METHYL 3-NITRO- AND 3-AMINO-3-DEOXY-β-D-GALACTOPYRANOSIDE AND -MANNOPYRANOSIDE

1963 ◽  
Vol 41 (6) ◽  
pp. 1606-1611 ◽  
Author(s):  
Hans Helmut Baer ◽  
Frank Kienzle
Keyword(s):  
Crystalline State ◽  
Major Reaction Product ◽  
Major Reaction ◽  
Amino Derivatives ◽  
Facile Preparation ◽  
Hydrolysis Of

The steric course of the nitromethane cyclization of L′-methoxy-D-hydroxymethyldiglycolic aldehyde was investigated. Methyl 3-nitro-3-deoxy-β-D-galactopyranoside was shown to arise as a second major reaction product in addition to the previously isolated principal stereoisomer, the gluco derivative. The corresponding manno stereoisomer is formed to a smaller extent. The configurations of the new methyl nitrodeoxyglycosides were established by conversion into the corresponding amino derivatives and hydrolysis of these latter to the known 3-amino-3-deoxy-D-galactose and -D-mannose hydrochlorides. All the products were obtained in a crystalline state. The reaction lends itself to a facile preparation of the nitrogenous galactose derivatives.

Synthesen und Strukturen von 2,5-Bis(2-arylvinyl)-1,4-benzochinonen und deren photochemisches Verhalten im Kristall / Syntheses and Crystal Structures of 2,5-Bis(2-arylvinyl)-1,4-benzoquinones and their Photochemical Reactivity in the Crystalline State

1993 ◽  
Vol 48 (10) ◽  
pp. 1411-1418 ◽  
Author(s):  
Hermann Irngartinger ◽  
Jochen Lichtenthäler ◽  
Dieter Fenske ◽  
Gerhard Baum
Keyword(s):  
Crystal Structures ◽  
Anodic Oxidation ◽  
Crystalline State ◽  
Double Bonds ◽  
Resonance Structures ◽  
Photochemical Reactivity ◽  
X Ray ◽  
Bond Lengths ◽  
Intermolecular Distances ◽  
Hydrolysis Of

The 2,5-bis(2-arylvinyl)-1,4-benzoquinones 1a-1e are formed from hydrolysis of their corresponding ketals 5 which are generated by anodic oxidation of the corresponding 1,4-dimethoxybenzene derivatives 4. The crystal structures of the quinone compounds 1a, 1d and 1e have been determined by X-ray analyses. The bond lengths of the quinone system are influenced by polar resonance structures. An α-type packing mode is observed for the three crystal structures of compounds 1. The vinylic double bonds have short intermolecular distances (1a: 4.417(5), 1d: 3.653(2), 1e: 4.224(5) Å). Only the crystals of 1d with the shortest contacts are photoreactive

Hydrogen Peroxide Decay in Waters with Suspended Soils: Evidence for Biologically Mediated Processes

1990 ◽  
Vol 47 (5) ◽  
pp. 888-893 ◽  
Author(s):  
William J. Cooper ◽  
Richard G. Zepp
Keyword(s):  
Hydrogen Peroxide ◽  
Natural Water ◽  
Water Samples ◽  
First Order ◽  
Natural Water Samples ◽  
Major Reaction Product ◽  
Major Reaction ◽  
Chemical Sterilization ◽  
Pseudo First Order ◽  
Catalyzed Oxidation

Hydrogen peroxide decay studies have been conducted in suspensions of several well-characterized soils and in natural water samples. Kinetic and product studies indicated that the decay was biologically-mediated, and could be described by pseudo first-order rate expressions. At an initial H2O2 concentration of 0.5 μM, the hydrogen peroxide half-life varied from 1 to 8 h. The decay was inhibited by thermal and chemical sterilization of the soils. Peroxidase activity was inferred in several natural water samples, where the suspended particles catalyzed the oxidation of p-anisidine by hydrogen peroxide. The mass spectrum of the major reaction product indicated that it was the dimer, possibly benzoquinone-4-methoxyanil, a product that also was observed from the horseradish peroxidase-catalyzed oxidation of p-anisidine by hydrogen peroxide.

scholarly journals One-pot synthesis of substituted pyrrolo[3,4-b]pyridine-4,5-diones based on the reaction of N-(1-(4-hydroxy-6-methyl-2-oxo-2H-pyran-3-yl)-2-oxo-2-arylethyl)acetamide with amines

2019 ◽  
Vol 15 ◽  
pp. 2840-2846
Author(s):  
Valeriya G Melekhina ◽  
Andrey N Komogortsev ◽  
Boris V Lichitsky ◽  
Vitaly S Mityanov ◽  
Artem N Fakhrutdinov ◽  
...  
Keyword(s):  
Starting Material ◽  
Primary Amines ◽  
Synthetic Method ◽  
One Pot ◽  
One Pot Synthesis ◽  
Major Reaction Product ◽  
Major Reaction

The condensation of primary amines with N-(1-(4-hydroxy-6-methyl-2-oxo-2H-pyran-3-yl)-2-oxo-2-arylethyl)acetamides was explored. Thus, a previously unknown recyclization of the starting material was observed in acidic ethanol in the presence of an amine, which provided the corresponding dihydropyrrolone derivative as the major reaction product. Based on this transformation, a practical and convenient one-pot synthetic method for substituted pyrrolo[3,4-b]pyridin-5-ones could be devised.

Calixarene Phosphorylation: Cation Control of Reaction Pathways

1993 ◽  
Vol 46 (11) ◽  
pp. 1673 ◽  
Author(s):  
LT Byrne ◽  
JM Harrowfield ◽  
DCR Hockless ◽  
BJ Peachey ◽  
BW Skelton ◽  
...  
Keyword(s):  
Phase Transfer ◽  
Tetrabutylammonium Bromide ◽  
Crystal Structure Analysis ◽  
Bidentate Ligand ◽  
Tetraethylammonium Bromide ◽  
Cone Conformation ◽  
Formation Reaction ◽  
Partial Cone ◽  
Major Reaction Product ◽  
Major Reaction

The hydroxide ion catalysed phosphorylation of p-t- butylcalix [4] arene by diethyl chlorophosphate under heterogeneous conditions shows a marked sensitivity to the nature of the phase transfer catalyst used. Thus, substitution of tetraethylammonium bromide for the tetrabutylammonium bromide prescribed for the synthesis of the calixarene tetraphosphate leads to a major reaction product becoming a bis (phosphate) in which the calixarene binds as a unidentate ligand to one phosphorus and as a bidentate ligand to the other. An X-ray crystal structure analysis on this new compound shows the calixarene to adopt a somewhat distorted 'cone' conformation with an unusual orientation of one of the t-butyl substituents into the cone cavity. It also reveals that a significant diastereoselectivity must operate in the formation reaction. The only other reaction product detected in this system appears to be the calixarene tetraphosphate in a partial cone conformation.

scholarly journals A Study of the Reaction Between Quinone and 2R4F Cigarette Smoke Condensate

2009 ◽  
Vol 23 (6) ◽  
pp. 359-367
Author(s):  
WM Coleman
Keyword(s):  
Cigarette Smoke ◽  
Chromatographic Separation ◽  
Atomic Emission ◽  
Operating Conditions ◽  
Chemical Mechanism ◽  
Cigarette Smoke Condensate ◽  
Major Reaction Product ◽  
Major Reaction ◽  
Independent Calibration ◽  
Emission Detection

AbstractA study using atomic emission detection (AED) as an approach to explore the fate of quinone added into 2R4F cigarette smoke condensate (CSC) have been performed. Both natural isotope quinone and 13C labeled quinone were used in the study. When coupled with a gas chromatographic separation (GC/AED), the AED provided informative new data on 13C isotope enriched products generated following reactions between 2R4F CSC and the quinone. Two 13C containing species were detected by GC/AED. Matching chromatographic separation using gas chromatography/mass selective detection (GC/MSD) allowed for a structural assignment of a relatively minor CSC 13C 6quinone reaction product as nitrohydroquinone (13C6NO2HQ). The chemical mechanism accounting for the formation of 13C6NO2HQ in the CSC was envisioned to be a reaction product between HONO and 13C 6Quinone (13C6Q) to form 13C6NO2Q, followed by reduction of 13C6NO2Q to 13C6NO2HQ. The amount of 13C6NO2HQ accounted for ~6% of the added 13C6Q. Identical trends in reaction chemistries were found for experiments with 12C6Q. The major reaction product detected upon addition of 13C6Q to the 2R4F CSC sample was 13C6HQ. 13C6HQ accounted for, on average, ~47% of the initial 13C6Q concentration. Identical trends in reaction chemistries were found for experiments with 12C6Q. No additional 13C containing species were detected. A 13C AED compound independent calibration (CIC) approach under the operating conditions was not possible. This work further expands the knowledge regarding possible reactions of quinone and hydroquinone in CSC.

Influences of thermal annealing and humidity exposure on surface structure of (100) single-crystal MgO substrate

1999 ◽  
Vol 14 (5) ◽  
pp. 2133-2137 ◽  
Author(s):  
M. P. Delplancke-Ogletree ◽  
M. Ye ◽  
R. Winand ◽  
J. F. de Marneffe ◽  
R. Deltour
Keyword(s):  
Surface Structure ◽  
Thermal Annealing ◽  
Substrate Surface ◽  
Reaction Products ◽  
X Ray Diffraction ◽  
Force Microscopy ◽  
Evaporation And Condensation ◽  
Atomic Force ◽  
Major Reaction Product ◽  
Major Reaction

We studied the influence of thermal annealing on the surface structure of (100) singlecrystal MgO substrates by atomic force microscopy (AFM). By annealing MgO substrates at various temperatures for 4 h in flowing oxygen, we showed that the surface reconstruction could be explained by considering surface diffusion, surface evaporation, and condensation. At an annealing temperature of 1473 K, a stepped structure was formed with screw dislocations acting as step sources. The influence of humidity on the surface morphology of MgO substrates was also studied by exposing them to a constant humidity of 40 and 80% for different times. After an exposure time of 1.5 h in 80% humidity, the substrate surface was already covered by reaction products. For the 40% humidity, the corresponding time is 10 h. The major reaction product was identified as Mg(OH)2 by x-ray diffraction.

scholarly journals Analysis of a cellulose synthase catalytic subunit from the oomycete pathogen of crops Phytophthora capsici

Cellulose ◽  
2020 ◽  
Vol 27 (15) ◽  
pp. 8551-8565
Author(s):  
Zhili Pang ◽  
Lauren S. McKee ◽  
Vaibhav Srivastava ◽  
Stefan Klinter ◽  
Sara M. Díaz-Moreno ◽  
...  
Keyword(s):  
Cell Wall ◽  
Biochemical Characterization ◽  
Phytophthora Capsici ◽  
Cellulose Synthase ◽  
Economic Losses ◽  
Cellulose Synthesis ◽  
Major Reaction Product ◽  
Major Reaction ◽  
Oomycete Pathogen ◽  
The Individual

Abstract Phytophthora capsici Leonian is an important oomycete pathogen of crop vegetables, causing significant economic losses each year. Its cell wall, rich in cellulose, is vital for cellular integrity and for interactions with the host organisms. Predicted cellulose synthase (CesA) proteins are expected to catalyze the polymerization of cellulose, but this has not been biochemically demonstrated in an oomycete. Here, we present the properties of the four newly identified CesA proteins from P. capsici and compare their domain organization with that of CesAs from other lineages. Using a newly constructed glucosyltransferase-deficient variant of Saccharomyces cerevisiae with low residual background activity, we have achieved successful heterologous expression and biochemical characterization of a CesA protein from P. capsici (PcCesA1). Our results demonstrate that the individual PcCesA1 enzyme produces cellobiose as the major reaction product. Co-immunoprecipitation studies and activity assays revealed that several PcCesA proteins interact together to form a complex whose multiproteic nature is most likely required for cellulose microfibril formation. In addition to providing important insights into cellulose synthesis in the oomycetes, our data may assist the longer term identification of cell wall biosynthesis inhibitors to control infection by pathogenic oomycetes.

scholarly journals Relationship between Antimalarial Activity and Heme Alkylation for Spiro- and Dispiro-1,2,4-Trioxolane Antimalarials

2008 ◽  
Vol 52 (4) ◽  
pp. 1291-1296 ◽  
Author(s):  
Darren J. Creek ◽  
William N. Charman ◽  
Francis C. K. Chiu ◽  
Richard J. Prankerd ◽  
Yuxiang Dong ◽  
...  
Keyword(s):  
Mechanism Of Action ◽  
Antimalarial Activity ◽  
Biologically Active ◽  
Radical Intermediate ◽  
Reaction Conditions ◽  
Artemisinin Derivatives ◽  
Major Reaction Product ◽  
Major Reaction ◽  
Insight Into

ABSTRACT The reaction of spiro- and dispiro-1,2,4-trioxolane antimalarials with heme has been investigated to provide further insight into the mechanism of action for this important class of antimalarials. A series of trioxolanes with various antimalarial potencies was found to be unreactive in the presence of Fe(III) hemin, but all were rapidly degraded by reduced Fe(II) heme. The major reaction product from the heme-mediated degradation of biologically active trioxolanes was an alkylated heme adduct resulting from addition of a radical intermediate. Under standardized reaction conditions, a correlation (R 2 = 0.88) was found between the extent of heme alkylation and in vitro antimalarial activity, suggesting that heme alkylation may be related to the mechanism of action for these trioxolanes. Significantly less heme alkylation was observed for the clinically utilized artemisinin derivatives compared to the equipotent trioxolanes included in this study.

scholarly journals Infrared Laser Photochemistry of Trans-1, 2-Dichloroethylene. Evidence For A CI Atom Chain Reaction

1990 ◽  
Vol 10 (3) ◽  
pp. 185-195
Author(s):  
Joseph R. Guckert ◽  
Robert W. Carr
Keyword(s):  
Laser Pulses ◽  
Chain Reaction ◽  
Bond Scission ◽  
Structural Isomerization ◽  
Atom Chain ◽  
Major Reaction Product ◽  
Major Reaction ◽  
Induced Decomposition ◽  
Cis Isomer ◽  
Energy Channels

The TEA-CO2 laser induced reaction of trans-l,2-dichloroethylene (TDCE) was investigated at 925 cm-1. The laser radiation was focused to yield beam waist fluences of approximately 125 J cm-2. The major reaction product was cis-1, 2-dichloroethylene (CDCE), with a few per cent of chloroacetylene, and minor amounts of acetylene, dichloroacetylene, chloroethylene and an unidentified C4 compound also being formed. The reaction of pure TDCE was studied as a function of number of laser pulses and total pressure (0.02 to 5 torr). Some experiments were also done with added ethane (20%) and propane (2%). Evidence was obtained that the formation of the cis isomer occurs via two mechanisms, (1) a unimolecular isomerization, and (2) a CI atom chain reaction. The results are consistent with laser induced decomposition of TDCE occurring through the three lowest energy channels: unimolecular structural isomerization (57.4 kcal/mol); molecular HCI elimination (69 kcal/mol); and C-CI bond scission (89 kcal/mol).

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