Determination of protonation constants of some fluorinated polyamines by means of 13 C NMR data processed by the new computer program HypNMR2000. Protonation sequence in polyamines

2003 ◽  
Vol 376 (7) ◽  
pp. 1041-1052 ◽  
Author(s):  
Alberto Vacca ◽  
Stefano Ghelli ◽  
Chiara Frassineti ◽  
Lucia Alderighi ◽  
Peter Gans ◽  
...  
Keyword(s):  
Computer Program ◽  
Protonation Constants ◽  
Nmr Data ◽  
Protonation Sequence ◽  
C Nmr

Program PKAS: a novel algorithm for the computation of successive protonation constants

1982 ◽  
Vol 60 (2) ◽  
pp. 168-173 ◽  
Author(s):  
Ramunas J. Motekaitis ◽  
Arthur E. Martell
Keyword(s):  
Numerical Analysis ◽  
Computer Program ◽  
Simultaneous Determination ◽  
Protonation Constants ◽  
Multidentate Ligands ◽  
Equilibrium Data ◽  
Unique Approach ◽  
Novel Algorithm

A new algorithm for the simultaneous determination of any number of protonation constants from potentiometric equilibrium data is described. This algorithm is characterized by a unique approach to the internal refinement of the constants and by the analytical nature of the numerical analysis whereby minimization is sought and achieved on the residuals between calculated and observed pH. The FORTRAN IV computer program PKAS utilizing this generalized algorithm has been written and developed and tested on 30 multidentate ligands. The details of the algorithm and the program are described and samples of its recorded usage are provided, indicating its versatility in application.

Structural determination of the polysaccharide antigens of Neisseria meningitidis serogroups Y, W-135, and BO

1976 ◽  
Vol 54 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Apurba K. Bhattacharjee ◽  
Harold J. Jennings ◽  
C. Paul Kenny ◽  
Adèle Martin ◽  
Ian C. P. Smith
Keyword(s):  
Sialic Acid ◽  
Acetyl Derivative ◽  
Major Product ◽  
Hydroxyl Group ◽  
Nmr Studies ◽  
Acetylneuraminic Acid ◽  
Nmr Data ◽  
Polysaccharide Antigens ◽  
C Nmr

The purified high molecular weight serogoup Y meningococcal polysaccharide contains equimolar proportions of D-glucose and N-acetylneuraminic acid and is partially O-acetylated. Carbon-13 nuclear magnetic resonance (NMR) studies, together with other chemical data, have indicated that the polysaccharide is linked only at C-6 of the D-glucose and C-4 of the sialic acid residues, all the linkages being in the α-configuration. The 13C NMR data also indicated that the Y polysaccharide is composed of an alternating sequence of these two different residues, and this was confirmed by its autohydrolysis where the major product was 4-O-α-D-glucopyranosyl-β-D-N-acetylneuraminic acid. The W-135 polysaccharide differs from that of Y only in the absence of O-acetylation and in the configuration of one hydroxyl group of the disaccharide repeating unit. In this case autohydrolysis yielded 4-O-α-D-galactopyranosyl-β-D-N-acetylneuraminic acid as the major product. Structural evidence indicates that the BO and Y polysaccharides are identical.Methanolysis of the Y polysaccharide yielded in addition to the methyl glycosides of glucose and sialic acid, a 9-O-acetyl derivative of the latter. This derivative was formed during the re-N-acetylation process and its formation was mainly due to the presence of sodium ions in the original polysaccharide.

Eine unerwartet stabile Sulfensäure: 4,6-Dimethoxy-1,3,5-triazin-2-sulfensäure; Synthese, Eigenschaften, Molekül- und Kristallstruktur / Unexpectedly Stable Sulfenic Acid: 4,6-Dimethoxy-1,3,5-triazine-2-sulfenic Acid; Synthesis, Properties, Molecular and Crystal Structure

1993 ◽  
Vol 48 (9) ◽  
pp. 1212-1222 ◽  
Author(s):  
Robert Tripolt ◽  
Ferdinand Belaj ◽  
Edgar Nachbaur
Keyword(s):  
Ionization Constant ◽  
Acid Synthesis ◽  
Crystalline Solid ◽  
Sulfenic Acid ◽  
X Ray ◽  
Nmr Data ◽  
Exact Determination ◽  
Synthesis Properties ◽  
C Nmr

4,6-Dimethoxy-1,3,5-triazine-2-sulfenic acid (1) was prepared by the reaction of 4,6-dimethoxy-1,3,5-triazine-2(1H)-thion (3) with 2-benzenesulfonyl-3-(p-nitrophenyl)-oxaziridine (2) in THF solution and isolated as a stable crystalline solid. The new compound was characterized by analytical and spectroscopic data (IR, 1H and 13C NMR, UV, MS) supported by MNDO-PM 3 calculations. UV spectrometry was used for exact determination of the ionization constant of 1(pKa = 5.86 ± 0.02 at 20°C). According to 13C NMR data and X-ray analysis the sulfenic acid 1 adopts the sulfenyl structure (R—SOH) in the condensed phase.Crystal data of 1 (90 K): a = 8.418(3), b = 21.289(6), c = 4.411(1) Å, Z = 4, P 21212, R = 0.0304, Rw = 0.0354 for 4105 unique reflections and 122 parameters. In the crystal, the molecules form dimers by two strong intermolecular O—H ••• N hydrogen bonds. The 6-membered ring shows alternating C—N bond lengths and is almost planar. The experimental electron deformation density (EDD) decreases in the order C—N > C—O ≈ C—S > S—O and is described in detail for the vicinity of the S atom.

MONOREG – an expert system for structural elucidation of monoterpenes

2001 ◽  
Vol 79 (12) ◽  
pp. 1915-1925 ◽  
Author(s):  
Marcelo J Ferreira ◽  
Gilberto V Rodrigues ◽  
Vicente P Emerenciano
Keyword(s):  
Expert System ◽  
Nmr Spectra ◽  
Structural Elucidation ◽  
Structural Determination ◽  
Systematic Data ◽  
Data Analyses ◽  
Nmr Data ◽  
Living Organisms ◽  
C Nmr

This paper describes a new expert system denominated MONOREG for structural determination of monoterpenes. This system is composed of five programs capable of performing 13C NMR spectra data analyses and analyses of systematic data from living organisms. At the end of this procedure, it shows the likely skeletons of the compound in question as well as the substructures compatible with the 13C NMR data. The system was tested on the skeleton elucidation of 40 monoterpenes from a wide variety of structure types and exhibited excellent results in the skeleton prediction process.

Synthesis and conformations of phosphine- and phosphinite-derivatized resorcinarenes

2004 ◽  
Vol 82 (2) ◽  
pp. 185-194 ◽  
Author(s):  
Dana J Eisler ◽  
Richard J Puddephatt
Keyword(s):  
Solid State ◽  
Functional Groups ◽  
Boat Conformation ◽  
Solution State ◽  
Nmr Data ◽  
C Nmr

The synthesis of resorcinarene derivatives with four or eight alkynyldiphenylphosphine or diphenyl phosphinite functional groups is reported. The tetraphosphinite derivatives have effective C2v symmetry and have the potential to adopt two different boat conformations in which the arene groups with phosphinite substituents are horizontal or vertical. A method for the determination of the solution-state conformation of the resorcinarene skeleton using correlated 1H and 13C NMR data is reported, and the boat conformation of one tetraphosphinite compound in the solid state has been determined crystallographically.Key words: phosphine, phosphinite, resorcinarene, conformation.

A general computer program for the extended plate overlap algorithm

1978 ◽  
Vol 48 ◽  
pp. 287-293 ◽  
Author(s):  
Chr. de Vegt ◽  
E. Ebner ◽  
K. von der Heide
Keyword(s):  
Computer Program ◽  
Simultaneous Determination ◽  
General Computer Program ◽  
General Computer

In contrast to the adjustment of single plates a block adjustment is a simultaneous determination of all unknowns associated with many overlapping plates (star positions and plate constants etc. ) by one large adjustment. This plate overlap technique was introduced by Eichhorn and reviewed by Googe et. al. The author now has developed a set of computer programmes which allows the adjustment of any set of contemporaneous overlapping plates. There is in principle no limit for the number of plates, the number of stars, the number of individual plate constants for each plate, and for the overlapping factor.

Comparative assessment of informational content of the equations of F.P. Hadlock and the computer program of V.N. Demidov in determination of term of gestation and fetal weight in the III trimester of gestation

2017 ◽  
Author(s):  
E.A. Derkach , O.I. Guseva
Keyword(s):  
Computer Program ◽  
High Precision ◽  
Gestational Age ◽  
Computer Programs ◽  
Comparative Assessment ◽  
Fetal Weight ◽  
Informational Content ◽  
Third Trimester ◽  
The Third

Objectives: to compare the accuracy of equations F.P. Hadlock and computer programs by V.N. Demidov in determining gestational age and fetal weight in the third trimester of gestation. Materials: 328 patients in terms 36–42 weeks of gestation are examined. Ultrasonography was performed in 0–5 days prior to childbirth. Results: it is established that the average mistake in determination of term of pregnancy when using the equation of F.P. Hadlock made 12,5 days, the computer program of V.N. Demidov – 4,4 days (distinction 2,8 times). The mistake within 4 days, when using the equation of F.P. Hadlock has met on average in 23,1 % of observations, the computer program of V.N. Demidov — 65,9 % (difference in 2,9 times). The mistake more than 10 days, took place respectively in 51,7 and 8,2 % (distinction by 6,3 times). At a comparative assessment of size of a mistake in determination of fetal mass it is established that when using the equation of F.P. Hadlock it has averaged 281,0 g, at application of the computer program of V.N. Demidov — 182,5 g (distinction of 54 %). The small mistake in the mass of a fetus which isn't exceeding 200 g at application of the equation of F.P. Hadlock has met in 48,1 % of cases and the computer program of V.N. Demidov — 64,0 % (distinction of 33,1 %). The mistake exceeding 500 g has been stated in 18 % (F.P. Hadlock) and 4,3 % (V.N. Demidov) respectively (distinction 4,2 times). Conclusions: the computer program of V.N. Demidov has high precision in determination of term of a gestation and mass of a fetus in the III pregnancy.

Glucan isolated from leaves of Althaea officinalis L.

1983 ◽  
Vol 48 (7) ◽  
pp. 2082-2087 ◽  
Author(s):  
Alžbeta Kardošová ◽  
Jozef Rosík ◽  
Rudolf Toman ◽  
Peter Capek
Keyword(s):  
Medicinal Plant ◽  
Periodate Oxidation ◽  
Linear Structure ◽  
Water Soluble ◽  
Partial Hydrolysis ◽  
Methylation Analysis ◽  
Glycosidic Bonds ◽  
Nmr Data ◽  
Althaea Officinalis ◽  
C Nmr

A water-soluble low-molecular D-glucan was isolated from leaves of the medicinal plant marsh-mallow (Althaea officinalis L.). The results of methylation analysis, partial hydrolysis, periodate oxidation, and 13C NMR data indicated a virtually linear structure with α-(1→6) glycosidic bonds.

Synthesis and characteristics of ethylenediamine-N,N'-di-S-α-isovalerate and isomers of its cobalt(III) complexes

1982 ◽  
Vol 47 (1) ◽  
pp. 210-216 ◽  
Author(s):  
Milan Strašák ◽  
František Bachratý ◽  
Jaroslav Majer
Keyword(s):  
Amino Acids ◽  
Absolute Configuration ◽  
Electronic Absorption ◽  
Electronic Absorption Spectra ◽  
Chemical Parameters ◽  
Methyl Group ◽  
Nmr Data ◽  
Physico Chemical ◽  
Natural Amino Acids ◽  
C Nmr

The synthesis and physico-chemical parameters are described of a new complexone based on natural amino acids, viz. ethylenediamine-N,N'-di-S-α-isovalerate (SS-EDDIV). 1H- and 13C-NMR data revealed that the methyl group in the substance are not equivalent. The isomers of the cobalt(III) complex with the asymmetric tetradentate SS-EDDIV ligand were prepared and separated; their characteristics are given. The absolute configuration of two of the five theoretically feasible isomers was determined based on their electronic absorption spectra and circular dichroism data.

21,22-Disubstituted 18α,19βH-Ursane Derivatives with Oxabicyclooctane System in Ring E

1993 ◽  
Vol 58 (1) ◽  
pp. 173-190 ◽  
Author(s):  
Eva Klinotová ◽  
Jiří Klinot ◽  
Václav Křeček ◽  
Miloš Buděšínský ◽  
Bohumil Máca
Keyword(s):  
Spectral Data ◽  
Spin Systems ◽  
Coupling Constants ◽  
Complete Analysis ◽  
Nmr Spectrum ◽  
Proton Proton ◽  
H Nmr ◽  
Proton Coupling ◽  
C Nmr

Reaction of 3β-acetoxy-21,22-dioxo-18α,19βH-ursan-28,20β-olide (IIIa) and 20β,28-epoxy-21,22-dioxo-19α,19βH-ursan-3β-yl acetate (IIIb) with diazomethane afforded derivatives XII-XIV with spiroepoxide group in position 21 or 22, which were further converted into hydroxy derivatives XV and XVII. Ethylene ketals VIII-X were also prepared. In connection with the determination of position and configuration of the functional groups at C(21) and C(22), the 1H and 13C NMR spectral data of the prepared compounds are discussed. Complete analysis of two four-spin systems in the 1H NMR spectrum of bisethylenedioxy derivative Xb led to the proton-proton coupling constants from which the structure with two 1,4-dioxane rings condensed with ring E, and their conformation, was derived.

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