the state of which depends on the solvent.
Abstract: From the hydroxylaminomethylation product of 2-naphthol (3) and aliphatic resp. aromatic aldehydes resulting compounds were examined by NMR spectroscopy. In solution the products of formaldehyde, acetaldehyde and benzaldehyde show equilibria of cyclic hydroxylamine and hydroxynitrone forms2 resp.1, the state of which depends on the solvent; with the derivatives of p-nitro- and p-dimethylaminobenzaldehyde only the hydroxynitrone form1 d resp.1 e is detectable.
TL;DR: The thermodynamic stability constants and thermodynamic parameters for complexation reaction of Y3+, La3+, and Ce3+ with tyrosine have been determined pH metrically as mentioned in this paper.
Abstract: The thermodynamic stability constants and thermodynamic parameters for complexation reaction of Y3+, La3+, and Ce3+ with tyrosine have been determined pH metrically. The study reveals the formation of 1∶1 complexes for La3+ and Ce3+ whereas Y3+ yields both 1∶1 and 1∶2 complexes. The values of enthalpy changes (ΔHo) indicate that unionised hydroxy group also participates in complexation.
TL;DR: In this paper, the properties of 3-pyridazinemethanol and its reactions with NH-compounds and methyl pyridazines were studied, and it was shown that thermally induced dismutation cannot be excluded also on 3-carbinols.
Abstract: by MnO2-oxidation of 3-pyridazinemethanol is reported. Properties of2 and its reactions with NH-compounds and methyl-pyridazines (3, 5) are studied. Reaction of2 with3 yields mainly products of aldol addition (10, 12). In contrast to pyridazinyl-4-carbinols elimination of H2O from10 leads to the alkene11. Isolation of the di-pyridazinyl-ethane6 as main product of reaction of2 with5 however shows, that thermally induced dismutation cannot be excluded also on pyridazinyl-3-carbinols.
TL;DR: In this paper, the half-wave potentials of tetrakis(triphenylphosphine)-platinum(0) [Pt(TPP)4] and Ni(TTP)4 were investigated in N, N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), acetonitrile (AN), propanediol carbonate (PDC), N,N-dimmethylthioformamide(DMTF) N-methylpyrrolidine-2-thione (NMTP) and nitrom
Abstract: The redox behaviour of tetrakis(triphenylphosphine)-platinum(0) [Pt(TPP)4], tetrakis(triphenylphosphine)-palladium(0) [Pd(TPP)4] and tetrakis(triphenylphosphine)-nickel(0) [Ni(TPP)4] has been studied in N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), acetonitrile (AN), propanediol carbonate (PDC), N,N-dimethylthioformamide (DMTF) N-methylpyrrolidine-2-thione (NMTP) and nitromethane (NM). The platinum complex was found to undergo irreversible two electron oxidations with partial or complete loss of the ligands in all solvents but nitromethane. The palladium complex was also oxidized to the divalent form in the solvents studied except inPDC andNM where the complex was found to be polarographically inactive; Ni(TTP)4 was reversibly or almost reversibly oxidized to a movovalent form inDMF, AN andDMTF followed by an irreversible oxidation to a divalent complex. Direct oxidation to the divalent form occurred inDMSO, no oxidation was observable inNMTP andPDC, decomposition took place in nitromethane. The half-wave potentials were recorded versus bisbiphenylchromium iodide (BBCr)I as an internal standard. The influence of the solvents on the redox behaviour and the dissociation of ligands is discussed.
TL;DR: The ternary system nickel-copper-boron was established at 700°C by means of X-ray diffraction and metallographic examinations as mentioned in this paper, which confirmed the well known binary nickel borides.
Abstract: The ternary system nickel-copper-boron was established at 700°C by means of X-ray diffraction and metallographic examinations. Confirming the well known binary nickel borides no ternary boride was found. The solubility of boron in the nickel-copper solid solution is very small and has its maximum of about 0.3 at% in the binary system copper-boron. Differential-thermoanalysis shows a quasibinary eutectic between Ni3B and copper solid solution.
TL;DR: Complexes of the type Cs[Ln(SO4)2(H2O)3] H2O, (Ln=La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) were prepared from aqueous solution as discussed by the authors.
Abstract: Complexes of the type Cs[Ln(SO4)2(H2O)3]H2O, (Ln=La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) were prepared from aqueous solution. The compounds are all isomorphous and crystallise monoclinic, space group P21/c,Z=4. Unit cell parameters were determined by the single crystal technique and correlated to the ionic radii of Ln3+.
TL;DR: In this article, N-trimethylsilylamides react with aminohalogenoboranes in nearly quantitative yield to monomeric amido(bis)aminobors.
Abstract: N-Trimethylsilylamides react with aminohalogenoboranes in nearly quantitative yield to monomeric amido(bis)aminoboranes. From the reaction of N-substituted acylamides with bis(amino)halogenoboranes and dialkoxyhalogenoboranes respectively and triethylamine corresponding amido-bis(amino)-and amido-bis(alkoxy)boranes were obtained in high yields. In certain cases equilibria between monomeric and dimeric forms are observed.1H,11R, and19F.-n.m.r. spectra, mass spectra and characteristic i.r. group frequencies are reported.
TL;DR: The mechanism of the reaction of 3-substituted pyrido-pyrimidinediones (2) and phenyl isocyanate (4 a) is discussed in this article.
Abstract: The reaction of N-(2-pyridyl)-carbaminates (3), 1-phenyl-3-(2-pyridyl)-urea (5 a) or alkyl and aryl substituted pyridopyrimidinediones (2) synthesized from 2-amino-pyridine with arylisocyanates (4 a, b) yields 3-aryl substituted pyrido-[1,2-a]-s-triazine-2,4-diones (1). 2-Aminopyridine and azamalonic derivatives (ethoxycarbonyl isocyanate, ethyl iminodicarboxylate) react to give the 3-unsubstituted triazine system (1 c). The isolation of monocyclic triazinediones obtained from the reaction of N-phenylbenzamidine (9) with aryl isocyanate (4 a) or ethoxycarbonyl isocyanate failed because of hydrolytic ring opening. The mechanism of the reaction of 3-substituted pyrido-pyrimidinediones (2) and phenyl isocyanate (4 a) is discussed.