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.

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.

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.

Rapid and efficient synthesis of metal-free phthalocyanine derivatives

2006 ◽  
Vol 10 (11) ◽  
pp. 1253-1258 ◽  
Author(s):  
Ahmad Shaabani ◽  
Ali Maleki
Keyword(s):  
Ionic Liquid ◽  
Microwave Irradiation ◽  
Phase Transfer ◽  
Tetrabutylammonium Bromide ◽  
Efficient Synthesis ◽  
Metal Free ◽  
High Yields ◽  
Short Times

Metal-free phthalocyanine derivatives have been synthesized in very short times with high yields in the presence of 1,1,3,3-tetramethylguanidinium trifluoroacetate (TMGT) as an ionic liquid or tetrabutylammonium bromide (TBAB) as a phase transfer reagent under both classical heating conditions and using microwave irradiation. The best results were obtained with ionic liquid. Both the ionic liquid and phase transfer reagent can be recycled for subsequent reactions and reused without appreciable loss of efficiency.

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.

Alpha track registration and revelation in CR-39 using new etching method for ultratrace alpha radioactivity quantification in solution media

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Sushma S. Chavan ◽  
Amol M. Mhatre ◽  
Ashok K. Pandey ◽  
Hemlata K. Bagla
Keyword(s):  
Induction Time ◽  
Chemical Etching ◽  
Etch Rate ◽  
Phase Transfer ◽  
Alpha Activity ◽  
Phase Transfer Catalyst ◽  
Tetraethylammonium Bromide ◽  
Etching Method ◽  
Track Etch ◽  
Registration Efficiency

Abstract A CR-39 based method was developed for measuring the ultra-trace alpha radio activities in aqueous samples having curie levels of γ/β-radio activities. The chemical etching method was optimized to reveal the alpha tracks in CR-39. This new chemical etching method involved the use of a phase transfer catalyst tetraethylammonium bromide which reduced the track revelation induction time without deteriorating the track-etch parameters. The alpha track-etch parameters such as bulk-etch rate, track-etch rate, induction time, and the critical angle of alpha track registration were measured at 60 and 70 °C, with and without using a phase transfer catalyst in the chemical etching for the comparison and optimization. The track registration efficiency of CR-39 in the solution medium was measured using the samples having known alpha activity of mixPu, and value obtained was found to be (4.42 ± 0.12) × 10−4 cm. The registration efficiency value thus obtained was corroborated with the expected efficiency expected from the calculated range of alpha particles in the solution. This CR-39 based method was employed to quantify the alpha activity, as low as 0.2 Bq mL−1, in the aqueous radiopharmaceutical samples having the curie levels of γ/β radio activities.

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.

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