SELECTIVE SUBSTITUTION IN SUCROSE: II. THE SYNTHESIS OF 2,3,3′,4,4′-PENTA-O-METHYL SUCROSE AND C4 TO C6 ACETYL MIGRATION IN SUCROSE

1957 ◽  
Vol 35 (9) ◽  
pp. 992-997 ◽  
Author(s):  
G. G. McKeown ◽  
L. D. Hayward
Keyword(s):  
Acetic Acid ◽  
Transition State ◽  
Acyl Migration ◽  
Hydrolytic Cleavage ◽  
Selective Substitution ◽  
Acetyl Migration

Deacetylation of crystalline tri-O-trityl-penta-O-acetyl sucrose gave an amorphous tri-O-trityl sucrose derivative and methylation of this product followed by graded hydrolysis with acetic acid yielded a sirupy penta-O-methyl sucrose. Hydrolytic cleavage of the penta-O-methyl sucrose to nearly equal amounts of 2,3,4-tri-O-methyl-D-glucose and 3,4-di-O-methyl-D-fructose established the original positions of the O-trityl groups at the primary carbons in the sucrose molecule. It was therefore evident that acetyl migration from C4 to C6 in the glucose moiety had occurred during an earlier synthesis of 1′,4,6′-tri-O-methyl sucrose from the tri-O-trityl-penta-O-acetyl sucrose. The probable conformation of the transition state in the acyl migration is discussed.

Bifurcated dissociative photoionization mechanism of acetic acid anhydride revealed by imaging photoelectron photoion coincidence spectroscopy

2016 ◽  
Vol 18 (36) ◽  
pp. 25161-25168 ◽  
Author(s):  
Krisztina Voronova ◽  
Chrissa M. Mozaffari Easter ◽  
Krisztián G. Torma ◽  
Andras Bodi ◽  
Patrick Hemberger ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Transition State ◽  
Acid Anhydride ◽  
Reaction Pathways ◽  
Dissociative Photoionization ◽  
Coincidence Spectroscopy

PEPICO allows us a peek beyond the transition state to identify bifurcated reaction pathways.

Oxidation of carbohydrates with chromium trioxide in acetic acid. I. Glycosides

1970 ◽  
Vol 23 (6) ◽  
pp. 1209 ◽  
Author(s):  
SJ Angyal ◽  
K James
Keyword(s):  
Acetic Acid ◽  
Hydrogen Atom ◽  
Catalytic Hydrogenation ◽  
Chromium Trioxide ◽  
Keto Ester ◽  
Keto Esters ◽  
Branched Chain ◽  
Acetyl Migration

Fully acetylated methyl β-D-hexopyranosides are oxidized by chromium trioxide in acetic acid to acetylated methyl 5-hexulosonates. Catalytic hydrogenation of these keto esters leads into the L-series. The corresponding a-D-glycosides are not oxidized in the same way, with the exception of methyl tetra-O-acetyl-α-D-idopyranoside. Both α- and β-anomers of the acetylated fnranosides are oxidized to aoetylated methyl 4-hexulosonates. The octaacetates of α- and β-lactose are similarly oxidized, the ring of the galactose moiety being opened. The methyl pyranoside of a branched-chain sugar, with no hydrogen atom on C5, is oxidized to a 4-keto ester, acetyl migration occurring from O4 to O5.

Mutarotation of some biologically important 2-substituted hexoses

1974 ◽  
Vol 337 (1610) ◽  
pp. 317-332 ◽  
Keyword(s):  
Acetic Acid ◽  
Transition State ◽  
Rate Constants ◽  
Activation Parameters ◽  
Water Molecules ◽  
Concerted Mechanism ◽  
Hydronium Ion ◽  
Thermodynamic Activation Parameters

Catalysis by water, hydronium ion, acetate ion, acetic acid, pyridine and 3-hydroxypyridine of the mutarotation of D-glucose, 2-deoxy-D-glucoso, 2-amino-2-deoxy-D-glucose and 2-acetamido-2-deoxy-n-glucose has been studied polarimetrically. Rate constants were measured at 298 and 308 K and the thermodynamic activation parameters have been calculated for each case. It is concluded that the mutarotation reaction probably takes place by a concerted mechanism in which two or more water molecules are involved in the transition state.

Acetoxylation by aryliodoso acetates. II. Kinetics of the reaction of phenyliodoso acetate with aceto-p-toluidide

1958 ◽  
Vol 11 (1) ◽  
pp. 34
Author(s):  
WD Johnson ◽  
NV Riggs
Keyword(s):  
Acetic Acid ◽  
Acetic Anhydride ◽  
Transition State ◽  
Arrhenius Equation ◽  
First Order ◽  
Temperature Range ◽  
Polar Transition ◽  
Kinetics Of

The reaction of phenyliodoso acetate and aceto-p-toluidide in acetic acid is first order in each reactant and measured rates fit the Arrhenius equation in the temperature range 15-45 �C. Addition of water to the solvent markedly accelerates the reaction, whereas addition of benzene lowers the rate and acetic anhydride has little effect. A polar transition state is indicated.

Sucrose phosphorylases catalyze transglycosylation reactions on carboxylic acid compounds

Biologia ◽  
2008 ◽  
Vol 63 (6) ◽  
Author(s):  
Kazuhisa Sugimoto ◽  
Koji Nomura ◽  
Hiromi Nishiura ◽  
Kohji Ohdan ◽  
Takahisa Nishimura ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Carboxylic Acid ◽  
Time Course ◽  
Acyl Migration ◽  
Dicarboxylic Acids ◽  
Short Chain Fatty Acids ◽  
2D Nmr ◽  
Sucrose Phosphorylase ◽  
Acceptor Specificity ◽  
Acidic Conditions

AbstractTwo sucrose phosphorylases were employed for glycosylation of carboxylic acid compounds. Streptococcus mutans sucrose phosphorylase showed remarkable transglycosylating activity, especially under acidic conditions. Leuconostoc mesenteroides sucrose phosphorylase exhibited very weak transglycosylating activity. Three main products were detected from the reaction mixture using benzoic acid and sucrose as an acceptor and a donor molecule, respectively. These compounds were identified as 1-O-benzoyl α-d-glucopyranoside, 2-O-benzoyl α-d-glucopyranose, and 2-O-benzoyl β-d-glucopyranose by 1D-and 2D-NMR analyses of the isolated products and their acetylated products. Time-course analyses proved that 1-O-benzoyl α-d-glucopyranoside was initially produced by the transglycosylation reaction of the enzyme. 2-O-Benzoyl α-d-glucopyranose and 2-O-benzoyl β-d-glucopyranose were produced from 1-O-benzoyl α-d-glucopyranoside by intramolecular acyl migration reaction. S. mutans sucrose phosphorylase showed broad acceptor-specificity. This sucrose phosphorylase catalyzed transglycosylation to various carboxylic compounds such as short-chain fatty acids, hydroxy acids, dicarboxylic acids, and phenolic carboxylic acids. 1-O-Acetyl α-d-glucopyranoside was also enzymatically synthesized by transglucosylation reaction of the enzyme. The sensory test of acetic acid and the glucosides revealed that the sour taste of acetic acid glucosides was significantly lower than that of acetic acid.

scholarly journals STUDY OF DOUBLE PROTONS MIGRATION MECHANISM IN SUPRAMOLECULAR STRUCTURES OF ACETIC ACID-WATER AND ACETIC ACID-AMMONIA BY AB INITIO METHOD

2010 ◽  
Vol 3 (2) ◽  
pp. 102-110
Author(s):  
Karna Wijaya ◽  
Iqmal Tahir ◽  
Harnowo Harnowo
Keyword(s):  
Acetic Acid ◽  
Transition State ◽  
Ab Initio ◽  
Computational Study ◽  
Basis Set ◽  
Acid Water ◽  
Product Models ◽  
Migration Mechanism ◽  
Package Program ◽  
Acetic Acid Water

The theoretical study of double protons migration mechanism on acetic acid-water and acetic acid-ammonia associations has been carried out. The research covered determinations the reactant, transition state and product structures. To gain the goal, the research was conducted in three steps, i.e. (i) designing the reactant, transition state and product models, (ii) optimizing of structures, and (iii) calculating of their uncorrected total energy and frequencies with ab initio methods (basis set 6-31G**). All calculations were performed using Hyperchem ver 5.0 for Windows and Gaussian 94W package program. The computational study result showed that the calculated structures were in good agreement with the hypothetical structures.   Keywords: double protons migration, acetic acid, water, ammonia, molecular mechanics and ab-initio

scholarly journals COORDINATION PROPERTIES OF NITRO-SUBSTITUTED 5,15-DIPHENYL-3,7,13,17-TETRAMETHYL-2,8,12,18-TETRAETHYLPORPHYRIN WITH MANGANESE ACETATE IN PYRIDINE AND ACETIC ACID

2020 ◽  
Vol 63 (9) ◽  
pp. 49-55
Author(s):  
Elizaveta M. Kuvshinova ◽  
Olga V. Gornukhina ◽  
Alexander S. Semeikin ◽  
Irina A. Vershinina ◽  
Sergey A. Syrbu
Keyword(s):  
Acetic Acid ◽  
Transition State ◽  
Reaction Rate ◽  
Planar Structure ◽  
Manganese Complexes ◽  
Manganese Acetate ◽  
Resonance Spectroscopy ◽  
Electron Absorption Spectroscopy ◽  
Phenyl Rings ◽  
Tetrapyrrole Macrocycle

The synthesis of 5,15-diphenyl-3,7,13,17-tetramethyl-2,8,12,18-tetraethylporphyrin and its nitro substituted was carried out. Nitro groups are located in meso-positions of the tetrapyrrole macrocycle and (or) para-positions of the phenyl rings. The synthesized porphyrins are characterized by a set of modern research methods: electron absorption spectroscopy; IR and nuclear magnetic resonance spectroscopy 1H. The reactions of the formation of manganese complexes with nitro-substituted 5,15-diphenyl-3,7,13,17-tetramethyl-2,8,12,18-tetraethylporphyrin and their stability in organic solvents are studied. It was found that the rate of reactions of formation of manganese complexes in pyridine with the introduction of nitrogroups in 5,15-diphenyl-3,7,13,17-tetramethyl-2,8,12,18-tetraethylporphine grows as the degree of deformation of the tetrapyrrole macrocycle increases. Obviously, in this case, not only the stretching of NH bonds, due to the presence of electron-withdrawing substituents (NO2) in the para positions of the phenyl rings, makes a decisive contribution to the energy of the transition state, but also the increase in the basicity of tertiary nitrogen atoms, which form strong bonds in the transition state with a solvated cation of salt. In acetic acid, the macrocycle deformation effect leads to a decrease in the reaction rate, which is due to the specific solvation of the porphine reaction center by acetic acid molecules. It was found that steric distortions of the planar structure of porphyrins have relatively little effect on the kinetic parameters of the solvoprotolytic dissociation of manganese complexes of 5,15-diphenyl-3,7,13,17-tetramethyl-2,8,12,18-tetraethylporphyrin and its nitro-substituted ones. This is probably due to the fact that the coordination of the manganese cation results in a more planar structure of the porphyrin macrocycle. The decrease in the dissociation reaction rate with an increase in the number of nitrogroups in 5,15-diphenyl-3,7,13,17-tetramethyl-2,8,12,18-tetraethylporphyrine is due to the influence of the negative inductive effect of nitrogroups, which reduces the effective charge in the macrocycle on nitrogen atoms that are attacked by a solvated proton.

SELECTIVE SUBSTITUTION IN SUCROSE: I. THE SYNTHESIS OF 1′,4,6′-TRI-O-METHYL SUCROSE

1957 ◽  
Vol 35 (1) ◽  
pp. 30-38 ◽  
Author(s):  
G. G. McKeown ◽  
R. S. E. Serenius ◽  
L. D. Hayward
Keyword(s):  
Acetic Acid ◽  
Periodate Oxidation ◽  
Selective Substitution ◽  
Acetyl Group ◽  
Group Migration

Sucrose was tritylated and acetylated to give a crystalline tri-O-trityl-penta-O-acetyl sucrose derivative, and detritylation of this product by graded hydrolysis with acetic acid followed by methylation and deacetylation yielded 1′,4,6′-tri-O-methyl sucrose. The structure of the tri-O-methyl sucrose was established by periodate oxidation and by hydrolysis to the corresponding O-methyl ethers of glucose and fructose. Acetyl group migration from C4 to C6 in the glucose moiety of sucrose probably occurred during the methylation reaction.Some aspects of syntheses involving sucrose are discussed.

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