Synthetic Versatility of β-Alkoxyvinyl Trichloromethyl Ketones for Obtaining [1,2,4]Triazolo[1,5-a]pyrimidines

Synthesis ◽  
2018 ◽  
Vol 50 (18) ◽  
pp. 3686-3695 ◽  
Author(s):  
Nilo Zanatta ◽  
Laura Souza ◽  
Josiane Santos ◽  
Mateus Mittersteiner ◽  
Valquiria Andrade ◽  
...  
Keyword(s):  
Reaction Medium ◽  
Alkyl Aryl ◽  
Trichloromethyl Group ◽  
Acidic Conditions

The synthetic versatility of 4-alkoxy-4-alkyl/aryl-1,1,1-trichloroalk-3-en-2-ones (enones) for the synthesis of [1,2,4]triazolo[1,5-a]pyrimidines, in which the trichloromethyl group is either maintained or eliminated from the product by simply controlling the reaction medium, is reported. These enones react with 3-amino-1H-1,2,4-triazoles under acidic conditions to furnish exclusively 7-(trichloromethyl)-[1,2,4]triazolo[1,5-a]pyrimidines, whereas under basic conditions [1,2,4]triazolo[1,5-a]pyrimidin-5/7(1H)-ones are obtained with elimination of the trichloromethyl group. The regioselectivity of the reactions performed under basic conditions is highly influenced by the substituents present in the starting enones. Twenty-one examples are synthesized using these two methodologies, with yields of up to 86%.

scholarly journals A Facile Synthesis Procedure for Sulfonated Aniline Oligomers with Distinct Microstructures

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1755 ◽  
Author(s):  
Ramesh Karunagaran ◽  
Campbell Coghlan ◽  
Diana Tran ◽  
Tran Tung ◽  
Alexandre Burgun ◽  
...  
Keyword(s):  
Synergistic Effects ◽  
Reaction Medium ◽  
Monomer Concentration ◽  
Molar Ratio ◽  
Water Medium ◽  
Oxidant Concentration ◽  
Aniline Oligomers ◽  
Acidic Conditions ◽  
Synthesis Procedure ◽  
Aniline Oligomer

Well-defined sulfonated aniline oligomer (SAO) microstructures with rod and flake morphologies were successfully synthesized using an aniline and oxidant with a molar ratio of 10:1 in ethanol and acidic conditions (pH 4.8). The synthesized oligomers showed excellent dispersibility and assembled as well-defined structures in contrast to the shapeless aggregated material produced in a water medium. The synergistic effects among the monomer concentration, oxidant concentration, pH, and reaction medium are shown to be controlling parameters to generate SAO microstructures with distinct morphologies, whether micro sheets or micro rods.

scholarly journals Enhancing microperoxidase activity and selectivity: immobilization in metal-organic frameworks

2019 ◽  
Vol 23 (07n08) ◽  
pp. 718-728 ◽  
Author(s):  
Effrosyni Gkaniatsou ◽  
Christian Serre ◽  
Jean-Pierre Mahy ◽  
Nathalie Steunou ◽  
Rémy Ricoux ◽  
...  
Keyword(s):  
Hybrid Materials ◽  
Metal Organic Frameworks ◽  
Environmental Pollutants ◽  
Reaction Medium ◽  
Alkaline Solutions ◽  
Phenol Derivatives ◽  
Low Concentrations ◽  
Lack Of Control ◽  
Metal Organic ◽  
Acidic Conditions

Microperoxidases 8 (MP8) and 11 (MP11) are heme-containing peptides obtained by the proteolytic digestion of Cytochrome c. They act as mini-enzymes that combine both peroxidase-like and Cytochrome P450-like activities that may be useful in the synthesis of fine chemicals or in the degradation of environmental pollutants. However, their use is limited by their instability in solution due to (i) the bleaching of the heme in the presence of an excess of H2O2, (ii) the decoordination of the distal histidine ligand of the iron under acidic conditions and, (iii) their tendency to aggregate in aqueous alkaline solutions, even at low concentrations. Additionally, both MP8 and MP11 show relatively low selectivity, due to the lack of control of the substrates by a specific catalytic pocket on the distal face of the heme. Both stability and selectivity issues can be effectively addressed by immobilization of microperoxidases in solid matrices, which can also lead to their possible recycling from the reaction medium. Considering their relatively small size, the pore inclusion of MPs into Metal-Organic Frameworks appeared to be more adequate compared to other immobilization methods that have been widely investigated for decades. The present minireview describes the catalytic activities of MP8 and MP11, their limitations, and various results describing their immobilization into MOFs which led to MP11- or MP8@MOF hybrid materials that display good activity in the oxidation of dyes and phenol derivatives, with remarkable recyclability due to the stabilization of the MPs inside the MOF cavities. An example of selective oxidation of dyes according to their charge by MP8@MOF hybrid materials is also highlighted.

High-voltage cytochemistry for three-dimensional observation of nuclei and calculation of total numbers of nuclear pores in retinal Mueller glia

1990 ◽  
Vol 48 (3) ◽  
pp. 956-957
Author(s):  
H. Ishigooka ◽  
S. Ueno ◽  
L.M. Hjelmeland ◽  
M.B. Landers ◽  
K. Ogawa
Keyword(s):  
Nuclear Envelope ◽  
High Voltage ◽  
Three Dimensional ◽  
Reaction Medium ◽  
Nuclear Pores ◽  
High Voltage Electron Microscopy ◽  
Voltage Electron ◽  
High Voltage Electron ◽  
G6pase Activity ◽  
Mueller Glia

Introduction: We have demonstrated that Glucose-6-phosphatase (G6Pase) activity is localized to the endoplasmic reticulum and nuclear envelope of Mueller glia in the normal and pathological guinea pig retina. Using a combination of this cytochemical technique and high voltage electron microscopy, the distribution of nuclear pores could be clearly observed on the nuclear envelope of Mueller glia because of their anatomical lack of reaction products. This technique was developed to study the three-dimensional structure of nuclei and to calculate total numbers of nuclear pores utilizing a computer graphic analysis system in the normal and pathological retina.Materials and methods: Normal and photocoagulated retina of pigmented adult guinea pigs were perfused with a cold mixture of 0.25% glutaraldehyde and 2% paraformaldehyde in 0.1M cacodylate buffer, and the enucleated globes were hemisected and immersed in the same fixative for 30 min. After sectioning and incubation in the reaction medium for the detection of G6Pase activity by the method of Wachstein-Meisel, the sections were postfixed, dehydrated and embedded in Spurr’s epoxy resin. Serial thick sections (1.0um) were prepared for the observation by a Hitachi high voltage electron microscope (H 1250-M) with an accelerating voltage of 1000 Kv. and pictures were analyzed and three-dimensionally reconstructed by TRI (RATOC Co., Ltd.).

Reaction of Acetaldehyde with Human Platelets

1992 ◽  
Vol 67 (01) ◽  
pp. 126-130 ◽  
Author(s):  
Olivier Spertini ◽  
Jacques Hauert ◽  
Fedor Bachmann
Keyword(s):  
Platelet Aggregation ◽  
Inhibitory Action ◽  
Ex Vivo ◽  
Platelet Rich Plasma ◽  
Shape Change ◽  
Reaction Medium ◽  
Human Platelets ◽  
Membrane Glycoproteins ◽  
Neutral Ph

SummaryPlatelet function defects observed in chronic alcoholics are not wholly explained by the inhibitory action of ethanol on platelet aggregation; they are not completely reproduced either in vivo by short-term ethanol perfusion into volunteers or in vitro by the addition of ethanol to platelet-rich plasma. As acetaldehyde (AcH) binds to many proteins and impairs cellular activities, we investigated the effect of this early degradation product of ethanol on platelets. AcH formed adducts with human platelets at neutral pH at 37° C which were stable to extensive washing, trichloracetic acid hydrolysis and heating at 100° C, and were not reduced by sodium borohydride. The amount of platelet adducts formed was a function of the incubation time and of the concentration of AcH in the reaction medium. At low AcH concentrations (<0.2 mM), platelet bound AcH was directly proportional to the concentration of AcH in the reaction medium. At higher concentrations (≥0.2 mM), AcH uptake by platelets tended to reach a plateau. The amount of adducts was also proportional to the number of exposures of platelets to pulses of 20 pM AcH.AcH adducts formation severely impaired platelet aggregation and shape change induced by ADP, collagen and thrombin. A positive correlation was established between platelet-bound AcH and inhibition of aggregation.SDS-PAGE analysis of AcH adducts at neutral pH demonstrated the binding of [14C]acetaldehyde to many platelet proteins. AcH adduct formation with membrane glycoproteins, cytoskeleton and enzymes might interfere with several steps of platelet activation and impair platelet aggregation.This in vitro study shows that AcH has a major inhibitory action on platelet aggregation and may account for the prolonged ex vivo inhibition of aggregation observed in chronic alcoholics even in the absence of alcoholemia.

Metal-Metal Cooperative Bond Activation by Heterobimetallic Alkyl, Aryl, and Acetylide PtII/CuI Complexes

2020 ◽  
Author(s):  
Shubham Deolka ◽  
Orestes Rivada Wheelaghan ◽  
Sandra Aristizábal ◽  
Robert Fayzullin ◽  
Shrinwantu Pal ◽  
...  
Keyword(s):  
Alkyl Group ◽  
Bond Activation ◽  
Bond Cleavage ◽  
Terminal Alkyne ◽  
Alkyl Aryl ◽  
Metal Metal ◽  
The Stability ◽  
Selective Formation ◽  
Organoplatinum Compounds

We report selective formation of heterobimetallic PtII/CuI complexes that demonstrate how facile bond activation processes can be achieved by altering reactivity of common organoplatinum compounds through their interaction with another metal center. The interaction of the Cu center with Pt center and with a Pt-bound alkyl group increases the stability of PtMe2 towards undesired rollover cyclometalation. The presence of the CuI center also enables facile transmetalation from electron-deficient tetraarylborate [B(ArF)4]- anion and mild C-H bond cleavage of a terminal alkyne, which was not observed in the absence of an electrophilic Cu center. The DFT study indicates that the role of Cu center acts as a binding site for alkyne substrate, while activating its terminal C-H bond.

Chemical Transformation of Fe, Air & Water to Ammonia: Variation of Reaction Rate with Temperature, Pressure, Alkalinity and Iron

2018 ◽  
Author(s):  
Ping Peng ◽  
Fang-Fang Li ◽  
Xinye Liu ◽  
Jiawen Ren ◽  
jessica stuart ◽  
...  
Keyword(s):  
Particle Size ◽  
Reaction Rate ◽  
Electrolyte Concentration ◽  
Iron Concentration ◽  
Reaction Medium ◽  
Iron Particle ◽  
Intermediate Step ◽  
Ammonia Production ◽  
Pure Nitrogen ◽  
Alkaline Reaction

The rate of ammonia production by the <u>chemical </u>oxidation of iron, N<sub>2</sub>(from air or as pure nitrogen) and water is studied as a function of (1) iron particle size, (2) iron concentration, (3) temperature, (4) pressureand (5) concentration of the alkaline reaction medium. The reaction meduium consists of an aqueous solution of equal molal concentrations of NaOH and KOH (Na<sub>0.5</sub>K<sub>0.5</sub>OH). We had previously reported on the <u>chemical </u>reaction of iron and nitrogen in alkaline medium to ammonia as an intermediate step in the <u>electrochemical </u>synthesis of ammonia by a nano-sized iron oxide electrocatlyst. Here, the intermediate <u>chemical </u>reaction step is exclusively explored. The ammonia production rate increases with temperature (from 20 to 250°C), pressure (from 1 atm to 15 atm of air or N<sub>2</sub>), and exhibits a maximum rate at an electrolyte concentration of 8 molal Na<sub>0,5</sub>K<sub>0,5</sub>OH in a sealed N<sub>2</sub>reactor. 1-3 µm particle size Fe drive the highest observed ammonia production reaction rate. The Fe mass normalized rate of ammonia production increases with decreasing added mass of the Fe reactant reaching a maximum observed rate of 2.2x10<sup>-4</sup>mole of NH<sub>3</sub>h<sup>-1</sup>g<sup>-1</sup>for the reaction of 0.1 g of 1-3 µm Fe in 200°C 8 molal Na<sub>0.5</sub>K<sub>0.5</sub>OH at 15 atm. Under these conditions 5.1 wt% of the iron reacts to form NH<sub>3</sub>via the reaction N<sub>2</sub>+ 2Fe + 3H<sub>2</sub>O ®2NH<sub>3</sub>+ Fe<sub>2</sub>O<sub>3</sub>.

Thermodynamic Properties of Microemulsion Formed by Different Kinds of Alkyl Aryl Sulfonates

2012 ◽  
Vol 29 (11) ◽  
pp. 1309
Author(s):  
Tao YU ◽  
Shiqiong LUO ◽  
Wei DING ◽  
Huimin WANG ◽  
Guangmiao QU ◽  
...  
Keyword(s):  
Thermodynamic Properties ◽  
Alkyl Aryl
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