Synthesis of Galloyl-Coenzyme A Thioester

1982 ◽  
Vol 37 (9) ◽  
pp. 778-783 ◽  
Author(s):  
Georg G. Gross
Keyword(s):  
Absorption Band ◽  
Hydroxamic Acid ◽  
Uv Spectra ◽  
Iron Complex ◽  
Difference Spectra ◽  
Extinction Coefficients ◽  
Thioester Bond ◽  
Maximal Absorption ◽  
Major Absorption Band ◽  
Molar Extinction Coefficients

Galloyl-CoA, a potential intermediate in the biosynthesis of gallotannins, has been prepared via N-succinimidyl 4-O-β-ᴅ-glucosidogallate and 4-O-β-ᴅ-glucosidogalloyl-CoA. Besides a major absorption band at 261 nm, the UV-spectra of the purified thioester and its corresponding 4-O-glucoside contain a longer wavelenght absorption band due to the thioester linkage at 305 nm (galloyl-CoA) or at 290 nm (shoulder, glucosidogalloyl-CoA). The molar extinction coefficients ε of the two thioesters were determined via the iron-complex of 4-O-β-ᴅ-glucosidogalloyl hydroxamic acid; ε261-values of 19.5 × 106 [cm2 mol-1] and 21.5 × 106 [cm2 mol-1] were calculated for galloyl-CoA and its glucoside, respectively. Difference spectra, i.e. absorbance before esterolysis and after, revealed maximal absorption of the thioester bond at 310 nm (⊿ε = 7.4 × 106 [cm2 mol-1]) for galloyl-CoA and at 282 nm (⊿ε = 7.2 × 106 [cm2 mol-6]) for glu- cosidogalloyl-CoA. The two thioesters were further characterized by determining their half-lifes during hydroxylaminolysis and alkaline hydrolysis.

Chemical Syntheses and Properties of Hydroxycinnamoyl- Coenzyme A Derivatives

1975 ◽  
Vol 30 (5-6) ◽  
pp. 352-358 ◽  
Author(s):  
J. Stöekigt ◽  
M. H. Zenk
Keyword(s):  
Coenzyme A ◽  
Uv Spectra ◽  
Cinnamic Acids ◽  
Extinction Coefficients ◽  
Chromatographic Behaviour ◽  
Thiol Esters ◽  
Hydroxysuccinimide Esters ◽  
Derivatives Of ◽  
Molar Extinction Coefficients

Abstract Coenzyme A Thiol Esters, Cinnamic Acids Acyl-CoA derivatives of several hydroxylated cinnamic acids have been synthesized in 30 to 50% yield via a. acyl phenyl thiol esters, b. acyl N-hydroxysuccinimide esters, and c. glucocinnamoyl derivatives. Properties of the intermediates have been determined. The cinnamyol-CoA thiol esters were characterized by their chromatographic behaviour and UV spectra. The molar extinction coefficients of these important intermediates in plant phenylpropane metabolism have been unequivocally determined. Recently published values13 for the molar extinction coefficients of these derivatives are incorrect; the methodological reason for this error has been established.

ASSOCIATION OF CERIC IONS WITH SULPHATE (A SPECTRAL STUDY)

1951 ◽  
Vol 29 (10) ◽  
pp. 828-837 ◽  
Author(s):  
T. J. Hardwick ◽  
E. Robertson
Keyword(s):  
Spectral Study ◽  
Association Constants ◽  
Extinction Coefficients ◽  
Ceric Ion ◽  
Molar Extinction Coefficients

Ceric ion has been shown to associate with sulphate ion to form successively Ce(SO4++, Ce(SO4)2, and Ce(SO4)3−. The association constants relating these species have been determined at 25 °C. The molar extinction coefficients of each associated complex have been found between 395 and 430 mμ. Migration experiments bear out the results qualitatively.

Synthesis and characterization of meso-to-meso directly linked porphyrin-diazaporphyrin triads

2018 ◽  
Vol 22 (09n10) ◽  
pp. 814-820
Author(s):  
Yingying Jia ◽  
Ling Xu ◽  
Bangshao Yin ◽  
Mingbo Zhou ◽  
Jianxin Song
Keyword(s):  
Nickel Complex ◽  
High Resolution Mass Spectrometry ◽  
Dihedral Angles ◽  
X Ray Diffraction ◽  
Extinction Coefficients ◽  
X Ray ◽  
H Nmr ◽  
First Time ◽  
Molar Extinction Coefficients

Beginning with 5,10,15-triarylporphyrin-nickel complex, five meso-to-meso directly linked porphyrin-diazaporphyrin triads were successfully prepared for the first time through a series of reactions including formylation via Vilsmeier–Haack reaction, condensation with pyrrole, bromination with [Formula: see text]-Bromosuccinimide (NBS), oxidation with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), metal-templated cyclization of dibromodipyrrin-metal complexes with NaN[Formula: see text] and demetalization. All these triads were comprehensively characterized by [Formula: see text]H NMR, high-resolution mass spectrometry and UV-vis absorption. In addition, the structure of compound 6Ni was unambiguously determined by X-ray diffraction analysis, which showed that the two dihedral angles are both 86.65 (4)[Formula: see text] between each mean plane of porphyrin and that of central diazaporphyrin The UV-vis absorption spectra disclosed that the longest wavelengths of Soret bands and Q bands for these triads were observed at 429 and 642 nm, respectively. In contrast to diazaporphyrin-porphyrin dyads, diazaporphyrin dimers and diazaporphyrin monomers reported previously the molar extinction coefficients, particularly for triad 8Ni are much higher.

scholarly journals Quantification of acidic sites of nanoscopic hydroxylated magnesium fluorides by FTIR and 15N MAS NMR spectroscopy

RSC Advances ◽  
2015 ◽  
Vol 5 (109) ◽  
pp. 89659-89668 ◽  
Author(s):  
Felix Hemmann ◽  
Iker Agirrezabal-Telleria ◽  
Christian Jaeger ◽  
Erhard Kemnitz
Keyword(s):  
Nmr Spectroscopy ◽  
Mas Nmr ◽  
New Method ◽  
Extinction Coefficients ◽  
Surface Sites ◽  
Acidic Sites ◽  
Molar Extinction Coefficients

A new method is described for the calculation of molar extinction coefficients for quantitative FTIR measurements of acidic surface sites.

EXPERIMENTAL STUDIES OF SOLUTION PROCESSES: VI. EFFECT OF SOLVENT ON INFRARED ABSORPTION SPECTRA

1960 ◽  
Vol 38 (10) ◽  
pp. 1921-1926 ◽  
Author(s):  
P. A. D. De Maine ◽  
L. H. Daly ◽  
M. M. De Maine
Keyword(s):  
Infrared Absorption ◽  
Experimental Studies ◽  
Absorption Data ◽  
Frequency Shifts ◽  
Extinction Coefficients ◽  
Effect Of Solvent ◽  
Solution Processes ◽  
Pure Substances ◽  
Infrared Absorption Spectra ◽  
Molar Extinction Coefficients

Here are reported infrared absorption data between 4000 cm−1 and 700 cm−1 near 19 °C for methanol, n-propanol, isopropanol, cyclohexanol, benzyl alcohol, diethyl ether, anisole, 1,4-dioxane, diisopropyl ether, nitromethane, acetone, p-xylene, benzene, and hexane as pure substances and in carbon tetrachloride solution. Band frequencies accurate to within 1 cm−1 are reported. Except for the 3340 cm−1 band in dilute MeOH solutions no frequency shifts were observed even with gross changes of the electrical properties of the solutions. Molar extinction coefficients at absorption maxima are discussed briefly.

scholarly journals Determination of Extinction Coefficients for Describing Gas Adsorption on Heterogeneous Catalysts Using In-Situ DRIFT Spectroscopy

Catalysts ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 735
Author(s):  
Maja Glorius ◽  
Tobias Reich ◽  
Cornelia Breitkopf
Keyword(s):  
Quantitative Evaluation ◽  
Sulfated Zirconia ◽  
Heterogeneous Catalysts ◽  
Gas Adsorption ◽  
Active Surface ◽  
Isomerization Reaction ◽  
Drift Spectroscopy ◽  
Active Centers ◽  
Difference Spectra ◽  
Extinction Coefficients

Diffuse reflection infrared Fourier transform (DRIFT) spectra have been quantitatively evaluated to determine unknown extinction coefficients as well as the number of active surface centers and the amount of adsorbed species. Sulfated zirconia with n-butane as probe gas was used as model system. For quantitative evaluation of n-butane adsorption at 323 K, the sulfate band S=O at 1400 cm−1 was chosen. During adsorption, this band is red-shifted to lower wavenumbers accompanied by a structural change of the band indicating isomerization reaction. By analyzing difference spectra and determining the areas of the selected band, the extinction coefficients as well as the number of active centers and the amount of chemisorbed n-butane were calculated. The quantitative evaluation results in a mean internal decadic extinction coefficient of 60 cm−1 µmol−1, an average amount of n-butane adsorbed to the sulfated zirconia of about 4 μmol, and a number of active centers of around 21 μmol/g. These results correspond very well with values from the literature obtained by microcalorimetry. Thus, this method is suggested to be transferred also to unknown systems of interest.

New Z-chalcones obtained from aloe-emodin: Synthesis, characterization and photophysical properties

2019 ◽  
Vol 43 (3-4) ◽  
pp. 101-106
Author(s):  
Nieves Canudas ◽  
Manuel Moreno ◽  
Sara Pekerar ◽  
Carlos Gámez ◽  
Estefania Sucre ◽  
...  
Keyword(s):  
Potassium Hydroxide ◽  
Room Temperature ◽  
Photophysical Properties ◽  
Emission Spectra ◽  
Nmr Studies ◽  
Extinction Coefficients ◽  
Chalcone Derivatives ◽  
Aloe Emodin ◽  
Aldehyde Derivative ◽  
Molar Extinction Coefficients

Three new Z-chalcone derivatives were synthesized under stereoselective conditions by condensation between an aldehyde derivative (prepared from aloe-emodin) and an acetophenone, using potassium hydroxide in dimethyl sulfoxide/H2O at room temperature. The Z configuration of the chalcone derivatives was established by nuclear magnetic resonance (NMR) studies. Photophysical properties related to the UV-Vis absorption/emission spectra and molar extinction coefficients (ε) in different solvents were determined.

IONIC SPECIES IN CERIC PERCHLORATE SOLUTIONS

1951 ◽  
Vol 29 (10) ◽  
pp. 818-827 ◽  
Author(s):  
T. J. Hardwick ◽  
E. Robertson
Keyword(s):  
Acid Solution ◽  
Perchloric Acid ◽  
Spectral Study ◽  
Wave Length ◽  
Ionic Species ◽  
Thermodynamic Quantities ◽  
Perchloric Acid Solution ◽  
Extinction Coefficients ◽  
Ceric Ion ◽  
Molar Extinction Coefficients

Ceric ion has been shown to exist in perchloric acid solution as a mixture of Ce4+, CeOH3+, and a dimer, probably (Ce-O-Ce)6+. From a spectral study between 395 and 430 mμ, the values of the equilibrium ratios have been determined, along with the molar extinction coefficients of each ion over this region of wave length. The thermodynamic quantities ΔH, ΔF°, and ΔS° have been determined for each reaction.

Reaction of picryl chloride with sodium ethoxide: Formation of a C 3 σ-complex

1975 ◽  
Vol 28 (11) ◽  
pp. 2403 ◽  
Author(s):  
LH Gan
Keyword(s):  
Thermodynamic Parameters ◽  
Sodium Ethoxide ◽  
Extinction Coefficients ◽  
Spectroscopic Evidence ◽  
Picryl Chloride ◽  
Molar Extinction Coefficients

Kinetic and spectroscopic evidence is presented for the formation of a C3 σ-complex from picryl chloride and sodium ethoxide in ethanol. Molar extinction coefficients of the complex were determined by the Benesi- Hildebrand method. Thermodynamic parameters were evaluated.

scholarly journals Effect of Al content on the strength of terminal silanol species in ZSM-5 zeolite catalysts: a quantitative DRIFTS study without the use of molar extinction coefficients

2018 ◽  
Vol 20 (6) ◽  
pp. 4250-4262 ◽  
Author(s):  
Pierre Bräuer ◽  
Olivia Situmorang ◽  
Pey Ling Ng ◽  
Carmine D’Agostino
Keyword(s):  
Zeolite Catalysts ◽  
Extinction Coefficients ◽  
Al Content ◽  
Molar Extinction Coefficients

DRIFTS is used to quantify the effect of Al content on the strength of silanol sites in ZSM-5 zeolites. The applied protocol does not require the use of molar extinction coefficients.

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