ChemInform Abstract: CATALYZED INSERTION REACTIONS INTO ALCOHOLIC HYDROXYL GROUPS BY DIAZO DERIVATIVES OF COMPOUNDS WITH ACTIVATED METHYLENE GROUPS

1976 ◽  
Vol 7 (51) ◽  
pp. no-no
Author(s):  
G. FERDINAND ◽  
W. JEBLICK ◽  
K. SCHANK
Keyword(s):  
Hydroxyl Groups ◽  
Insertion Reactions ◽  
Methylene Groups ◽  
Derivatives Of ◽  
Alcoholic Hydroxyl

Analytical Methods in Rubber Chemistry. Part V. Estimation of the Oxygen of Highly Autoöxidized Rubber Contained in Carboxyl, Ester, Carbonyl, Epoxide and Hydroxyl Groups

1942 ◽  
Vol 15 (4) ◽  
pp. 965-977
Author(s):  
F. Hilton
Keyword(s):  
Functional Groups ◽  
Hydroxyl Groups ◽  
Double Bonds ◽  
Primary Products ◽  
Secondary Reactions ◽  
Methylene Groups ◽  
Products Of Reaction ◽  
Methylene Group ◽  
Alcoholic Hydroxyl ◽  
Oxidative Attack

Abstract In the course of a study of the autoöxidation of natural rubber and of low-molecular olefins of allied structure, it has been necessary to ascertain the nature and relative proportions of the functional groups to which the ingoing oxygen may give rise. Up to the present it has been established that the products of autoöxidation reactions are in general highly complex mixtures, and that even such simple olefins as dihydromyrcene and cyclohexene may give rise to molecules which bear a varied assortment of hydroperoxide, alcoholic hydroxyl, epoxide and carbonyl groups. Available evidence further indicates that the primary products of autoöxidation are hydroperoxides, formed by the reaction of oxygen at methylene groups adjacent to double bonds, and that it is the secondary reactions which these hydroperoxides undergo which are responsible, directly or indirectly, for the formation of the other oxygen-containing groups which have been observed. Molecules of rubber hydrocarbon contain, on an average, several thousand methylene groups adjacent to double bonds. Each such methylene group is at least the potential seat of oxidative attack, and it might be anticipated that if the autoöxidation of rubber proceeds in a manner analogous to that of simpler olefins, the products of reaction would be extremely complex and that they might contain any or all of the following functional groups

Comparative Studies of Brown Coal and Lignin. I. Infra-Red Spectra

1960 ◽  
Vol 13 (1) ◽  
pp. 156 ◽  
Author(s):  
RA Durie ◽  
BM Lynch ◽  
S Sternhell
Keyword(s):  
Brown Coal ◽  
Hydriodic Acid ◽  
Conclusive Evidence ◽  
Hydroxyl Groups ◽  
Infra Red ◽  
Aliphatic Ether ◽  
Derivatives Of ◽  
Alcoholic Hydroxyl ◽  
Chemical Evidence

The infra-red spectra of two softwood lignins are discussed with reference to the spectra of their acetyl and methoxyl derivatives. The spectra of the respective acetyl derivatives provide conclusive evidence for the presence of both phenolic and alcoholic groups in lignin and oxidized lignin, and of alcoholic groups only in the methoxyl derivatives of both these samples. Treatment of lignin with hydriodic acid in the conventional Zeisel determination of methoxyl groups eliminates the alcoholic hydroxyl groups and appears to split aliphatic ether linkages. The spectrum of lignin treated with hydriodic acid is very similar to that of brown coal, which supports previous chemical evidence that brown coal appears to be essentially " demethylated dehydrated lignin ". The progress of the isolation of lignin from wood was followed by infra-red spectroscopy.

The role of secondary alcoholic groups of D-galacturonan in its degradation with exo-D-galacturonanase

1980 ◽  
Vol 45 (2) ◽  
pp. 427-434 ◽  
Author(s):  
Kveta Heinrichová ◽  
Rudolf Kohn
Keyword(s):  
Acetyl Derivative ◽  
Competitive Inhibitor ◽  
Hydroxyl Groups ◽  
Pectic Acid ◽  
Substrate Complex ◽  
Enzyme Substrate ◽  
The Individual ◽  
Degradation Degree ◽  
Derivatives Of

The effect of exo-D-galacturonanase from carrot on O-acetyl derivatives of pectic acid of variousacetylation degree was studied. Substitution of hydroxyl groups at C(2) and C(3) of D-galactopyranuronic acid units influences the initial rate of degradation, degree of degradation and its maximum rate, the differences being found also in the time of limit degradations of the individual O-acetyl derivatives. Value of the apparent Michaelis constant increases with increase of substitution and value of Vmax changes. O-Acetyl derivatives act as a competitive inhibitor of degradation of D-galacturonan. The extent of the inhibition effect depends on the degree of substitution. The only product of enzymic reaction is D-galactopyranuronic acid, what indicates that no degradation of the terminal substituted unit of O-acetyl derivative of pectic acid takes place. Substitution of hydroxyl groups influences the affinity of the enzyme towards the modified substrate. The results let us presume that hydroxyl groups at C(2) and C(3) of galacturonic unit of pectic acid are essential for formation of the enzyme-substrate complex.

scholarly journals Titanium Dioxide Modified with Alcoholic Hydroxyl Groups

1994 ◽  
Vol 67 (8) ◽  
pp. 489-495 ◽  
Author(s):  
Tsuneo SUHARA ◽  
Hiroshi HUKUI ◽  
Michihiro YAMAGUCHI
Keyword(s):  
Titanium Dioxide ◽  
Hydroxyl Groups ◽  
Alcoholic Hydroxyl

Proton spin–spin coupling constants and intramolecular hydrogen bonding in bromine derivatives of 1,3-dihydroxybenzene

1976 ◽  
Vol 54 (14) ◽  
pp. 2228-2230 ◽  
Author(s):  
Ted Schaefer ◽  
J. Brian Rowbotham
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Proton Spin ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Hydroxyl Groups ◽  
Oh Groups ◽  
Spin Coupling Constants ◽  
Spin Spin Coupling ◽  
Derivatives Of

The conformational preferences in CCl4 solution at 32 °C of the hydroxyl groups in bromine derivatives of 1,3-dihydroxybenzene are deduced from the long-range spin–spin coupling constants between hydroxyl protons and ring protons over five bonds. Two hydroxyl groups hydrogen bond to the same bromine substituent in 2-bromo-1,3-dihydroxybenzene but prefer to hydrogen bond to different bromine substituents when available, as in 2,4-dibromo-1,3-dihydroxybenzene. When the OH groups can each choose between two ortho bromine atoms, as in 2,4,6-tribromoresorcinol, they apparently do so in a very nearly statistical manner except that they avoid hydrogen bonding to the common bromine atom.

scholarly journals Characteristic Flavonoids from Acacia burkittii and A. Acuminata Heartwoods and their Differential Cytotoxicit to Normal and Leukemia Cells

2009 ◽  
Vol 4 (1) ◽  
pp. 1934578X0900400
Author(s):  
Mary H. Grace ◽  
George R. Wilson ◽  
Fayez E. Kandil ◽  
Eugene Dimitriadis ◽  
Robert M. Coates
Keyword(s):  
Cell Line ◽  
Relative Concentration ◽  
Hydroxyl Groups ◽  
L1210 Cells ◽  
Green Monkey ◽  
Bioassay Guided Fractionation ◽  
Acetone Extracts ◽  
Derivatives Of ◽  
Hplc Analyses ◽  
Mouse Lymphoma

Bioassay-guided fractionation of extracts from Acacia burkittii and A. acuminata heartwoods against an L1210 (mouse lymphoma) cell line led to the isolation of two flavan-3,4-diols, melacacidin (1) and isomelacacidin (2), and three flavonoids, 3,7,8,3′,4′-pentahydroxyflavone (3), 7,8,3′,4′-tetrahydroxyflavanone (4) and 3,7,8,3′,4′-pentahydroxyflavanone (5). HPLC analyses (280 nm) of the 70% acetone extracts of the two plants showed different profiles in terms of the relative concentration of the five identified compounds. When tested against L1210, compounds 1 and 2 were the most active, giving ID50 values of 2.5 and 4.5 μg/mL, respectively. The lower activity of the other isolated compounds indicated the importance of the 3,4-hydroxyl groups for the cytotoxic activity of these flavonoids. The isolated compounds were either non-toxic or had very low toxicities against the “normal” CV-1 cell line (green monkey kidney cells). The O-methyl and O-acetyl derivatives of these compounds were inactive. Ten commercially available phenolic compounds (6-15) were also tested for their activity against both CV-1 and L1210 cell lines. Flavan-3,4-diols 1 and 2 were more cytotoxic to L1210 cells than all tested compounds, including catechin and epicatechin, the most abundant flavan-3-ols in many fruits and vegetable.

Molecular recognition XI. The synthesis of extensively deoxygenated derivatives of the H-type 2 human blood group determinant and their binding by an anti-H-type 2 monoclonal antibody and the lectin 1 of Ulexeuropaeus

1992 ◽  
Vol 70 (1) ◽  
pp. 254-271 ◽  
Author(s):  
Ulrike Spohr ◽  
Eugenia Paszkiewicz-Hnatiw ◽  
Naohiko Morishima ◽  
Raymond U. Lemieux
Keyword(s):  
Monoclonal Antibody ◽  
Molecular Recognition ◽  
Blood Group ◽  
Human Blood ◽  
Water Molecules ◽  
Hydroxyl Groups ◽  
Human Blood Group ◽  
Derivatives Of ◽  
Hydrogen Bonded

The relative potencies of a wide variety of deoxygenated derivatives of the methyl glycoside of α-L-Fuc-(1 → 2)-β-D-Gal-(1 → 4)- β-D-GlcNAc (the H-type 2 human blood group related trisaccharide) for the inhibition of the binding of an artificial H-type 2 antigen by the lectin I of Ulexeuropaeus confirmed the previous evidence that the key and productive interaction involves only the three hydroxyl groups of the α-L-fucose unit, the hydroxyl at the 3-position of the β-D-galactose residue, and the nonpolar groups in their immediate environment. Except for the acetamido group and the hydroxymethyl of the β-D-Gal unit, which stay in the aqueous phase, on complex formation the remaining three hydroxyl groups appear to come to reside at or near the periphery of the combining site since their replacement by hydrogen causes relatively small changes (< ± 1 kcal/mol) in the stability of the complex (ΔG0). Relatively much larger but compensating changes occur for the enthalpy and entropy terms, and these may arise primarily from the differences in the water structure about the periphery of the combining site and the oligosaccharide both prior to and after complexation. It is proposed that steric constraints lead to an ordered state of the water molecules hydrogen-bonded to the polar groups within the cleft formed by the key region of the amphiphilic combining site. Their release to form less ordered clusters of more strongly hydrogen-bonded water molecules in bulk solution would contribute importantly to the driving force for complexation. It is demonstrated that the surface used for the binding of H-type 2-OMe by a monoclonal anti-H antibody is virtually identical to that used by the Ulex lectin. Keywords: molecular recognition, H-type 2 blood group determinant and deoxygenated derivatives, lectin I of Ulexeuropaeus, anti-H-type 2 monoclonal antibody, enthalpy–entropy compensation.

Synthesis and Biological Evaluation of Acetylcholinesterase Inhibitor Macakurzin C and Its Derivatives

Synlett ◽  
2015 ◽  
Vol 26 (08) ◽  
pp. 1131-1134 ◽  
Author(s):  
Hyoungsu Kim ◽  
Seung-Hoon Baek ◽  
Hongjun Jang
Keyword(s):  
Inhibitory Activity ◽  
Acetylcholinesterase Inhibitor ◽  
Biological Evaluation ◽  
Hydroxyl Groups ◽  
Structural Requirements ◽  
Ache Inhibitory Activity ◽  
Synthesis And Biological Evaluation ◽  
Derivatives Of

The derivatives of macakurzin C containing a modified D ring and protected C(3)/C(5)-hydroxyl groups were synthesized and their in vitro AChE inhibitory activity and neurotoxicity were evaluated to identify the structural requirements for the activities. The results indicated that C(3)-benzyl-protected derivative has a more potent AChE inhibitory activity (IC50, 2.6 μM) and a less neurotoxicity (GI50, >100 μM) than synthetic macakurzin C (IC50, 9.1 μM; GI50, 16.6 μM).

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