- Nitrosyl Complexes of Molebdenum and Tungsten. Part 15. Iodo(monoalkylamido)nitrosylmolybdenum Complexes, some Related Tungten Compounds, and the Crystal and Molecular Structure of Ethylamido(iodo)nitrosylmolybdenum
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The complexes (NO)I(Y)> (Y=NMe2 or NHR, where R=H, Me, Et, nPr, iPr, nBu, tBu, C6H11, C3H5, or CH2Ph) and (NO)Br(Y)> (Y=H, iPr, or CH2Ph) have been prepared by treatment of the species where Y=I(Mo) or Br(W) with ammonia primary amines, and NHMe2 respectively.Reaction of HB(3,5-Me2C3HN2)3>(NO)I(NH2)> with HCl, and with acetone in the presence of NEt3 respectively, gives (NO)Cl2> and Cl, and (NO)I(N=CMe2)>*Me2CO.The crystal and molecular structure of (NO)I(NHEt)>, as a di-isopropyl ether solvate, has been determined by X-ray diffraction methods using counter data and refined by block-diagonal least-squares procedures, to R=0.0534 for 3150 reflections.The molecule is six co-ordinate, with a linear Mo-N-O group, and a short Mo-NHEt bond.Crystals are monoclinic with a=40.00(3), b=12.751(10), c=10.60(3) angstroem.β=97.23(2) deg, space group P21/a, and Z=8.
- McCleverty, Jon A.,Rae, A. Elizabeth,Wotochowicz, Iwona,Bailey, Neil A.,Smith, John M. A.
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- P-P orbital interaction: via magnesium isovalent doping enhances optoelectronic properties of halide perovskites
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p-p orbital interaction through Mg(ii) isovalent doping in methylammonium lead chloride perovskite significantly enhances the electronic properties while not affecting the optical bandgap. This chemical behaviour shows promising applications to optoelectr
- Qian, Feng,Gong, Jue,Hu, Mingyu,Ge, Chunyu,Padture, Nitin P.,Zhou, Yuanyuan,Feng, Jing
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- Low-temperature photoluminescence spectroscopy of CH3NH3PbBrxCl3-x perovskite single crystals
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Organic-inorganic halide perovskite (OIHP) has attracted tremendous attention due to its potential applications in optoelectronics such as light emitting device and photodetector. Here, we have grown high quality CH3NH3PbBrx/su
- Xu, Qiang,Shao, Wenyi,Zhang, Xinlei,Liu, Jun,Ouyang, Xiaoping,Tang, Xiaobin,Jia, Wenbao
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- Visual clarity methylammonium lead trichloride perovskite single crystals for X and gamma rays protection
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Ionization radiation photons such as X-ray and gamma ray have been widely applied in the nuclear power industry, medical imaging, scientific research, and aerospace exploration. Developing a protective material with excellent shielding properties and clear visibility is an urgent demand in order to protect people who are working in a radiation environment. Hence, we present a highly efficient radiation shielding material based on lead halide organic-inorganic perovskite single crystals with visual clarity, high efficiency and attenuation coefficient, and thin half-value layer. Our results indicate that the shielding performances (mass attenuation coefficients, effective atomic numbers and half value layer) of the perovskite crystals are at least one order higher than the current commercial products, such as Bone-equivalent plastic, Polyethylene terephthalate, and colorless glass. In addition, physical properties (density), and optical properties (transmission, refractive index), can be slightly tuned by the dopant Br concentration in crystals. The present results demonstrate that the organic-inorganic perovksite single crystals are optimized for high attenuation radiation shielding materials with visual clarity.
- Xu, Qiang,Shao, Wenyi,Li, Yang,Zhang, Hang,Ouyang, Xiao,Zhang, Xinlei,Nie, Jing,Ouyang, Xiaoping,Liu, Bo
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- Stereodynamics of Diethylmethylamine and Triethylamine
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Diethylamine is the simplest acyclic trialkylamine that possesses the requisite symmetry that allows, in principle, the direct observation of both nitrogen inversion and isolated nitrogen-carbon bond rotation using 1H dynamic nuclear magnetic resonance (DNMR) spectroscopy.DNMR studies of diethylmethylamine and two deuterated derivatives complemented by empirical force-field calculations reveal a comprehensive picture of the stereodynamics of this representative acyclic trialkylamine.The DNMR studies show clear evidence for pyramidal inversion at nitrogen.In addition to nitrogen inversion, the results also speak for several "families" of rotamers for diethylmethylamine that undergo very rapid, DNMR-invisible intrafamily conformational exchange via isolated N-CH2 rotation while also undergoing higher barrier DNMR-visible interfamily exchange also via isolated N-CH2 rotation.The DNMR-visible N-CH2 rotation processes involve CCH3/N-alkyl eclipsing in the transition state while the DNMR-invisible processes involve CCH3/lone pair eclipsing.Although the symmetry of triethylamine precludes the DNMR-observation of nitrogen inversion, (1)H DNMR evidence for restricted N-CH2 rotation and empirical force-field calculations reveal stereodynamics for triethylamine that are highly analogous to diethylmethylamine.
- Bushweller, C. Hackett,Fleischman, Stephen H.,Grady, Gilbert L.,McGoff, Paul,Rithner, Christopher D.,et al.
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- Crystal Growth, Structural Phase Transitions, and Optical Gap Evolution of CH3NH3Pb(Br1-xClx)3 Perovskites
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Chemically tuned inorganic-organic hybrid halide perovskites based on bromide and chloride anions CH3NH3Pb(Br1-xClx)3 have been crystallized and investigated by synchrotron X-ray diffraction (SXRD), scanning electron microscopy, and UV-vis spectroscopy. CH3NH3PbBr3 and CH3NH3PbCl3 experience successive phase transitions upon cooling, which are suppressed for intermediate compositions probably due to compositional disorder. For CH3NH3PbCl3, a transient phase, formerly described as tetragonal, was identified at 167.5 K; the analysis of SXRD data demonstrated that it is indeed orthorhombic, with space group Pnma, and a ≈ 2ap; b ≈ 2ap; c ≈ 2ap (ap is the ideal cubic perovskite unit-cell parameter). The band gap engineering brought about by the chemical management of CH3NH3Pb(Br1-xClx)3 perovskites can be controllably tuned: the gap progressively increases with the concentration of Cl ions from 2.2 to 2.9 eV, and shows a concomitant variation with the unit-cell parameters of the cubic phases at 295 K. This study provides an improved understanding of the structural and optical properties of the mixed CH3NH3Pb(Br1-xClx)3 perovskites.
- Alvarez-Galván,Alonso,López,López-Linares,Contreras,Lázaro,Fauth,Martínez-Huerta
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- Reduction of Amides to Amines with Pinacolborane Catalyzed by Heterogeneous Lanthanum Catalyst La(CH2C6H4NMe2- o)3@SBA-15
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Hydroboration of amides is a useful synthetic strategy to access the corresponding amines. In this contribution, it was found that the supported lanthanum benzyl material La(CH2C6H4NMe2-o)3@SBA-15 was highly active for the hydroboration of primary, secondary, and tertiary amides to amines with pinacolborane. These reactions selectively produced target amines and showed good tolerance for functional groups such as -NO2, -halogen, and -CN, as well as heteroatoms such as S and O. This reduction procedure exhibited the recyclable and reusable property of heterogeneous catalysts and was applicable to gram-scale synthesis. The reaction mechanisms were proposed based on some control experiments and the previous literature. This is the first example of hydroborative reduction of amides to amines mediated by heterogeneous catalysts.
- Guo, Chenjun,Zhang, Fangcao,Yu, Chong,Luo, Yunjie
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supporting information
p. 13122 - 13135
(2021/08/31)
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- Deoxygenation of primary amides to amines with pinacolborane catalyzed by Ca[N(SiMe3)2]2(THF)2
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Deoxygenative reduction of amides is a challenging but favorable synthetic method of accessing amines. In the presence of a catalytic amount of Ca[N(SiMe3)2]2(THF)2, pinacolborane (HBpin) could efficiently reduce a broad scope of amides, primary amides in particular, into corresponding amines. Functional groups and heteroatoms showed good tolerance in this process of transformation, and a plausible reaction mechanism was proposed.
- Gong, Mingliang,Guo, Chenjun,Jiang, Linhong,Luo, Yunjie,Yu, Chong
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supporting information
p. 1201 - 1206
(2021/05/29)
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- Blue-emitting NH4+-doped MAPbBr3perovskite quantum dots with near unity quantum yield and super stability
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Novel NH4+-doped MA1?x(NH4)xPbBr3perovskite quantum dots were synthesized at room temperature. The introduction of NH4+results in larger lattice formation energy and b
- Deng, Jidong,Xun, Jiao,Qin, Youcheng,Li, Ming,He, Rongxing
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supporting information
p. 11863 - 11866
(2020/10/13)
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- Solvent-free, solid phase synthesis of hybrid lead halide perovskites with superior purity
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A method of synthesizing a mixed-halide perovskite is disclosed herein. The method includes the steps of mixing a first single-halide perovskite and a second single-halide perovskite to form a solid phase mixture and heating the solid phase mixture at a temperature below a first decomposition temperature of the first single-halide perovskite and below a second decomposition temperature of the second single-halide perovskite for a time sufficient to form the mixed-halide perovskite. During the mixing, the first and second single-halide perovskite are both in the solid phase. A mixed-halide perovskite made according to the method is also disclosed herein. The mixed-halide perovskite is free of amorphous and/or semicrystalline phases. The mixed-halide perovskite can be utilized in a photovoltaic cell in a solar panel.
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Page/Page column 6-7
(2020/12/30)
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- Transition metal-free catalytic reduction of primary amides using an abnormal NHC based potassium complex: Integrating nucleophilicity with Lewis acidic activation
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An abnormal N-heterocyclic carbene (aNHC) based potassium complex was used as a transition metal-free catalyst for reduction of primary amides to corresponding primary amines under ambient conditions. Only 2 mol% loading of the catalyst exhibits a broad substrate scope including aromatic, aliphatic and heterocyclic primary amides with excellent functional group tolerance. This method was applicable for reduction of chiral amides and utilized for the synthesis of pharmaceutically valuable precursors on a gram scale. During mechanistic investigation, several intermediates were isolated and characterized through spectroscopic techniques and one of the catalytic intermediates was characterized through single-crystal XRD. A well-defined catalyst and isolable intermediate along with several stoichiometric experiments, in situ NMR experiments and the DFT study helped us to sketch the mechanistic pathway for this reduction process unravelling the dual role of the catalyst involving nucleophilic activation by aNHC along with Lewis acidic activation by K ions.
- Bhunia, Mrinal,Sahoo, Sumeet Ranjan,Das, Arpan,Ahmed, Jasimuddin,Sreejyothi,Mandal, Swadhin K.
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p. 1848 - 1854
(2020/03/03)
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- Room temperature growth of CH3NH3PbCl3 single crystals by solvent evaporation method
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We report a new route to synthesize high-quality, large-size crystals of CH3NH3PbCl3 through proper selection of DSMO-GBL solution via solvent evaporation method at room temperature. A detailed evaluation of the structural, electronic, optical and electrical properties of these crystals was carried out. Our XPS studies suggested that organic-inorganic halide perovskites are sensitive to X-ray-induced damage, and hence, their properties may get altered. Also, photoluminescence studies displayed two peak spectra, indicating coexistence of order-disorder domains of CH3NH3 in the sample. Further observation of low defect concentration and longer diffusion length indicates that crystals grown by the presented method can offer promising solutions for optoelectronic devices.
- Nandi, Pronoy,Giri, Chandan,Swain, Diptikanta,Manju,Topwal, Dinesh
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p. 656 - 661
(2019/01/26)
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- A high performance perovskite CH3NH3PbCl3 single crystal photodetector: Benefiting from an evolutionary preparation process
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Hybrid organic-inorganic lead halide perovskites (CH3NH3PbX3, X = Cl, Br, or I) are deemed to be the highest potential semiconducting materials due to their unique optoelectronic properties. Nowadays, most perovskite photodetectors are fabricated on the basis of thin films, and their performances are limited by the low carrier mobility and high trap density of the thin films. Herein, a high performance photodetector was fabricated via a method involving inversion temperature precision gradient crystallization (ITPGC) for the first time, which is an improvement on traditional methods. The structure of the bulk single crystal is confirmed via XRD and TEM characterization. Also, in terms of nucleation and growth theory, the growth mechanism is explained in detail and the best growth temperature is suggested to be 80 °C for the first time. Benefiting from this, a photodetector with ultra-high responsivity of 7.97 A W-1 is obtained, which is superior to thin film photodetectors. Also, a rise time of 1.27 ms and a fall time of 1.84 ms are obtained, which are regarded as pioneering values for this type of system. Meanwhile, the study also provides new ideas for the preparation of bulk single crystals.
- Yuan, Zhishuai,Huang, Wei,Ma, Shoutao,Ouyang, Gang,Hu, Wei,Zhang, Wei
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p. 5442 - 5450
(2019/05/21)
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- Excellent microwave absorption of lead halide perovskites with high stability
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Given the remarkable progress in physical and structural performances of organic-inorganic lead halide perovskites as a superstar in the photovoltaic field, the study of some of their intrinsic properties is still missing. Herein, we report the microwave absorption performance of MAPbX3 (MA = CH3NH3+, X = I-, Br- or Cl-) perovskite crystals in terms of complex permittivity and permeability. We find that the MAPbI3, MAPbBr3 and MAPbCl3 perovskites possess excellent microwave absorbability, and the optimum reflection losses reach -55.23, -54.70 and -46.44 dB at 16.77, 15.46 and 13.54 GHz with a matching thickness of 1.62, 1.76 and 1.95 mm, respectively. Thereafter, we explore the absorption mechanism and find that the microwave absorption properties can be ascribed to the combination of dielectric loss and magnetic loss, but mainly dielectric loss. In addition, the stability of microwave absorbability is also investigated and it is proved to depend significantly on the decomposition of corresponding perovskites. These results highlight the importance of the discovery of microwave absorbability of organic-inorganic lead halide perovskites. More importantly, our study provides perovskite absorbers as a new variable to be considered in the quest for future microwave devices.
- Guo, Heng,Yang, Jian,Pu, Bingxue,Chen, Haiyuan,Li, Yulan,Wang, Zhiming,Niu, Xiaobin
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p. 4201 - 4207
(2018/04/27)
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- Method for producing methyl ammonium halide for perovskite solar cell
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The invention relates to a method for producing methyl ammonium halide for a perovskite solar cell. The method is low in cost and comprises the following steps: uniformly mixing ammonium halide powder and solid paraformaldehyde powder according to a molar ratio of 1:(2-2.4), wherein the granularity of the crushed ammonium halide powder and solid paraformaldehyde powder reaches 0.01-0.5 mm; heating to 120-180 DEG C to trigger a 1-6 hours' reaction of the solid powder mixture under the molten condition, and further heating to 190-210 DEG C to continue the reaction till no clear gas is released; and dissolving the produced methyl ammonium halide at 50-70 DEG C by using a C1-C4 aliphatic alcohol and C1-C4 aliphatic ether mixed solvent, slowly cooling the obtained solution to negative 5 DEG C to 5 DEG C, separating out a white methyl ammonium halide crystal, and carrying out vacuum filtering and drying to obtain a high-purity white methyl ammonium halide crystal, wherein the content of high-purity methyl ammonium halide is 99.0-99.5% and the content of impurities is 0.01-0.2%. According to the method provided by the invention, a by-product and an excessive raw material, namely formic acid and formaldehyde, can be subjected to gas-phase volatile separation, and high-purity methyl ammonium halide is easy to obtain.
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Paragraph 0013
(2017/06/08)
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- Rapid Conventional and Microwave-Assisted Decarboxylation of L-Histidine and Other Amino Acids via Organocatalysis with R-Carvone under Superheated Conditions
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This article reports a new methodology taking advantage of superheated chemistry via either microwave or conventional heating for the facile decarboxylation of alpha amino acids using the recoverable organocatalyst, R-carvone. The decarboxylation of amino acids is an important synthetic route to biologically active amines, and traditional methods of amino acid decarboxylation are time consuming (taking up to several days in the case of L-histidine), are narrow in scope, and make use of toxic catalysts. Decarboxylations of amino acids including L-histidine occur in just minutes while replacing toxic catalysts with green catalyst, spearmint oil. Yields are comparable to or exceed previous methods and purification of product ammonium chloride salts is aided by an isomerization reaction of residual catalyst to phenolic carvacrol. The method has been shown to be effective for the decarboxylations of a range of natural, synthetic, and protected amino acids.
- Jackson, Douglas M.,Ashley, Robert L.,Brownfield, Callan B.,Morrison, Daniel R.,Morrison, Richard W.
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p. 2691 - 2700
(2015/12/18)
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- The role of chlorine in the formation process of CH3NH3PbI3-xClx perovskite
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CH3NH3PbI3-xClx is a commonly used chemical formula to represent the methylammonium lead halide perovskite fabricated from mixed chlorine- and iodine-containing salt precursors. Despite the rapid progress in improving its photovoltaic efficiency, fundamental questions remain regarding the atomic ratio of Cl in the perovskite as well as the reaction mechanism that leads to its formation and crystallization. In this work we investigated these questions through a combination of chemical, morphological, structural and thermal characterizations. The elemental analyses reveal unambiguously the negligible amount of Cl atoms in the CH3NH3PbI3-xClx perovskite. By studying the thermal characteristics of methylammonium halides as well as the annealing process in a polymer/perovskite/FTO glass structure, we show that the formation of the CH3NH3PbI3-xClx perovskite is likely driven by release of gaseous CH3NH3Cl (or other organic chlorides) through an intermediate organometal mixed halide phase. Furthermore, the comparative study on CH3NH3I/PbCl2 and CH3NH3I/PbI2 precursor combinations with different molar ratios suggest that the initial introduction of a CH3NH3+ rich environment is critical to slow down the perovskite formation process and thus improve the growth of the crystal domains during annealing; accordingly, the function of Cl- is to facilitate the release of excess CH3NH3+ at a relatively low annealing temperatures.
- Yu, Hui,Wang, Feng,Xie, Fangyan,Li, Wenwu,Chen, Jian,Zhao, Ni
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p. 7102 - 7108
(2015/04/14)
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- METHOD FOR DECARBOXYLATION OF AMINO ACIDS VIA IMINE FORMATION
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The present application provides methods for decarboxylation of amino acids via imine formation with a catalyst under superheated conditions in either a microwave or oil bath.
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Page/Page column 0045; 0046; 0066; 0067
(2014/09/30)
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- Fast Pd- and Pd/Cu-catalyzed direct C - H arylation of cyclic nitrones. Application to the synthesis of enantiopure quaternary α-amino esters
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Cocatalysis by pivalic acid or copper bromide allows a very fast, clean, and high-yielding palladium-catalyzed coupling of a large array of aryl, thienyl, and pyridyl halides with cyclic nitrones, including DMPO. The study of the reaction conditions, scope, and mechanism is presented. Applied to the chiral nitrone MiPNO, this transformation provides a straightforward access to enantiopure a-methyl α-arylglycine esters.
- Demory, Emilien,Farran, Daniel,Chavant, Pierre Y.,Blandin, Veronique,Baptiste, Benoit
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p. 7901 - 7912,12
(2020/10/15)
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- β-AMINO ACID DERIVATIVES
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The present invention relates to a compound of formula (I) or a pharmaceutically acceptable salt or solvate thereof, wherein R1, R2, R3, R8 and R9 are as defined herein, as well as to compositions containing such a compound and the uses of such a compound. Compounds of formula (I) are especially useful in the treatment of pain.
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Page/Page column 41
(2010/11/24)
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- A convenient method for the preparation of primary amines using tritylamine
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A simple method for the preparation of primary amines by treating N-tritylamines with trifluoroacetic acid has been established. The N-tritylamines were prepared by the reaction of alkyl halides or alkyl p-toluenesulfonates with tritylamine, or by the reaction of alkyl bromides with lithium tritylamide.
- Theodorou, Vassiliki,Ragoussis, Valentine,Strongilos, Alexandros,Zelepos, Evangelos,Eleftheriou, Argyro,Dimitriou, Maria
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p. 1357 - 1360
(2007/10/03)
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- Silicon-boron-carbon-nitrogen ceramics and precursor compounds, methods for the production and use thereof
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The present invention relates to novel processes for preparing borylsilylamines, novel amines, novel borosilazane compounds, novel oligoborosilazane or polyborosilazane compounds which have the structural feature Si—N—B, ceramic material and methods of producing and using them.
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- High temperature-stabile silicon boron carbide nitride ceramics comprised of silylalkyl borazines,method for the production thereof, and their use
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The present invention concerns a process for producing silylalkylboranes containing the structural feature Si—C—B, new molecular silylalkylboranes, new molecular silyalkylborazines, new oligoborocarbosilazanes and polyborocarbosilazanes, a process for their production and their use as well as silicon boron carbide nitride ceramics and a process for their production.
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- Zinc/hydrazine: A low cost-facile system for the reduction of nitro compounds
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The nitro group in aliphatic and aromatic nitro compounds also containing reducible substituents such as ethene, nitrile, carboxylic acid, phenol, halogen, ester etc., are selectively and rapidly reduced at room temperature to corresponding amines in good yields by employing 99-100% hydrazine hydrate, in the presence of commercial zinc dust. It was observed that, this system is equally compatible with existing methods, which employ expensive catalysts like palladium, platinum, ruthenium etc.
- Gowda, Shankare,Gowda, D. Channe
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p. 180 - 183
(2007/10/03)
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- Hydrazinium monoformate: A new hydrogen donor. Selective reduction of nitrocompounds catalyzed by commercial zinc dust
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The nitro group in aliphatic and aromatic nitro compounds also containing reducible substituents such as ethene, nitrile, acid, phenol, halogen, ester, etc., are selectively and rapidly reduced at room temperature to corresponding amines in good yields by employing hydrazinium monoformate, in the presence of commercial zinc dust. It was observed that, hydrazinium monoformate is more effective than hydrazine or formic acid and reduction of nitro group occurs without hydrogenolysis in the low cost zinc dust compared to expensive metals like palladium.
- Gowda, Shankare,Gowda, B. K. Kempe,Gowda, D. Channe
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p. 281 - 289
(2007/10/03)
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- Nickel-catalyzed formic acid reductions. A selective method for the reduction of nitro compounds
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Aliphatic and aromatic nitro compounds were selectively reduced to their corresponding amino derivatives in good yields using formic acid and raney nickel. This system is found to be compatible with several sensitive functionalities such as halogens, -OH, -OCH3, -CHO, -COCH3-COC6H5, -COOH, -COOC2H5, -CONH2, -CN, -CH=CH-COOH, -NHCOCH3. The reduction can be carrid out not only with HCOOH but also with HCOONH4.
- Channe Gowda,Prakasha Gowda,Ramesha Baba,Gowda, Shankare
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p. 2889 - 2895
(2007/10/03)
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- Bis(chloromethylsilyl)amine and bis(chloromethylsilyl)methylamine; preparation, reactivity and spectroscopic studies of their stereoisomers and conformers
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The compounds NH(SiHMeCl)2 I and NMe(SiHMeCl)2 2 have been prepared by treating SiHMeCl2 with CaCl2·8NH3 and NH2Me respectively. Each was characterised by elemental analysis, mass spectrometry, NMR and IR spectroscopy. Dipole moments were also measured. The NMR spectra indicate that both compounds form 1:1 mixtures of the rac and meso diastereomers, their abundances corresponding to a statistically controlled synthetic pathway. The NMR and mass spectra also show that 1,5-dichloro-1,2,3,4,5-pentamethyltrisilazane, SiHMe[NMe(SiHMeCl)]2 3, which is formed as a side product in the synthesis of 2, also consists of two diastereomers. Variable-temperature 1H NMR spectra of NH(SiHMeCl)2 indicate participation of H(N) in hydrogen bonding. The compound is decomposed by heat and reacts with pyridine to form NH4Cl, SiHMeCl2 and polysilazanes, whereas NMe(SiHMeCl)2 shows only slight decomposition up to 80°C and does not react with pyridine. Infrared spectra in the v(SiH) region are interpreted in terms of the results of ab initio calculations of frequency, intensity and conformer abundance. The two bands near 2200 cm-1 in the spectrum of 2 have their origin in two effects: different orientations of the Si-H bonds relative to the Si-N-Si plane in several conformers and an unprecedented strong dipole-dipole coupling between the two Si-H bond stretching motions in situations where the bonds are roughly parallel. The absence of such an observed splitting for 1 is likely to be due in part to signal averaging during a free internal rotation. Significant couplings are also calculated to occur between Si-Cl bond-stretching motions, whose source must be different from that for the Si-H bond stretches.
- Fleischer, Holger,McKean, Donald C.,Pulham, Colin R.,Buehl, Michael
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p. 585 - 592
(2007/10/03)
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- Cycloadditions of nitrile oxides to amidoximes. A general synthesis of 3,5-disubstituted 1,2,4-oxadiazole-4-oxides
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The cycloaddition of nitrile oxides to amidoximes is a general method for the synthesis of 3,5-disubstituted 1,2,4-oxadiazole-4-oxides with the same or different substituents. The yields are only moderate since an equivalent amount of the nitrile oxide is consumed by reaction with the amine released in the fragmentation of the primary cycloadducts and reforms the amidoxime. With excess nitrile oxides the 1,2,4-oxadiazole-4-oxides undergo a disproportionation reaction to yield nitroso carbonyl intermediates and 1,2,4-oxadiazoles.
- Quadrelli, Paolo,Invernizzi, Anna Gamba,Falzoni, Mario,Caramella, Pierluigi
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p. 1787 - 1796
(2007/10/03)
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- Optionally substituted pyrido[2,3-d]pyridine-2,4(1H,3H)-diones and pyrido[2,]pyrimidine-2(1H,3H)-ones
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The present invention relates to optionally substituted pyrido[2,3-d]pyrimidine-2,4(1H,3H)-diones or optionally substituted pyrido[2,3-d]pyrimidine-2(1H,3H)-ones, i.e., compounds of Formula I: STR1 wherein: Y is --CH2 -- or --C(O)--; R1 is hydrogen or --(CH2)n --R7, wherein: R7 is aryl or heteroaryl, and n is 1 or 2, provided that when Y is --C(O)--, R7 is heteroaryl; and R2, R3, R4, R5 and R6 are hydrogen, or one is selected from lower alkyl, halo, carboxy, methoxycarbonyl, carbamoyl, methylcarbamoyl, di-methylcarbamoyl, methylcarbonyl, methylthio, methylsulfinyl, methylsulfonyl, hydroxymethyl, amino, trifluoromethyl, cyano or nitro; or R2, R3, R4 and R5 are independently selected from hydrogen, lower alkyl, nitro, chloro, fluoro, methoxycarbonyl or methylcarbonyl, provided at least one is hydrogen, and R6 is hydrogen; or a pharmaceutically acceptable ester, ether or salt thereof.
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- HYDROLYSIS OF FLUOROALKYL-CONTAINING β-AMINOVINYL KETONES
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The kinetics of hydrolysis of fluoroalkyl-containing β-aminovinyl ketones R1C(O)CHC(NHR3)R2, in which the substituents CF3 and HCF2CF2 are in the ketone (R1) or enamine parts of the molecule (R2), was studied.In acid (pH 10) media, they hydrolyze with the formation of the corresponding amines and β-diketones.In an alkaline medium, the β-diketones undergo cleavage to fluorinated acids and methyl ketones.The rate constants of hydrolysis in an acid medium change within a range of four orders, depensdng on the nature of the substituents.The presence of a fluoroalkyl group at the enamine reaction center increases the hydrolysis rate.In an alkaline medium, the rate constants vary within one order.
- Bazhenova, L. N.,Filyakova, V. I.,Kirichenko, V. E.,Pashkevich, K. I.
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p. 581 - 585
(2007/10/02)
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- A Convenient Synthesis of Primary Amines Using Sodium Diformylamide as A Modified Gabriel Reagent
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Sodium diformylamide (1) was used as a convenient substitute for phthalimide in the Gabriel synthesis of primary amines.Reagent 1 undergoes smooth N-alkylation with alkyl halides or p-toluenesulfonates 2 in acetonitrile or dimethylformamide to give the corresponding N,N-diformylalkylamines 3 in good yields, except with alkylating agents which are susceptible to base-catalyzed elimination.The formyl group of 3 can be easily removed by hydrochloric acid to give the corresponding alkylamine hydrochlorides 5 or free alkylamines 4.
- Yinglin, Han,Hongwen, Hu
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p. 122 - 124
(2007/10/02)
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- Si,Si'diorganyl-N-alkyl-tetrachloro-disilazanes and a process for their preparation
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The invention relates to a process for the preparation of Si,Si'-diorganyl-N-alkyl-tetrachloro-disilazanes of the formula RSiCl2 --NR'--SiCl2 R, in which R is C1 -C4 -alkyl, vinyl or phenyl and R' is C1 -C4 -alkyl, and to these compounds themselves, with the exception of those where R=R'=CH3. To prepare the compounds mentioned, organyltrichlorosilanes RSiCl3 and monoalkylamines R'NH2 are reacted with one another in an aprotic solvent at -10° C. to +70° C., the molar ratio of RSiCl3 :R'NH2 being at least 0.3:1.
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- Substituted pyridinesulfonamide compounds, herbicidal composition containing them, and method of preparing these compounds
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A substituted pyridinesulfonamide compound and a salt thereof represented by the following general formula I: group, each of R1 and R2 independently represents a hydrogen atom, an alkyl group, a haloalkyl group, an alkenyl group, an alkynyl group, an alkoxy group, a haloalkoxy group, an alkoxyalkyl group, a haloalkoxyalkyl group, a cycloalkyl group, a halocycloalkyl group, an alkoxycarbonyl group, a haloalkoxycarbonyl group, a phenyl group or a halophenyl group, provided that when one of R1 and R2 represents a hydrogen atom, the other represents one of the groups excluding the hydrogen atom; R1 and R2 together with an adjacent nitrogen atom may constitute a heterocycle; Y represents, a halogen atom, an alkyl group, a haloalkyl group, an alkoxy group, a haloalkoxy group, an alkylthio group, a haloalkylthio group, an alkoxyalkyl group, a haloalkoxyalkyl group, or an group (wherein each of R3 and R4 represents a hydrogen atom or an alkyl group); nrepresents 0 or an integer of l or 2; and each of X1 and X2 independently represents a methyl group, a methoxy group or an ethoxy group. The compounds of formula I are effective as herbicides for corn fields.
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- Carbon-13 NMR Study of Reaction of Aqueous Formaldehyde with Amine Salts: Evidences for Reductive Methylation by Intramolecular Hydride Transfer
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Reductive methylation of amine salts by aqueous formaldehyde under acidic conditions proceeds through the initial formation of hydroxymethylamine intermediates, followed by intramolecular hydride transfer. 13C NMR studies on this reaction and the mechanism are discussed.
- Narasimhan, S.,Balakrishnan, M.,Kumar, A. S.,Venkatasubramanian, N.
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p. 568 - 570
(2007/10/02)
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- A Simple Synthesis pf Primary Amines via their N,N-Bis(trimethylsilyl) Derivatives
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Primary halogen compounds 1 or the corresponding tosylates react with sodium bis(trimethylsilyl)amide (2) in hexamethyldisilazane to form N,N-bis(trimethylsilyl)amines 3, which are converted into the amine hydrochlorides 5 by treatment with aqueous HCl.
- Bestmann, Hans Juergen,Woelfel, Gerhard
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p. 1250 - 1254
(2007/10/02)
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- Lithiation of α-Nitrosaminoalkyl Ethers. Synthetic Equivalents of α-Primary Amino Carbanions
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Successful experiments directed toward the C-1 alkylation and hydroxyalkylation of primary amines are reported.Primary amines are converted into their N-nitroso-N-(1-methoxyethyl) derivatives, which are subsequently lithiated and condensed with various electrophiles, denitrosated, and hydrolyzed to produce the desired compounds in good to excellent yields.
- Saavedra, Joseph E.
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p. 2388 - 2392
(2007/10/02)
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- The Stabilisation of P(NH2)Hal2 (Hal = Cl, Br, I) and P(NHMe)2Cl as Complex Ligands
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The phosphanes P(NH2)Hal2 and P(NHMe)2Cl are stabilised as ligands in (CO)5MoP(NH2)Hal2 and (CO)5MoP(NHMe)2Cl (10) by reactions of (CO)5MoP(NH2)3 (1) with HHal or of (CO)5MoP(NHMe)3 (8) with HCl, respectively. 4 decomposes at room temperature and reacts with t-BuNH2 to give (CO)5MoP(NH-t-Bu)2NH2 (6). 1 and HI form (CO)5MoPI3. 3 can also be prepared from 2 with HBr, 4 from 2 and 3 with HBr and HI, respectively.The reactions of 2-4 with NR3 produce polymers, whereas the reaction of 3 with pyridine leads to (CO)5MoNC5H5.The mixtures (CO)5MoP(NH Me)Br2/(CO)5MoPBr3 and (CO)5MoP(NH-i-Pr)2Cl/(CO)5MoP(NH-i-Pr)Cl2 are isolated from reactions of 8 with HBr and of 9 with HI, and 9 reacts with HBr to give (CO)5MoPBr3. (CO)5MoP(NHMe)I2 is formed in small amounts by the reaction of 8 with HI, the main product is an insoluble solid, which is probably the impure intermediate (2+)*2I(1-).Reaction of 10 with NEt3 leads to the formation of the dinuclear complex 12 in which the new diazadiphosphetidine 2 functions as a bridging ligand between two (CO)5Mo units. - Keywords: Ligand Reactions, Hydrogen Halides, Phosphanes
- Maisch, Hartmut
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- Alkyl and haloalkyl N,N'-dialkyl-N-methylolphosphorodiamidates
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Alkyl and haloalkyl N,N'-dialkyl-N-methylolphosphorodiamidates, for example, methyl N,N'-dimethyl-N,N'-dimethylolphosphorodiamidate, useful for rendering combustible cellulosic materials flame resistant.
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- Possible intermediates in the formation of 1,3,5-trimethylborazine
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The 110° pyrolysis of H2B(NH2CH3)2+Cl -, H2CH3NBH2NHCH3BH2NH 2CH3+Cl-, and mixtures of (H2BNHCH3)3 and CH3NH3Cl give H3B3N3(CH3)3, CH3NH3Cl, and H2. The intermediates in the formation of the borazine ring have been investigated by studying the conversion of H2B(NH2CH3)2+Cl - to H3B3N3(CH3)3 in a mass spectrometer and by attempting to prepare possible intermediates. The current experimental evidence suggests that an initial intermediate is a linear, six-membered boron-nitrogen chain. Then, an intramolecular dehydrogenation ring-closure reaction between the ends of the chain leads to a species analogous to cyclohexenes. The more stable borazine ring is then formed from the cyclohexene type of species by the rapid loss of H2.
- Beachley Jr.
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p. 701 - 703
(2008/10/08)
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- Intermediates in the formation of N-methylaminoborane trimer and N,N-dimethylaminoborane dimer
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Experimental evidence for the intermediates in the formation of N-methylaminoborane trimer, (H2BNHCH3)3, and N,N-dimethylaminoborane dimer, (H2BN(CH2)2)2, has been obtained by synthetic methods and trapping procedures. The pyrolysis of methylamine borane, H3BNH2CH3, yields the six-membered ring of (H2BNHCH3)3 by initially forming H2B(NH2CH3)2+BH 4-, then [H2CH3NBH2NHCH3BH2NH 2CH3]+BH4- through a series of successive dehydrogenation condensation reactions. The final step of the proposed mechanism is ring closure by dehydrogenation. The new compound, [H2CH3NBH2NHCH3BH2NH 2CH3]+Cl-, was prepared by heating a mixture of H2B(NH2CH3)2+Cl - and H3BNH2CH3 and was characterized by elemental analysis, its reactions with FeCl3 and NaBH4, and its pmr spectrum. The experimental evidence for the intermediates during the pyrolysis of dimethylamine borane to form (H2BN(CH3)2)2 is consistent with monomeric H2BN(CH3)2 species which then associate to give the dimer.
- Beachley Jr.
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p. 870 - 874
(2007/10/05)
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