The hydroxyl stretching frequencies and conformations of Flavan-4-ols and Thiaflavan-4-ols

1969 ◽  
Vol 22 (11) ◽  
pp. 2337 ◽  
Author(s):  
GF Katekar ◽  
AG Moritz
Keyword(s):  
Carbon Tetrachloride ◽  
Benzene Ring ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Frequency Shifts ◽  
Characteristic Frequencies ◽  
Carbon Tetrachloride Solution ◽  
Free Hydroxyl ◽  
Related Compounds

The hydroxyl stretching frequencies of some 2,4-cis and 2,4-trans flavan-4-ols, thiaflavan-4-ols, and related compounds have been measured in dilute carbon tetrachloride solution. Characteristic frequencies are observed at 3626�2 cm-1 (free hydroxyl), 3616�1, and 3597�2 cm-1. The 3616 and 3597 cm-1 bands are assigned to pseudo-axial and pseudo-equatorial hydroxyl groups respectively. Evidence is presented to show that the frequency shifts arise from differences in the interaction of the hydroxyl group with the π-electrons of the fused benzene ring, and that these flavans and thiaflavans exist in half- chair, rather than sofa conformations.

THE INFRARED FREQUENCIES AND INTENSITIES OF THE HYDROXYL GROUP IN 2,6-DI-tert-BUTYL-4-SUBSTITUTED PHENOLS

1960 ◽  
Vol 38 (7) ◽  
pp. 1092-1098 ◽  
Author(s):  
K. U. Ingold
Keyword(s):  
Carbon Tetrachloride ◽  
Benzene Ring ◽  
Hydroxyl Group ◽  
Steric Repulsion ◽  
Substituted Phenols ◽  
Tert Butyl ◽  
Carbon Tetrachloride Solution ◽  
Butyl Group ◽  
Tert Butyl Group ◽  
Infrared Frequencies

The infrared frequencies, intensities, and apparent half band widths of the O—H stretching band of a series of 2,6-di-tert-butyl-4-substituted phenols have been measured in carbon tetrachloride solution and compared with the corresponding 4-substituted phenols. The frequencies of the former are 36 cm−1 higher than the latter and the intensities are also slightly higher. Both the frequency and intensity follow a Hammett ρσ relation. It is shown that the O—H bond lies in the plane of the benzene ring, the increase in frequency and intensity being ascribed to a steric repulsion of the phenolic hydrogen by the adjacent tert-butyl group.

scholarly journals Synthesis and Characterizations of Dipeptide Derivative of Gentamicin

2019 ◽  
Vol 28 (2) ◽  
pp. 73-82
Author(s):  
Oun D. Khudair ◽  
Diar A. Fatih
Keyword(s):  
Acid Chloride ◽  
Solution Method ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Free Hydroxyl ◽  
Ester Linkage ◽  
Amine Groups ◽  
Conventional Solution ◽  
Dipeptide Derivative

Abstract       The target derivative are gentamicin linked with L-Val- L-Ala by an ester linkage. These were synthesized by esterification method, which included the reaction of -OH hydroxyl group on (carbon No.5) of gentamicin with the acid chloride of the corresponding dipeptide, The preparation of new derivative of gentamicin involved protected the primary & secondary amine groups of Gentamicin, by Ethylchloroformate (ECF) to give N-carbomethoxy Gentamicin which was used for further chemical synthesis involving the free hydroxyl groups. Then prepared dipeptide (L-Val- L-Ala) by conventional solution method in present DCC & HoBt then reacted with thionyl chloride to prepared acid chloride of dipeptides, then after, linked by ester linkage to N-protection gentamicin in present pyridine as base, finally deportation the amino group of synthesized compound by using TFAA in present anisole. The characterization of the titled compounds were performed utilizing FTIR spectroscopy, CHNS elemental analysis, and by measurements of their physical properties.  

The Dielectic properties of Crystalline Alcohols containing sterically hindered Hydroxyl groups

1953 ◽  
Vol 6 (2) ◽  
pp. 104 ◽  
Author(s):  
RJ Meakins
Keyword(s):  
Hydrogen Bonding ◽  
Hydroxyl Group ◽  
Appreciable Amount ◽  
Hydroxyl Groups ◽  
Dipole Orientation ◽  
Hindered Rotation ◽  
Dielectric Absorption ◽  
Free Hydroxyl ◽  
Sterically Hindered ◽  
High Dielectric

It has been previously suggested that the high dielectric absorption of certain crystalline forms of long-chain alcohols is associated with hydrogen-bonding of the hydroxyl groups. This theory is supported by the results given in the present paper, which show that with other alcohols, in which the hydroxyl groups are sterically hindered, the loss is almost completely eliminated. The smallest losses are obtained with triphenylcarbinol and cholesterol which both possess hydroxyl groups embedded in a bulky molecular structure. For the former compound, infra-red data from the literature indicate the absence of any appreciable amount of hydrogen-bonding and are thus in agreement with the evidence from dielectric measurements. High frequency absorption observed in these compounds is considered to be associated with dipole orientation resulting from hindered rotation of the free hydroxyl groups. The effects of steric hindrance of the hydroxyl group are also observed in tert.-butanol.

STUDIES ON LIGNIN AND RELATED COMPOUNDS: IX. ETHERS OF GLYCOL-LIGNIN

1931 ◽  
Vol 5 (3) ◽  
pp. 302-305
Author(s):  
Harold Hibbert ◽  
Léo Marion
Keyword(s):  
Sodium Hydroxide ◽  
Sodium Salt ◽  
Aqueous Sodium Hydroxide ◽  
Hydroxyl Groups ◽  
Acidic Properties ◽  
Aqueous Sodium ◽  
Spruce Wood ◽  
Free Hydroxyl ◽  
Chloro Derivatives ◽  
Related Compounds

Glycol-lignin prepared from spruce wood has been found to form a sodium salt which reacts with chloro-derivatives, giving rise to the corresponding glycol-lignin ethers. These compounds are insoluble in aqueous sodium hydroxide but still contain free hydroxyl groups which can be methylated without the ethereal linkage being broken. Hence glycol-lignin contains several free hydroxyl groups, one or more of which possess acidic properties. Both the methoxymethyl ether and the 2:4-dinitrophenyl ether of glycol-lignin have been prepared. The evidence would seem to indicate the presence of both phenolic and aliphatic hydroxyl groups.

scholarly journals SIGNIFICANCE OF THE HYDROXYL GROUPS OF STEROIDS IN PROMOTING GROWTH

1954 ◽  
Vol 100 (3) ◽  
pp. 241-246 ◽  
Author(s):  
Charles Huggins ◽  
Elwood V. Jensen
Keyword(s):  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Critical Importance ◽  
Hydrogen Atoms ◽  
Albino Rat ◽  
Ketone Group ◽  
Related Compounds

The presence of a 17ß-hydroxyl group endows the simple androstane molecule with the ability to produce growth of the uterus, vagina, and prostate of the female hypophysectomized albino rat. It appears that hydrogen atoms at position 17 are of critical importance since related compounds with a ketone group at this site are inactive. Monofunctional steroids with a hydroxyl or a ketone group at position 3 likewise are devoid of activity. If a phenolic A-ring is present in monofunctional steroids the 17ß-hydroxyl group is not obligatory for growth. Proliferation of the uterus and vagina were found to follow the administration of 17-desoxyestradiol.

Studies on the Lignin of Eucalyptus regnans. II. The Nature of the Hydroxyl Groups and the Presence of the Carbonyl Group in Thiolignin

1948 ◽  
Vol 1 (2) ◽  
pp. 241
Author(s):  
JWT Merewether
Keyword(s):  
Benzoyl Chloride ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Carbonyl Groups ◽  
Eucalyptus Regnans ◽  
Trimethyl Ether ◽  
Free Hydroxyl ◽  
Active Methylene ◽  
Methylene Group ◽  
Alcoholic Hydroxyl

E. regnans thiolignin reacts with p-toluenesulphonyl chloride in pyridine to form a hexatosyl derivative ; its trimethyl ether reacts likewise to form a tritosyl derivative. Both compounds still have a free hydroxyl group which can be acetylated. Similarly they yield a hexabenzoate and tribenzoate respectively by the Schotten-Baumann reaction, but in pyridine, thiolignin reacts with benzoyl chloride to give a heptabenzoate and trimethylthiolignin a tetrabenzoate. No reaction takes place when trimethyl thiolignin is treated with triphenylchloromethane in pyridine. The above data are interpreted as evidence that of the four alcoholic hydroxyl groups three are secondary and one tertiary. With phenylhydrazine, thiolignin yields a phenylosazone ; with p-nitrophenylhydrazine it yields a p-nitrophenylhydrazone. On the other hand, trimethylthiolignin does not react with phenylhydrazine, indicating the absence of non-enolizable carbonyl groups. Thiolignin condenses with benzaldehydes indicating the presence of an active methylene group. From this evidence it is deduced that the grouping CH2-CO-CHOH- is present.

Configurational effects on 13C chemical shifts of 1,6-anhydro-hexopyranoses and related compounds. Utility of 13C–1H coupling patterns for signal assignments

1976 ◽  
Vol 54 (14) ◽  
pp. 2301-2309 ◽  
Author(s):  
R. George S. Ritchie ◽  
Natsuko Cyr ◽  
Arthur S. Perlin
Keyword(s):  
Relative Stability ◽  
Chemical Shifts ◽  
Axial Orientation ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
First Order ◽  
Bicyclic Compounds ◽  
Saturated Ring ◽  
Bond Polarization ◽  
Related Compounds

An analysis of configurational effects on the 13C chemical shifts of bicyclic compounds of the 1,6-anhydrohexopyranose and 2,7-anhydroheptulopyranose type is presented. As with other saturated ring Systems, strong upfield shifts are found in association with an axial orientation of the substituents, although in this respect 13C nuclei of the anhydro ring appear to exhibit atypical behaviour. Deshielding changes characterize a syn-diaxial orientation of hydroxyl groups, and also of a hydroxyl group with respect to the bridgehead bonds. No appreciable effects of antiperiplanar hydroxyl groups on 13C chemical shifts have been detected. Possible interrelationships between 13C or 1H chemical shifts and steric interactions are discussed with reference to the relative stability of isomeric anhydrosugars and C—H bond polarization. Some characteristics of one-, two-, and three-bond 13C–1H coupling are described, and are shown to be of value in several instances for the assignment of 13C signals. The 1H-coupled signal for methylenic C-6 of 1,6-anhydrides is commonly non-first order, in contrast to the simpler pattern exhibited by methylenic C-1 of 2,7-anhydrides.

Microdetermination of Nodososide and Related Compounds Using Ceric Sulphate as Oxidizing Agent

1971 ◽  
Vol 26 (11) ◽  
pp. 1137-1139
Author(s):  
S. A. I. Rizvi ◽  
Tajwar Sultana
Keyword(s):  
Carbon Dioxide ◽  
Sulphuric Acid ◽  
Hydroxyl Groups ◽  
Oxidizing Agent ◽  
Cassia Occidentalis ◽  
Free Hydroxyl ◽  
Ceric Sulphate ◽  
Related Compounds ◽  
Acetic Acids

Nodososide and emodin from the flowers of Cassia nodosa and physcion-1-glucoside and physcion from the seeds of Cassia occidentalis can be determined in micro amounts by oxidation with eerie sulphate in presence of sulphuric acid. The reactions required 48, 26, 54 and 30 moles of oxidant respectively, resulting in the formation of formic and acetic acids in each case while carbon dioxide was also produced in the cases of nodososide and physcion-1-glucoside. The conditions of stoichiometric oxidation of the anthraquinones have been studied. Methylation of the hydroxyl groups has been found to retard the rate of oxidation of the anthraquinones whereas free hydroxyl groups are easily attacked by ceric ions. The ranges of errors observed are 0.2 -1.7%, 0.3 - 2.9%, 0.2 -3.5% and 0.2 - 3.5% respectively.

scholarly journals Preparation of a set of selectively protected disaccharides for modular synthesis of heparan sulfate fragments: toward the synthesis of several O-sulfonated [β-D-GlcUA-(1→4)-β-D-GlcNAc]OPr types

2005 ◽  
Vol 3 (4) ◽  
pp. 803-829 ◽  
Author(s):  
Hammed Hassan
Keyword(s):  
Heparan Sulfate ◽  
Building Blocks ◽  
Protecting Groups ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Allyl Ethers ◽  
Modular Synthesis ◽  
Stereocontrolled Synthesis ◽  
Benzyl Ethers ◽  
Free Hydroxyl

AbstractA concise method for a stereocontrolled synthesis of a set of selectively protected disaccharides is reported. Coupling of the donor 11 onto acceptors 23 and 24, promoted by trimethylsilyl triflate-N-iodosuccinimide (TMSOTf-NIS), generated the disaccharides 25 and 26. Under typical conditions, condensation of the fully protected donor 12 onto acceptors 23 and 24 produced the disaccharides 27 and 28. The building blocks 25–28 were prepared in moderate yields having exclusive β-stereoselectivity. A unique pattern of protecting groups distinguished clearly between positions to be sulfated and functional groups remaining as free hydroxyl groups. Acetyl and/or levulinoyl esters temporarily protected the positions to be sulfated, while benzyl ethers were used for permanent protection. The anomeric positions were protected as allyl ethers, whereas the 4′-positions were masked as p-methoxybenzyl (PMB) ethers. The orthogonality of the PMB and allyl groups can then be used for further elongation of the chain by recurrent deprotection and activation steps. The hydroxyl group, OH-6, of glucosamine moieties was protected as a TBDPS ether to avoid oxidation. A five-step deprotection/sulfonation sequence was applied to the disaccharide 27 to generate the corresponding sulfated [β-D-GlcUA-2-OSO3Na-(1→4)-β-D-Glc pNAc]-(1→O-Pro) 34.

scholarly journals Actinobacillus actinomycetemcomitans Serotype b Lipopolysaccharide Mediates Coaggregation with Fusobacterium nucleatum

2003 ◽  
Vol 71 (6) ◽  
pp. 3652-3656 ◽  
Author(s):  
Graciela Rosen ◽  
Ira Nisimov ◽  
Monica Helcer ◽  
Michael N. Sela
Keyword(s):  
Fusobacterium Nucleatum ◽  
Actinobacillus Actinomycetemcomitans ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Binding Studies ◽  
Monosaccharide Residue ◽  
Sugar Binding ◽  
Free Hydroxyl ◽  
Serotype B

ABSTRACT Purified Actinobacillus actinomycetemcomitans serotype b lipopolysaccharide (LPS) was found to be able to bind Fusobacterium nucleatum cells and to inhibit binding of F. nucleatum to A. actinomycetemcomitans serotype b. Sugar binding studies showed that the requirements for binding of A. actinomycetemcomitans serotype b LPS to the F. nucleatum lectin are the presence of a metal divalent ion, an axial free hydroxyl group at position 4, and free equatorial hydroxyl groups at positions 3 and 6 of d-galactose, indicating that the β-N-acetyl-d-galactosamine in the serotype b LPS trisaccharide repeating unit is the monosaccharide residue recognized by the F. nucleatum lectin. These data strongly suggest that A. actinomycetemcomitans serotype b LPS is one of the receptors responsible for the lactose-inhibitable coaggregation of A. actinomycetemcomitans to fusobacteria.

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