Synthesis of 2, 2, 5, 5-tetramethyltetrahydrothiophene

Under the conditions of the Grignard reaction, 2, 5-dimethyl-2, 5-hexanediol has been obtained from diethyl succinate. Under the action of sulfuric acid, the latter has been cyclized to 2, 2, 5, 5-tetramethyl-tetrahydrofuran which, in its turn, by treatment with phosphorus pentasulfide, has given 2, 2, 5, 5-tetramethyltetrahydrothiophene. Its reaction with methyl iodide has given 2, 2, 5, 5-tetramethyltetrahydrothiophene methiodide.     

Reactions of 1,3-dioxacycloalkanes and their 2-arsena, 2-bora, 2-germa, 2-sila,and 2-thia analogs with nitriles

New reactions of five-, six-, and seven-membered 1,3-dioxacycloalkanes and their 2-arsena, 2-bora, 2-germa, 2-sila, and 2-thia analogs with nitriles giving rise to 1,3-oxazacycloalkanes and then to amino alcohols are surveyed. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1499–1507, July, 2005.     

Syntheses,Crystal Structure,and Properties of Hf2Ni2In,Hf2Ni2Sn,Hf2Cu2In,and Hf2Pd2In with Ordered Zr3Al2 Type Structure

Hf₂Ni₂In, Hf₂Ni₂Sn, Hf₂Cu₂In, and Hf₂Pd₂In were synthesized by reacting the elements in an arc-melting furnace under argon and subsequent annealing at 970 K. They crystallize with an ordered Zr₃Al₂ type structure, space group P4₂/mnm which was refined from single crystal X-ray data for Hf₂Ni₂In (a = 713.9(1) pm, c = 660.4(2) pm, wR2 = 0.0665, 513 F² values) and Hf₂Ni₂Sn (a = 703.1(1) pm, c = 676.1(2) pm, wR2 = 0.0423, 507 F² values) with 18 parameters for each refinement. The lattice constants for Hf₂Cu₂In and Hf₂Pd₂In are a = 715.5(1) pm, c = 677.0(1) pm and a = 742.6(1) pm, c = 679.4(2) pm, respectively. The structures may be considered as an intergrowth of distorted CsCl- and AlB₂-like slabs. Magnetic susceptibility measurements indicate Pauli paramagnetism for Hf₂Ni₂In and Hf₂Ni₂Sn, which is consistent with the metallic conductivity observed for Hf₂Ni₂In. ¹¹⁹Sn Mössbauer spectroscopy of Hf₂Ni₂Sn shows one signal with an isomer shift of δ = 1.59(1) mm/s subjected to quadrupole splitting of δE_q = 0.81(1) mm/s.     

Trace Element Analysis of USGS Standards AGV2, BCR2, BHVO2, DTS2 and GSP2 by INAA

Five second generation USGS standards AGV2, BCR2, BHVO2, DTS2 and GSP2 were analyzed for trace elements by instrumental neutron activation analysis. Abundances of the rare earth elements La, Ce, Nd, Sm, Eu, Tb, Yb, Lu and eight other elements Co, Cr, Cs, Hf, Na, Sc, Ta and Th were determined in all samples, except for DTS2 which was analyzed only for Co, Cr, Na and Sc. Experimental precision and accuracy were evaluated. In general abundances of trace elements in this new generation of USGS standards are similar to the earlier standards. Abundances of Cr are, however, substantially higher in AGV2, BCR2, GSP2 and especially DTS2.     

The confirmation of accurate combination of functional and basis set for transition‐metal dimers: Fe2, Co2, Ni2, Ru2, Rh2, Pd2, Os2, Ir2, and Pt2

Eight kinds of density functionals named B3LYP, PBE1PBE, B1B95, BLYP, BP86, G96PW91, mPWPW91, and SVWN along with two different valence basis sets (LANL2DZ and CEP‐121g) are employed to study the transition‐metal dimers for the elements of group VIII. By comparing the equilibrium bond distances, vibrational frequencies, and dissociation energies of the ground state of these dimers with the available experimental values and theoretical data, we show that the “pure” DFT methods (G96PW91, BLYP, and BP86) with great‐gradient approximation always give better results relative to the hybrid HF/DFT schemes (B3LYP, PBE1PBE, and B1B95). The striking case found by us is that the G96PW91 functional, which is not tested in previous systemic studies, always predicts the dissociation energy to be well. The Ru₂ and Os₂ dimers are sensitive to not only the functionals employed but also the valence basis sets adopted. The natural bond orbital population is analyzed, and the molecular orbitals of the unpaired electrons are determined. Furthermore, our results indicate that the s and d orbitals of these dimers always hybridize with each other except for Rh₂ and Pt₂ molecules. And by analyzing the electron configuration of the bonding atom, the dissociation limit of the ground state is obtained. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008     

Nouvelle Synthese Des 2-Thioxoethylphosphonates, 2- mercaptovinylphosphonates, 2-Phosphoryl-3-thioxopropanoates, 2-Thiomethylvinylphosphonates, 2-Thioethoxycarbonylmethylvinylphosphonates

The cyanomethylphosphonates 1 and the ethyl phosphoacetates 2 were reacted with some fluorophenylisothiocyanates to give the 2-thioxoethylphosphonates 3 in tautomeric equilibrium with the corresponding 2-mercaptovinylphosphonates 3 ′ and the 2-phosphoryl-3-thioxopropanoates 4 , respectively. Reaction of the cyanomethylphosphonates 1 with fluorophenylisothiocyanates in presence of methyliodide furnished the 2- thiometylvinylphosphonates 5 . The 2-mercaptovinylphosphonates 3 ′ reacted with ethyl chloroacetate in refluxing ethanol in the presence of triethylamine to give S-substitued derivatives 6 .     

Zur Kenntnis der Dialkalimetalldichalkogenide β-Na2S2, K2S2, α-Rb2S2, β-Rb2S2, K2Se2, Rb2Se2, α-K2Te2, β-K2Te2 und Rb2Te2

On Dialkali Metal Dichalcogenides β-Na₂S₂, K₂S₂, α-Rb₂S₂, β-Rb₂S₂, K₂Se₂, Rb₂Se₂, α-K₂Te₂, β-K₂Te₂ and Rb₂Te₂ The first presentation of pure samples of α- and β-Rb₂S₂, α- and β-K₂Te₂, and Rb₂Te₂ is described. Using single crystals of K₂S₂ and K₂Se₂, received by ammonothermal synthesis, the structure of the Na₂O₂ type and by using single crystals of β-Na₂S₂ and β-K₂Te₂ the Li₂O₂ type structure will be refined. By combined investigations with temperature-dependent Guinier-, neutron diffraction-, thermal analysis, and Raman-spectroscopy the nature of the monotropic phase transition from the Na₂O₂ type to the Li₂O₂ type will be explained by means of the examples α-/β-Na₂S₂ and α-/β-K₂Te₂. A further case of dimorphic condition as well as the monotropic phase transition of α- and β-Rb₂S₂ is presented. The existing areas of the structure fields of the dialkali metal dichalcogenides are limited by the model of the polar covalence.     

Syntheses,Spectroscopic Studies,and Crystal Structures of Me2Sn(O2PPh2)2, Ph2Pb(O2PMe2)2, and Ph2Pb(O2PPh2)2

Me₂Sn(O₂PPh₂)₂ ( 1 ), Ph₂Pb(O₂PMe₂)₂ ( 2 ), and Ph₂Pb(O₂PPh₂)₂ ( 3 ) have been synthesized by the reactions of Me₂SnCl₂ or Ph₃PbCl with the corresponding diorganophosphinic acid in methanol. X‐ray diffraction studies show that the diorganophosphinate groups behave as double bridges between the metal atoms leading to polymeric ring‐chain structures with M₂O₄P₂ (M = Pb, Sn) eight‐membered rings. The organic groups bonded to the metal atoms are in trans‐position in the resulting octahedral arrangement around the metal atoms. The IR and the mass spectra were reported and discussed.     

Gaseous HgH2, CdH2, and ZnH2

Gaseous HgH2, CdH2, and ZnH2 molecules were synthesized by the direct gas-phase reaction of excited mercury, cadmium, and zinc atoms with molecular hydrogen. The molecules were identified by their high-resolution infrared emission spectra, and the metal-hydrogen bond lengths were determined from the rotational analysis of the antisymmetric stretching fundamental bands.     

CO2 laser-induced decomposition of propan-2-ol,butan-2-ol,pentan-2-ol,pentan-3-ol,and hexan-2-ol

The pulsed CO₂ laser-induced decompositions of propan-2-ol, butan-2-ol, pentan-2-ol, pentan-3-ol, and hexan-2-ol in the gas phase have been investigated. Like ethanol which we examined previously [1] the absorption cross section of propan-2-ol for pulsed 9R14 radiation increases with pressure at low pressures, an effect attributed to rotational hole-filling. In contrast the absorption cross section of butan-2-ol (10R24) has only a small pressure dependence and those of pentan-2-ol (9R26), pentan-3-ol (10R14), and hexan-2-ol (9P20) show little or no variation with pressure in the range 0.1–5.0 torr. Decomposition products have been investigated at low pressure where the excitation of the alkanols was essentially collision free. The observed products for all the alkanols can be rationalized on the basis of primary dehydration and C? C fission channels, with minor contributions from other molecular eliminations. © 1994 John Wiley & Sons, Inc.     

Structure and properties of single crystalline CaMg2Bi2, EuMg2Bi2, and YbMg2Bi2

Single crystals of CaMg(2)Bi(2), EuMg(2)Bi(2), and YbMg(2)Bi(2) were obtained from a Mg-Bi flux cooled to 650 °C. These materials crystallize in the CaAl(2)Si(2) structure-type (P ?3m1, No. 164), and crystal structures are reported from refinements of single crystal and powder X-ray diffraction data. EuMg(2)Bi(2) displays an antiferromagnetic transition near 7 K, which is observed via electrical resistivity, magnetization, and specific heat capacity measurements. Magnetization measurements on YbMg(2)Bi(2) reveal a weak diamagnetic moment consistent with divalent Yb. Despite charge-balanced empirical formulas, all three compounds are p-type conductors with Hall carrier concentrations of 2.0(3) × 10(19) cm(-3) for CaMg(2)Bi(2), 1.7(1) × 10(19) cm(-3) for EuMg(2)Bi(2), and 4.6(7) × 10(19) cm(-3) for YbMg(2)Bi(2), which are independent of temperature to 5 K. The electrical resistivity decreases with decreasing temperature and the resistivity ratios ρ(300 K)/ρ(10 K) ≤ 1.6 in all cases, indicating significant defect scattering.     

Polyfluorobicyclo[2, 2, 2]octanes. Part II. Syntheses of polyfluorobicyclo[2, 2, 2]oct-2-enes from polyfluoro-cyclohexa-1,3-dienes

Diels-Alder reactions between ethylene and octa-, 1$\text{H}$-hepta-, and 1H, 4H-hexa-fluorocyclohexa-1,3-diene gave, respectively, 1,2,3,4,5,5,6,6-octa-, 1,2,3,5,5,6,6-hepta-, and 2,3,5,5,6,6-hexa-fluorobicyclo[2, 2, 2]oct-2-ene, each characterised by oxidation to the corresponding polyfluorocyclohexane-1,4-dicarboxylic acid.     

Photoacoustic spectra of naphthalenes: 2-fluoro, 2-chloro, 2-bromo and 2-hydroxynaphthalenes

The photoacoustic spectra of 2-fluoro, 2-chloro, 2-bromo and 2-hydroxynaphthalenes have been recorded in the powder form. A method of analysing these spectra is suggested in the light of solution phase and vapour phase data on these molecules. It is observed that the non-radiative transitions in the region of 200 nm decrease in these molecules as the substituent in the 2-position is changed from F to Cl to Br to OH.     

哌啶酮催化氢化制备哌啶醇催化剂的研究

研究了2,2,6,6-四甲基-哌啶酮-4-催化氢化合成2,2,6,6-四甲基-哌啶醇-4。重点研究催化剂种类对催化反应的影响。确定RaneyNi(4)为最适宜催化剂,并对其最佳用量进行了研究。对哌啶酮催化氢化的反应历程进行了探讨。选用常压塔式反应器进行氢化。对其它有关工艺参数进行研究,确定最佳条件:哌啶酮浓度为30%,20%异丙醇水溶液为溶剂、催化剂用量为20%、温度为80℃、时间为2h,哌啶醇产率97.3%,m.p.130.0-131.0℃。     

Synthesis, structure, and properties of BaAl2Si2

Single crystals of BaAl2Si2 were grown from an Al molten flux and characterized using single-crystal X-ray diffraction at 10 and 90 K and neutron diffraction at room temperature. BaAl2Si2 crystallizes with the alpha-BaCu2S2 structure type (Pnma), is isostructural with alpha-BaAl2Ge2, and is an open 3D framework compound, where Al and Si form a covalent cagelike network with Ba2+ cations residing in the cages. BaAl2Si2 has a unit cell of a=10.070(3) A, b=4.234(1) A, and c=10.866(3) A, as determined by room-temperature single-crystal neutron diffraction (R1=0.0533, wR2=0.1034). The structure as determined by single-crystal neutron and X-ray diffraction (10 and 90 K) indicates that BaAl2Si2 (Pnma) is strictly isostructural to other (alpha)-BaCu2S2-type structures, requiring site specificity for Al and Si. Unlike BaAl2Ge2, no evidence for an alpha to beta (BaZn2P2-type, I4/mmm) phase transition was observed. This compound shows metallic electronic resistivity and Pauli paramagnetic behavior.     

Gas-chromatographische Simultanbestimmung von O2, N2, CO,CO2, N2O,SO2, CH4, C2H4 und C2H6 im ppm-Bereich. I. Mitteilung

Zusammenfassung Die vorliegende Arbeit beschreibt ein neues Verfahren zur gas-chromatographischen Simultananalyse von N₂, O₂, CO, CO₂, N₂O, SO₂, CH₄, C₂H₄ und C₂H₆ im Konzentrations-bereich von 10% bis 10 ppm ohne Voranreicherung. Die temperaturprogrammierte Trennung der Einzelkomponenten erfolgt nach Vorsäulensplitting auf zwei parallel geschalteten Säulen. Zur Emittlung der Retentionszeiten und der Peakflächen werden zwei voneinander unabhängige Ultraschalldetektoren verwendet, deren Analogsignale nach Digitalisierung in einem Mikrocomputer verarbeitet werden. Instrumentierung und chromatographische Einzelheiten werden beschrieben und diskutiert.

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Simultaneous gas chromatographic determination of N₂, O₂, CO, CO₂, N₂O, SO₂, CH₄, C₂H₄ and C₂H₆ at the ppm-level. Part I

Summary A new procedure for the simultaneous determination of N₂, O₂, CO, CO₂, N₂O, SO₂, CH₄, C₂H₄ and C₂H₆ by gas chromatography is described. Concentrations from 10% down to 10 ppm can be determined without preconcentration. After a pre-column splitting the individual compounds of the sample are separated by a uniform temperature program on two different columns in parallel. Detection of the effluents is achieved by two individual ultrasonic detectors, the data from which are processed in a micro-computer. Instrumentation and gas chromatographic details are described and discussed.

     

Determination of Trace Impurities of H2, O2, Ar, N2, CO, CO2, and Hydrocarbons in High-Purity Monosilane by Gas Chromatography

Procedures were proposed for the determination of impurities of permanent gases (H₂, O₂, Ar, N₂, and CO), carbon dioxide, and hydrocarbons in high-purity monosilane by gas chromatography with detection limits of 1–3 ppm, 2 ppm, and 0.02–0.04 ppm, respectively, which are lower by 1–2 orders of magnitude than those published in the literature. The procedures make it possible to check the compliance of the purity of monosilane with present standards of microelectronics (TU 48-0513-057.0-91).     

Skin Bond Electron Relaxation Dynamics of Germanium Manipulated by Interactions with H2, O2, H2O,H2O2, HF,and Au

Although germanium performs amazingly well at sites surrounding hetero‐coordinated impurities and under‐coordinated defects or skins with unusual properties, having important impact on electronic and optical devices, understanding the behavior of the local bonds and electrons at such sites remains a great challenge. Here we show that a combination of density functional theory calculations, zone‐resolved X‐ray photoelectron spectroscopy, and bond order length strength correlation mechanism has enabled us to clarify the physical origin of the Ge 3d core‐level shift for the under‐coordinated (111) and (100) skin with and without hetero‐coordinated H₂, O₂, H₂O, H₂O₂, HF impurities. The Ge 3d level shifts from 27.579 (for an isolated atom) by 1.381 to 28.960 eV upon bulk formation. Atomic under‐coordination shifts the binding energy further to 29.823 eV for the (001) and to 29.713 eV for the (111) monolayer skin. Addition of O₂, HF, H₂O, H₂O₂ and Au impurities results in quantum entrapment by different amounts, but H adsorption leads to polarization.     

Structural chemistry of Ba2CdS3, Ba2CdSe3, BaCdS2, BaCu2S2 and BaCu2Se2

The structures of all compounds were determined from three dimensional single crystal X-ray diffraction data and refined by least squares. Ba₂CdS₃ and Ba₂CdSe₃ are isostructural, Pnma, a = 8.9145(6)Å, b = 4.3356(2)Å, c = 17.2439(9)Å for the former compound and a = 9.2247Å, b = 4,4823(6)Å, c = 17.8706(11)Å for the latter, z = 4, R = 0.0751 and R = 0.0462, respectively. The compounds are isostructural with the previously reported Mn analogues and with K₂AgI₃. Cd ions are in tetrahedral environment and the tetrahedra form infinite linear chains by corner sharing. Ba ions are in 7-fold coordination in which 6 anions form a trigonal prism and 1 anion caps one of the rectangular faces. BaCdS₂, Pnma, a = 7.2781(3)Å, b = 4.1670(1)Å, c = 13.9189(6)Å, z = 4, R = 0.0685. Cd ions can be considered to have a triangular planar coordination with CdS distances of 2.47 and 2.53 Å (twice). Two additional S ions are at 2.89 and 3.22 Å to complete a triangular bipyramidal configuration. Ba is in 7-fold coordination with the anions forming a trigonal prism which is capped on one rectangular face. The compound is isostructural with BaCdO₂ and is related to the structure of BaMnS₂. BaCdSe₂ could not be prepared. BaCu₂S₂ and BaCu₂Se₂ are isostructural, Pnma, a = 9.3081(4)Å, b = 4.0612(3)Å, c = 10.4084(5)Å for the sulfide and a = 9.5944(6)Å, b = 4.2142(4)Å, c = 10.7748(8)Å for the selenide, z = 4, R = 0.0634 and 0.0373, respectively. Ba ions are in the usual 7-fold, capped hexagonal prism, coordination. However, 9 Cu ions also can be considered to form a trigonal prism with all rectangular faces capped, around Ba since the BaCu distances range from 3.24 to 3.54 Å for the sulfide and from 3.37 to 3.67 Å for the selenide. One of the Cu ions is in a very distorted tetrahedral environment and the second one is located in a more regular tetrahedral configuration of the anions. Two independent infinite chains of tetrahedra are present. They are formed by sharing of two adjacent edges of each tetrahedron and then these chains in turn are linked by corner sharing into a three-dimensional network of tetrahedra.     

Syntheses,Structures, and Properties of New Quaternary Gold-Chalcogenides: K2Au2Ge2S6, K2Au2Sn2Se6, and Cs2Au2SnS4

The new compounds K₂Au₂Ge₂S₆ ( 1 ), K₂Au₂Sn₂Se₆ ( 2 ), and Cs₂Au₂SnS₄ ( 3 ) have been synthesized through direct reaction of the elements with a molten polyalkalithiogermanate(stannate) flux at 650, 550, and 400 °C, respectively. Their crystal structures have been determined by single crystal X-ray diffraction techniques. 1 crystallizes in the monoclinic space group P2₁/n with a = 10.633(2) Å, b = 11.127(2) Å, c = 11.303(2) Å, β = 115,37(3)°, V = 1208,2(3) ų and Z = 4, final R(Rw) = 0.045(0.106). 2 crystallizes in the tetragonal space group P4/mcc with a = 8.251(1) Å, c = 19.961(4) Å, V = 1358,9(4) ų and Z = 4, final R(Rw) = 0.040(0.076). 3 crystallizes in the orthorhombic space group Fddd with a = 6.143(1) Å, b = 14.296(3) Å, c = 24.578(5) Å, V = 2158.4(7) ų and Z = 4, final R(Rw) = 0.039(0.095). The structures of 1 , 2 , and 3 consist of infinite, one-dimensional anionic chains containing X₂Q₆^4– units linked by Au⁺ ions and charge balancing K⁺/Cs⁺ ions situated between the chains. All compounds were investigated with differential thermal analysis, FT-IR, and solid state UV/VIS diffuse reflectance spectroscopy.