Search results for "Potassium"
showing 10 items of 930 documents
Synthesis of 4-amino-5-fluoropyrimidines and 5-amino-4-fluoropyrazoles from a β-fluoroenolate salt
2020
A synthesis of fluorinated pyrimidines under mild conditions from amidine hydrochlorides and the recently described potassium 2-cyano-2-fluoroethenolate was developed. A broad substrate scope was tested and mostly excellent yields were obtained. The synthesis of fluorinated aminopyrazoles from the same fluorinated precursor could be demonstrated but proceeded with lower efficiency.
Isobaric Vapor−Liquid Equilibrium for Ethanol + Water + Strontium Nitrate
1996
Isobaric vapor−liquid equilibrium for ethanol (1) + water (2) + potassium nitrate (3) at various concentrations of salt and with ethanol mole fractions from 0 to 0.642 has been measured at 100.0 kPa. The results were correlated by assuming that the salt was in ionic form and it was associated only with the water.
Potassium silver thiocyanate
2001
The structure of K[Ag(SCN)2] forms a three-dimensional network consisting of seven-coordinated K atoms and four-coordinated Ag atoms connected together by bridging thiocyanate groups.
ChemInform Abstract: Imidazolium and Potassium Hydrogen Carbonate Salts as Ecofriendly Organocatalysts for Oxazolidinone Synthesis.
2016
Although oxazolidinones are valuable intermediate compounds for industrial applications, no synthetic method is suitable for their production on a large scale owing to the use of reagents/catalysts that are hazardous or toxic to human health or ecotoxic for the environment. In this manuscript, we describe new and efficient catalysts, that is, the nontoxic hydrogen carbonate anion in combination with a potassium or diisobutylimidazolium ([iBu(2)IM]) countercation, for the conversion of -amino alcohols into cyclic oxazolidinones in high yields of 69 to 90%. Depending on the catalytic conditions, both catalysts could be easily recovered from the crude reaction products and reused several times…
PLASMOGENY, A NEW SCIENCE OF THE ORIGIN OF LIFE
2014
The Church has always hampered the progress of Mankind so as to retain its hold over awareness, which is the basis of secular exploitation of the people.
Nucleophilic Additions of the Cyanide Anion to 4,4-Dichloro-1,1-Diphenyl-2-Azabuta-1,3-Diene
2002
The unexpected formation of a 2H-pyrrole by reaction of potassium cyanide with 4,4-dichloro-1,1-diphenyl-2-azabuta-1,3-diene and the mechanism of this reaction are described and the structures of the product and a trapped intermediate confirmed by X-ray crystallographic studies.
Über die anionische polymerisation von acrolein. Polymere acroleine. 34. Mitt.1
1967
Acrolein wurde mit Lithium-, Natrium- oder Kaliumcyanid in Tetrahydrofuran bzw.in Toluol polymerisiert. Die Abhangigkeit der Polymerisationsgeschwindigkeit und der Struktur der Polymeren von Reaktionsmedium, Temperatur und Gegenion wurde untersucht. Unterhalb -10°C polymerisiert Acrolein mit Natriumcyanid nur uber die CO. Doppelbindung. Es entstehen hochmolekulare, losliche Poly-3,4-acroleine. Oberhalb -10°C wird dagegen auch Polymerisation uber die Vinylgruppe beobachtet. Die Kurve fur die Abhangigkeit der Polymerisationsgeschwindigkeit von der Reaktionstemperatur durchlauft Extremwerte. Es wird ein Mechanismus aufgestellt, der die jeweilige Struktur des Polymeren als Ergebnis von Gleichge…
Electrochemical Syntheses of Carboxylic Acids from Carbon Dioxide
1987
The first report on the reduction of carbon dioxide is due to the venerable name of Hermann Kolbe, who, in 1861, published with R. Schmitt the reduction of carbon dioxide to formate with metallic potassium (1). Seven years later he introduced to the Chemical Society in London his assistant E. Drechsel, who “after many unsuccessful experiments, made during several years” (2) at the end succeeded in reducing carbon dioxide to oxalate with metallic sodium or with potassium amalgam in anhydrous conditions. Soon afterwards Beketov (3) and Royer (4) opened the series of papers dealing with the direct involvement of carbon dioxide in electrolytic processes. Since then the reduction of carbon dioxi…
Catalytic combustion of ethane over high surface area Ln1−xKxMnO3 (Ln = La, Nd) perovskites: The effect of potassium substitution
1997
Publisher Summary As a general trend, the substitution of the rare earth cation by potassium decreased the intrinsic activity, reduced the reaction order in oxygen, and, for the more substituted samples (x>0.10), it increased the selectivity to ethene. Supported platinum or palladium catalysts have so far been used almost exclusively, because of their excellent activity. However, their high price, tendency to be poisoned, and volatility in some applications have estimulated the search for suitable substitutes. LaCoO3, as a potential auto exhaust catalyst, starting a wide interest in the catalytic properties of perovskites. Their specific application as catalysts in flameless combustion has …
The bleaching efficacy of carbamide peroxide gels containing potassium nitrate desensitizer
2020
Background To evaluate the bleaching efficacy of at-home carbamide peroxide (CP) gels in two concentrations, containing or not a desensitizing agent. Material and methods Forty incisors were divided into four groups (n=10), according to gel concentrations (10% or 22%), and presence or not of 3% potassium nitrate in the gel. A thin layer of gel was applied to the buccal surface of each tooth for 2h/day for 4 weeks. Bleaching efficacy was measured using a spectrophotometer, and ∆E*ab, ∆E00 and ∆WID were calculated. Measurements were performed at baseline, 7, 14, 21, 28, and 35 days following the first gel application. Data were analyzed by two-way RM-ANOVA and Tukey's test (α=0.05). Results R…