Mechanistic approach to a photochemical/thermal dual-cure initiating system based on pyrylium salt–hydroperoxide for epoxide cationic polymerization

2017 ◽  
Vol 8 (2) ◽  
pp. 388-395 ◽  
Author(s):  
M. Lecompère ◽  
X. Allonas ◽  
D. Maréchal ◽  
A. Criqui
Keyword(s):  
Cationic Polymerization ◽  
Promising Method ◽  
Pyrylium Salt ◽  
Hydroperoxide Group ◽  
Pyrylium Salts ◽  
Mechanistic Approach

An initiating system based on pyrylium salts and the hydroperoxide group is a promising method to perform a dual-cure of epoxides via cationic polymerization.

Reaction of pyrylium salts with hydrazine and methylhydrazine. Concerning the scope of the 1,2(4H)-diazepine synthesis

1980 ◽  
Vol 58 (5) ◽  
pp. 494-500 ◽  
Author(s):  
D. J. Harris ◽  
G.Y.-P. Kan ◽  
T. Tschamber ◽  
V. Snieckus
Keyword(s):  
Pyrylium Salt ◽  
Minor Components ◽  
Counter Anion ◽  
Methyl Substitution ◽  
Pyrylium Salts ◽  
Product Composition

The reaction of pyrylium salts 1a–e with methylhydrazine gives pyrazolines (2), pyrazoles (3), pyridines (4), 1,2-diazepine (5), and N-methylaminopyridinium salts (6). Product composition has been studied as a function of pyrylium salt counter anion, concentration of methylhydrazine, and conditions of the reaction (Table 1). Pyridines (4) and 1,2-diazepines (5) are minor components, the major products being the pyrazolines (2) and pyrazoles (3). The reactions of more unusual pyrylium salts (1f–i, 8a, 9a, 9c, and 11a) with hydrazine have been shown to provide 1,2(4H)-diazepines (10, 12–15) and N-aminopyridinium salts (8b, 9b) (Table 2), the nature of the product apparently depending on the absence or presence of 2-methyl substitution respectively in the starting pyrylium salts.

scholarly journals Pyrylium Salts with Long Alkyl Substituents, II 2,4-Dimethyl-6-undecylpyrylium Perchlorate and Derived Pyridinium Salts

1992 ◽  
Vol 47 (7) ◽  
pp. 1011-1015 ◽  
Author(s):  
Mariana Bogatian ◽  
Calin Deleanu ◽  
Gheorghe Mihai ◽  
Teodor Silviu Balaban
Keyword(s):  
Column Chromatography ◽  
Perchloric Acid ◽  
Nmr Spectra ◽  
Mesityl Oxide ◽  
Pyridinium Salts ◽  
Pyrylium Salt ◽  
Pyrylium Salts ◽  
High Yields

The crystalline title pyrylium salt was obtained by SnCl4 catalysed acylation of mesityl oxide with lauroyl chloride followed by treatment with perchloric acid and column chromatography. This new pyrylium salt was converted in high yields into the corresponding pyridine and N-substituted pyridinium salts (N-methyl, N-phenyl, N-(4-n-butylphenyl), and N-dodecyl) whose proton (300 MHz) and carbon-13 (75 MHz) NMR spectra are presented.

scholarly journals Stereospecific, Pyrylium Salt-Catalyzed O-Glycosylations of Phenols and Alkyl Alcohols

2021 ◽  
Author(s):  
Michael Martin Nielsen ◽  
Thomas Holmstrøm ◽  
Christian Marcus Pedersen
Keyword(s):  
Catalytic Reaction ◽  
Mechanistic Study ◽  
Pyrylium Salt ◽  
Carbohydrate Chemistry ◽  
Scientific Impact ◽  
Pyrylium Salts ◽  
Stereoselective Glycosylation ◽  
Wide Range ◽  
Made In

Despite many years of invention, the field of carbohydrate chemistry remains rather inaccessible to non-specialists, which limits the scientific impact and reach of the discoveries made in the field. Aiming to increase the availability of stereoselective glycosylation chemistry for non-specialists, we have discovered that several commercially available pyrylium salts catalyze stereospecific O-glycosylations of a wide range of phenols and alkyl alcohols. This catalytic reaction utilizes trichloroacetimidates, an easily accessible and synthetically proven electrophile, takes place under air and only initiates when all three reagents are mixed, which should provide better reproducibility by non-specialists. The reaction is stereospecific, resulting in β-specific glycosylations from α-trichloroacetimidates, whilst an α-selective glycosylation proceeds from β-trichloroacetimidates. A mechanistic study revealed that the reaction likely proceeds via an SN2-like substitution on the protonated electrophile.

Towards a Tangible Philosophy through Design

2019 ◽  
Vol 2 (1) ◽  
Author(s):  
Jelle VAN DIJK ◽  
Jonne VAN BELLE ◽  
Wouter EGGINK
Keyword(s):  
Digital Age ◽  
Promising Method ◽  
Design Approach ◽  
The World ◽  
First Results

The combined philosophy and design approach called Philosophy-through-Design (PtD) is proposed using an exemplary project about being-in-the-world in the digital age. PtD is a practical way to do philosophy through designing interventions, and involves various people in the exploration of philosophical concepts. It stems from the overlapping questions found in philosophy and design regarding human-technology interaction. By intertwining both, they benefit from describing, understanding and proposing human-technology interactions to unfold new questions and perspectives. In the exemplary project, being-in-the-world refers to a way of being that is embodied, active, open-ended and situational, based on the phenomenological and embodied theories of Tim Ingold. This concept questions what it means to be human in the digital age and how our lives with technology are built. The first results show the process of weaving together observation, creation and reflection, which presents Philosophy-through-Design as a promising method for designers to practice a tangible philosophy.

Epoxy-titania composites of cationic polymerization: synthesis conditions and properties

2015 ◽  
Vol 37 (4) ◽  
pp. 402-407
Author(s):  
S.V. Zhil’tsova ◽  
◽  
V.M. Mikhal’chuk ◽  
N.G. Leonova ◽  
R.I. Lyga ◽  
...  
Keyword(s):  
Cationic Polymerization ◽  
Synthesis Conditions

Mechanistic Study and Development of Catalytic Reactions of Sm(II)

2018 ◽  
Author(s):  
Sandepan Maity ◽  
Robert Flowers
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Proton Donor ◽  
Catalytic Reactions ◽  
Mechanistic Study ◽  
Mechanistic Studies ◽  
Cyclization Reactions ◽  
Mechanistic Approach ◽  
Donor Source

Despite the broad utility and application of SmI<sub>2</sub>in synthesis, the reagent is used in stoichiometric amounts and has a high molecular weight, resulting in a large amount of material being used for reactions requiring one or more equivalents of electrons. We report mechanistic studies on catalytic reactions of Sm(II) employing a terminal magnesium reductant and trimethyl silyl chloride in concert with a non-coordinating proton donor source. Reactions using this approach permitted reductions with as little as 1 mol% Sm. The mechanistic approach enabled catalysis employing HMPA as a ligand, facilitating the development of catalytic Sm(II) 5-<i>exo</i>-<i>trig </i>ketyl olefin cyclization reactions.

4-(azulen-1-yl)-2,6-diphenylchalcogenopyrylium Perchlorates; Synthesis and Characterization

2020 ◽  
Vol 71 (6) ◽  
pp. 89-95
Author(s):  
Liviu Birzan ◽  
Mihaela Cristea ◽  
Constantin Draghici ◽  
Victorita Tecuceanu ◽  
Maria Maganu ◽  
...  
Keyword(s):  
Synthesis And Characterization ◽  
Pyrylium Salts ◽  
Chloro Derivatives

2,6-Diphenyl substituted thio- and seleno-pyrylium salts with azulen-1-yl moieties in 4-position were prepared from phenylacetylene going through chalcogenopyrones and 4-chloro-chalcogenopyrylium salts as intermediates. The final step of synthesis involves the electrophile substitution in 1-position of azulenes with the obtained chloro-derivatives and the products isolation as stable perchlorates. The electronic and magnetic spectra of products are presented and compared with those of the corresponding pyrylium salts.

Some Considerations Regarding the 1H and 13C Spectra of 4-(1-azulenyl)-2,6-bis(2-heteroaryl-vinyl)- pyrylium and Pyridinium and their Corresponding Pyridines

2018 ◽  
Vol 69 (1) ◽  
pp. 64-69
Author(s):  
Liviu Birzan ◽  
Mihaela Cristea ◽  
Constantin C. Draghici ◽  
Alexandru C. Razus
Keyword(s):  
Double Bond ◽  
13C Nmr ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Pyridinium Salts ◽  
13C Nmr Spectra ◽  
1H And 13C Nmr ◽  
Pyrylium Salts

The 1H and 13C NMR spectra of several 2,6-diheteroarylvinyl heterocycles containing 4-azulenyl moiety were recorded and their proton and carbon chemical shifts were compared with those of the compounds without double bond between the heterocycles. The influence of the nature of central and side heterocycles, molecule polarization and anisotropic effects were revealed. The highest chemical shifts were recorded for the pyrylium salts and the lowest at pyridines, but in the case of the pyridinium salts, the protons chemical shifts at the central heterocycle are more shielded due to a peculiar anisotropy of the attached vinyl groups.

Brazing as a promising method of producing permanent joints

2020 ◽  
Vol 2020 (3) ◽  
pp. 34-40
Author(s):  
S.V. Maksymova ◽  
Keyword(s):  
Promising Method
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