Reductivetrans-2,6-diallylation of pyridines with allylboranes. Synthesis oftrans- andcis-2,6-diallyl-1,2,5,6-tetrahydropyridines and their deuterated derivatives

The reductivetrans-2,6-diallylation of pyridines with triallyl- and allyl(dialkyl)boranes has been discovered. Heating (40–100 °C) of pyridine, deuteropyridine, or 3-bromopyridine complexes with triallylborane in the presence of alcohols (ROH or CH₃OD), water, or Et₂NH results in the respectivetrans-2,6-diaIlyl-1,2,5,6-tetrahydropyridines (2,3,22, or25) in 20–97 % yields. A preparative method for the isomerization oftrans-2,6-diallyl compounds2 and25 into the respectivecis-isomers4 and28 by heating them with triallyl- or allyl(dialkyl)boranes (125–150 °C) has been suggested. The hydrogenation oftrans- orcis-2,6-diallyl-1,2,5,6-tetrahydropyridines gavetrans- orcis-2,6-dipropylpiperidines, respectively. Thecis- andtrans-configurations of compounds2 and4 were established by analyzing the NMR spectra ofN-benzyl (7 and13) andN,N-dimethyl (6 and 14) derivatives of piperidine derivatives5 and8. A possible mechanism for the reductive diallylation of pyridines has been discussed.Translated fromIzyestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 693–704, April, 1994.This study was financially supported by the Russian Foundation for Basic Research (Project 93-03-18193).     

Free radical copolymerization of 1-vinyl naphthalene with styrene,methyl methacrylate,and acrylonitrile

Investigations on free radical copolymerization of 1-vinyl naphthalene (1-VNph, monomerM ₂) with styrene (St), methyl methacrylate (MMA) and acrylonitrile (AN) (monomersm ₁) in bulk at 60°C with AIBN as initiator are presented. Relative reactivity ratios were calculated by the Kelen-Tüdös method yielding:r _st=0.70 ±0.23 andr _1–VNph=2.02 ±0.40 for system St/1-VNph;r _MMA=0.32 ±0.10 andr _1–VNph=0.57 ±0.07 for system MMA/1-VNph andr _AN=0.11 ±0.03 andr _1–VNph=0.45 ±0.09 for system AN/1-VNph.Q, e values for 1-VNph according to Alfrey, Price scheme were calculated toQ _1–VNph=1.02,e ₁–VNph=–0.62.     

Mittlere Schwingungsamplituden der Hexachloro- und Hexabromo-Anionen einiger Lanthanide

Mean amplitudes of vibration for various octahedral complex compounds of the typeLnCl₆ ^3– andLnBr₆ ^3– (withLn=Nd, Eu, Gd, Dy, Er, and Yb) have been calculated, at different temperatures, using known spectroscopic data. The results are briefly discussed and it is found that theLn–Cl andLn–Br amplitude values are highly characteristic.

     

Metal Schiff-Base Complex Catalyzed Oxidation of p-Xylene and Methyl 4-Methylbenzoate to Carboxylic Acids

Oxidation of p-xylene and methyl 4-methylbenzoate were catalyzed by transition metal Schiff-base complexes having the general formula LMCl_1–2 (where M = manganese or ruthenium and L = salen, salicylaldehydeethylenediimine, saloph, salicylaldehyde-o-phenylenediimine and EDTA, ethylenediaminetetraacetate) at 150°C and 500 psig air and gave p-toluic acid (> 85 %) and monomethyl terephthalate (> 70%) as the major oxidation products, respectively.     

Evaluation of thermodynamic functions for complexation reactions involving bivalent metal ions and ethyl-2,3-dioxobutyrate-2 p -bromophenylhydrazone

Complexation reactions of bivalent metal ions and ethyl-2,3-dioxobutyrate-2p-bromophenylhydrazone (EDOB-2p-BPH) have been studied potentiometrically in 50% (v/v) ethanol/water medium at different ionic strengths with respect to NaClO₄ and at different temperatures and their stability constants determined. The method of Bjerrum and Calvin as modified by Irving and Rossotti has been used to determine then andpL values. S_min values which have the same significance as ‘T²’ have also been calculated. The thermodynamic stability constants and standard free energy change (ΔG) have also been calculated. ΔG values are negative in all cases indicating that the reactions are spontaneous. The ligand field stabilization energy (δH) has also been calculated for the 3d transition metals.     

Buffers for the Physiological pH Range: Thermodynamics of the Second Dissociation of N-(2-Hydroxyethyl)piperazine-N′-2-hydroxypropanesulfonic Acid From 5 to 55°C

The second acidic dissociation constants pK ₂ of the ampholyte N-(2-hydroxyethyl) piperazine-N-2-hydroxypropanesulfonic acid (HEPPSO) have been determined at seven temperatures from 5 to 55°C from emf measurements utilizing hydrogen and silver–silver chloride cells without liquid junction. The thermodynamic quantities, G°, H°,S°, and C _p ^o have been calculated from the temperature coefficient of pK ₂. At 25°C, the pK ₂ = 8.042 and at 37°C, pK ₂ = 7.876; hence, buffer solutions of HEPPSO and NaHEPPSOate are important for pH control in the region close to that of clinical fluids (blood serum). Conventional pH values from 5 to 55°C as well as those obtained from liquid junction correction at 25 and 37°C have been reported for three buffer solutions with the compositions (molality scale): (1) equimolal mixture of HEPPSO (0.04 m) + NaHEPPSOate (0.04 m) + NaCl (0.12 m); (2) HEPPSO (0.08 m) + NaHEPPSOate (0.08 m); and (3) HEPPSO (0.08 m) + NaHEPPSOate (0.08 m) + NaCl (0.08 m).     

Thermochemical behavior of mixtures ofN,N-dimethylformamide with dimethylsulfoxide,acetonitrile, andN-methylformamide: Volumes and heat capacities

Densities and molar heat capacities have been measured for mixtures ofN,N-dimethylformamide with dimethylsulfoxide, acetonitrile, andN-methylformamide at 25°C over the complete mole fraction range. From these data the apparent molar volumes and heat capacities have been calculated for both components. These quantities, as a function of the mole fraction, deviate very little from their molar values, indicating that the mixtures can be regarded as almost ideal.     

Effects of ionization on the phase behavior of poly(<Emphasis Type="Italic">N</Emphasis>-isopropylacrylamide-co-acrylic acid) and poly(<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-diethylacrylamide-co-acrylic acid) in water

Phase transitions of poly(N-isopropylacrylamide-co-acrylic acid) (PiPA-AA) and poly(N,N- diethylacrylamide-co-acrylic acid) (PdEA-AA) in water have been investigated by means of turbidimetry, Fourier transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC). The phase transition temperatures (T_p) of these copolymers increase with the degree of ionization () of the acrylic acid (AA) units, which in turn is dependent on the pH of the solutions. Apparent values of pK_a for the AA units, determined from the pH dependencies of T_p, are 4.7 and 5.4 for PiPA-AA and PdEA-AA, respectively. Differences between T_p for PiPA-AA and T_p for PiPA homopolymer (T_p) are +1.5 and –0.2 °C/mol% of AA at =1 and 0, respectively. The values of T_p for PdEA-AA are +2.6 (ionic) and –0.5 (nonionic)°C/mol%, indicating that the incorporated AA units have a larger effect on PdEA than on PiPA. DSC measurements performed with each of these copolymers at different pH values show a linear relationship between T_p and the enthalpy of transition (H). IR measurements of PiPA-AA show that the profiles of IR bands from both iPA and AA units exhibit critical changes at T_p of the copolymer. Heating the solution above T_p leads to shifts of the amide II, C–H stretch, and C–H bend bands from the iPA units toward lower wavenumbers, as well as a shift of the amide I band from the iPA units toward higher wavenumbers. A decrease in the intensity of the symmetric C=O stretch IR band from carboxylate anions (1560 cm^–1), and an increase in the intensity of the C=O stretch band from COOH groups (1705 cm^–1) suggest that a partial protonation of the carboxylate groups (COO^–+H⁺COOH) takes place upon the phase transition.     

Stereochemie von Metallocenen, 43. Mitt.: Torsionsisomere Biphenyl-tricarbonylchrom-Komplexe: Darstellung,Konformationsanalyse und Kinetik der Interkonversion

Complexation of methyl 3-nitro-2-(o-tolyl)-benzoate (2, ano-trisubstituted biphenyl) with hexacarbonyl chromium gave the isomeric Cr(CO)₃ complexes3 and4 both existing as two torsional isomersa andb, as seen by nmr. For the main product3 the preferred conformations of the two torsional isomersa andb were deduced by the lanthanide induced shift (LIS) technique. The activation energy for the interconversion process could be determined from kinetic measurements and especially from¹H-nmr coalescence temperature of the methylsignals. The barrier of 91±1.5 kJ/mol (21.7±0.3 kcal/mol) in3 reflects the interaction of theo-H-atom of the benzene ring passing the Cr(CO)₃ moiety of the benchrotrene ring during the interconversion.A partial optical resolution of3 was achieved by asymmetric reduction with a chiral lithium-aluminium hydride yielding (+)-3 with [] _D ²⁰ +30° (benzene) and the levorotatory alcohol (–)-7.

42. Mitt.:K. Schlögl undR. Schölm, Mh. Chem.109, 1227 (1978).     

Mutual diffusion coefficients,electrical conductances,osmotic coefficients,and ionic transport coefficientsl ij for aqueous CuSO4 at 25°C

Experimental thermodynamic and transport data are presented for aqueous CuSO₄ solution at 25°C from low concentrations to near saturation. Included are diffusion coefficients (Rayleigh interferometry), electrical conductances (DC method), and osmotic coefficients (isopiestic). These data and corresponding literature data are critically compared, as are literature density data. The resulting best values, together with previously compared transference number results, provide an extensive set of critically reviewed data for aqueous CuSO₄. Onsager coefficientsl _ij have been calculated for this salt and are compared with data for other valence types.     

Thermal dehydration and decomposition of nickel chloride hydrate (NiCl2·xH2O)

The dehydration and decomposition characteristics of an undried and a partly dried sample of NiCl₂·xH₂O have been investigated by isothermal and non-isothermal (TG and DTA) methods in static air as well as flowing nitrogen environment. While the isothermal weight loss method fails to distinguish between different steps of reaction, TG curves upto 800°C reveal as many as five steps in static air and four steps in nitrogen atmosphere. However, both methods indicate that NiCl₂ is stable upto 400°C above which dehydrochlorination takes place in presence of water vapour. The intermediate products of dehydration and decomposition at different temperatures have been characterized by chemical analysis, X-ray diffraction, infrared and diffuse reflectance spectroscopy. All these methods reveal the presence of water in samples calcined at even 400°–600°C. Thermodynamic functions for different steps of dehydration have been calculated and discussed in the light of the possible structural changes occurring in the partially dehydrated products.The authors wish to express their sincere thanks to Mr. D. N. Dey, Head, Pyrometallurgy Division for his keen interest and constant support during the course of investigation. Thanks are also due to Director, Regional Research Laboratory, Bhubaneswar for his kind permission to publish this paper. One of the authors (S. K. M.) is thankful to the Council of Scientific and Industrial Research, New Delhi for awarding a Junior Research Fellowship.     

The preparation,properties and gas-phase molecular structure of difluoro(germylthio)phosphine

Difluoro(germylthio)phosphine, PF₂(SGeH₃), has been prepared by the reaction of S(PF₂)₂ with GeH₃Cl, and has been characterised by i.r.,Raman, n.m.r. and mass spectroscopy. Cleavage reactions with Cl₂ and HBr, donor reactions of the phosphorus atom and exchange reactions with platinum complexes have been studied. The molecular structure of PF₂(SGeH₃) in the gas phase has been determined by electron diffraction. Principal parameters (r _a) are:r(Ge–S) 225.6(4)pm;r(P–S) 211.5(8)pm;r(P–F) 159.0(9)pm; <(GeSP) 99.0(6)° <(SPF) 99.9(4)° <(FPF) 97.0(10)°. The conformation adopted is such that there are short non-bonded F...H contacts, with the PF₂ group twisted 18° from the position in which the FPF angle bisector eclipses the Ge–S bond.

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Difluor(germylthio)phosphin. Darstellung, Eigenschaften und Molekülstruktur in der Gasphase

Zusammenfassung PF₂(SGeH₃) wurde über die Reaktion von S(PF₂)₂ mit GeH₃Cl dargestellt und mittels IR,Raman, NMR and MS charakterisiert. Es wurden Spaltungs-reaktionen mit Cl₂ und HBr, Donor-Reaktionen des Phosphor und Austausch-reaktionen mit Platinkomplexen untersucht. Die Molekülstruktur von PF₂(SGeH₃) in der Gasphase wurde mittels Elektronendiffraktion bestimmt. Die Hauptparameter (r _a) sind:r(Ge–S) 225,6(4)pm;r(P–S) 211,5(8)pm;r(P–F) 159,0(9)pm; <(GeSP) 99,0(6)° <(SPF) 99,9(4)° <(FPF) 97,0(10)°.

     

Stereoselective synthesis of (±)-indolizidines 167B and 209D and theirtrans-isomers based on the reductive allylboration of pyridine

A general method for the synthesis of 5-substituted indolizidines based on intramolecular cyclization oftrans- andcis-2-allyl-6-R-1,2,3,6-tetrahydropyridines, obtained from pyridine and triallylborane, has been elaborated. The closure of the five-membered ring is carried out by hydroboration-oxidation followed by cyclization of the resulting δ-amino alcohols in the presence of the Ph₃P−CBr₄−Et₃N system. (Pr₂BH)₂ and Pr₃B are used as the hydroborating reagents, and H₂O₂ in an acid medium is used for the oxidation of 2-[3-(dipropylboryl]-Δ²-piperideines formed. This method has been used for the synthesis of two natural alkaloids: indolizidine 209D (cis-5-hexylindolizidine) and itstrans-isomer were prepared fromcis- andtrans-2-allyl-6-hexyl-1,2,3,6-tetrahydropiridine, respectively; indolizidine 167B andtrans-5-propylindolizidine were synthesized fromcis- andtrans-2,6-diallyl-1,2,3,6-tetra-hydropyridine, respectively. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 971–979, May, 1998.     

Asymmetrische Hg(II)-Komplexe mit Organothiolato- bzw. Organoselenolato-und Triazenato-Liganden

The mixed mercury complexes (2XC₆H₄)₂N₃HgY (X=CH₃, F, Cl, Br, I;Y=SC₂H₅, SC₆H₅, SeC₆H₅) have been prepared. Both the Hg–S and Hg–Se bonds and, in contrast to other mixed triazenato-mercury compounds, the triazenato-mercury bonds have been shown to be kinetically labile on the NMR time scale by means of⁷⁷Se and¹⁹⁹Hg NMR spectroscopy. Evidence has been obtained for the presence of (2XC₆H₄)₂N₃HgY together with HgY ₂ and [(2XC₆H₄)₂N₃]₂Hg in solution.

     

Molecular Structure of ortho-Fluoronitrobenzene Studied by Gas Electron Diffraction and Ab Initio MO Calculations

The molecular structure of ortho-fluoronitrobenzene (o-FNB) has been investigated by gas-phase electron diffraction and ab initio MO calculations. The geometrical parameters and force fields of o-FNB were calculated by ab initio and DFT methods. The obtained force fields were used to calculate vibrational amplitudes required as input parameters in an electron diffraction analysis. Within the experimental error limits, the geometrical parameters obtained from the gas-phase electron diffraction analysis are mostly in agreement with the results obtained from the ab initio calculations. The main results are: the molecular geometry of o-FNB is nonplanar with a dihedral angle about C–N of 38(3)°. The r _g (C–F) bond is shortened to 1.307(13) Å in comparison with r _g (C–F) = 1.356(4) Å in C₆H₅F.     

Kinetische und thermodynamische Untersuchungen im System AgCl-LiCl-NaCl

In the ternary system silver chloride-lithium chloride-sodium chloride the kinetics of the galvanic deposition of silver on graphite electrodes was investigated as well as its dissolution without current in the molten salt saturated with chlorine gas.In addition the emf-values were measured in the temperature range between 923 K and 1,173 K by means of, the formation cell graphite/Ag(s)/AgCl(l)–LiCl(l)–NaCl(l)/Cl₂ graphite From these data the partial molar free excessGibbs energies were calculated. Using the equation for a multicomponent system as suggested byRedlich-Kister ¹ G _AgCl ^E values were obtained by a non-linear fitting process, where the fit was performed for all investigated temperatures and over the entire concentration range in the ternary system. With the parameters obtained the partial and integral excess valuesG _i ^E ,G ^E ,H _i ^E ,H ^E ,S _i ^E andS ^E were calculated.

     

Untersuchung von Eisen(II)phosphiten im Hinblick auf die Ausbildung von Wasserstoffbindungen

Ferrous phosphites FeHPO₃·3 H₂O, FeH₂P₂O₅, FeH₄P₂O₆·1/2 H₂O and FeH₁₀P₄O₁₂·4 H₂O were studied using X-ray powder patterns, thermography, electron reflectance spectroscopy, magnetic susceptibility measurements andRaman and infrared molecular spectra. The results obtained indicate that all the phosphites studied contain an approximately octahedral coordination sphere consisting of oxygen atoms, which produces a weak crystal field around the iron atom. Phosphite FeHPO₃·3 H₂O contains an HPO₃ ^2– anion with the symmetry decreased from point groupC _3v toC _s. Ferrous diphosphite FeH₂P₂O₅ contains a non-linear P–O–P bond with a valence angle of 159°. The hydrogen bonds between the water molecule and the HPO₃ ^2– anion indicate a positive hydratation of the phosphite anion. Medium-strong or strong hydrogen bonds, 258–270 pm long, correspond to mutual interactions of the anions in the crystal lattice of hydrogenphosphites. Hydrogen bonding in hydrogenphosphites causes a decrease in theDq values.

     

Volumetic Properties of Glycerol with N,N-Dimethylformamide and with Water at 25 and 35°C

Densities of glycerol + N,N-Dimethylformamide (DMF) and glycerol + water mixtures have been measured over the full range of compositions at 25 and 35°C. Excess molar volumes and excess partial molar volumes, of each system have been calculated. All mixtures show negative values of the excess molar volume due to increased interactions between unlike molecules.     

Orientational order in liquid normal alkanes: An investigation using gas-chromatographic data

Using retention voluems, obtained from gas-liquid chromatography with then-alkanesn-C₂₈,n-C₃₂, andn-C₃₆ and the branched alkane squalane (2,6,10,15,19,23-hexamethyltetracosane) as the solvents and small branched andn-alkane molecules as solutes, excess chemical potentials were determined at 80, 100, and 120°C. From these data Flory'sX ₁₂ parameter was calculated, which is related to differences in force field and in orientatinal order of the two compounds. After correction for end effects, theX ₁₂ parameter in then-alkane solvents appeared to decrease with rising temperature and to increase with increasing chain length of then-alkane solvent. In addition,X ₁₂ was dependent on the shape of the order-disturbing substance. These results all point to the presence of short-range orientational order in liquidn-alkanes, which was deduced to occur before from enthalpies of mixing by Patterson and from depolarized Rayleigh scattering by Bothorel. In addition, it is shown that theX ₁₂ values are influenced by coupling of torsional oscillations of the molecules of the mixture components.     

19F NMR study ofcis- andtrans- effects of substituted triphenylphosphine ligands intrans-(4-fluorophenyl)triarylphosphine-tri(4-fluorophenyl)phosphineplatinum 4-fluorothiophenoxides

A number of compounds of the type oftrans-4-FC₆H₄Pt(PAr₃)₂SC₆H₄F-4, where Ar is a substituted phenyl group, have been prepared starting from the corresponding chlorides. By exchange reactions oftrans-4-FC₆H₄Pt[P(C₆H₄F-4)₃]₂SC₆H₄F-4 with the above-mentioned compounds or Ar₃P,trans-4-FC₆H₄Pt[P(C₆H₄F-4)₃][PAr₃]SC₆H₄F-4 have been generated in solution. For the latter compounds, the effect of Ar₃P oncis- andtrans-ligands has been studied by the¹⁹F NMR technique. It has been shown that thecis- andtrans-effects of Ar₃P run parallel and are well described by pK _a values and ionization potentials of the unshared electron pair in Ar₃P, as well as by ⁰ constants of the aryl groups.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1359–1363, July. 1995.