Piptoside, a novel alkali-labile glucoside from Piptocalyx moorei Oliv.

1966 ◽  
Vol 19 (4) ◽  
pp. 683 ◽  
Author(s):  
NV Riggs ◽  
JD Stevens
Keyword(s):  
Periodate Oxidation ◽  
Aqueous Sodium Hydroxide ◽  
Carbon Chain ◽  
Hydroxyl Group ◽  
Reaction Products ◽  
Spectroscopic Information ◽  
Michael Type Addition ◽  
Angelic Acid ◽  
Methyl Derivatives ◽  
Fission Yields

The β-D-glucopyranoside, piptoside, is cleaved by hot dilute acid to glucose and aglucone, the latter being partly converted with loss of carbon dioxide into a furan keto acid. Glucose is also liberated by the action of bases. With sodium methoxide, the aglucone residue rearranges to a pair of isomeric dilactone esters, whereas, with aqueous sodium hydroxide, fission of the carbon chain to (-)-2,3-dimethylsuccinic acid occurs; with alkaline hydrogen peroxide, oxidative chain fission yields a buty- rolactone-4,4-dicarboxylic acid. The structure and partial stereochemistry of each of the products follows from chemical and spectroscopic information. These results, as also those of periodate oxidation, are accounted for by formulation of the aglucone as a system of two spiro-joined γ-lactone rings, one of which is fused to a ketofuranose ring. The reaction products are analogous to well-known products from simple sugars. The hemiacetal hydroxyl group of the ketofuranose remains free in the glucoside and is unusally acidic towards diazomethane, the methyl derivatives not being alkalilabile.��� Biogenesis of the aglucone may follow Michael-type addition of a 3-dehydrohexonic acid (of unknown stereochemistry) to angelic acid, or some variant.

scholarly journals Impact of Chitosan-Genipin Films on Volatile Profile of Wine along Storage

2021 ◽  
Vol 11 (14) ◽  
pp. 6294
Author(s):  
M. Angélica Rocha ◽  
Manuel Coimbra ◽  
Sílvia Rocha ◽  
Cláudia Nunes
Keyword(s):  
Volatile Compounds ◽  
Carbon Chain ◽  
White Wine ◽  
Maillard Reaction Products ◽  
Red Wines ◽  
Reaction Products ◽  
Ethyl Hexanoate ◽  
Organoleptic Characteristics ◽  
Strecker Aldehydes ◽  
Key Odorants

Chitosan-genipin films have been proposed for preservation of white wine, maintaining their varietal key odorants and organoleptic characteristics of sulfur dioxide treated wines. Nevertheless, these wines showed aroma notes that slightly distinguish them. It is possible that during the contact of films with wine for at least 2 months, after fermentation and prior to bottling, interactions or chemical reactions are promoted. In this work, wine model solutions with volatile compounds in contact with chitosan-genipin films were performed to evaluate their evolution along time. To complement these analyses, the volatile compounds of white and red wines kept in contact with chitosan-genipin films during 2 and 8 months were also studied. The results obtained allowed us to conclude that the contact of chitosan-genipin films with both white and red wines tend to retain long carbon chain volatile compounds, such as ethyl hexanoate and octan-3-one. It also promoted the formation of Maillard reaction products, such as furfural by dehydration of pentoses and Strecker aldehydes, such as 3-methylbutanal and phenylacetaldehyde, by degradation of amino acids. This study reveals that the use of chitosan-genipin films for wine preservation is also able to promote the formation of compounds that can modulate the wines aroma, maintaining the varietal notes.

scholarly journals Synthesis and biotical activity of bacterial cellulose 6-(2-phthalimidoethanesulfonate)

2020 ◽  
Vol 61 (2) ◽  
pp. 29-36
Author(s):  
Zoya P. Belousova ◽  
Keyword(s):  
Bacterial Cellulose ◽  
Side Reaction ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Cellulose Derivatives ◽  
Wound Surface ◽  
Reaction Products ◽  
Absorption Bands ◽  
Hydroxymethyl Group ◽  
Antibacterial And Antifungal

Bacterial cellulose obtained by culturing Gluconacetobacter sucrofermentans in HS environment was converted to sulfonate derivatives using methane-, toluene- and 2-phthalimidoethanesulfonic acids in pyridine. When the ratio of the starting reagents is 1 : 1, the modification of bacterial cellulose according to the primary hydroxyl group of glucopyranose fragments is most likely. The formation of 6-substituted bacterial cellulose derivatives was observed in the reaction mixture. The IR spectra of the reaction products contain absorption bands, which are specific for (O–SO2) group in the region 1377-1338 cm−1 (as), 1178-1154 cm−1 (s), fragments of the corresponding sulfonic acids, as well as free hydroxyl groups of glucopyranose in the region 3495-3382 cm−1. Bacterial cellulose 2-phthalimidoethanesulfonate was dissolved in pyridine. After drying with a desiccant in a desiccator, it turned into a dense transparent film of brown color. The increased molecular film allows to explain the side reaction occurring between the oxo group and fragments of one of the chains of modified cellulose and the non-substituted hydroxymethyl group. The IR spectrum of bacterial cellulose 6-(2-phthalimidoethanesulfonate) contains absorption bands in the region 1711 cm−1, which are specific for (Ar–CO–O) group, and absorption bands in the region 1618 cm−1, which prove the presence of (CO–NH) group. In order to impart antibiotic properties to the bacterial cellulose 6-(2-phthalimido-ethanesulfonate) film, it was physically modified with clotrimazole. The obtained experimental data showed that the films subjected to treatment with a 1% solution of clotrimazole have antibacterial and antifungal effects and prevent the growth of pathogenic microbiota on the wound surface. The exit rates of clotrimazole from the bacterial cellulose 6-(2-phthalimidoethanesulfonate) film and from the pure bacterial cellulose film differed, but only slightly. 2-Phthalimidoethanesulfonate bacterial cellulose films can be used to form composites of effective wound covering, since in addition to the unique properties of bacterial cellulose itself (low allergenicity and adhesion to the wound surface, high hygroscopicity) they will have a regenerating effect.

scholarly journals Bacterial Conversion of Hydroxylamino Aromatic Compounds by both Lyase and Mutase Enzymes Involves Intramolecular Transfer of Hydroxyl Groups

2003 ◽  
Vol 69 (5) ◽  
pp. 2786-2793 ◽  
Author(s):  
Lloyd J. Nadeau ◽  
Zhongqi He ◽  
Jim C. Spain
Keyword(s):  
Aromatic Compounds ◽  
Ralstonia Eutropha ◽  
Transfer Mechanism ◽  
Bacterial Degradation ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Reaction Products ◽  
Comamonas Acidovorans ◽  
Label Incorporation ◽  
Intramolecular Transfer

ABSTRACT Hydroxylamino aromatic compounds are converted to either the corresponding aminophenols or protocatechuate during the bacterial degradation of nitroaromatic compounds. The origin of the hydroxyl group of the products could be the substrate itself (intramolecular transfer mechanism) or the solvent water (intermolecular transfer mechanism). The conversion of hydroxylaminobenzene to 2-aminophenol catalyzed by a mutase from Pseudomonas pseudoalcaligenes JS45 proceeds by an intramolecular hydroxyl transfer. The conversions of hydroxylaminobenzene to 2- and 4-aminophenol by a mutase from Ralstonia eutropha JMP134 and to 4-hydroxylaminobenzoate to protocatechuate by a lyase from Comamonas acidovorans NBA-10 and Pseudomonas sp. strain 4NT were proposed, but not experimentally proved, to proceed by the intermolecular transfer mechanism. GC-MS analysis of the reaction products formed in H2 18O did not indicate any 18O-label incorporation during the conversion of hydroxylaminobenzene to 2- and 4-aminophenols catalyzed by the mutase from R. eutropha JMP134. During the conversion of 4-hydroxylaminobenzoate catalyzed by the hydroxylaminolyase from Pseudomonas sp. strain 4NT, only one of the two hydroxyl groups in the product, protocatechuate, was 18O labeled. The other hydroxyl group in the product must have come from the substrate. The mutase in strain JS45 converted 4-hydroxylaminobenzoate to 4-amino-3-hydroxybenzoate, and the lyase in Pseudomonas strain 4NT converted hydroxylaminobenzene to aniline and 2-aminophenol but not to catechol. The results indicate that all three types of enzyme-catalyzed rearrangements of hydroxylamino aromatic compounds proceed via intramolecular transfer of hydroxyl groups.

scholarly journals The nature of the 5'-linked 5' nucleotide sequence at the 5' end of rabbit globin messenger ribonucleic acid

1976 ◽  
Vol 155 (3) ◽  
pp. 637-644 ◽  
Author(s):  
J A Hunt ◽  
G N Oakes
Keyword(s):  
Messenger Rna ◽  
Periodate Oxidation ◽  
Hydroxyl Group ◽  
Globin Mrna ◽  
Pancreatic Ribonuclease ◽  
Phosphodiester Bond ◽  
Messenger Ribonucleic Acid ◽  
End Groups ◽  
A Charge ◽  
End Group

Poly(A)-containing messenger RNA isolated from rabbit reticulocytes as estimated by periodate oxidation and condensation with [3H]isoniazid has two oxidizable end groups per molecule of mol. wt. 220000. When the mRNA is subjected to stepwise degradation by beta-elimination, only one oxidizable end-group is found. This indicates that one of the 2′,3′ hydroxyl end-groups is linked through the normal 3′-5′ phosphodiester bond, but that the other is linked in such a way that after stepwise degradation no new 2′,3 hydroxyl group is revealed. This structure could be a 5′-linked 5′-phospho di- or tri-ester. On digestion with ribonuclease the isoniazid-labelled RNA produced oligonucleotide hydrazones consistent with a poly(A) sequence at the 3′ end plus fragments that are not found after stepwise degradation. These fragments have a charge of -6 and -8 from pancreatic ribonuclease or -7 from ribonuclease T1 digestion. These charges are changed to -3.4 and -4.1 after pancreatic ribonuclease, ribonuclease T2 and alkaline phosphatase digestion. methyl-3H-labelled-poly(A)-containing RNA isolated from late erythroid cells contain a methyl-labelled fragment resistant to endonuclease and phosphodiesterase II digestion. After digestion with phosphodiesterase I this fragment produces methyl-3 H-labelled nucleotides with the electrophoretic mobility of pm7G and pAm. It is concluded that globin mRNA has the 5′ sequences m7G(5′)ppp′AmpYpGp ... and m7G(5′)pppAmpApGpYp.

Rubber. XVIII. Various Ozonides of Rubber and the Problem of the Existence of the Primary Ozonides of Harries

1938 ◽  
Vol 11 (1) ◽  
pp. 7-31
Author(s):  
Rudolf Pummerer ◽  
Hermann Richtzenhain
Keyword(s):  
Carbon Chain ◽  
Mesityl Oxide ◽  
Addition Reactions ◽  
Reaction Products ◽  
Primary Reaction ◽  
Carbon Chains ◽  
Fundamental Objection ◽  
Great Stress ◽  
Valuable Service ◽  
General Method

Abstract A permanently valuable service was rendered by Harries when he introduced the ozone cleavage of unsaturated compounds as a general method of investigation in organic chemistry. By analogy with other addition reactions of double bonded carbon atoms he derived the formula (a) for the ozonides which are first formed, but to support the existence of which he was able to obtain only scant experimental data. Harries relied above all on two observations, first, that mesityl oxide ozonide reverts to mesityl oxide when heated by itself, and, secondly, that fumaric acid is supposed to combine loosely with ozone and then readily split off again. Both of these suppositions have remained undisputed up to the present time. Harries reported that it was not possible, with any of a wide variety of reducing agents, to reduce the ozonides to the original compounds or to 1,2-glycols, as would be expected from their structure. Staudinger has laid great stress on this fundamental objection, and he considers that most ozonides have an isoözinide formula, as shown by formula (b) above, in which the carbon chain is already ruptured, so that by reduction only the usual types of cleavage products rather than glycols with intact carbon chains can be formed, as has been found experimentally. Staudinger assumed that the primary reaction products of treatment with ozone are molozonides containing the group:

scholarly journals Synthesis of Siloxyalumoxanes and Alumosiloxanes Based on Organosilicon Diols

2017 ◽  
Author(s):  
Galina I. Shcherbakova ◽  
Pavel A. Storozhenko ◽  
Alexander V. Kisin
Keyword(s):  
Steric Hindrance ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
High Polymer ◽  
Cyclic Structure ◽  
Reaction Products ◽  
Equimolar Ratio ◽  
Aluminum Alkyl ◽  
A Chain ◽  
Alkyl Residue

We have drawn a few interesting conclusions while studying reaction products of Ph2Si(OH)2 with Al(iBu)3 and tetraisobutyl alumoxane. In the first place, this is the production (at Ph2Si(OH)2 and Al(iBu)3 equimolar ratio) of oligomer alumoxanesiloxane structure with alternating four- and six-member rings, as well as isobutyl and phenyl groups migration between aluminum and silicon due to formation of intramolecular four-member cyclic alumosiloxane complex [Ph2(OH)SiO]Al(iBu)2 → [(iBu)Ph(OH)SiO]Al(iBu)Ph. Ph2Si(OH)2 interaction with Al(iBu)3 not only starts from intramolecular alumosiloxane complex production, but the chain is terminated for the same reason, which in the case of Ph2Si(OH)2 reaction with tetraisobutylalumoxane results in failure of obtaining high-polymer alumosiloxane compounds. When Al(iBu)3 interacts with α- and γ-diols, no oligomer compounds are produced. Al(iBu)3 reaction with α, γ-diols results in monomer compounds that are likely to have cyclic structure. Notably at Al(iBu)3 interaction with α-diol only double excess of Al(iBu)3 allows full replacement of hydrogen in α-diol hydroxyl groups by aluminum alkyl residue with 1,3-bis(diisobutylalumoxymethyl)-1,1,3,3-tetramethyldisiloxane production. At equimolar ratio of initial reagents the second isobutyl radical at Al does not interact with the second hydroxyl group of α-diol, apparently due to steric hindrance and 1-(diisobutylalumoxymethyl)-3-(hydroxymethyl)-1,1,3,3-tetramethyl-disiloxane is produced. Al(iBu)3 reactions with γ-diol also result in monomer compounds but the presence of a chain consisting of three СН2-groups between Si and hydroxyl group facilitates interaction between the second hydroxyl group of γ-diol and the second isobutyl radical Al(iBu)3. Tetraisobutylalumoxane reactions with α- and γ-diols results in oligomer compounds.

scholarly journals Structural Composition Explains Differences in Stretchability for Compression-Molded Arabinoxylan-Based Thermoplastic Films

2020 ◽  
Author(s):  
Parveen Kumar Deralia ◽  
Amit Kumar Sonker ◽  
Anja Lund ◽  
Anette Larsson ◽  
Anna Ström ◽  
...  
Keyword(s):  
Sustainable Development ◽  
Glass Transition ◽  
Glycidyl Ether ◽  
Periodate Oxidation ◽  
Value Added ◽  
Hydroxyl Group ◽  
Epoxide Ring ◽  
Barley Husk ◽  
Butyl Glycidyl Ether ◽  
Thermoplastic Properties

<div><div><div><p>Valorization of argi-waste polymers into value-added materials is essential for sustainable development of polymeric industry. Reported herein is a 1-step and 2-step strategy for fabrication of flexible and stretchable thermoplastics prepared by compression molding from two structurally different arabinoxylans (AX). The synthesis was accomplished using n-butyl glycidyl ether whose epoxide ring opened on hydroxyl group and resulted in introduction of alkoxide sidechains for the 1-step synthesis. AX was preactivated by periodate oxidation as 1st step for the 2-step synthesis. Two structurally different AXs, i.e. wheat bran extracted arabinoxylan (AXWB, araf/xylp=3/4) and barley husk extracted arabinoxylan (AXBH, araf/xylp=1/4) were used to understand the effects of the araf/xylp on thermoplastic properties because melt processability has been rare for low araf/xylp AXs. AXBH-derived samples demonstrated melt compression processability. AXWB and AXBH derived thermoplastics featured dual and single glass transition (Tg) characteristics respectively as confirmed by DSC and DMA, but AXBH derived thermoplastics had lower stretchability (maximum 160%) compared to AXWB samples (maximum 300 %). Higher araf/xylp and thus in turn longer alkoxide side chains in AXWB derived thermoplastics explained differences in stretchability.</p></div></div></div>

scholarly journals First Principles Study of Reactions in Alucone Growth: the Role of the Organic Precursor

2020 ◽  
Author(s):  
Arbresha Muriqi ◽  
Michael Nolan
Keyword(s):  
Ethylene Glycol ◽  
First Principles ◽  
Molecular Layer ◽  
Triethylene Glycol ◽  
Detailed Comparison ◽  
Hydroxyl Group ◽  
Tetraethylene Glycol ◽  
Hydroxyl Groups ◽  
Reaction Products ◽  
Organic Precursor

Organic-inorganic hybrid materials are a unique class of materials with properties driven by the organic and inorganic components, making them useful for flexible devices. Molecular layer deposition (MLD) offers novel pathways for the fabrication of such hybrids by using inorganic metal precursors and the vast range of organic molecules with tunable properties. To investigate and understand the mechanism of growth a combination of theoretical and experimental data is needed. In this contribution, we present a first principles investigation of the molecular mechanism of the growth of hybrid organic−inorganic thin films of aluminium alkoxides, known as “alucones” grown by MLD. We explore the interactions between precursors by analyzing the MLD reaction products of the alumina surface terminated with Al(CH<sub>3</sub>) groups after the trimethyl aluminium pulse; this yields monomethyl-Al<sub>2</sub>O<sub>3</sub> (Al-CH<sub>3</sub>-Al<sub>2</sub>O<sub>3</sub>) and dimethyl- Al<sub>2</sub>O<sub>3</sub> (Al(CH<sub>3</sub>)<sub>2</sub>- Al<sub>2</sub>O<sub>3</sub>) terminated surfaces. The organic precursors are ethylene glycol (EG), diethylene glycol (DEG), triethylene glycol (TEG) and tetraethylene glycol (FEG). A detailed comparison with alucones grown with ethylene glycol (EG) and glycerol (GL) precursors is presented to assist the interpretation of experimental findings regarding the differences in the hybrid films grown by EG and GL. The results show that Al-O formation with release of methane is favorable for all precursors. EG and GL can lie flat and create so-called double reactions through the reaction of the two terminal hydroxyl groups with the surface fragments. This phenomenon removes active hydroxyl sites for EG. However, for GL the third hydroxyl group is available and growth can proceed. This analysis shows the origin of differences in thickness of alucones found for EG and GL.

AN AUTOMATED METHOD FOR THE DETERMINATION OF URINARY 17-HYDROXYCORTICOSTEROIDS

1967 ◽  
Vol 38 (4) ◽  
pp. 363-374 ◽  
Author(s):  
J. D. CAISEY ◽  
K. J. CHILD
Keyword(s):  
Aqueous Solution ◽  
Periodate Oxidation ◽  
Passage Time ◽  
Borohydride Reduction ◽  
Reaction Products ◽  
Automated Method ◽  
Adequate Accuracy ◽  
Working Day

SUMMARY An automated method for measuring urinary 17-hydroxycorticosteroids is described. The preliminary borohydride reduction of pre-existing 17-oxo-steroids is performed manually and the reduced urine transferred to the sample cups of an Auto-Analyzer. The urine is submitted to periodate oxidation, mild alkaline hydrolysis and then extracted with dichloromethane. The dichloromethane extract is mixed with an aqueous solution of m-dinitrobenzene in hyamine and the mixture passed through a 'solvent exchanger' at 75° to evaporate the dichloromethane. Alkali is added and the Zimmermann reaction performed at 55°. After extraction of the reaction products into n-hexanol their light absorption is measured at 510 mμ. The method has been evaluated for accuracy, precision, sensitivity and validity. Urine samples can be assayed in duplicate at the rate of 5/hr. with adequate accuracy. Passage time through the automated procedure is 36 min.; thus 30 to 40 samples can easily be assayed in a normal working day. Details are given of the recovery of cortisone from urine and of comparison between the results obtained with the automated method and with a manual method. The choice of cortisone as the standard, and the role of the temperature and the pH maintained during periodate oxidation are discussed.

NUCLEAR MAGNETIC RESONANCE SPECTRA OF GLYCOL-CLEAVAGE OXIDATION PRODUCTS OF METHYL ALDOPENTOPYRANOSIDES

1966 ◽  
Vol 44 (15) ◽  
pp. 1757-1764 ◽  
Author(s):  
A. S. Perlin
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Deuterium Oxide ◽  
Periodate Oxidation ◽  
Chair Conformation ◽  
The Other ◽  
Oxidation Products ◽  
Hydroxyl Group ◽  
Resonance Spectroscopy ◽  
Nuclear Magnetic

The products obtained by the periodate oxidation of methyl α- and β-D-xylopyranosides have been examined by nuclear magnetic resonance spectroscopy. In deuterium oxide each product exists mainly in two forms, one of which is a hydrated dialdehyde and the other a hemialdal (1,4-dioxane derivative). In dimethyl sulfoxide the dialdehyde cyclizes slowly to yield the hemialdal which, at equilibrium, is found to be by far the most stable of the many isomeric forms possible. The spectrum of this hemialdal in both solvents provides an example of a degenerate ABX type of pattern. The spectra of the products prepared from 5-deuterated xylosides show that the 1-methoxyl group of each hemialdal is axial and the 4-hydroxyl group equatorial, and that the one derived from the β-anomer possesses an inverted chair conformation relative to that of the other hemialdal and of the glycoside itself. The 2-hydroxyl group of each hemialdal appears to be axially oriented. The data support the long-standing view that glycol scission of anomeric aldopentopyranosides leads to products that are mirror images.It has been found also that each product yields a mixture of several p-nitrobenzoates.

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