The Apparent Acidity Function (H0) of Polyphosphoric Acid

1961 ◽  
Vol 83 (7) ◽  
pp. 1718-1721 ◽  
Author(s):  
R. G. Downing ◽  
D. E. Pearson
2018 ◽  
Vol 21 (8) ◽  
pp. 602-608 ◽  
Author(s):  
Zainab Ehsani-Nasab ◽  
Ali Ezabadi

Aim and Objective: In the present work, 1, 1’-sulfinyldiethylammonium bis (hydrogen sulfate) as a novel room temperature dicationic ionic liquid was synthesized and used as a catalyst for xanthenediones synthesis. Material and Method: The dicationic ionic liquid has been synthesized using ethylamine and thionyl chloride as precursors. Then, by the reaction of [(EtNH2)2SO]Cl2 with H2SO4, [(EtNH2)2SO][HSO4]2 was prepared and after that, it was characterized by FT-IR, 1H NMR, 13C NMR as well as Hammett acidity function. This dicationic ionic liquid was used as a catalyst for the synthesis of xanthenediones via condensation of structurally diverse aldehydes and dimedone under solvent-free conditions. The progress of the reaction was monitored by thin layer chromatography (ethyl acetate/n-hexane = 3/7). Results: An efficient solvent-free method for the synthesis of xanthenediones has been developed in the presence of [(EtNH2)2SO][HSO4]2 as a powerful catalyst with high to excellent yields, and short reaction times. Additionally, recycling studies have demonstrated that the dicationic ionic liquid can be readily recovered and reused at least four times without significant loss of its catalytic activity. Conclusion: This new dicationic ionic liquid can act as a highly efficient catalyst for xanthenediones synthesis under solvent-free conditions.


1982 ◽  
Vol 47 (5) ◽  
pp. 1382-1391 ◽  
Author(s):  
Jiří Jílek ◽  
Josef Pomykáček ◽  
Jiřina Metyšová ◽  
Miroslav Protiva

Acids IIa-c were prepared by reactions of (4-fluoro-2-iodophenyl)acetic acid with 4-methoxythiophenol, 4-ethoxythiophenol and 4-(ethylthio)thiophenol and cyclized with polyphosphoric acid in boiling toluene to dibenzo[b,f]thiepin-10(11H)-ones IIIa-c. Reduction with sodium borohydride afforded the alcohols IVa-c which were treated with hydrogen chloride and gave the chloro derivatives Va-c. Substitution reactions with 1-methylpiperazine resulted in the title compounds Ia-c out of which the methoxy derivative Ia was transformed by demethylation with boron tribromide to the phenol Id. Compounds Ia-d are very potent neuroleptics exhibiting a clear prolongation of the central depressant and some prolongation of the cataleptic activity.


1987 ◽  
Vol 52 (9) ◽  
pp. 2212-2216
Author(s):  
Oldřich Pytela ◽  
Martin Kaska ◽  
Miroslav Ludwig ◽  
Miroslav Večeřa

The decomposition kinetics has been measured of fourteen 3-acetyl-1,3-bis(subst. phenyl)triazenes in 40% (v/v) ethanol and sulphuric acid. The kinetic acidity function and catalytic rate constants have been determined from the rate constants observed. Mechanism has been suggested for the general acid-catalyzed solvolysis from comparison of the course of the kinetic acidity function and H0 function and from the reaction constant of the Hammett equation.


1980 ◽  
Vol 45 (10) ◽  
pp. 2688-2694 ◽  
Author(s):  
Irena Červená ◽  
Marta Hrubantová ◽  
Emil Svátek ◽  
Jiří Holubek ◽  
Miroslav Ryska ◽  
...  

The acid VI, obtained from 2,5-difluorothiophenol (IV) and (2-iodophenyl)acetic acid, afforded by cyclization with polyphosphoric acid 6,9-difluorodibenzo[b,f]thiepin-10(11H)-one (VII) in a satisfactory yield. Two further steps led to the chloro derivative X giving by a substitution reaction with 1-methylpiperazine the title compound III. This substance exhibits some 10% incoordinating activity of the unsubstituted compound I and an indication of cataleptic activity, in contrast to the inactive analogous dichloro compound II. The bulky atom of chlorine in the vicinity of the methylpiperazine residue interferes evidently with the CNS activity; the influence of the atom of fluorine is much less pronounced in this line.


Molecules ◽  
2021 ◽  
Vol 26 (14) ◽  
pp. 4240
Author(s):  
Manar M. Arafeh ◽  
Ebrahim Saeedian Moghadam ◽  
Sirin A. I. Adham ◽  
Raphael Stoll ◽  
Raid J. Abdel-Jalil

A novel series of 2-(aryldiazenyl)-3-methyl-1H-benzo[g]indole derivatives (3a–f) were prepared through the cyclization of the corresponding arylamidrazones, employing polyphosphoric acid (PPA) as a cyclizing agent. All of the compounds (3a–f) were characterized using 1H NMR, 13C NMR, MS, elemental analysis, and melting point techniques. The synthesized compounds were evaluated for cytotoxic activity against diverse human cancer cell lines by the National Cancer Institute. While all of the screened compounds were found to be cytotoxic at a 10 µM concentration, two of them (2c) and (3c) were subjected to five dose screens and showed a significant cytotoxicity and selectivity.


1988 ◽  
pp. 1375-1383
Author(s):  
Tadao KENJO ◽  
Kimio INABA ◽  
Hideichi YAMASHITA ◽  
Hitoshi KIMURA

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