STUDIES ON REACTIONS RELATING TO CARBOHYDRATES AND POLYSACCHARIDES. XXXIV. THE CONSTITUTION OF LEVAN AND ITS RELATION TO INULIN

1931 ◽  
Vol 4 (3) ◽  
pp. 221-239 ◽  
Author(s):  
Harold Hibbert ◽  
R. Stuart Tipson ◽  
F. Brauns
Keyword(s):  
Carbonyl Group ◽  
Methyl Alcohol ◽  
Hydroxyl Groups ◽  
Complete Hydrolysis ◽  
Subsequent Hydrolysis ◽  
Group A ◽  
And Behavior ◽  
Hydrolysis Of

A description is given of the properties of levan, a polysaccharide obtained by the action of Bacillus mesentericus, and of its enzyme, on sucrose; in particular, its complete hydrolysis to fructose, and behavior when subjected to acetylation and methylation.By hydrolysis of trimethyl levan, a crystalline trimethyl fructose was obtained (the first crystalline methylated γ-sugar to be synthesized). This yielded a trimethyl methylfructoside on condensation with methyl alcohol containing HCl. The properties of these compounds are described for the first time.On methylation and subsequent hydrolysis of the glucide, a tetramethyl fructose was obtained having properties identical with those of the tetramethyl fructose obtained by hydrolysis of heptamethyl sucrose.Oxidation of the new trimethyl fructose yielded a dibasic dimethyl lactol acid, and esterification of the latter, followed by methylation and treatment with dry ammonia, gave a crystalline diamide. These results show that the new crystalline trimethyl fructose is 1:3:4-trimethyl fructofuranose.It follows from this that levan is a polymerized anhydro-fructofuranose with linkages at positions 2 and 6 of the fructose chain, thus differing from inulin which has been shown to be an anhydro-fructofuranose with linkages at positions 1 and 2.The synthesis of levan thus represents a further example of the polymerization of an anhydro sugar taking place through the medium of the γδ hydroxyl groups. It serves to emphasize the importance of these spatial positions with reference to the carbonyl group, a phenomenon to which attention has been drawn repeatedly by Hibbert.

Studies on the lignin of Eucalyptus regnans F. Muell. VII. The acid hydrolysis of ethanyol lignin-A

1953 ◽  
Vol 6 (2) ◽  
pp. 156 ◽  
Author(s):  
JWT Merewether
Keyword(s):  
Hydrochloric Acid ◽  
Acid Hydrolysis ◽  
Carbonyl Group ◽  
Dilute Hydrochloric Acid ◽  
Hydroxyl Groups ◽  
Eucalyptus Regnans ◽  
Ethoxyl Group ◽  
Hydrolysis Of

Ethanol lignin-A from the ethanolysis of Eucalyptus regnans P. Muell. has been hydrolysed with dilute hydrochloric acid with the object of ascertaining whether the combined ethoxyl is present as an acetal or as ether. Hydrolysis with 12 per cent. hydrochloric acid was found to split off one ethoxyl group, while hydrolysis with 20 per cent. acid brought about complete de-ethylation. The de-ethylated ethanol lignin-A contained one carbonyl group less and two hydroxyl groups more than the original ethanol lignin-A. These results lend no support to the hypothesis that alcohol lignins are acetals, and favour the theory that the combined alkoxyl is probably present as ether.

Cyclobutanes in organic synthesis. Part I. Fragmentation to 1,4-dicarbonyl compounds. General considerations

1970 ◽  
Vol 48 (9) ◽  
pp. 1436-1445 ◽  
Author(s):  
N. R. Hunter ◽  
G. A. MacAlpine ◽  
H. J. Liu ◽  
Z. Valenta
Keyword(s):  
Carbonyl Group ◽  
Organic Synthesis ◽  
Alkyl Group ◽  
Acetate Group ◽  
Dicarbonyl Compounds ◽  
Group A ◽  
Hydrolysis Of

Photo-cycloaddition of vinyl acetates to 2-cyclohexenones followed by hydrolysis of the acetate group and by oxidative fragmentation leads to 2-alkyl-2-cyclohexenones in which the newly introduced alkyl group bears a 2′-carbonyl group. A similar, less generally applicable method, involving photo-cycloaddition, bromination, and heterolytic fragmentation is also described. Possible applications of this sequence in organic synthesis are discussed.

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.

DFT study on the hydrolysis of metsulfuron-methyl: A sulfonylurea herbicide

2018 ◽  
Vol 17 (08) ◽  
pp. 1850050 ◽  
Author(s):  
Qiuhan Luo ◽  
Gang Li ◽  
Junping Xiao ◽  
Chunhui Yin ◽  
Yahui He ◽  
...  
Keyword(s):  
Free Energy ◽  
Water Molecule ◽  
Carbonyl Group ◽  
Energy Barrier ◽  
Density Functional ◽  
Free Energy Barrier ◽  
Functional Theory ◽  
Metsulfuron Methyl ◽  
Catalytic Role ◽  
Hydrolysis Of

Sulfonylureas are an important group of herbicides widely used for a range of weeds and grasses control particularly in cereals. However, some of them tend to persist for years in environments. Hydrolysis is the primary pathway for their degradation. To understand the hydrolysis behavior of sulfonylurea herbicides, the hydrolysis mechanism of metsulfuron-methyl, a typical sulfonylurea, was investigated using density functional theory (DFT) at the B3LYP/6-31[Formula: see text]G(d,p) level. The hydrolysis of metsulfuron-methyl resembles nucleophilic substitution by a water molecule attacking the carbonyl group from aryl side (pathway a) or from heterocycle side (pathway b). In the direct hydrolysis, the carbonyl group is directly attacked by one water molecule to form benzene sulfonamide or heterocyclic amine; the free energy barrier is about 52–58[Formula: see text]kcal[Formula: see text]mol[Formula: see text]. In the autocatalytic hydrolysis, with the second water molecule acting as a catalyst, the free energy barrier, which is about 43–45[Formula: see text]kcal[Formula: see text]mol[Formula: see text], is remarkably reduced by about 11[Formula: see text]kcal[Formula: see text]mol[Formula: see text]. It is obvious that water molecules play a significant catalytic role during the hydrolysis of sulfonylureas.

scholarly journals Adjustment of Hydrophobic Properties of Cellulose Materials

Polymers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1241
Author(s):  
Michael Ioelovich
Keyword(s):  
Ester Group ◽  
Hydroxyl Groups ◽  
Chemical Methods ◽  
Hydrophobic Properties ◽  
Cellulose Esters ◽  
Cellulose Modification ◽  
Polar Groups ◽  
Polar Substituents ◽  
Hydrolysis Of ◽  
Cellulose Materials

In this study, physicochemical and chemical methods of cellulose modification were used to increase the hydrophobicity of this natural semicrystalline biopolymer. It has been shown that acid hydrolysis of the initial cellulose increases its crystallinity, which improves hydrophobicity, but only to a small extent. A more significant hydrophobization effect was observed after chemical modification by esterification, when polar hydroxyl groups of cellulose were replaced by non-polar substituents. The esterification process was accompanied by the disruption of the crystalline structure of cellulose and its transformation into the mesomorphous structure of cellulose esters. It was found that the replacement of cellulose hydroxyls with ester groups leads to a significant increase in the hydrophobicity of the resulting polymer. Moreover, the increase of the number of non-polar groups in the ester substituent contributes to rise in hydrophobicity of cellulose derivative. Depending on the type of ester group, the hydrophobicity increased in the following order: acetate < propionate < butyrate. Therefore, tributyrate cellulose (TBC) demonstrated the most hydrophobicity among all studied samples. In addition, the mixed ester, triacetobutyrate cellulose (TAB), also showed a sufficiently high hydrophobicity. The promising performance properties of hydrophobic cellulose esters, TBC and TAB, were also demonstrated.

scholarly journals Lysosomal Cholesterol Accumulation Inhibits Subsequent Hydrolysis of Lipoprotein Cholesteryl Ester

2008 ◽  
Vol 14 (2) ◽  
pp. 138-149 ◽  
Author(s):  
W. Gray Jerome ◽  
Brian E. Cox ◽  
Evelyn E. Griffin ◽  
Jody C. Ullery
Keyword(s):  
Cholesteryl Ester ◽  
Free Cholesterol ◽  
Oxidized Ldl ◽  
Lipoprotein Metabolism ◽  
Foam Cells ◽  
Acidic Ph ◽  
Cholesterol Accumulation ◽  
Lysosomal Ph ◽  
Subsequent Hydrolysis ◽  
Hydrolysis Of

Human macrophages incubated for prolonged periods with mildly oxidized LDL (oxLDL) or cholesteryl ester-rich lipid dispersions (DISP) accumulate free and esterified cholesterol within large, swollen lysosomes similar to those in foam cells of atherosclerosis. The cholesteryl ester (CE) accumulation is, in part, the result of inhibition of lysosomal hydrolysis due to increased lysosomal pH mediated by excessive lysosomal free cholesterol (FC). To determine if the inhibition of hydrolysis was long lived and further define the extent of the lysosomal defect, we incubated THP-1 macrophages with oxLDL or DISP to produce lysosome sterol engorgement and then chased with acetylated LDL (acLDL). Unlike oxLDL or DISP, CE from acLDL normally is hydrolyzed rapidly. Three days of incubation with oxLDL or DISP produced an excess of CE in lipid-engorged lysosomes, indicative of inhibition. After prolonged oxLDL or DISP pretreatment, subsequent hydrolysis of acLDL CE was inhibited. Coincident with the inhibition, the lipid-engorged lysosomes failed to maintain an acidic pH during both the initial pretreatment and subsequent acLDL incubation. This indicates that the alterations in lysosomes were general, long lived, and affected subsequent lipoprotein metabolism. This same phenomenon, occurring within atherosclerotic foam cells, could significantly affect lesion progression.

Transformations of the Herbicide N-(1,1-dimethylpropynyl)-3,5-dichlorobenzamide in Soil

Weed Science ◽  
1970 ◽  
Vol 18 (5) ◽  
pp. 604-607 ◽  
Author(s):  
Roy Y. Yih ◽  
Colin Swithenbank ◽  
D. Harold McRae
Keyword(s):  
Soil Moisture ◽  
High Temperature ◽  
Soil Moisture Content ◽  
Chemical Change ◽  
Herbicidal Activity ◽  
Compound I ◽  
Subsequent Hydrolysis ◽  
Compound Ii ◽  
Hydrolysis Of

Transformation of N-(1,1-dimethylpropynyl)-3,5-dichlorobenzamide (compound I) in soil occurs readily and two products are produced, initial cyclization giving 2-(3,5-dichlorophenyl)-4,4-dimethyl-5-methyleneoxazoline (compound II) followed by subsequent hydrolysis to N-(1,1-dimethylacetonyl)-3,5-dichlorobenzamide (compound III). These transformations can be brought aboutin vitro, the first step by means of acid or base, and the second by extended treatment with acid. The rate of cyclization and hydrolysis of compound I varies directly with soil temperature, being rapid at high temperature (37 C) and very slow at low temperature (5 C). The rate of chemical change of compound I in soil is influenced to a much greater degree by temperature than by soil moisture content. The effect of soil type on transformation of compound I was studied and compounds II and III were present in five of the six soils examined. The herbicidal activity of compounds II and III was negligible in comparison to compound I.

scholarly journals Use of a Hydrolytic Procedure and Spectrometric Methods in the Structure Elucidation of a Thiocarbonyl Analogue of Sildenafil Detected as an Adulterant in an Over-the-Counter Herbal Aphrodisiac

2009 ◽  
Vol 92 (5) ◽  
pp. 1336-1342 ◽  
Author(s):  
John C Reepmeyer ◽  
D Andr d'Avignon
Keyword(s):  
Dietary Supplement ◽  
Carbonyl Group ◽  
Minor Component ◽  
Pyrimidine Ring ◽  
Over The Counter ◽  
Methyl Group ◽  
Nmr Spectrometry ◽  
A Minor ◽  
Hydrolysis Of ◽  
Hydroxyethyl Group

Abstract A sildenafil-related compound was detected in an herbal dietary supplement marketed as an aphrodisiac. The compound was identified as an analogue of sildenafil in which the carbonyl group in the pyrimidine ring of sildenafil was substituted with a thiocarbonyl group, and the methyl group on the piperazine ring was substituted with a hydroxyethyl group. Based on this structure, the compound was named thiohydroxyhomosildenafil. The structure of the compound was established using HPLC/MS, UV spectrometry, electrospray ionization-MS/MS, NMR spectrometry, and a hydrolytic process. One key product of hydrolysis was 1-(2-hydroxyethyl)-piperazine; the identification of this product defined the amine portion of the compound. Another key product of hydrolysis was hydroxyhomosildenafil, generated by hydrolysis of the thiocarbonyl group to a carbonyl group (C S C O). Hydroxyhomosildenafil was detected as a minor component in the dietary supplement.

Hydration of the Carbonyl Group. A Theoretical Study of the Cooperative Mechanism

1995 ◽  
Vol 117 (15) ◽  
pp. 4240-4260 ◽  
Author(s):  
Saul Wolfe ◽  
Chan-Kyung Kim ◽  
Kiyull Yang ◽  
Noham Weinberg ◽  
Zheng Shi
Keyword(s):  
Carbonyl Group ◽  
Theoretical Study ◽  
Group A
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