The Cardiac Glycosides of Gomphocarpus fruticosus R.Br. II. Gomphoside

1957 ◽  
Vol 10 (1) ◽  
pp. 79 ◽  
Author(s):  
RR Watson ◽  
SE Wright
Keyword(s):  
Acetic Acid ◽  
Absorption Spectra ◽  
Cardiac Glycosides ◽  
Chromium Trioxide ◽  
Periodic Acid ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Colour Reaction ◽  
Infra Red ◽  
Hydrolysis Of

Gomphoside is the second glycoside which has been isolated from Gomphocarpus fruticosus R.Br. grown in Australia. This compound analyses for the formula C29H44O8 and contains neither methoxyl nor acetyl groups, but forms a diacetate, C33H48O10, which is unstable to chromium trioxide in acetic acid. Although gomphoside gives a negative Keller-Kiliani reaction, a quantitative oxidation by periodic acid indicates the presence of two free adjacent hydroxyl groups in the molecule. Hydrolysis of gomphoside gives gomphogenin, C23H34O5, which does not give a colour reaction with tetranitromethane. The acetylation of gomphogenin yields acetylgomphogenin, C25H36O6, which is unstable to chromium trioxide in acetic acid. Gomphoside and its derivatives have ultraviolet and infra-red absorption spectra typical of those of the normal digitaloid compounds. The reactions which have been carried out on these substances indicate the presence of an hydroxyl group in gomphogenin, besides the normal hydroxyl groups at C3 and C14, which is resistant to acetylation, but which can be oxidized by chromium trioxide in acetic acid. The nature of the carbohydrate is as yet unknown.

scholarly journals Investigations of infra-red spectra-absorption of some hydroxy compounds in the region of 3 μ

1937 ◽  
Vol 162 (910) ◽  
pp. 419-441 ◽  
Author(s):  
John Jacob Fox ◽  
A. E. Martin ◽  
Robert Robertson
Keyword(s):  
Absorption Band ◽  
Absorption Spectra ◽  
Polar Solvent ◽  
Hydroxyl Group ◽  
Infra Red ◽  
Hydroxy Compounds ◽  
Hydroxyl Compounds ◽  
Hydroxyl Band

It has been realized by several investigators that with some exceptions compounds containing the hydroxyl group have a sharp absorption band close to 2.75 μ , and frequently another much wider band about 3 μ . Erreta and Mollet (1936, 1937) and Erreta (1937) have shown that the latter is an "association" band which diminishes on dilution in a non-polar solvent, or by raising the temperature, when the association complexes split up and the hydroxyl band at 2.75 μ becomes more pronounced. (Compare also Barchewitz (1937) and Freymann (1937). In the present investigations of the infra-red absorption spectra of certain hydroxyl compounds in the 3 μ region we have made observation of the effect of the structure of the molecule on both the above-mentioned bands, as well as on the CH vibration bands. The OH bands in the region about 1.4-1.6 μ have been investigated by Wulf and his co-workers (1935, 1936) for the most part with solutions of about 0.01 mol./l/ in which the association band had practically disappeared.

scholarly journals Antioxidant activity of some coumarins / Antioxidačná activita niektorých kumarínov

2015 ◽  
Vol 62 (s9) ◽  
pp. 41-45 ◽  
Author(s):  
F. Šeršeň ◽  
M. Lácová
Keyword(s):  
Antioxidant Activity ◽  
Acetic Acid ◽  
Superoxide Anion ◽  
The Other ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Coumarin Derivatives ◽  
Antioxidant Effectiveness ◽  
Derivatives Of ◽  
Superoxide Anion Radicals

AbstractNineteen derivatives of coumarin were tested on the scavenging of 2,2-diphenyl-1-picrylhydrazyl, hydroxyl and superoxide anion radicals. It was found that antioxidant activity exhibits only such coumarins that contain hydroxyl groups. The derivatives without hydroxyl group showed very low antioxidant effectiveness or they were ineffective. On the other hand, the greatest antioxidant effectiveness was exhibited by coumarin derivatives that contained hydroxyl groups in 6 or 8 position, whereas the effectiveness of derivatives with one hydroxyl group in 4, 5 or 7 position was very low. Based on scavenging of the above-mentioned radicals, it was found that the most effective scavengers were 7,8-dihydroxy-4-methylcoumarin (i.e. compound that contains two hydroxyl groups in 7 and 8 positions), (7,8-dihydroxy-2-oxo-2H-chromen-4-yl)acetic acid (this compound contains in addition to two hydroxyl groups in 7 and 8 positions also one hydroxyl group in the acidic residue), esculetin (6,7-dihydroxycoumarin) and 6,7-dihydroxy-4-methylcoumarin.

Theoretische Untersuchungen zum Absorptionsverhalten von Hydroxyindolen / Theoretical Studies about the Absorption Spectra of Hydroxyindoles

1983 ◽  
Vol 38 (5) ◽  
pp. 566-569
Author(s):  
Walter Fabian
Keyword(s):  
Charge Transfer ◽  
Absorption Band ◽  
Absorption Spectra ◽  
Similarity Measure ◽  
Bathochromic Shift ◽  
Electronic States ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Theoretical Studies ◽  
Locally Excited

The absorption spectra of hydroxyindoles are calculated by means of the PPP and INDO/S-CI methods. The results of the PPP calculations are analyzed in terms of molecular subunits using the parsorbital method, similarity measure and configuration analysis. These methods show that the electronic states of the hydroxyindoles are best described by fragmentation in indole + hydroxyl groups. On the basis of this fragmentation the bathochromic shift of the first absorption band of 5- and 6-hydroxyindole as compared to 4- and 7-hydroxyindole and indole itself can be explained by the contribution of the charge transfer configuration from the hydroxyl group to the locally excited indole state.

The cardiac glycosides of Gomphocarpusf ruticosus R.Br. I. Afroside

1956 ◽  
Vol 9 (4) ◽  
pp. 497 ◽  
Author(s):  
TR Watson ◽  
SE Wright
Keyword(s):  
Simple Structure ◽  
Lactone Ring ◽  
Aldehyde Group ◽  
Hydroxyl Group ◽  
Naturally Occurring ◽  
Ring Junction ◽  
Infra Red ◽  
Free Aldehyde ◽  
Acetyl Group ◽  
Hydrolysis Of

Afroside, C29H42O9, is a new cardiac glycoside which has been obtained from Gomphocarpus fruticosus R.Br. It contains a carbonyl (aldehyde) group at C10, and a secondary hydroxyl group in the nucleus, which has been placed provisionally at position C11. On the basis of the available evidence, afroside appears to consist of a mixture of the isomeric free aldehyde and the 19-11 cyclic hemiacetal forms. Of these substances, the cyclic hemiacetal form is the only one which has been isolated in pure condition (afroside B). Acetylation of afroside produced a triacetate, C35H46O12.H2O, which is identical with that obtained by the acetylation of afroside B. Reduction of afroside with sodium borohydride produces afrosidol, C29H44O9, which shows no evidence for a carbonyl group at C10. Hydrolysis of afroside produces α-anhydroafrogenin, C23H28-30O5.H2O, which forms a monoacetate, C25H32O7.H2O. The infra-red spectra of these compounds show the presence of a saturated γ-lactone ring in the structure of the nucleus, besides the normal Δα-β-γ-lactone ring at C17 (1786, 1755, 1633 cm-1). Acetyl-α-anhydroafrogenin also shows an intense absorption band of simple structure at 1238 cm-1, which indicates an equatorially orientated acetyl group at C3. As all the naturally occurring cardiac aglycones of known structure have a β-orientated hydroxyl group at C3, for the substituent in this position to be equatorial, the A/B ring junction is probably trans. Hydrolysis of afrosidol produces α-anhydroafrogenol, C23H32O5.H2O, which forms a diacetate, C27H36O7.H2O. The infra-red spectrum of α-anhydroafrogenol shows no evidence of the saturated y-lactone ring which is present in the structure of α-anhydroafrogenin.

The Course of Autoöxidation Reactions in Polyisoprene and Allied Compounds. III. The Oxidation of Rubber in the Presence of Acetic Acid or Acetic Anhydride

1944 ◽  
Vol 17 (2) ◽  
pp. 267-276
Author(s):  
George F. Bloomfield
Keyword(s):  
Acetic Acid ◽  
Acetic Anhydride ◽  
Chain Scission ◽  
Considerable Proportion ◽  
Hydroxyl Groups ◽  
Carbonyl Groups ◽  
Free Hydroxyl ◽  
Hydrolysis Of ◽  
Oxygenated Products ◽  
Oxidative Attack

Abstract Oxidation of rubber by oxygen in the presence of acetic anhydride leads to formation of highly oxygenated products containing a considerable proportion of acetoxyl groups. The residual unsaturation of the products of highest acetoxyl content, taken in conjunction with other analytical characteristics, indicates that three, rather than two, acetoxyl groups normally combine with each isoprene unit attacked. Although the bulk of the oxygen introduced is present in the form of acetoxyl groups, a portion occurs as carboxyl and carbonyl groups; also, whenever acetic acid is used (partly or wholly) in place of acetic anhydride, some free hydroxyl groups appear in the oxidized rubber. The proportions of carboxyl and carbonyl groups observed can be correlated satisfactorily with the extent of chain-scission occurring during the oxidation, the groups in question forming the new ends of the severed molecules. Hydrolysis of the acetylated products yields hydroxy acids, which readily undergo lactonic elimination of water. Acetic anhydride and acetic acid can clearly act as auxiliary reagents in autoöxidation reactions, and the detailed results obtained with rubber can be best accounted for on the basis of α-methylene peroxidation, followed by decay reactions involving incorporation of the auxiliary reagent as well as oxidative attack at the double bonds of the rubber.

Remarkable stereoselectivity in the hydrolysis of dioxolenium ions and orthoesters fused to anchored six-membered rings

1970 ◽  
Vol 48 (11) ◽  
pp. 1754-1769 ◽  
Author(s):  
J. F. King ◽  
A. D. Allbutt
Keyword(s):  
Acetic Acid ◽  
Good Yield ◽  
Benzoyl Chloride ◽  
Stereoselective Synthesis ◽  
Transition States ◽  
Hydroxyl Group ◽  
Potential Utility ◽  
Silver Acetate ◽  
Steric Strain ◽  
Hydrolysis Of

Hydrolysis of dioxolenium (acyloxonium) ions fused to anchored six-membered rings gives almost exclusively that hydroxyester in which the ester function is axial (and the hydroxyl group equatorial). With the exception of the orthoformate, a group of related orthoesters reacted similarly. The potential utility of these observations in stereoselective synthesis is suggested by the following examples, (a) With trans-decalin-cis-2,3-diol (21) formation of the mono-benzoate via the orthoester leads to the axial ester (23d) in good yield; this procedure is complementary to reaction with benzoyl chloride and pyridine, which gives the equatorial ester (24d) as the only isolated product, (b) The action of silver acetate and iodine in wet acetic acid (the Woodward–Prevost reaction) on trans-Δ2-octaIin gives the axial acetate–equatorial alcohol (23b) again as the only significant product. The generality of this stereoselectivity is further supported by a number of individual examples drawn from the chemistry of carbohydrates. A rationalization is offered which qualitatively accounts for the observed stereoselectivity and its absence in the hydrolysis of the orthoformate, and which is based on the differences in steric strain among the possible transition states that fulfil the stereoelectronic requirements of dialkoxycarbonium ion formation.

Synthesis, Structure and Applications of TiO2 Gels

1986 ◽  
Vol 72 ◽  
Author(s):  
J. Livage
Keyword(s):  
Acetic Acid ◽  
Molecular Level ◽  
Sol Gel ◽  
Titanium Alkoxides ◽  
Chemical Additives ◽  
Display Devices ◽  
Sol Gel Process ◽  
Infra Red ◽  
Tio2 Gels ◽  
Hydrolysis Of

AbstractTiO2 gels are usually obtained through hydrolysis of titanium alkoxides. Chemical additives can however react with the precursor at a molecular level and therefore modify the hydrolysis-condensation reactions. Several examples will be described :acetic acid, acetylacetone or Cr(acac)3. The whole sol-gel process is followed all the way from the precursors to the gel and each step is characterized by spectroscopic experiments (Infra-red, N.M.R, E.S.R.). Some electronic properties of TiO2 gels are then described. Chemical addi-tives allow an optimization of thý sol-gel process according to each speci-fic applications : electrochromic display devices, photoanodes or photoche-mical reactions.

Organic material dissolved during oxygen-alkali pulping of hot water extracted birch sawdust

TAPPI Journal ◽  
2015 ◽  
Vol 14 (4) ◽  
pp. 237-244 ◽  
Author(s):  
JONI LEHTO ◽  
RAIMO ALÉN
Keyword(s):  
Acetic Acid ◽  
Betula Pendula ◽  
Cooking Time ◽  
Hot Water ◽  
Partial Hydrolysis ◽  
Chemical Pulping ◽  
Black Liquors ◽  
Aliphatic Carboxylic Acids ◽  
Hydrolysis Of ◽  
Cooking Conditions

Untreated and hot water-treated birch (Betula pendula) sawdust were cooked by the oxygen-alkali method under the same cooking conditions (temperature = 170°C, liquor-to-wood ratio = 5 L/kg, and 19% sodium hydroxide charge on the ovendry sawdust). The pretreatment of feedstock clearly facilitated delignification. After a cooking time of 90 min, the kappa numbers were 47.6 for the untreated birch and 10.3 for the hot water-treated birch. Additionally, the amounts of hydroxy acids in black liquors based on the pretreated sawdust were higher (19.5-22.5g/L) than those in the untreated sawdust black liquors (14.8-15.5 g/L). In contrast, in the former case, the amounts of acetic acid were lower in the pretreated sawdust (13.3-14.8 g/L vs. 16.9-19.1 g/L) because the partial hydrolysis of the acetyl groups in xylan already took place during the hot water extraction of feedstock. The sulfur-free fractions in the pretreatment hydrolysates (mainly carbohydrates and acetic acid) and in black liquors (mainly lignin and aliphatic carboxylic acids) were considered as attractive novel byproducts of chemical pulping.

Novel Compound from Flowers of Moringa oleifera Active Against Multi- Drug Resistant Gram-negative Bacilli

2020 ◽  
Vol 20 (1) ◽  
pp. 69-75
Author(s):  
Santi M. Mandal ◽  
Subhanil Chakraborty ◽  
Santanu Sahoo ◽  
Smritikona Pyne ◽  
Samaresh Ghosh ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Moringa Oleifera ◽  
Aqueous Acetic Acid ◽  
Phytochemical Analysis ◽  
Hydroxyl Groups ◽  
Drug Resistant ◽  
Gram Negative ◽  
Isolated Compound ◽  
Conventional Antibiotics

Background: The need for suitable antibacterial agents effective against Multi-drug resistant Gram-negative bacteria is acknowledged globally. The present study was designed to evaluate the possible antibacterial potential of an extracted compound from edible flowers of Moringa oleifera. Methods: Five different solvents were used for preparing dried flower extracts. The most effective extract was subjected to fractionation and further isolation of the active compound with the highest antibacterial effect was obtained using TLC, Column Chromatography and reverse phase- HPLC. Approaches were made for characterization of the isolated compound using FTIR, NMR and Mass spectrometry. Antibacterial activity was evaluated according to the CLSI guidelines. Results: One fraction of aqueous acetic acid extract of M. oleifera flower was found highly effective and more potent than conventional antibiotics of different classes against Multi-drug resistant Gram-negative bacilli (MDR-GNB) when compared. The phytochemical analysis of the isolated compound revealed the presence of hydrogen-bonded amine and hydroxyl groups attributable to unsaturated amides. Conclusion: The present study provided data indicating a potential for use of the flowers extract of M. oleifera in the fight against infections caused by lethal MDR-GNB. Recommendations: Aqueous acetic acid flower extract of M. oleifera is effective, in-vitro, against Gram-negative bacilli. This finding may open a scope in pharmaceutics for the development of new classes of antibiotics.

scholarly journals Reactivity of Aliphatic and Phenolic Hydroxyl Groups in Kraft Lignin towards 4,4′ MDI

Molecules ◽  
2021 ◽  
Vol 26 (8) ◽  
pp. 2131
Author(s):  
Leonardo Dalseno Antonino ◽  
Júlia Rocha Gouveia ◽  
Rogério Ramos de Sousa Júnior ◽  
Guilherme Elias Saltarelli Garcia ◽  
Luara Carneiro Gobbo ◽  
...  
Keyword(s):  
Experimental Work ◽  
Chemical Structure ◽  
31P Nmr ◽  
Kraft Lignin ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Diphenylmethane Diisocyanate ◽  
Complex Chemical ◽  
Heterogeneous Reactivity ◽  
Phenolic Hydroxyl Groups

Several efforts have been dedicated to the development of lignin-based polyurethanes (PU) in recent years. The low and heterogeneous reactivity of lignin hydroxyl groups towards diisocyanates, arising from their highly complex chemical structure, limits the application of this biopolymer in PU synthesis. Besides the well-known differences in the reactivity of aliphatic and aromatic hydroxyl groups, experimental work in which the reactivity of both types of hydroxyl, especially the aromatic ones present in syringyl (S-unit), guaiacyl (G-unit), and p-hydroxyphenyl (H-unit) building units are considered and compared, is still lacking in the literature. In this work, the hydroxyl reactivity of two kraft lignin grades towards 4,4′-diphenylmethane diisocyanate (MDI) was investigated. 31P NMR allowed the monitoring of the reactivity of each hydroxyl group in the lignin structure. FTIR spectra revealed the evolution of peaks related to hydroxyl consumption and urethane formation. These results might support new PU developments, including the use of unmodified lignin and the synthesis of MDI-functionalized biopolymers or prepolymers.

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