Hemi-Synthesis of Chiral Imine, Benzimidazole and Benzodiazepines from Essential Oil of Ammodaucus leucotrichus subsp. leucotrichus

The hemi-synthesis of chiral imine, benzimidazole and benzodiazepine structures is reported by the condensation of (S)-(−)-perillaldehyde, the major phytochemical of Ammodaucus leucotrichus subsp. leucotrichus essential oil, with different amine derivatives of 2,3-diaminomaleonitrile, o-phenylenediamine and 3-[(2-aminoaryl)amino]dimedone. The reaction proceeds in situ at ambient temperature without prior isolation of the natural (S)-(−)-perillaldehyde. Final products precipitate in the ethanolic reaction medium. 2D NMR and single-crystal X-ray diffraction studies were used to unequivocally characterize the structures in solution and in the solid state, respectively. Chiral HPLC analysis confirms the formation of unique enantiomers and diastereomeric mixtures.

Download Full-text

Green rust as a precursor for magnetite: an in situ synchrotron based study

Mineralogical Magazine ◽

10.1180/minmag.2008.072.1.201 ◽

2008 ◽

Vol 72 (1) ◽

pp. 201-204 ◽

Cited By ~ 40

Author(s):

A. Sumoondur ◽

S. Shaw ◽

I. Ahmed ◽

L. G. Benning

Keyword(s):

Direct Evidence ◽

Green Rust ◽

Stable Phase ◽

X Ray Diffraction ◽

Time Resolved ◽

X Ray ◽

Subsequent Transformation ◽

Rapid Formation ◽

Reaction Proceeds

AbstractIn this study, direct evidence for the formation of magnetite via a green rust intermediate is reported. The Fe(II) induced transformation of ferrihydrite, was quantified in situ and under O2-free conditions using synchrotron-based time-resolved energy dispersive X-ray diffraction. At pH 9 and Fe(II)/Fe(III) ratios of 0.5 and 1, rapid growth (6 min) of sulphate green rust and its subsequent transformation to magnetite was observed. Electron microscopy confirmed these results, showing the initial rapid formation of hexagonal sulphate green rust particles, followed by the corrosion of the green rust as magnetite growth occurred, indicating that the reaction proceeds via a dissolution-reprecipitation mechanism. At pH 7 and Fe(II)/Fe(III) ratio of 0.5, sulphate green rust was the stable phase, with no transformation to magnetite.

Download Full-text

The kinetics of dehydration in Ca-montmorillonite: an in situ X-ray diffraction study

Mineralogical Magazine ◽

10.1180/002646198548034 ◽

1998 ◽

Vol 62 (5) ◽

pp. 647-656 ◽

Cited By ~ 59

Author(s):

Helen J. Bray ◽

Simon A. T. Redfern ◽

Simon M. Clark

Keyword(s):

Interlayer Spacing ◽

X Ray Diffraction ◽

Interlayer Water ◽

X Ray ◽

Shock Heating ◽

Naturally Occurring ◽

Reaction Proceeds ◽

Two Stages ◽

Kinetics Of

AbstractThe thermal dehydration of naturally occurring Ca-montmorillonite has been studied by in situ X-ray diffraction at temperatures between 60–120°C. The time-temperature-dependence of the position of the basal (001) reflection reveals that interlayer water loss on isothermal dehydration occurs in two stages. After an initial rapid decrease in interlayer spacing (on shock heating to an isothermal soak temperature) the reaction proceeds towards equilibrium more slowly. Furthermore, the width of the (001) reflection changes with time, reflecting transformation-dependent changes in homogeneity perpendicular to (001) with a maximum in peak width at the point where the rate of the reaction appears to change. This suggests that, as the interlayer spacing collapses, a local change is induced in the structure, affecting the means of movement of the water from the interlayer.

Download Full-text

Regioselective synthesis of methyl 5-(N-Boc-cycloaminyl)-1,2-oxazole-4-carboxylates as new amino acid-like building blocks

Beilstein Journal of Organic Chemistry ◽

10.3762/bjoc.18.11 ◽

2022 ◽

Vol 18 ◽

pp. 102-109

Author(s):

Jolita Bruzgulienė ◽

Greta Račkauskienė ◽

Aurimas Bieliauskas ◽

Vaida Milišiūnaitė ◽

Miglė Dagilienė ◽

...

Keyword(s):

Amino Acid ◽

Nmr Spectroscopy ◽

Diffraction Data ◽

Hplc Analysis ◽

Hydroxylamine Hydrochloride ◽

Building Blocks ◽

Chiral Hplc ◽

Efficient Synthesis ◽

X Ray Diffraction ◽

X Ray

A convenient and efficient synthesis of novel achiral and chiral heterocyclic amino acid-like building blocks was developed. Regioisomeric methyl 5-(N-Boc-cycloaminyl)-1,2-oxazole-4-carboxylates were prepared by the reaction of β-enamino ketoesters (including azetidine, pyrrolidine or piperidine enamines) with hydroxylamine hydrochloride. Unambiguous structural assignments were based on chiral HPLC analysis, 1H, 13C, and 15N NMR spectroscopy, HRMS, and single-crystal X-ray diffraction data.

Download Full-text

MgCO3 + SiO2 reaction at pressures to 32 GPa studied using in situ X-ray diffraction and synchrotron radiation

Геохимия ◽

10.31857/s0016-75256491003-1012 ◽

2019 ◽

Vol 64 (9) ◽

pp. 1003-1012

Author(s):

K. D. Litasov ◽

A. F. Shatskiy

Keyword(s):

Synchrotron Radiation ◽

Reaction Temperature ◽

Eutectic Mixture ◽

Silicate Melt ◽

Stability Field ◽

Reaction Products ◽

X Ray Diffraction ◽

X Ray ◽

Reaction Proceeds

The results of the experimental study of the decarbonation and melting reactions in the MgCO3–SiO2 system at pressures up to 32 GPa using multi-anvil technique, in situ X-ray diffraction and synchrotron radiation have been reported. At 3–7 GPa and 1400–1700 K, the reaction proceeds with the release of carbon dioxide and the formation of enstatite. At 9–13 GPa and 1850–1930 K, clinoenstatite, carbonate-silicate melt, and CO2 were found among the reaction products. At 16 GPa and 1825 K, the reaction is accompanied by the formation of wadsleyite and at higher temperature by the formation of a carbonated melt, with a Mg/Si ratio close to wadsleyite, stishovite and CO2 fluid. At this pressure, which coincides with the wadsleyite-stishovite assemblage stability field in the MgSiO3 phase diagram, a decrease in the reaction temperature by about 100 K is observed. At higher pressures, the reaction proceeds with the formation of the MgSiO3 (akimotoite or bridgmanite) + melt assemblage. The reaction temperature at 25–35 GPa does not change and is about 2000 K. With a further increase in temperature to 2100 K, bridgmanite melts incongruently, reacting with a carbonate-silicate melt to form stishovite. The composition of the eutectic mixture shifts towards MgCO3 with increasing pressure. The studied reaction marks the upper temperature limit of the stability of magnesite and the free phase of SiO2 in the Earth’s mantle and generally coincides with the mantle adiabat at depths of 300–900 km.

Download Full-text

Synthesis of 3-Aryl-ortho-carboranes with Sensitive Functional Groups

Molecules ◽

10.3390/molecules26237297 ◽

2021 ◽

Vol 26 (23) ◽

pp. 7297

Author(s):

Sergey A. Anufriev ◽

Akim V. Shmal’ko ◽

Kyrill Yu. Suponitsky ◽

Igor B. Sivaev

Keyword(s):

Functional Groups ◽

Intramolecular Hydrogen Bonding ◽

X Ray Diffraction ◽

One Pot ◽

X Ray ◽

The One ◽

Intramolecular Hydrogen ◽

Solid State Structures ◽

Derivatives Of

A simple and efficient method was developed for the one-pot synthesis of 3-aryl derivatives of ortho-carborane with sensitive functional groups using 3-iodo-ortho-carborane and aryl zinc bromides that were generated in situ. A series of 3-aryl-ortho-carboranes, including those containing nitrile and ester groups, 3-RC6H4-1,2-C2B10H11 (R = p-Me, p-NMe2, p-OCH2OMe, p-OMe, o-CN, p-CN, o-COOEt, m-COOEt, p-COOEt) was synthesized using this approach. The solid-state structures of 3-RC6H4-1,2-C2B10H11 (R = p-OMe, o-CN, and p-CN) were determined by single crystal X-ray diffraction. The intramolecular hydrogen bonding involving the ortho-substituents of the aryl ring and the CH and BH groups of carborane was discussed.

Download Full-text

Thermostable α-Glucan Phosphorylase-Catalyzed Enzymatic Copolymerization to Produce Partially 2-Deoxygenated Amyloses

Processes ◽

10.3390/pr8091070 ◽

2020 ◽

Vol 8 (9) ◽

pp. 1070

Author(s):

Jun-ichi Kadokawa ◽

Shota Nakamura ◽

Kazuya Yamamoto

Keyword(s):

Substrate Recognition ◽

Reaction Medium ◽

Aquifex Aeolicus ◽

X Ray Diffraction ◽

Casting Method ◽

X Ray ◽

Amorphous Nature ◽

Monomer Feed ◽

Glucan Phosphorylase

α-Glucan phosphorylase catalyzes the enzymatic polymerization of α-d-glucose 1-phosphate (Glc-1-P) monomers from a maltooligosaccharide primer to produce α(1→4)-glucan—i.e., amylose. In this study, by exploiting the weak specificity for the substrate recognition of a thermostable α-glucan phosphorylase (from Aquifex aeolicus VF5), we investigated the enzymatic copolymerization of 2-deoxy-α-d-glucose 1-phosphate (dGlc-1-P), which was produced in situ from d-glucal, with Glc-1-P to obtain non-natural heteropolysaccharides composed of α(1→4)-linked dGlc/Glc units—i.e., partially 2-deoxygenated amylose. The reactions were carried out at different monomer feed ratios using a maltotriose primer at 40 °C for 24 h. The products were precipitated from the reaction medium, isolated by centrifugation, and subjected to 1H NMR spectroscopic and powder X-ray diffraction measurements to evaluate their chemical and crystalline structures, respectively. Owing to its amorphous nature, the partially 2-deoxygenated amylose with adapted unit ratios formed a film when subjected to a casting method.

Download Full-text

The Use of Advanced Analytical Techniques for Characterization of the Chemical, Physical, and Crystallographic Nature of a Surface

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100071107 ◽

1973 ◽

Vol 31 ◽

pp. 132-133 ◽

Cited By ~ 1

Author(s):

R. E. Herfert

Keyword(s):

Surface Characterization ◽

Analytical Techniques ◽

X Ray Diffraction ◽

Depth Of Penetration ◽

X Ray ◽

The Past ◽

Transmission Electron ◽

Scanning Electron

Studies of the nature of a surface, either metallic or nonmetallic, in the past, have been limited to the instrumentation available for these measurements. In the past, optical microscopy, replica transmission electron microscopy, electron or X-ray diffraction and optical or X-ray spectroscopy have provided the means of surface characterization. Actually, some of these techniques are not purely surface; the depth of penetration may be a few thousands of an inch. Within the last five years, instrumentation has been made available which now makes it practical for use to study the outer few 100A of layers and characterize it completely from a chemical, physical, and crystallographic standpoint. The scanning electron microscope (SEM) provides a means of viewing the surface of a material in situ to magnifications as high as 250,000X.

Download Full-text