Chemical structure of tar-sand bitumens by 13C and 1H n.m.r. spectroscopic methods

Abstract A natural rubber vulcanizate containing almost entirely monosulfidic crosslinks was oxidized in oxygen and with tert-butyl hydroperoxide. The changes in physical properties due to oxidation were followed by stress—strain measurements, and the changes in chemical structure were investigated with chemical probes, and by spectroscopic methods. The results show that when the oxidized vulcanizates are heated at 75° C, the monosulfidic crosslinks are broken, that crosslinks containing two sulfur atoms are formed, and that conjugated diene and triene structures are introduced into the main polyisoprene chains.

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Four Flavan-3-ol Compounds From The Stembark of Chisocheton balansae C.DC. (MELIACEAE)

Molekul ◽

10.20884/1.jm.2021.16.1.642 ◽

2021 ◽

Vol 16 (1) ◽

pp. 9

Author(s):

Unang Supratman ◽

Mohamad Fajar ◽

Supriatno Salam ◽

Rani Maharani ◽

Desi Harneti ◽

...

Keyword(s):

Ethyl Acetate ◽

13C Nmr ◽

Chemical Structure ◽

Ethyl Acetate Extract ◽

2D Nmr ◽

Stem Bark ◽

Spectroscopic Methods ◽

Endemic Plants ◽

North Sulawesi ◽

First Time

Chisocheton balansae C.DC., is one of the Meliaceae family plants which is the endemic plants from Soputan Mountain, North Sulawesi, Indonesia. This study was aimed to determine the chemical structure of flavan-3-ol compounds from ethyl acetate extract of C. balansae C.DC stembark. Dried powder of C. balansae C.DC stem bark was extracted consecutively with n-hexane, ethyl acetate, and methanol solvents. Four flavan-3-ol compounds, named catechin (1), epicatechin (2), epigallocatechin-3-O-gallate (3), and epicatechin-3-O-gallate (4) were successfully isolated from ethyl acetate extract. The chemical structure of these isolates was determined by spectroscopic methods (1H-NMR, 13C-NMR, DEPT, and 2D-NMR) and comparison with previous reported spectral data. These compounds are first time reported from this plant.

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Anionic Copolymerization of Styrene Sulfide with Elemental Sulfur (S8)

Materials ◽

10.3390/ma13112597 ◽

2020 ◽

Vol 13 (11) ◽

pp. 2597

Author(s):

Jakub Wręczycki ◽

Dariusz M. Bieliński ◽

Marcin Kozanecki ◽

Paulina Maczugowska ◽

Grzegorz Mlostoń

Keyword(s):

Thermal Stability ◽

Raman Spectroscopy ◽

Ring Opening ◽

Chemical Structure ◽

Elemental Sulfur ◽

Ring Opening Polymerization ◽

Spectroscopic Methods ◽

Initial Ratio ◽

Anionic Copolymerization ◽

Thermal Stability Of

The superior ability of thiiranes (episulfides) to undergo ring-opening polymerization (ROP) in the presence of anionic initiators allows the preparation of chemically stable polysulfide homopolymers. Incorporation of elemental sulfur (S8) by copolymerization below the floor temperature of S8 permits the placement of a large quantity of sulfur atoms in the polysulfide mainchain. The utility of styrene sulfide (2-phenylthiirane; StS) for copolymerization with elemental sulfur is reported here. A few polysulfides differing depending on the initial ratio of S8 to StS and copolymerization time were synthesized. Various spectroscopic methods (1H NMR, 13C NMR, Raman spectroscopy and FTIR spectroscopy) were applied to characterize the chemical structure of the copolymers. Additionally, the phase structure and thermal stability of the synthesized polysulfides were investigated using DSC and TGA, respectively. The successful anionic copolymerization of styrene sulfide and elemental sulfur has been demonstrated.

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Thujin, a novel lactone isolated from the discolored heartwood of Thuja plicata Donn.

Canadian Journal of Chemistry ◽

10.1139/v88-007 ◽

1988 ◽

Vol 66 (1) ◽

pp. 51-53 ◽

Cited By ~ 6

Author(s):

Lehong Jin ◽

Jack W. Wilson ◽

Eric P. Swan

Keyword(s):

Chemical Structure ◽

Thuja Plicata ◽

Spectroscopic Methods ◽

Red Cedar ◽

Western Red Cedar ◽

Thuja Plicata Donn

The chemical structure of a novel lactone isolated from the discolored heartwood of living western red cedar (WRC) (Thuja plicata Donn.) trees has been determined as 3,3,4,7,7,8-hexamethyl-2,6-dioxa-1,5-anthracene-dione, and given the trivial name thujin (1). The isolation, purification, and determination of the structure were carried out by a combination of chemical, chromatographic, and spectroscopic methods.

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Isolation and Identification of the Antimicrobial Agent Beauvericin from the EndophyticFusarium oxysporum5-19 with NMR and ESI-MS/MS

BioMed Research International ◽

10.1155/2016/1084670 ◽

2016 ◽

Vol 2016 ◽

pp. 1-4 ◽

Cited By ~ 4

Author(s):

Huawei Zhang ◽

Chuanfen Ruan ◽

Xuelian Bai ◽

Miao Zhang ◽

Shuangshuang Zhu ◽

...

Keyword(s):

Chemical Structure ◽

Fermentation Broth ◽

Inhibitory Effect ◽

Positive Control ◽

Spectroscopic Methods ◽

Isolation And Identification ◽

Esi Ms ◽

Bioactive Natural Products ◽

Pathogenic Microbes ◽

C Nmr

Endophytic microbe has been proved to be one of rich sources of bioactive natural products with potential application for new drug and pesticide discovery. One cyclodepsipeptide, beauvericin, was firstly isolated from the fermentation broth ofFusarium oxysporum5-19 endophytic onEdgeworthia chrysanthaLinn. Its chemical structure was unambiguously identified by a combination of spectroscopic methods, such as HRESI-MS and1H and13C NMR. ESI-MS/MS was successfully used to elucidate the splitting decomposition route of the positive molecule ion of beauvericin. Antimicrobial results showed that this cyclodepsipeptide had inhibitory effect on three human pathogenic microbes,Candida albicans,Escherichia coli, andStaphylococcus aureus. In particular, beauvericin exhibited the strongest antimicrobial activity againstS. aureuswith MIC values of 3.91 μM, which had similar effect with that of the positive control amoxicillin.

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Design and Synthesis of Two Azete Derivatives Using some Chemical Strategies

Biointerface Research in Applied Chemistry ◽

10.33263/briac124.55675578 ◽

2021 ◽

Vol 12 (4) ◽

pp. 5567-5578

Keyword(s):

Chemical Structure ◽

Spectroscopic Methods ◽

Design And Synthesis ◽

Good Yielding ◽

Chemical Strategies

There are several methods for preparing nitrogen-containing four-membered heterocycles using some reagents that require special conditions such as higher temperatures or differences in the pH. This research aimed to prepare two azete derivatives from 1-Bromo-3,5-dinitrobenzene using some chemical strategies. The chemical structure was characterized by NMR spectroscopic methods. The results indicate that protocols used to synthesize two azete analogs do not require special conditions to give a good yielding. In conclusion, is reported a facile method for the synthesis of two azete derivatives.

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2′-Hydroxylated 3-Deoxyanthocyanin from the Flowers of Cosmos sulphureus Cultivars

Natural Product Communications ◽

10.1177/1934578x19876219 ◽

2019 ◽

Vol 14 (9) ◽

pp. 1934578X1987621

Author(s):

Tsukasa Iwashina ◽

Kotarou Amamiya ◽

Tsunashi Kamo ◽

Junichi Kitajima ◽

Takayuki Mizuno ◽

...

Keyword(s):

Nuclear Magnetic Resonance ◽

High Performance Liquid Chromatography ◽

Liquid Chromatography ◽

Magnetic Resonance ◽

High Performance ◽

Mass Spectra ◽

Chemical Structure ◽

Resonance Spectroscopy ◽

Spectroscopic Methods ◽

Liquid Chromatograph

A new 3-deoxyanthocyanin was isolated from the orange flowers of Cosmos sulphureus cultivar “Diabolo,” together with known aurone, chalcone, flavone, flavonol, and flavanone. The chemical structure of 3-deoxyanthocyanin was established as 5,7,2′,4′-tetrahydroxyflavylium 4′- O-β-d-glucopyranoside by chemical and spectroscopic methods including UV, FAB MS, and 1H and 13C nuclear magnetic resonance spectroscopy (NMR), and named as cosmonidin 4′- O-glucoside (1a). Other known flavonoids were characterized as sulfuretin 6- O-glucoside (2), butein 4′- O-glucoside (3), quercetin 3- O-glucoside (4), luteolin 7- O-glucuronide (5), and eriodictyol 7- O-glucuronide (6) by UV, liquid chromatograph - mass spectra (LC-MS), NMR, and high performance liquid chromatography comparisons with authentic samples. Anthocyanin, which 2′-position is hydroxylated, has not been reported until now. Compound (1a) was also found in other 10 C. sulphureus cultivars “Lamala Lemon,” “Sunrise,” “Dwarf Yellow,” “Cosmic Yellow,” “Carpet Gold,” “Mandarin,” “Cosmic Orange,” “Orange Flare,” “Cosmic Red,” and “Sunset.”

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Aromatic Amines in Organic Synthesis. Part II. p-Aminocinnamaldehydes

Molecules ◽

10.3390/molecules26144360 ◽

2021 ◽

Vol 26 (14) ◽

pp. 4360

Author(s):

Marek Pietrzak ◽

Beata Jędrzejewska

Keyword(s):

Organic Synthesis ◽

13C Nmr ◽

Aromatic Amines ◽

Chemical Structure ◽

Spectroscopic Properties ◽

Spectroscopic Methods ◽

Amino Group ◽

The One ◽

Ir Spectroscopic ◽

Derivatives Of

Ten derivatives of p-aminocinnamic aldehydes were prepared from the reaction of either aromatic amines with dimethylaminoacrolein or benzaldehydes with acetaldehyde. Their chemical structure and purity were verified by 1H NMR, 13C NMR and IR spectroscopic methods. We found that the synthesis applying dimethylaminoacrolein as the reagent gets better yields than the one based on the reaction with acetaldehyde. The yields of the cinnamic aldehydes varied according to the type of the amino group and the number and position of the substituents. The basic spectroscopic properties of the p-aminocinnamic aldehydes are also described since the compounds may be a precursor for the synthesis of dyes for diverse applications, e.g., in medicine and optoelectronics.

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The Identification of Polyester Fibers Dyed with Disperse Dyes for Forensic Purposes

Molecules ◽

10.3390/molecules24030613 ◽

2019 ◽

Vol 24 (3) ◽

pp. 613 ◽

Cited By ~ 4

Author(s):

Daria Śmigiel-Kamińska ◽

Jan Pośpiech ◽

Joanna Makowska ◽

Piotr Stepnowski ◽

Jolanta Wąs-Gubała ◽

...

Keyword(s):

Chemical Structure ◽

Forensic Analysis ◽

Disperse Dyes ◽

Spectroscopic Methods ◽

Spectroscopic Techniques ◽

Specific Chemical ◽

Synthetic Fibers ◽

Detection Systems ◽

Chromatographic Techniques ◽

Polyester Fibers

In forensic laboratories, the most commonly analyzed microtraces are microscopic fragments of single fibers. One of the main goals of the examination of fragments of fibers a few millimeters long is to determine their characteristic physicochemical properties and compare them with fibers originating from a known source (e.g., a suspect’s clothes). The color and dyes of fiber microtraces play an important role in their research and evaluation, being analyzed by means of microscopic, spectroscopic, and chromatographic methods. The results of examinations conducted with the use of spectroscopic techniques might be ambiguous due to overlapping bands of absorption and the transmission and dispersion of electromagnetic radiation corresponding to the specific chemical structure of the fibers and their dyes. For this reason, it is very important to improve currently available spectroscopic methods and/or to propose new ones that allow evidential materials to be analyzed in a much more reliable way. In this review, the possibility of the use of chromatographic techniques with different detection systems for such analyses is underlined. This review covers the different analytical methods used in the forensic analysis of polyester fibers dyed with disperse dyes. Polyester fibers occupy the first position among synthetic fibers in their use for a variety of purposes, and disperse dyes are commonly applied for dyeing them.

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Cytochrome c oxidase: some current biochemical and biophysical problems

Quarterly Reviews of Biophysics ◽

10.1017/s0033583500001578 ◽

1973 ◽

Vol 6 (4) ◽

pp. 389-431 ◽

Cited By ~ 140

Author(s):

Bo G. Malmström

Keyword(s):

Chemical Structure ◽

Mitochondrial Respiratory Chain ◽

Spectroscopic Properties ◽

Thermodynamic Theory ◽

Quantum Mechanical ◽

Spectroscopic Methods ◽

Paramagnetic Resonance ◽

Oxidation Reduction ◽

Electron Paramagnetic ◽

Haem Proteins

Few fields of biochemistry have seen such widespread applications of physical theories and techniques as that of biological oxidation. There are obvious reasons for this. Oxidation-reduction reactions form the foundations of bioenergetics, an area which can only be understood in terms of thermodynamic theory. Most components of the mitochondrial respiratory chain contain transition metals, and these elements and their chemical environment can often be studied by modern spectroscopic methods, such as electron-paramagnetic resonance (EPR). The relation between spectroscopic properties and chemical structure of metallo-proteins, e.g. haem proteins, represents one of the few branches of present-day biochemistry to which quantum mechanical calculations can profitably be applied (see, for example, Zerner, Gouterman & Kobayashi, 1966).

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