Solubility of Triethylamine in Tetraethylammonium Chloride Aqueous Solutions from 20 to 35°C

Solubilities of triethylamine in aqueous tetraethylammonium chloride solutions were measured at 20, 25, and 35°C. The molalities in Et₄NCl of the aqueous solvents ranged from 0.03 to 1 mol-kg^–1. The data were evaluated from density measurements using a vibrating-tube densimeter. At each temperature, least-squares method was used to fit experimental density data points to double polynomial equations of various degrees. Triethylamine molalities of the saturated aqueous phases were estimated by extrapolation from those equations. Experimental data were interpreted in terms of hydrophobic and electrostatic perturbed domains in the hydration shells of the noneleceory and of the cation of the salt, as a function of temperature and salt concentration. The conclusions obtained are consistent with previous volumetric studies.     

Effect of substituents on ionization potentials of phosphorus compounds. Conjugation in radical cations

The first vertical ionization potentials (I) of phosphorus compounds P(X_i)₃, OP(X_i)₃, SP(X_i)₃, (4-XC₆H₄)₃P, and PCX are related to the inductive, resonance, and polarizability parameters of inorganic, organic, and organometallic substituents X by dependences of the type I = I _H + a_I + b_R ⁺ + c, where I _H is the I value for X = H. The I values are also affected by hyperconjugation. The ratio of the contributions of the resonance (b_R ⁺) and polarizability (c) effects to the I value is determined by the degree of delocalization of the unpaired electron and the positive charge in the radical cations formed upon ionization of neutral molecules. The _R ⁺ resonance parameters of organosilicon, organogermanium, and organotin substituents bound to the P ^·+ radical cation center were calculated for the first time.     

Crystal Structure and Property of Perovskite-Type Oxides Containing Ion Vacancy

Studies on the role of oxygen vacancy in structural change of nonstoichiometric perovskites and a property of oxygen-deficient perovskite-related K₂NiF₄ compounds are reviewed.The structural changes on which the authors focused are cation ordering and lattice distortion. The relationship between the distortion and oxygen vacancy was investigated by comparing the structures of Sr₂(Sr_1-xM_x)TaO_6-d (M = Ca²⁺ and Nd³⁺) solid solutions. It was found that distortion of a perovskite-type lattice decreased with an increasing amount of oxygen vacancies. In order to investigate the relationship between the cation ordering on octahedral sites and oxygen vacancy, structures of stoichiometric Sr_2-xLa_xCo_1-yTa_1+yO₆ and oxygen-deficient Sr_2-xLa_xMg_1-yTa_1+yO_6-d solid solutions were compared. The authors' work reveals that the cation ordering affects the amount of oxygen vacancies in addition to cation charge and size.     

(Me3Si)2NBCl2和(Me3Si)2NB(Cl)NHSiMe3的合成及其成环反应

自从氮化硼陶瓷纤维用聚合物先驱体法[1]合成以后,硼氮六元环化合物越来越为人们所重视[2],文中在制备氮化硼纤维先驱体的过程中,合成了其中间产物,通过热缩合成环反应,合成了含有硼氮六员环的化合物,并采用色-质联用技术对其进行了表征。1　实验部分参照文献[3],改用液氮和丙酮为冷冻剂,控制温度在-50到-40℃,搅拌下向三氯化硼的正戊烷溶液中缓慢滴加三乙胺的正戊烷溶液,滴完后Ｎ2气氛下-50℃加丙酮冷凝回流2ｈ,慢慢由-50℃升至室温,抽滤即得到白色产物Ｅｔ3ＮＢＣｌ3(Ａ)。将Ａ溶于适量苯中[4,5],加入等物质的量的三乙胺,加热回流搅拌…     

Specific Sorption Sites for Nitrogen in Zeolites NaLSX and LiLSX

Specific sorption sites for nitrogen, N₂, in NaLSX and LiLSX zeolites were investigated using a DRIFT spectroscopic method. Sorption of molecular hydrogen, H₂, by NaLSX or LiLSX zeolite at 77 K with DRIFT control of perturbation of sorbed molecules allowed to discriminate two or three different types of specific sorption sites in the respective zeolites. Their H–H stretching frequencies are 4077 and 4081 cm^–1 for NaLSX, and 4061, 4084 and 4129 cm^–1 for LiLSX. With reference to an independent investigation by methods of both sorption thermodynamics and molecular modeling for N₂ sorption on LiLSX, the first two of the corresponding bands were ascribed to H₂ sorption on lithium cations, Li⁺, localized in supercages of the faujasite, FAU, zeolite framework at sites SIII and SIII, while the latter band most likely belongs to H₂ sorption on Li⁺ cations at sites SII, and on hydroxyl groups, OH. Sorption of N₂ by Li⁺ cations at sites SIII and SIII is the strongest, resulting in a decrease of intensity of the corresponding DRIFT bands that stem from subsequent H₂ sorption. Nitrogen sorption by Li⁺ cations at sites SII is much weaker. Sorption of N₂ on Na⁺ cations at sites SIII in NaLSX zeolite is also stronger than by Na⁺ cations at sites SII.     

Preparation and Crystal Structures of 4-(4′-Pyridylthio)-1-methylpyridinium Salts: Assembly of a Donor-Acceptor-Type Molecule Containing a Sulfide Bridge

A series of ionic 4-(4′-pyridylthio)-1-methylpyridinium salts with different counteranions (1, I⁻; 2, BF⁻₄; 3, PF⁻₆; and 4, OTf⁻, where OTf=trifluoromethanesulfonate) have been prepared. Structural analysis reveals that the cation exhibits a variety of stacking structures dependent on the anion. Compound 1 crystallizes in space group P2_1/n (#14), with a=10.764(3) Å, b=9.601(5) Å, c=13.105(3) Å, β=108.35(2), V=1285.4(8) ų, and Z=4. In this compound, each cation moiety is stacked in a helical arrangement along the c-axis. Compound 2, which is isomorphous to 1, has space group P2_1/n (#14), with a=11.647(2) Å, b=9.203(3) Å, c=13.232(2) Å, β=108.42(2), V=1345.6(5) ų, and Z=4. Compound 3 crystallizes in space group P2_1/n (#14), with a=8.06(1) Å, b=17.43(1) Å, c=10.30(1) Å, β=103.0(1), V=1410(3) ų, and Z=4. In this salt, the cation molecules assume a head-to-tail stacking arrangement, forming a polar pseudo 1-D chain. Compound 4 crystallizes in space group Pb? (#2), with a=7.585(4) Å, b=15.443(7) Å, c=6.775(4) Å, α=99.33(4), β=108.35(2)^o, γ=98.37(4), V=756.6(7) ų, and Z=2. The structure of 4 consists of a columnar stacking of pyridine moieties, with the cation moieties surrounded by the counteranions. Calculations show that the 4-(4′-pyridylthio)-1-methylpyridinium cation may be a good building block for second harmonic generation (SHG) materials, even though salts 1-4 crystallized in centrosymmetric structures and were SHG inactive.     

Pentafluorphenyliod(III)-Verbindungen. 2. Fluor-Aryl Substitution an Iodtrifluorid: Synthese von Pentafluorphenylioddifluorid C6F5IF2 und Bis(pentafluorphenyl)iodonium Pentafluorphenylfluoroboraten [(C6F5)2I]+[(C6F5)nBF4−n]−

Pentafluorophenyliodine(III) Compounds. 2. Fluorine-Aryl Substitution Reactions on Iodinetrifluoride: Synthesis of Pentafluorophenyliodinedifluoride C₆F₅IF₂ and Bis(pentafluorophenyl)iodonium Pentafluorophenylfluoroborates[(C₆F₅)₂I]⁺[(C₆F₅)_nBF_4?n]^? Mono- and disubstitution can be achieved in the fluorine-aryl substitution reaction on the low-temperature phase IF₃ in CH₂Cl₂ at ?78°C depending on the aryl transfer reagent. With B(C₆F₅)₃ [(C₆F₅)₂I]⁺ [(C₆F₅)_nBF_4?n]^? (68% yield) and with Cd(C₆F₅)₂ C₆F₅IF₂ (97% yield) is obtained whereas with C₆F₅SiMe₃ no fluorine-aryl substitution takes place on IF₃ even under basic conditions (EtCN or F^? addition). At ?78°C in EtCN solution IF₃ does not disproportionate but attacks the solvent under formation of HF.     

Formation and Crystal Structure of [(F5TeOXe)+·SO2ClF][Sb(OTeF5)6-]

Xe(OTeF₅)₂ reacts with Sb(OTeF₅)₃ under the formation of [Xe₂(OTeF₅)₃]⁺[Sb(OTeF₅)₆]^-. From SO₂ClF solution a yellow solvate [F₅TeOXe]⁺·SO₂ClF· [Sb(OTeF₅)₆]^- is formed with the crystal data: a = 1028.1(1), b = 1040.9(1), c = 1780.2(3) pm, α = 98.07(1), β = 97.68(1), γ = 105.82(1)°, space group . The O-Xe···O fragment is essentially linear (176.1(2)°), and the two Xe-O distances are quite different 197.1(4) and 242.6(4) pm.     

Multi-element characterization of silicon nitride powders by atomic and mass spectrometric solution methods

A sample pretreatment technique for silicon nitride involving digestion and matrix/traces separation was developed by means of radiotracers and applied to analysis of this material by inductively coupled plasma atomic emission spectrometry, inductively coupled plasma mass spectrometry and graphite furnace atomic absorption spectrometry. The results obtained for a high purity silicon nitride material by these methods are compared each with the other and with those obtained by neutron activation analysis. The limits of detection and the capabilities of the methods are compared and discussed.     

镧对V2O5/γ-Al2O3催化剂在异丁烷脱氢中活性的影响

V2O5／γ-Al2O3是用于异丁烷脱氢的新型催化剂，引入适量的镧不仅可改善活性组分的分散度，提高催化脱氢活性，而且还增强了催化剂的抗积炭能力，通过FTIR，BET，TG，TPR和TEM等手段研究了镧对催化剂性能的影响。