scholarly journals Solid state intramolecular cyclization of leucyl-alanine and alanyl-leucine

2014 ◽  
Vol 70 (a1) ◽  
pp. C910-C910
Author(s):  
Farukh Ali ◽  
Dmitriy Soldatov
Keyword(s):  
Solid State ◽  
Organic Compounds ◽  
Intramolecular Cyclization ◽  
Solid State Reaction ◽  
Synthetic Methods ◽  
Green Economy ◽  
Solid State Reactions ◽  
Solid State Transformation ◽  
Experimental Conditions ◽  
High Biological Activity

Solid state organic synthesis is a future alternative to traditional, solution-based laboratory and industrial synthetic procedures. Solvent-free synthetic methods allow for quantitative yields, high stereospecificity, need no solvent, and are easy to conduct. They may contribute to green economy by reducing pollution, cutting the consumption of energy, and lowering the cost of production of various organic compounds. Although solid state reactions have been reported for almost all main classes of organic compounds and reaction types[1], the reactivity of peptides in the solid state has not been well explored. One potential product of the solid state transformation of dipeptides is 2,5-diketopiperazines (DKPs), the cyclic forms of dipeptides. They have attracted attention due to their high biological activity and use in medicinal chemistry[2,3]. In this study, we investigated the thermally induced intramolecular cyclization of leucyl-alanine and alanyl-leucine in the solid state. The reaction was conducted in a range of experimental conditions using thermogravimetric analyzer (TGA), differential scanning calorimeter (DSC), and gas chromatograph - mass spectrometer (GC-MS). The progress of the reaction was observed in situ through monitoring the release of water (mass loss and infra-red spectra) as well as the characterization of the solid residue (1H and 13C NMR, powder and single crystal XRD). The scalability of the reaction was tested with larger samples using a ventilation oven, and a microwave reactor. We found that the both dipeptides easily undergo the cyclization reaction upon mild heating, to give a stereospecific product with ~100% yield. However, the study was complicated with polymorphism displayed by the cyclic product. The solid state reaction yielded an orthorhombic form of the cyclic dipeptide, while its recrystallization produced a triclinic polymorph. The crystal structure and relative stability of the forms were investigated with XRD and DSC techniques. When the solid-state reaction was conducted at higher temperature, partial racemization and distereomerization were observed which led to new crystal structures. The degree of racemization was evaluated by a polarimeter and the NMR analysis.

The wustite-spinel interface

1987 ◽  
Vol 45 ◽  
pp. 268-269
Author(s):  
S.R. Summerfelt ◽  
C.B. Carter
Keyword(s):  
Solid State ◽  
Solid State Reaction ◽  
Strain Energy ◽  
Matrix Material ◽  
Lattice Misfit ◽  
Solid State Reactions ◽  
Oxygen Sublattice ◽  
Large Particles ◽  
Small Lattice ◽  
Coherent Interfaces

The wustite-spinel interface can be viewed as a model interface because the wustite and spinel can share a common f.c.c. oxygen sublattice such that only the cations distribution changes on crossing the interface. In this study, the interface has been formed by a solid state reaction involving either external or internal oxidation. In systems with very small lattice misfit, very large particles (>lμm) with coherent interfaces have been observed. Previously, the wustite-spinel interface had been observed to facet on {111} planes for MgFe2C4 and along {100} planes for MgAl2C4 and MgCr2O4, the spinel then grows preferentially in the <001> direction. Reasons for these experimental observations have been discussed by Henriksen and Kingery by considering the strain energy. The point-defect chemistry of such solid state reactions has been examined by Schmalzried. Although MgO has been the principal matrix material examined, others such as NiO have also been studied.

Solid-State Reactions in Multilayer Ni/Ti Thin Film Composites

1990 ◽  
Vol 205 ◽  
Author(s):  
Gillian E. Winters ◽  
K.M. Unruh ◽  
C.P. Swann ◽  
M.E. Patt ◽  
B.E. White ◽  
...  
Keyword(s):  
Solid State ◽  
Solid State Reactions ◽  
Metastable Solid Solution ◽  
State Transformation ◽  
Solid State Transformation ◽  
Scanning Calorimetry ◽  
The Individual ◽  
Thin Film Composites ◽  
Film Composites ◽  
Rf Sputter Deposition

AbstractMultilayer films, consisting of alternating layers of crystalline Ni and Ti, have been prepared by RF sputter deposition over a range of modulation wavelengths corresponding to an overall composition of Ni50Ti50. These films have been characterized by xray diffraction and Rutherford backscattering measurements. The solid-state transformation by interdiffusional mixing of the individual layers has been directly studied by differential scanning calorimetry and correlated with structural measurements. These measurements indicate that the solid-state reaction of Ni and Ti multilayers proceeds through the formation of a metastable solid solution of Ti in Ni followed by the formation of intermetallic equilibrium compounds. No direct calorimetric or structural evidence for the formation of an amorphous Ni-Ti phase has been found in these samples.

Paradigm Change for Solid State Reactions: Synthesis of Lithium Orthophosphate Li3PO4 Nanoparticles by a Water Assisted Solid State Reaction (WASSR) Method

2017 ◽  
Vol 10 (4) ◽  
pp. 592-596 ◽  
Author(s):  
Sun Woog Kim ◽  
Kenji Toda ◽  
Takuya Hasegawa ◽  
Mizuki Watanabe ◽  
Tatsuro Kaneko ◽  
...  
Keyword(s):  
Solid State ◽  
Solid State Reaction ◽  
Solid State Reactions ◽  
Paradigm Change

Solid-State Reactions in Fe/Si Multilayer Nanofilms

2014 ◽  
Vol 215 ◽  
pp. 144-149 ◽  
Author(s):  
Sergey M. Zharkov ◽  
Roman R. Altunin ◽  
Evgeny T. Moiseenko ◽  
Galina M. Zeer ◽  
Sergey N. Varnakov ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Solid State ◽  
Electron Diffraction ◽  
Solid State Reaction ◽  
Room Temperature ◽  
Solid State Reactions ◽  
Transmission Electron ◽  
Reaction Processes

Solid-state reaction processes in Fe/Si multilayer nanofilms have been studied in situ by the methods of transmission electron microscopy and electron diffraction in the process of heating from room temperature up to 900ºС at a heating rate of 8-10ºС/min. The solid-state reaction between the nanolayers of iron and silicon has been established to begin at 350-450ºС increasing with the thickness of the iron layer.

On the applicability of solventless and solid-state reactions to the meteoritic chemistry

2011 ◽  
Vol 11 (1) ◽  
pp. 43-50 ◽  
Author(s):  
Vera M. Kolb
Keyword(s):  
Solid State ◽  
Organic Compounds ◽  
Chemical Reactions ◽  
Solid State Reactions ◽  
Melting Points ◽  
Aqueous Alteration ◽  
Solid Materials ◽  
Intimate Contact ◽  
Chemical Conditions ◽  
Secondary Chemical

AbstractMost chemical reactions on asteroids, from which meteors and meteorites originate, are hypothesized to occur primarily in the solid mixtures. Some secondary chemical reactions may have occurred during the periods of the aqueous alteration of the asteroids. A myriad of organic compounds have been isolated from the meteorites, but the chemical conditions during which they were formed are only partially elucidated. In this paper, we propose that numerous meteoritic organic compounds were formed by the solventless and solid-state reactions that were only recently explored in conjunction with the green chemistry. A typical solventless approach exploits the phenomenon of the mixed melting points. As the solid materials are mixed together, the melting point of the mixture becomes lower than the melting points of its individual components. In some cases, the entire mixture may melt upon mixing. These reactions could then occur in a melted state. In the traditional solid-state reactions, the solids are mixed together, which allows for the intimate contact of the reactants, but the reaction occurs without melting. We have shown various examples of the known solventless and solid-state reactions that are particularly relevant to the meteoritic chemistry. We have also placed them in a prebiotic context and evaluated them for their astrobiological significance.

Supported High Temperature Protonic Films Produced by Solid State Reaction

2006 ◽  
Vol 972 ◽  
Author(s):  
Wilhelm A Meulenberg ◽  
José M. Serra
Keyword(s):  
Solid State ◽  
Solid State Reaction ◽  
Nominal Composition ◽  
Barium Zirconate ◽  
Barium Cerate ◽  
Strontium Zirconate ◽  
State Transformation ◽  
Solid State Transformation ◽  
Proton Conducting ◽  
Homogeneous Composition

AbstractThis work presents the last progresses in the development of thin oxidic proton conducting electrolytes supported on mixed conducting cermets making use of a solid state reaction. The procedure includes preparation routes applying solid state transformation of an already-gastight oxide layer (typically doped zirconia and ceria) by reacting with an alkali-earths layer (stoichiometric amount) deposited by screen printing on top of that. This kind of supported films can find application as IT-SOFC, H2-membranes and advanced catalytic converters. Thin-film (∼5μm) proton conducting membranes with the nominal composition as for instance BaZr0.85Y0.15O3-δ and BaCe0.8Gd0.2O3-δ were prepared over porous Ni-8YSZ or Ni-CGO substrates by solid state reaction. The produced films are gastight with a homogeneous composition, and showed a highly crystalline cubic perovskite structure. The solid state reaction promoted the formation of (i) a different grain size distribution from 0.1 μm for barium zirconate to 2-3μm for barium cerate, and (b) the formation of a porous fibrous top-layer (for barium zirconate) or a just flat surface (for strontium zirconate), depending on the exact composition of the reacting oxides.

scholarly journals Extension of the HCOOH and CO2 solid-state reaction network during the CO freeze-out stage: inclusion of H2CO

2019 ◽  
Vol 626 ◽  
pp. A118 ◽  
Author(s):  
D. Qasim ◽  
T. Lamberts ◽  
J. He ◽  
K.-J. Chuang ◽  
G. Fedoseev ◽  
...  
Keyword(s):  
Solid State ◽  
Solid State Reaction ◽  
Reaction Pathway ◽  
Branching Ratio ◽  
Oh Radicals ◽  
Reaction Products ◽  
Experimental Conditions ◽  
Prestellar Cores ◽  
Molecular Abundances ◽  
Freeze Out

Context. Formic acid (HCOOH) and carbon dioxide (CO2) are simple species that have been detected in the interstellar medium. The solid-state formation pathways of these species under experimental conditions relevant to prestellar cores are primarily based off of weak infrared transitions of the HOCO complex and usually pertain to the H2O-rich ice phase, and therefore more experimental data are desired. Aims. Here, we present a new and additional solid-state reaction pathway that can form HCOOH and CO2 ice at 10 K “non-energetically” in the laboratory under conditions related to the “heavy” CO freeze-out stage in dense interstellar clouds, i.e., by the hydrogenation of an H2CO:O2 ice mixture. This pathway is used to piece together the HCOOH and CO2 formation routes when H2CO or CO reacts with H and OH radicals. Methods. Temperature programmed desorption – quadrupole mass spectrometry (TPD-QMS) is used to confirm the formation and pathways of newly synthesized ice species as well as to provide information on relative molecular abundances. Reflection absorption infrared spectroscopy (RAIRS) is additionally employed to characterize reaction products and determine relative molecular abundances. Results. We find that for the conditions investigated in conjunction with theoretical results from the literature, H + HOCO and HCO + OH lead to the formation of HCOOH ice in our experiments. Which reaction is more dominant can be determined if the H + HOCO branching ratio is more constrained by computational simulations, as the HCOOH:CO2 abundance ratio is experimentally measured to be around 1.8:1. H + HOCO is more likely than OH + CO (without HOCO formation) to form CO2. Isotope experiments presented here further validate that H + HOCO is the dominant route for HCOOH ice formation in a CO-rich CO:O2 ice mixture that is hydrogenated. These data will help in the search and positive identification of HCOOH ice in prestellar cores.

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