Partial methylation of methyl 4,6-dideoxy-α- and β-L-ribo-hexopyranosides

1984 ◽  
Vol 49 (9) ◽  
pp. 2130-2140 ◽  
Author(s):  
Karel Kefurt ◽  
Zdeňka Kefurtová ◽  
Jiří Jarý
Keyword(s):  
Gas Chromatography ◽  
Ir Spectra ◽  
Sodium Hydroxide ◽  
Methyl Iodide ◽  
Rate Constants ◽  
Hydroxyl Groups ◽  
View Point ◽  
Partial Methylation ◽  
H Nmr ◽  
Analogous Data

Anomeric methyl 4,6-dideoxy-L-ribo-hexopyranosides I and V, prepared from aldose IX, were etherified with methyl iodide in acetonitrile in the presence of sodium hydroxide. From the products of partial methylation methyl 4,6-dideoxy-2-O-methyl-α-L-ribo-hexopyranoside (II) and methyl 4,6-dideoxy-2,3-di-O-methyl-α-L-ribo-hexopyranoside (IV), or methyl 4,6-dideoxy-2-O-methyl-β-D-ribo-hexopyranoside (VI) and methyl 4,6-dideoxy-2,3-O-methyl-β-L-ribo-hexopyranoside (VIII), respectively, were isolated. The substances were identified by 1H NMR, mass and IR spectra and comparison with standards. The course of etherification of glycosides I and V was checked by gas chromatography and the reactivity of the hydroxyl groups was evaluated by determining the rate constants or their ratios. The observed values were compared with analogous data for other isomers of methyl 4,6-dideoxyhexopyranosides and discussed from the view-point of sterical and polar influence on the reactivity of both their hydroxylic groups.

Partial methylation of methyl α-D- and β-D-threofuranoside

1990 ◽  
Vol 55 (7) ◽  
pp. 1777-1782 ◽  
Author(s):  
Jiří Jarý ◽  
Miroslav Marek ◽  
Ivan Raich
Keyword(s):  
Sodium Hydroxide ◽  
Methyl Iodide ◽  
Rate Constants ◽  
Relative Rate ◽  
Hydroxyl Groups ◽  
Partial Methylation ◽  
Methylation Rate ◽  
Consecutive Reactions ◽  
Relative Rate Constants ◽  
The Individual

The methylation rate of hydroxyl groups of the title glycosides I and II has been studied in their reaction with methyl iodide and sodium hydroxide in acetonitrile. From the relative rate constants determined for the side and consecutive reactions taking place the differences in methylation rate of the individual hydroxyl groups have been deduced and are discussed from the standpoint of possible steric and polar effects.

Partial methylation of methyl 2,6-dideoxy-α-D-xylo- and α-D-lyxo-hexopyranoside

1981 ◽  
Vol 46 (10) ◽  
pp. 2410-2420 ◽  
Author(s):  
Jiří Jarý ◽  
Miroslav Marek
Keyword(s):  
Sodium Hydroxide ◽  
Methyl Iodide ◽  
Rate Constants ◽  
Relative Rate ◽  
Reaction Rates ◽  
Steric Effects ◽  
Side Reactions ◽  
Hydroxyl Groups ◽  
Partial Methylation ◽  
Relative Rate Constants

Rate of methylation of the hydroxyl groups in the title glycosides was investigated during their reaction with methyl iodide and sodium hydroxide in acetonitrile. Relative rate constants of the side-reactions and subsequent reactions taking place were calculated. The differences in the reaction rates of methylation of individual hydroxyl groups are discussed in connection with the possible polar and steric effects.

Kinetics of Methylation of Methyl 5-Deoxy-α/β-D-xylofuranosides

2004 ◽  
Vol 69 (10) ◽  
pp. 1877-1888
Author(s):  
Mária Oščendová ◽  
Jitka Moravcová
Keyword(s):  
Sodium Hydroxide ◽  
Methyl Iodide ◽  
Rate Constants ◽  
Reaction Rate ◽  
Steric Effect ◽  
Order Reaction ◽  
Half Time ◽  
First Order ◽  
Consecutive Reactions ◽  
Kinetics Of

The kinetics of methylation of methyl 5-deoxy-α-D-xylofuranoside (1), methyl 5-deoxy-β-D-xylofuranoside (2) and their partly methylated derivatives with methyl iodide in the presence of sodium hydroxide in acetonitrile was studied. The reaction rate was independent of the base concentration during the first half-time only and the methylation proceeded as a first-order reaction. The rate constants of all side and consecutive reactions were calculated and the influence of both polar and steric effect is discussed. The methylation of 1 was highly regioselective giving almost exclusively 5-deoxy-2-O-methyl-α-D-xylofuranoside.

Selective Accessibilities of Hydroxyl Groups in the Microstructure of Cotton Cellulose

1969 ◽  
Vol 39 (6) ◽  
pp. 530-542 ◽  
Author(s):  
S. P. Rowland ◽  
E. J. Roberts ◽  
C. P. Wade
Keyword(s):  
Sodium Hydroxide ◽  
Rate Constants ◽  
Relative Rate ◽  
Heterogeneous Systems ◽  
Heterogeneous Reactions ◽  
Cotton Cellulose ◽  
Hydroxyl Groups ◽  
Relative Rate Constants ◽  
The Individual ◽  
Liquid Chromatographic

The reactions of 2-chloroethyldiethylamine with the hydroxyl groups at C-2, C-3, and C-6 of the d-glucopyranosyl unit of cotton cellulose were investigated as a means of evaluating the relative accessibilities of these hydroxyl groups in heterogeneous reactions of fibrous cellulose. The relative rate constants for reactions of the individual types of hydroxyl groups were determined from reactions of cellulose in solution and from reactions of disordered cellulose in heterogeneous systems. Quantitative determinations of the distributions of 2-(diethylamino)ethyl substituents in the mono-substituted d-glucopyranosyl units involved hydrolysis of the chemically modified cellulose to glucose and substituted glucoses followed by gas-liquid chromatographic analysis. The relative accessibilities of the hydroxyl groups at C-2 and C-3 vs those at C-6 were estimated for crystalline celluloses by employing the relative rate constants (noted above) together with the experimentally measured distributions of substituents resulting from heterogeneous reactions of crystalline celluloses and appropriate kinetic expressions. The relative accessibilities of the hydroxyl groups at C-2, C-3, and C-6 in cellulose in strong mercerizing media approach those of cellulose in solution. In media of lower concentration of sodium hydroxide (i.e., 4 N or 13.9%), selective accessibilities of the individual types of hydroxyl groups become evident, and these selective accessibilities become pronounced in sodium hydroxide solutions of still lower concentrations (e.g., N and 2 N).

119Sn, 13C and 1H NMR Spectra of Tris(1-butyl)stannyl D-Glucuronate

1997 ◽  
Vol 62 (8) ◽  
pp. 1169-1176 ◽  
Author(s):  
Antonín Lyčka ◽  
Jaroslav Holeček ◽  
David Micák
Keyword(s):  
Chemical Shift ◽  
Carbonyl Group ◽  
1H Nmr ◽  
Equatorial Plane ◽  
Title Compound ◽  
Nmr Spectra ◽  
Hydroxyl Groups ◽  
Carboxylic Group ◽  
H Nmr ◽  
Oxygen Atoms

The 119Sn, 13C and 1H NMR spectra of tris(1-butyl)stannyl D-glucuronate have been measured in hexadeuteriodimethyl sulfoxide, tetradeuteriomethanol and deuteriochloroform. The chemical shift values have been assigned unambiguously with the help of H,H-COSY, TOCSY, H,C-COSY and 1H-13C HMQC-RELAY. From the analysis of parameters of 119Sn, 13C and 1H NMR spectra of the title compound and their comparison with the corresponding spectra of tris(1-butyl)stannyl acetate and other carboxylates it follows that in solutions of non-coordinating solvents (deuteriochloroform) the title compound is present in the form of more or less isolated individual molecules with pseudotetrahedral environment around the central tin atom and with monodentately bound carboxylic group. The interaction of tin atom with oxygen atoms of carbonyl group and hydroxyl groups of the saccharide residue - if they are present at all - are very weak. In solutions in coordinating solvents (hexadeuteriodimethyl sulfoxide or tetradeuteriomethanol), the title compound forms complexes with one molecule of the solvent. Particles of these complexes have a shape of trigonal bipyramid with the 1-butyl substituents in equatorial plane and the oxygen atoms of monodentate carboxylic group and coordinating solvent in axial positions.

Determination of the Accurate Values of the Rate Constant and Thermodynamic Parameters for the Rotation About the C(sp2)-C(aryl) Bond; Adamantan-1-yl 3-Bromo-2,4,6-trimethylphenyl Ketone

1998 ◽  
Vol 63 (7) ◽  
pp. 955-966
Author(s):  
Eva Přibylová ◽  
Miroslav Holík
Keyword(s):  
Thermodynamic Parameters ◽  
Shape Analysis ◽  
Rate Constants ◽  
Line Shape ◽  
Microsoft Excel ◽  
Hindered Rotation ◽  
H Nmr ◽  
Line Shape Analysis ◽  
Coalescence Temperature

Four programs for the 1H NMR line shape analysis: two commercial - Winkubo (Bruker) and DNMR5 (QCPE 165) and two written in our laboratory - Newton (in Microsoft Excel) and Simtex (in Matlab) have been tested in order to get highly accurate rate constants of the hindered rotation about a single bond. For this purpose four testing criteria were used, two of them were also developed by us. As supplementary determinations the rate constants obtained for the coalescence temperature and for the thermal racemization of chromatographically separated enantiomers were used which fitted well the temperature dependence of the rate constants determined by the line shape analysis. As a test compound adamantan-1-yl 3-bromo-2,4,6-trimethylphenyl ketone was prepared and studied. It was shown that supermodified simplex method used in our algorithm (Simtex), though time consuming, gives the most accurate values of the rate constants and consequently the calculated thermodynamic parameters Ea, ∆H≠, and ∆S≠ lay in relatively narrow confidence intervals.

scholarly journals Utilization and simulation of innovative new binuclear Co(ii), Ni(ii), Cu(ii), and Zn(ii) diimine Schiff base complexes in sterilization and coronavirus resistance (Covid-19)

2021 ◽  
Vol 19 (1) ◽  
pp. 772-784
Author(s):  
Moamen S. Refat ◽  
Ahmed Gaber ◽  
Walaa F. Alsanie ◽  
Mohamed I. Kobeasy ◽  
Rozan Zakaria ◽  
...  
Keyword(s):  
Schiff Base ◽  
Molecular Docking ◽  
Metal Ions ◽  
Free Ligand ◽  
Schiff Base Complexes ◽  
Hydroxyl Groups ◽  
Binuclear Complexes ◽  
Central Metal ◽  
H Nmr ◽  
Biological Studies

Abstract This article aimed at the synthesis and molecular docking assessment of new diimine Schiff base ligand, namely 2-((E)-(2-((Z)-2-(4-chlorophenyl)-2-hydroxyvinyl)hydrazono) methyl)-6-methoxyphenol (methoxy-diim), via the condensation of 1-(4-chloro-phenyl)-2-hydrazino-ethenol compound with 2-((E)-(2-((Z)-2-(4-chlorophenyl)-2-hydroxy vinyl) hydrazono)methyl)-6-methoxyphenol in acetic acid as well as the preparation of new binuclear complexes of Co(ii), Ni(ii), Cu(ii), and Zn(ii). The following synthesized complexes were prepared in a ratio of 2:1 (metal/ligand). The 1H-NMR, UV-Vis, and FTIR spectroscopic data; molar conductivity measurements; and microanalytical, XRD, TGA/DTG, and biological studies were carried out to determine the molecular structure of these complexes. According to the spectroscopic analysis, the two central metal ions were coordinated with the diamine ligand via the nitrogen of the hydrazine and oxygen of the hydroxyl groups for the first metal ions and via the nitrogen of the hydrazine and oxygen of the phenol group for the second metal ions. Molecular docking for the free ligand was carried out against the breast cancer 3hb5-oxidoreductase and the 4o1v-protein binding kidney cancer and COVID-19 protease, and good results were obtained.

scholarly journals Kinetics and Mechanism of the Change of the 4-Nitrobenzylthio-System into 4,4′-Diformylazoxybenzene in Alkaline Dioxane-Water Media

1985 ◽  
Vol 40 (11) ◽  
pp. 1128-1132
Author(s):  
Y. Riad ◽  
Adel N. Asaad ◽  
G.-A. S. Gohar ◽  
A. A. Abdallah
Keyword(s):  
Acetic Acid ◽  
Sodium Hydroxide ◽  
Rate Constants ◽  
Main Product ◽  
Reaction Medium ◽  
Aqueous Dioxane ◽  
Proton Abstraction ◽  
First Order ◽  
Water Media ◽  
Different Temperatures

Sodium hydroxide reacts with α -(4-nitrobenzylthio)-acetic acid in aqueous-dioxane media to give 4,4'-diformylazoxybenzene as the main product besides 4,4'-dicarboxyazoxybenzene and a nitrone acid. This reaction was kinetically studied in presence of excess of alkali in different dioxane-water media at different temperatures. It started by a fast reversible a-proton abstraction step followed by two consecutive irreversible first-order steps forming two intermediates (α -hydroxy, 4-nitrosobenzylthio)-acetic acid and 4-nitrosobenzaldehyde. The latter underwent a Cannizzaro's reaction, the products of which changed in the reaction medium into 4,4'-diformylazoxybenzene and 4,4'-dicarboxyazoxybenzene. The rate constants and the thermodynamic parameters of the two consecutive steps were calculated and discussed. A mechanism was put forward for the formation of the nitrone acid.Other six 4-nitrobenzyl, aryl sulphides were qualitatively studied and they gave mainly 4,4'-diformylazoxybenzene beside 4,4'-dicarboxyazoxybenzene or its corresponding azo acid.

Anhydride und Thioanhydride von tert-Butylstibinig-und -stibonigsäuren / Anhydrides and Thioanhydrides of tert-Butylstibinous-and Stibonous Acids

1981 ◽  
Vol 36 (9) ◽  
pp. 1105-1109 ◽  
Author(s):  
Hans Joachim Breunig ◽  
Helmut Kischkel
Keyword(s):  
Sodium Hydroxide ◽  
Sodium Sulfide ◽  
H Nmr

Abstract The reactions of di-tert-butylantimony chloride with sodium hydroxide or sodium sulfide yield new anhydrides or thioanhydrides of tert-butylstibinous acids, which have structures with bridging oxygen or sulfur atoms. Analogous reactions of tert-butylantimonydichloride produce the first examples of anhydrides or thioanhydrides of tertbutylstibonous acids, which have cyclic structures (t-BuSbE)n E = O, n = 3, 4; E = S, n = 2, 3, 4, 5. Structural evidence is based on IR, 1H NMR and MS data.

scholarly journals Isocyanate und verwandte Verbindungen des trimeren Phosphornitriddifluorids / Isocyanates and Related Compounds of Trimeric Phosphor-difluoronitride

1971 ◽  
Vol 26 (7) ◽  
pp. 679-683 ◽  
Author(s):  
Herbert W. Roesky ◽  
Enno Janssen
Keyword(s):  
Ir Spectra ◽  
Elemental Analysis ◽  
Mass Spectra ◽  
H Nmr ◽  
Carbonic Acids ◽  
Related Compounds

P3N3F5NCO was prepared by reaction of P3N3F5NSO with (COCl) 2. Substituted amides were obtained from the reaction of P3N3F5NSO with carbonic acids e. g. P3N3F5NHCOCH3, P3N3F5NHCOC2H5, and P3N3F5NHCOC3H7. If these substances were treated with PCl5 the following compounds P3N3F5N = CClCH3, P3N3F5N = CClCH5, and P3N3F5TN = CClC3H7 were formed. They reacted with nucleophiles to give P3N3F5N = CNH2CH3, P3N3F5N = TN (CH3) 2C2H5, and P3N3F5N = CN (CH3) 2CH7. The properties of these compounds are described. They were characterized by elemental analysis and IR-spectra. 19F-, 1H-NMR, and mass spectra are reported.

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