6A6B, 6A6C,and 6A6D-ditosylates of β-cyclodextrin

Regio-isomers, 6A6B, 6A6C, and 6A6D-ditosylates of β-cyclodextrin prepared by the reaction of β-cyclodextrin with tosyl chloride were easily and effectively separated through reversed phase column chromatography and assigned.     

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℃。     

Gas-phase molecular structures of third row transition-metal hexafluorides WF6, ReF6, OsF6, IrF6, and PtF6. An electron-diffraction and ab initio study

The molecular structures of WF6, ReF6, OsF6, IrF6, and PtF6 have been measured by electron diffraction from the gases, the last from both PtF6 itself and from a vapor assumed to consist of a mixture of O2 and PtF6 obtained by heating the salt O2PtF6. For models of Oh symmetry the bond lengths in the first three members of the series are essentially identical, but the Ir-F and Pt-F bonds are respectively about 0.01 and 0.02 A longer. Models of D4h symmetry were also tested for ReF6, OsF6, and IrF6 in which operation of the Jahn-Teller effect is thought possible. For these models the same trend was seen in the average bond-length values. The effect of three-atom multiple scattering was also investigated, and experimental estimates of the effects of vibrational averaging ("shrinkage") on the distances were obtained. Normal-coordinate analyses based on the observed wavenumbers yielded stretching force constants consistent with the usual inverse bond-length/force-constant relationship. Ab initio molecular orbital optimizations of the molecules constrained to Oh symmetry were carried out at several levels of theory and basis-set size. Less extensive optimizations of ReF6, OsF6, and IrF6 with D4h symmetry were also carried out. The best overall agreement with both the experimental values and the distance trend for Oh symmetry was obtained with the Hay-Wadt (n+1)VDZ basis on the metals and the aug-cc-pVTZ on the fluorines at the MP2 level, but these bases with B3P86 and B3PW91 density functional theory were nearly as good and with B3LYP only slightly worse. The D4h structures for ReF6, OsF6, and IrF6 with the cited bases at the B3P86 level were slightly more stable (respectively 0.8, 2.6, and 1.4 kcal/mol) with the axial bonds shorter by about 0.04 A in ReF6 and 0.07 A in OsF6, but about 0.05 A longer in IrF6. The significance of these values is uncertain. The experimental bond lengths (rg/A) with estimated 2sigma uncertainties for the models of Oh symmetry are W-F = 1.829(2), Re-F = 1.829(2), Os-F = 1.828(2), Ir-F = 1.839(2), and Pt-F = 1.852(2); the Pt-F value from the O2PtF6 sample was 1.851(2) A. Although the experimental data neither confirm nor refute the existence of the Jahn-Teller effect in ReF6, OsF6, and IrF6, they ensure that if present the distortion from Oh symmetry must be small.     

Arachno, nido, and closo aromatic isomers of the Li6B6H6 molecule

We analyzed chemical bonding in low-lying isomers of the recently computationally predicted B(6)H(6)Li(6) molecule. According to our calculations the benzene-like B(6)H(6)Li(6) (D(2h), (1)A(1g)) arachno structure with the planar aromatic B(6)H(6)(6-) anion is the most stable one. A nido isomer with two aromatic B(6)H(6)(4-) (pentagonal pyramid) and Li(3)(+) (triangular) moieties, which can be considered as derived from the global minimum structure through a two-electron intramolecular transfer from B(6)H(6)(6-) to three Li(+) cations, was found to be 10.7 kcal/mol higher in energy. A closo isomer with three aromatic moieties (octahedral B(6)H(6)(2-) and two Li(3)(+)) was found to be 31.3 kcal/mol higher in energy than the global minimum. Another isomer with three aromatic moieties (two B(3)H(3)(2-) and Li(3)(+)) was found to be substantially higher in energy (74.4 kcal/mol). Thus, the intramolecular electron transfers from the highly charged B(6)H(6)(6-) anion to cations are not favorable for the B(6)H(6)Li(6) molecule, even when a formation of three-dimensional aromatic B(6)H(6)(2-) anion and two sigma-aromatic Li(3)(+) cations occurs in the closo isomer.     

Singlet-triplet energy separation in divalent seven-membered cyclic conjugated compounds C6H6C, C6H6Si, C6H6Ge, C6H6Sn, and C6H6Pb

The electronic and thermal energy differences, ΔE(t-s); enthalpy differences, ΔH(t-s); and free energy differences between the singlet and triplet states, ΔG(t-s), were calculated for C₆H₆C, C₆H₆Si, C₆H₆Ge, C₆H₆Sn, and C₆H₆Pb at the B3LYP/6-311++G (3df, 2p) level. The singlet-triplet splitting, G _s-t, of C₆H₆C, C₆H₆Si, C₆H₆Ge, C₆H₆Sn, and C₆H₆Pb generally increased from C₆H₆C toward C₆H₆Pb. The most stable tautomers and conformers were suggested for the singlet and triplet states of C₆H₆M (M = C, Si, Ge, Sn and Pb). The geometrical parameters were calculated and discussed. The text was submitted by the authors in English.     

6-Desoxy-L-idose, 6-Desoxy-L-sorbose und 6-Desoxy-L-psicose. Desoxyzucker, 41. Mittelung [1]

Although crystalline 6-deoxy-L -idose ( 2 ) and crystalline 6-deoxy-L -sorbose ( 3 ) have similar melting points and specific rotations, they can be conclusively differentiated from one another through paper chromatography and paper electrophoresis. 6-Deoxy-L -idose cannot be converted into 6-deoxy-L -sorbose on short heating in very dilute aequeous mineral acids. The synthesis of amorphous 6-deoxy-L -psicose ( 17 ), through oxidative fermentation of 6-deoxy-L -allitol with Acetobacter suboxydans, has been described.     

Porosity control in nylon-6/nylon-6, 6 membranes

The possibility of porosity control in N6/N66 membranes prepared from N6/N66 blend solutions of calcium chloride – methanol mixture was investigated. For N6/N66 blend solutions at 10 °C and 20 °C, the four-phase structure of solid, gel 1, gel 2 and solution was observed clearly in the pore formation process after adding water on a solution surface. In the boundary part between gel 1 and gel 2, the phase separation of N6 and N66 was predicted. The macroscopic pores of blend membranes prepared at 10°C and 20 °C were almost spherical.     

The tautomerism of 6-hydroxy-, 6-amino- and 6-acylamino-7-azaindolines

The lactam-lactim tautomerism of 6-hydroxy-7-azaindolines and amino-imine tautomerism of 6-amino- and 6-acylamino-7-azaindolines has been studied by IR and UV spectroscopy. It is shown that the lactam-lactim tautomeric equilibrium of 6-hydroxy-7-azaindolines in contrast to the other analogous N-heteroaromatic compounds is not completely shifted for the lactam. The commensurable amounts of both tautomeric forms can be observed in the solutions of 6-hydroxy-7-azaindolines and it is possible to elucidate the influence of the solvent polarity upon the lactam-lactim tautomeric equilibrium. The tautomeric equilibrium of 6-amino- and 6-acylamino-7-azaindolines is practically completely shifted for the amino form, and even acylation with p-toluene-sulfonic acid does not result in a noticeable shift of the tautomeric equilibrium for the amino form in contrast to the other N-heterocyclic amines.     

Synthesis, crystal structure, and catalytic properties of MgCo6Ge6

The ternary compound MgCo6Ge6 represents a novel member of the RM6X6 phases, which contains a graphite-type Ge network, Kagomé nets of Co atoms, and Ge2 dumbbells with an unexpected short Ge-Ge contact in the range of a localized Ge-Ge single bond. The title compound shows a large variety of chemical bonding, which ranges from metallic to multicenter and covalent bonding. The role of polar intermetallic alloys as promising candidates for the application as catalysts for the selective hydrogenation of alpha,beta-unsaturated aldehydes is discussed. MgCo6Ge6 possesses a remarkable activity and selectivity for the hydrogenation of cis/trans-citral to geraniol and nerol.     

Reactions of 6-hydrazino-, 6-hydroxylaminopurines and related derivatives

7H-Tetrazolo[5,1-i]purine was prepared by nitrosation of 6-hydrazinopurine and by reaction of 6-chloropurine with sodium azide; it was converted to adenine upon catalytic hydrogenation. 6-Hydroxylaminopurine was oxidized to 6-nitrosopurine with manganese dioxide, while alkaline treatment of the former gave 6,6′-azoxypurine. Nitrosation of 6-hydroxylaminopurine afforded 6-(N-nitroso)hydroxylaminopurine. Reaction of 6-chloropurine with 6-hydrazinopurine led to 6,6′-bisadenine; the corresponding ribosyl derivatives gave 6,6′-bisadenosine. Upon air oxidation, 6,6′-bisadenine was converted into 6,6′-azopurine. The related 6-thiosemicarbazino- and 6-(N-methyl)ureidopurine derivatives are also described. 6-N-(Nitroso)hydroxylaminopurine showed an inhibitory activity against several mouse tumors and leukemias.     

C60NH5/6, 6/6异构体的理论研究

用半经验的AM1, PM3及ab initio方法对C60NH两种异构体的结构及光谱进行了理论计算。结果表明, 具有开环结构的C60NH的5/6异构体稳定性要高于具有闭环结构的6/6异构体。计算了两种异构体开环与闭环过程的反应坐标, 发现6/6开环异构体是势能面上的一局部最小点, 而5/6闭环异构体不存在6/6异构体的H可以在两种镜面异构体之间快速翻转, 使其核磁共振谱呈现C2v对称性。通过振动分析确认了所优化的构型确实为势能面的能量最低点, 并得到了C60NH各异构体的红外光谱。     

Neue Synthesen und Kristallstrukturen von Bis(fluorphenyl)quecksilber,Hg(Rf)2 (Rf = C6F5, 2, 3, 4, 6‐F4C6H, 2, 3, 5, 6‐F4C6H, 2, 4, 6‐F3C6H2, 2, 6‐F2C6H3)

New Syntheses and Crystal Structures of Bis(fluorophenyl) Mercury, Hg(R_f)₂ (R_f = C₆F₅, 2, 3, 4, 6‐F₄C₆H, 2, 3, 5, 6‐F₄C₆H, 2, 4, 6‐F₃C₆H₂, 2, 6‐F₂C₆H₃) Bis(fluorophenyl) mercury compounds, Hg(R_f)₂ (R_f = C₆F₅, C₆HF₄, C₆H₂F₃, C₆H₃F₂), are prepared in good yields by the reactions of HgF₂ with Me₃SiR_f. The crystal structures of Hg(2, 3, 4, 6‐F₄C₆H)₂ (monoclinic, P2₁/n), Hg(2, 3, 5, 6‐F₄C₆H)₂ (monoclinic, C2/m), Hg(2, 4, 6‐F₃C₆H₂)₂ (monoclinic, P2₁/c) and Hg(2, 6‐F₂C₆H₃)₂ (triclinic, P1) are described.     

Electron attachment to MoF6, ReF6, and WF6; reaction of MoF6(-) with ReF6 and reaction of Ar+ with MoF6

Rate constants were measured for electron attachment to MoF(6), ReF(6), and WF(6) in 133 Pa of helium gas using a flowing-afterglow Langmuir-probe apparatus. The experiment is a thorny one because the molecules tend to form oxide impurities on feedline surfaces and because of thermal decomposition of MoF(6) on surfaces as the gas temperature is increased. The electron attachment rate constant for MoF(6) is (2.3+/-0.8)x10(-9) cm(3) s(-1) at 297 K; only MoF(6) (-) is formed in the temperature range of 297-385 K. The rate constant increases with temperature up to the point where decomposition becomes apparent. Electron attachment to ReF(6) occurs with a rate constant of (2.4+/-0.8)x10(-9) cm(3) s(-1) at 297 K; only ReF(6) (-) is produced. MoF(6) (-) reacts with ReF(6) to form ReF(6) (-) on essentially every collision, showing definitively that the electron affinity of ReF(6) is greater than that of MoF(6). A rate constant of (5.0+/-1.3)x10(-10) cm(3) s(-1) was measured for this ion-molecule reaction at 304 K. The reverse reaction is not observed. The reaction of Ar(+) with MoF(6) was found to produce MoF(5) (+)+F, with a rate constant of (1.8+/-0.5)x10(-9) cm(3) s(-1). WF(6) attaches electrons so slowly at room temperature that the attachment rate was below detection level (< or =10(-12) cm(3) s(-1)). By 552 K, the attachment rate constant reaches a value of (2+/-1)x10(-10) cm(3) s(-1).     

Ready Access to 6-Alkyl, 6-Phenyl, 5,6-Dialkyl, and 5-Alkyl-6-phenyl Substituted 1,2,3,4-Tetrahydroisoquinolines

 Readily available bicyclic enone precursors were used in a novel strategy for the synthesis of 6-mono- and 5,6-disubstituted tetrahydroisoquinolines (alkyl and phenyl in position 6, hydrogen and methyl in position 5). After 1,2-addition of the respective organometallic reagents to the enones, the crude intermediate alcohols were subjected to a dehydratization/aromatization procedure using the in situ generated triphenylmethyl cation. Overall yields obtained by this procedure were between 27 and 86%. Whereas the synthesis of N-benzyl protected 6-t-butyl-tetrahydroisoquinoline was successful, partial dealkylation occurred in the 5-methyl-6-t-butyl analogue. Some of the new N-benzyl tetrahydroisoquinolines were transformed into the corresponding unprotected heterocycles.     

Isomerization of B_6,B_6~- and B_6~+ clusters

The interconversions between isomers with the same spin multiplicity of neutral B6 and charged B6-and B6+ clusters have been investigated at the B3LYP/6-311+G level of theory,including determination of the minimum energy pathways with transition states connecting the corresponding reactants and products.In dynamic calculations,26 isomers were optimized,including 11 novel isomers.In order to further refine the energies,single-point B3LYP/6-311+G(3df) calculations were carried out on the corresponding B3LYP/6...     

富烯与2-吡啶甲基锂及2-喹啉甲基锂的反应: 含氮杂环取代二茂 铁的合成

在四氢呋喃-乙醚溶剂中,6-甲基-2-吡啶甲基锂与6,6-二烷基富烯或6,6-n亚甲基富烯(n=4,5,6)均发生环外双键加成反应。在类似反应条件下,2-喹啉甲基锂与6-甲基-6-乙基富烯或6,6-五亚甲基富烯皆发生加成反应和α-攫氢的竞争反应。用上述反应产生的取代环戊二烯基锂与二氯化铁配位,合成了一系列含氮杂环取代二茂铁衍生物。其结构经^1HNMR,元素分析和MS确证。在该类化合物的质谱裂解中,发现吡啶环对铁原子存在配位作用。     

Ready Access to 6-Alkyl, 6-Phenyl, 5,6-Dialkyl, and 5-Alkyl-6-phenyl Substituted 1,2,3,4-Tetrahydroisoquinolines

Summary.  Readily available bicyclic enone precursors were used in a novel strategy for the synthesis of 6-mono- and 5,6-disubstituted tetrahydroisoquinolines (alkyl and phenyl in position 6, hydrogen and methyl in position 5). After 1,2-addition of the respective organometallic reagents to the enones, the crude intermediate alcohols were subjected to a dehydratization/aromatization procedure using the in situ generated triphenylmethyl cation. Overall yields obtained by this procedure were between 27 and 86%. Whereas the synthesis of N-benzyl protected 6-t-butyl-tetrahydroisoquinoline was successful, partial dealkylation occurred in the 5-methyl-6-t-butyl analogue. Some of the new N-benzyl tetrahydroisoquinolines were transformed into the corresponding unprotected heterocycles. Received March 22, 2001. Accepted May 22, 2001     

Über Hexafluoroferrate(III): Cs2TlFeF6, Cs2KFeF6, Rb2KFeF6, Rb2NaFeF6 und Cs2NaFeF6

On Hexafluoroferrates(III): Cs₂TlFeF₆, Cs₂KFeF₆, Rb₂KFeF₆, Rb₂NaFeF₆, and Cs₂NaFeF₆ New prepared are the compounds Cs₂TlFeF₆ (a = 9.21₁ Å), Cs₂KFeF₆ (a = 9.04₁ Å), Rb₂KFeF₆ (a = 8.86₈ Å) and Rb₂NaFeF₆ (a = 8.46 ₄Å) all cubic Elpasolithes as well as Cs₂NaFeF₆ (Cs₂NaCrF₆?type, hexagonal with a = 6.28₁, c = 30.53₂ Å), all colourless. Cs₂KFeF₆ was measured magnetically (70–297,2 K). The spectra of reflection were measured (9000–36000 cm^?1). The Madelung Part of Lattice Energy, MAPLE, is calculated and discussed.     

Ca4IrO6, Ca3MgIrO6 and Ca3ZnIrO6

Single crystals of tetracalcium iridium hexaoxide, Ca₄IrO₆, tricalcium magnesium iridium hexaoxide, Ca₃MgIrO₆, and tricalcium zinc iridium hexaoxide, Ca₃ZnIrO₆, were prepared via high-temperature flux growth and structurally characterized by single-crystal X-ray diffraction. The three compounds are isostructural and adopt the K₄CdCl₆ structure type, comprised of chains of alternating face-shared [CaO₆], [MgO₆] or [ZnO₆] trigonal prisms and [IrO₆] octahedra, surrounded by columns of Ca²⁺ ions.     

Investigation of solution‐grown,chain‐folded lamellar crystals of the even‐even nylons: 6 6, 8 6, 8 8, 10 6, 10 8, 10 10, 12 6, 12 8, 12 10, and 12 12

Chain‐folded lamellar crystals of the ten even‐even nylons: 6 6, 8 6, 8 8, 10 6, 10 8, 10 10, 12 6, 12 8, 12 10, and 12 12 have been grown from solution and their morphologies and structures studied using transmission electron microscopy, both imaging and diffraction. Sedimented mats were examined using X‐ray diffraction. The solution‐grown crystals are lath‐shaped lamellae and diffraction from these crystals, at room temperature, reveals that three crystalline forms are present in differing ratios. The crystals are composed of chain‐folded, hydrogen‐bonded sheets, the linear hydrogen bonds within which generate a progressive shear of the chains (p‐sheets). The sheets are found to stack in two different ways. Some p‐sheets stack with a progressive shear, to form the “α_p structure”; others sheets stack with an alternate stagger, to form the “β_p structure”. Both the α_p and β_p structures give two strong diffraction signals at spacings of 0.44 nm and 0.37 nm; these signals represent a projected intrasheet interchain distance (actual value 0.48 nm) and the intersheet spacing, respectively. Preparations of nylons 6 6, 8 6, 8 8, 12 6, and 12 8 consisted almost entirely of α_p‐structure material, with only a trace of β_p‐structure material being present. In contrast, nylons 10 6, 10 8, 10 10, 12 10, and 12 12 contained substantial quantities of both α_p‐ and β_p‐structure material, with α_p‐structure material always being in the majority. Preparations of nylons 10 8, 12 10, and 12 12 also showed an additional diffraction signal at 0.42 nm; this signal is characteristic of the pseudohexagonal (high temperature) structure. The melting temperature of solution‐grown lamellae of these even‐even nylons decreases with decreasing linear amide density. On heating, the strong diffraction signals (0.44 nm and 0.37 nm) gradually moved together and merge at the Brill temperature to form a single diffraction signal (0.42 nm), characteristic of the pseudohexagonal structure. This single diffraction signal remained until melting. For nylons 6 6, 8 6, 8 8, 10 6, and 12 6, the Brill temperatures were substantially below the respective melting temperatures and the single 0.42 nm diffraction signal was stable over temperature ranges of 14 °C to 56 °C, depending on the nylon. Conversely, nylons 10 8, 10 10, 12 8, 12 10, and 12 12 had coincident melting and extrapolated Brill temperatures. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 1209–1221, 2000