scholarly journals New solid form of Norfloxacin: Structural studies

2011 ◽  
Vol 25 (1) ◽  
pp. 53-62 ◽  
Author(s):  
I. Bratu ◽  
G. Borodi ◽  
Iren KacsÓ ◽  
Z. Moldovan ◽  
C. Filip ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Organic Solvents ◽  
Molar Ratio ◽  
Structural Studies ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cell Parameters ◽  
Triclinic System ◽  
Solid Form ◽  
C Nmr

The aim of the present paper was to obtain new solid forms of Norfloxacin. For this purpose Norfloxacin was recrystallized from: acetic acid and its mixtures with several organic solvents. By recrystallization of Norfloxacin from acetic acid and from its mixture with several organic solvents a new solvate was found. To evidence this new solid form of Norfloxacin different investigation techniques were used: powder X-ray diffraction, FTIR, DSC,13C NMR spectroscopy and mass spectrometry. The solvate is consisting on Norfloxacin and acetic acid in 1:1 molar ratio and crystallizes in triclinic system and the cell parameters were determined also.

An unusual reaction of a bridged triterpenoid α-diketone with acetic anhydride

1991 ◽  
Vol 56 (12) ◽  
pp. 2917-2935 ◽  
Author(s):  
Eva Klinotová ◽  
Václav Křeček ◽  
Jiří Klinot ◽  
Miloš Buděšínský ◽  
Jaroslav Podlaha ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Nmr Spectroscopy ◽  
Acetic Anhydride ◽  
Spectral Methods ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mild Conditions ◽  
Condensation Products ◽  
Unsaturated Lactones ◽  
C Nmr

3β-Acetoxy-21,22-dioxo-18α,19βH-ursan-28,20β-olide (IIIa) reacts with acetic anhydride in pyridine under very mild conditions affording β-lactone IVa and γ-lactones Va and VIIa as condensation products. On reaction with pyridine, lactones Va and VIIa undergo elimination of acetic acid to give unsaturated lactones VIIIa and IXa, respectively. Similarly, the condensation of 20β,28-epoxy-21,22-dioxo-18α,19βH-ursan-3β-yl acetate (IIIb) with acetic anhydride leads to β-lactone IVb and γ-lactone Vb; the latter on heating with pyridine affords unsaturated lactone VIIIb and 21-methylene-22-ketone Xb. The structure of the obtained compounds was derived using spectral methods, particularly 1H and 13C NMR spectroscopy; structure of lactone IVa was confirmed by X-ray diffraction.

Structural studies on monofluorinated derivatives of the phytohormone indole-3-acetic acid (auxin)

1996 ◽  
Vol 52 (4) ◽  
pp. 651-661 ◽  
Author(s):  
A. Antolić ◽  
B. Kojić-Prodić ◽  
S. Tomić ◽  
B. Nigović ◽  
V. Magnus ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Side Chain ◽  
Structural Studies ◽  
X Ray Diffraction ◽  
Molecular Conformations ◽  
X Ray ◽  
Structure Activity ◽  
Planar Conformation ◽  
Derivatives Of ◽  
Indole 3 Acetic Acid

As part of the molecular recognition studies on the phytohormone indole-3-acetic acid (IAA) a series of fluorinated IAA's has been examined. The phenyl ring substitution at positions 4, 5, 6 and 7 resulted in four compounds, which were analyzed. Structure–activity correlation includes the analysis of their molecular conformations, based on the X-ray diffraction and computational chemistry results, and bioactivity determinations in the Avena coleoptile and the Pisum sativum stem straight-growth tests, lipophilicity and UV absorbance. The conformations of monofluorinated IAA's and a free hormone are defined by rotations about two bonds: one describes the relative orientation of a side chain towards the indole plane and the second the orientation of the carboxylic group. The results of X-ray structure analysis revealed the folded shape of the molecules in all compounds studied. Molecular mechanics and dynamics located the folded conformation as the local minimum, but failed to detect the planar conformation as one of the local minima, which according to ab initio results on IAA and 4-CI-IAA could also be possible. Crystal data at 295 K for 4-F-IAA and at 297 K for 5-F-IAA, and at 100 K for 6-F-IAA and 7-F-IAA using Mo Kα radiation (λ = 0.71073 Å) and Cu Kα (λ = 1.5418 Å, for 7-F-IAA), are as follows: 4-F-IAA, C10H8NO2F, Mr = 193.18, monoclinic, C2/c, a = 17.294 (5), b = 13.875 (4), c = 7.442 (4) Å, β = 103.88 (6)°, V = 1734 (1) Å3, Z = 8, Dx = 1.480 g cm−3, μ = 1.1 cm−1, F(000) = 800, R = 0.043, wR = 0.044 for 823 symmetry-independent [I ≥ 3σ(I)] reflections; 5-F-IAA, C10H8NO2F, monoclinic, P21/c, a = 19.284 (5), b = 5.083 (4), c = 9.939 (4) Å, β = 117.28 (6)°, V = 865.9 (1) Å3, Z = 4, Dx = 1.482 g cm−3, μ = 1.1  cm−1, F(000) = 400, R = 0.062, wR = 0.057 for 729 symmetry-independent [I ≥ 3σ(I)] reflections; 6-F-IAA, C10H8NO2F, monoclinic, P21/a, a = 9.360 (1), b = 5.167 (4), c = 17.751 (4) Å, β = 93.75 (1)°, V = 856.7 (8) Å3, Z = 4, Dx = 1.498 g cm−3, μ = 1.1 cm−1, F(000) = 400, R = 0.048, wR = 0.048 for 1032 symmetry-independent [I ≥ 2σ(I)] reflections; 7-F-IAA, C10H8NO2F, monoclinic, P21/a, a = 9.935 (5), b = 5.0059 (4), c = 17.610 (1) Å, β = 102.13 (1)°, V = 856.3 (1) Å3, Z = 4, Dx = 1.498 g cm−3, μ = 9.8 cm−1 (Cu Kα, F(000) = 400, R = 0.035, wR = 0.040 for 1504 symmetry-independent [I ≥ 2σ(I)] reflections.

scholarly journals Crystallization and preliminary X-ray diffraction analysis of human DNA primase

2014 ◽  
Vol 70 (2) ◽  
pp. 206-210 ◽  
Author(s):  
Andrey G. Baranovskiy ◽  
Jianyou Gu ◽  
Nigar D. Babayeva ◽  
Vinod B. Agarkar ◽  
Yoshiaki Suwa ◽  
...  
Keyword(s):  
Active Site ◽  
Large Subunit ◽  
Structural Studies ◽  
Asymmetric Unit ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Human Dna ◽  
Structural Details

Human primase synthesizes RNA primers and transfers them to the active site of Pol α with subsequent extension with dNTPs. Human primase is a heterodimer of two subunits: a small catalytic subunit (p49) and a large subunit (p58). The structural details of the initiation and elongation steps of primer synthesis, as well as primer length counting, are not known. To address these questions, structural studies of human primase were initiated. Two types of crystals were obtained. The best diffracting crystals belonged to space groupP1, with unit-cell parametersa= 86.2,b= 88.9,c= 94.68 Å, α = 93.82, β = 96.57, γ = 111.72°, and contained two heterodimers of full-length p49 and p59 subunits in the asymmetric unit.

Synthesis and Characterization of Polyaniline Nanotubes Doped with Amino Acetic Acid

2012 ◽  
Vol 184-185 ◽  
pp. 1285-1288 ◽  
Author(s):  
Xue Lian Bai ◽  
Jian Ting Mei ◽  
Yun Bai ◽  
Zhong Guo Mu
Keyword(s):  
Acetic Acid ◽  
Self Assembly ◽  
Ammonium Persulfate ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
X Ray ◽  
Structure And Property ◽  
Assembly Method ◽  
Doped Polyaniline

Doped polyaniline (PANI) nanostructure has been prepared at room temperature using amino acetic acid (AA) as dopant and ammonium persulfate (APS) as oxidant by a self-assembly method. The structure and property of polyaniline nanostructure were characterized by SEM, TEM，IR and X-ray diffraction (XRD) and applying the 4 probes method. The results showed the production was PANI. The effect of molar ratio of AA to An affected the morphology of the product and room template conductivity of the products were studied.

Darstellung und Kristallstrukturbestimmung von 1,2-Di-t-butyl-1,2-diiodo- diarsan (t-C4H9AsI)2 und Synthese von 1,2,3,4-Tetrakis(t-butyl)tetraarsetan (t-C4H9As)4 über selektive Reduktion von t-Butylarsendiiodid t-C4H9AsI2 Synthesis and Crystal Structure of 1,2-Di-t-butyl-1,2-diiododiarsane (t-C4H9AsI)2 and Synthesis of 1,2,3,4-Tetrakis(t-butyl)tetraarsetane (t-C4H9As)4 via Selective Reduction of t-Butylarsenic Diiodide t-C4H9AsI2

1997 ◽  
Vol 52 (7) ◽  
pp. 790-794 ◽  
Author(s):  
Klaus Megges ◽  
Evgeni V. Avtomonov ◽  
Jörg Lorberth
Keyword(s):  
Crystal Structure ◽  
Low Temperatures ◽  
Selective Reduction ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
Synthesis And Crystal Structure ◽  
X Ray ◽  
Elemental Analyses ◽  
High Yields ◽  
C Nmr

Abstract 1,2,3,4-Tetrakis(t-butyl)tetraarsetane (t-C4H9As)4(4) has been synthesized by reduction of t-butylarsenic (III) diiodide (1) with equivalent quantities of either Mg, Ca, Zn, Li, or CoCp2 in THF at low temperatures in high yields. Treatment of 1 with CoCp2 in a molar ratio 1:1 in n-pentane at -78 °C leads to the formation of 1,2-di-t-butyl-1,2-diiododiarsine (2) (t-C4H9AsI)2 in 69 % yield. The products have been characterized by spectroscopic methods (H, 13C-NMR, EI-MS) and elemental analyses. The crystal structure of 2 has been determined by X-ray diffraction methods.

scholarly journals Catalytic Behaviors of Expansible Graphite in the Synthesis of Butyl Acetate

2012 ◽  
Vol 9 (4) ◽  
pp. 1816-1822
Author(s):  
Xiu-Yan Pang
Keyword(s):  
Acetic Acid ◽  
Butyl Acetate ◽  
Molar Ratio ◽  
Expandable Graphite ◽  
Energy Dispersive Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ester Yield ◽  
Esterification Rate ◽  
Acid Dosage

The catalysis of expandable graphite EG for esterification has been studied. EG was prepared with KMnO4as oxidant and H2SO4as inserting reagent. Eexpanded volume，x-ray diffraction and energy dispersive analysis for EG were carried, and its catalytic activity was detected in the reaction of acetic acid with butanol. Influence of mole ratio of butanol and acetic acid, dosage of EG on ester yield were optimumed single factor experiments. The suitable esterification condition is: molar ratio of butanol to acetic acid keeps 1.6:1.0, mass of EG keeps 9.0% of the total mass of reactants; reaction keeping up 1.0 h at the boling point, and esterification rate of 98.2% can be achieved. The reuse ester yield is 86.6% for first reuse and 61.2% for the second reuse.

Synthesis, structural characterization, and hydrogen bonds of Co9(OH)14[SO4]2

2017 ◽  
Vol 72 (7) ◽  
pp. 505-510
Author(s):  
Hamdi Ben Yahia ◽  
Masahiro Shikano ◽  
Ilias Belharouak
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Single Crystal ◽  
Structural Characterization ◽  
Diffraction Data ◽  
Atmospheric Oxygen ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
X Ray ◽  
Triclinic System

AbstractThe new compound Co9(OH)14[SO4]2 was synthesized using a hydrothermal method from LiF, Na2SO3, and Co(CH3COO)2·4H2O in a molar ratio of 1:1:1 in the presence of atmospheric oxygen. Its crystal structure was determined from single crystal X-ray diffraction data. Co9(OH)14[SO4]2 crystallizes in the triclinic system, space group P1̅ with a=7.693(2) Å, b=8.318(2) Å, c=8.351(2) Å, α=82.375(5)°, β=77.832(4)°, γ=68.395(4)°, V=484.8(2) Å3, and Z=2. Its structure is composed of cobalt-containing sheets interconnected by SO4 tetrahedra. Bent and symmetrically trifurcated hydrogen bonds have been observed. Furthermore, structural similarities with hydrozincite and brucite minerals have been noticed.

scholarly journals Structural study of a series of synthetic goethites obtained in aqueous solutions containing cadmium(II) ions

2003 ◽  
Vol 18 (1) ◽  
pp. 50-55 ◽  
Author(s):  
E. E. Sileo ◽  
P. S. Solı´s ◽  
C. O. Paiva-Santos
Keyword(s):  
Metal Content ◽  
Alkaline Media ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Crystalline Product ◽  
Structural Frame ◽  
Nitrate Solutions

The capacity of goethite for CdII substitution has been explored in a series of synthetic samples prepared from FeIII and CdII nitrate solutions aged 21 days in alkaline media. The total metal content ([Fe]+[Cd]) was 0.071 M in all preparations. The samples have been characterized by chemical and X-ray diffraction analysis; the morphology of the solids is described. The cell parameters for all samples were obtained by the Rietveld fits to the X-ray diffraction data. Refined structures show that for samples prepared at the final molar ratio μCd≤5.50 (expressed as μCd=100×[Cd]/[Cd]+[Fe]), a (Cd, Fe)-goethite is the only crystalline product. In these samples, the unit cell parameters increased as a function of Cd concentration, indicating Cd incorporation in the structural frame. At the preparative ratio, μCd=7.03, the incorporation of Cd in the goethite structure is drastically reduced and a probable Cd-substituted hematite is formed together with the Fe,Cd-goethite.

Microstructural evolution of mullites produced from single-phase gels

2007 ◽  
Vol 40 (2) ◽  
pp. 260-276 ◽  
Author(s):  
Marek Andrzej Kojdecki ◽  
Esther Ruiz de Sola ◽  
Francisco Javier Serrano ◽  
Estefanía Delgado-Pinar ◽  
María Mercedes Reventós ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Unit Cell ◽  
Molar Ratio ◽  
Model Parameters ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Transmission Electron ◽  
Diffraction Patterns

The crystalline microstructure of mullites obtained by heating monophasic gels has been investigated. Gels with alumina to silica molar ratio of 3:2 (as in secondary mullite) and 2:1 (as in primary mullite) were prepared by gelling mixtures of aluminium nitrate and tetraethylorthosilicate. Phase transformations were induced by heating the gel precursors, with different final treatment temperatures between 1173 and 1873 K. The mullites formed as a result of thermal treatment were studied by means of X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The crystalline structure (unit-cell parameters) and microstructure were determined from X-ray diffraction patterns. The formation of mullites of homogeneous chemical composition and with unit-cell parameters depending almost linearly on the treatment temperature was found. Their compositions, expressed as alumina to silica molar ratio, were determined from the unit-cell parameters and were in the range of those characterizing primary and secondary mullites. Mullites processed at lower temperatures were accompanied by small amounts of vitreous phase. The crystalline microstructure of the obtained mullites was interpreted by means of a mathematical model of polycrystalline material, involving prevalent crystallite shape, volume-weighted crystallite size distribution and second-order crystalline lattice strain distribution as model parameters. The model parameters were determined for each sample by modelling its X-ray diffraction pattern and fitting it to a measured pattern. Bimodality of the size distribution was observed and explained as a consequence of two crystallite nucleation and growth processes, which started from small alumina-rich and alumina-poor domains, spontaneously formed in a precursor gel at early stages of heating. Images produced by scanning and transmission electron microscopy agreed well with the characteristics obtained from the analysis of the X-ray diffraction patterns.

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