scholarly journals Protonation constants of hydroxybenzenes in hydrochloric acid

1999 ◽  
Vol 64 (9) ◽  
pp. 533-538
Author(s):  
D.S. Veselinovic ◽  
M.V. Obradovic ◽  
S.B. Tosic
Keyword(s):  
Hydrochloric Acid ◽  
Aqueous Solutions ◽  
Absorption Spectra ◽  
Protonation Constants ◽  
Acidity Function ◽  
Absorption Bands ◽  
Graphic Dependence ◽  
Mineral Acids ◽  
Hammett Acidity Function

The absorption spectra of monohydroxybenzene (Fen), 1,3-dihydroxybenzene (Rez), 1,4-dihydroxybenzene (Hi), 1,2,3-trihydroxybenzene (Pg) and 1,3,5-trihydroxy-benzene (Fg) in aqueous solutions of hydrochloric acid with different values of the Hammett acidity function(H0) have two absorption bands in the region between 190-220 nm and 260-290 nm. This behavior is similar in another mineral acids (H2SO4, H3PO4, HClO4). The absorbance decreases with increasing of acidity (with decreasing of H0 values) because of O-protonation. The absorption maxima shift to longer wave-lengths, and the graphic dependence of the absorption of the second band as a function of H0 gives characteristic S-curves. These curves show the different effect of the acid on the form the protonation of the investigated hydroxybenzenes. The potonation constants of the hydroxybenzenes were calculated: pKFen=-1.95; pKRez=-2.40; pKHi= -1.93; pKPg=-2.95; pKFg=-1.83.

IONIZATION OF ORGANIC COMPOUNDS: III. BASICITIES OF PROPIONIC ACID AND PROPIONAMIDE

1962 ◽  
Vol 40 (5) ◽  
pp. 966-975 ◽  
Author(s):  
J. T. Edward ◽  
I. C. Wang
Keyword(s):  
Sulphuric Acid ◽  
Propionic Acid ◽  
Organic Compounds ◽  
Acid Concentration ◽  
Ultraviolet Absorption ◽  
Protonation Constants ◽  
Acidity Function ◽  
Hammett Acidity Function ◽  
Ionization Ratio

Protonation constants (pKBH+) of −6.8 and −0.9 have been determined for propionic acid and propionamide, respectively, from measurements of their ultraviolet absorption in various concentrations of sulphuric acid. The ionization ratio of propionamide and of other amides increases more slowly than the Hammett acidity function, h0, with increase in acid concentration. This may be explained by assuming that in a given concentration of sulphuric acid the protonated amide is more heavily hydrated than the protonated Hammett indicator used to establish the h0 scale for this region of acid concentrations.

THE ULTRAVIOLET ABSORPTION SPECTRA OF THE FERRIC ION AND ITS FIRST HYDROLYSIS PRODUCT IN AQUEOUS SOLUTIONS

1957 ◽  
Vol 35 (9) ◽  
pp. 1002-1009 ◽  
Author(s):  
R. C. Turner ◽  
Kathleen E. Miles
Keyword(s):  
Aqueous Solution ◽  
Aqueous Solutions ◽  
Absorption Spectra ◽  
Perchloric Acid ◽  
Hydrolysis Product ◽  
Ultraviolet Absorption ◽  
Ferric Ion ◽  
Absorption Bands

The absorption spectra of the ferric ion and its first hydrolysis product in an aqueous solution of perchloric acid was determined. The Fe3+ ion has two absorption bands, one with a maximum at 240 mμ and another which extends into the region below 200 mμ. The FeOH2+ ion also has two absorption bands, the maxima of which occur at 300 mμ and 205 mμ. A figure shows the magnitude of the absorption of each of these ions from 200 to 350 mμ.

scholarly journals Исследование изменений в спектре поглощения современных хлоринсодержащих препаратов для фотодинамической терапии и метиленового синего в результате воздействия светодиодного излучения с длиной волны 656± 10 nm

2020 ◽  
Vol 129 (7) ◽  
pp. 972
Author(s):  
А.В. Беликов ◽  
Ю.В. Семяшкина ◽  
С.Н. Смирнов ◽  
А.Д. Тавалинская
Keyword(s):  
Methylene Blue ◽  
Aqueous Solutions ◽  
Absorption Spectra ◽  
Exposure Time ◽  
Spectral Range ◽  
Color Model ◽  
Absorption Bands ◽  
Lab Color Model ◽  
Cie Lab ◽  
The Impact

The changes in absorption spectra of aqueous solutions of modern chlorine-containing photosensitizing preparations "Revixan" (Areal, Russia) and "Chloderm" (Chloderm, Russia) depending on the intensity of LED radiation with wavelength of 656 ± 10 nm and exposure time were studied in spectral range 600-700 nm. The parameters of the CIE Lab color model of the image of "Revixan" aqueous solution before and after LED exposure were investigated. The changes in absorption spectra of aqueous solutions of methylene blue with different initial concentrations arising after exposure to LED radiation with intensity of 180 ± 20 mW/cm2 were studied in the spectral range 400-900 nm. It was shown that the impact of LED radiation changes the absorption spectra of the studied preparations and increases the parameter L (lightness) of the CIE Lab color model for "Revixan". An increase in the LED radiation intensity and exposure time leads to a decrease in absorption for "Revixan" and "Chloderm" in spectral range 600-700 nm and to a shift of the peaks of absorption bands lying in this range towards a longer wavelength. The impact of LED radiation on aqueous solutions of methylene blue leads to a decrease in their absorption in spectral range 400-900 nm.

Comparative Interpretation of Absorption Spectra of Technetium (IV) and Rhenium (IV) Hexahalides

1965 ◽  
Vol 20 (1) ◽  
pp. 65-75 ◽  
Author(s):  
Chr. Klixbüll Jørgensen ◽  
Klaus Schwochau
Keyword(s):  
Electron Transfer ◽  
Aqueous Solutions ◽  
Absorption Spectra ◽  
Vibrational Structure ◽  
Octahedral Symmetry ◽  
Absorption Bands ◽  
Nephelauxetic Effect

Absorption spectra of aqueous solutions of TcX6- and ReX6- (X = F, Cl, Br, I) are measured between 8 000 and ∼ 50 000 cm-1 and theoretically discussed. The electron transfer spectra indicate the optical electronegativity xopt= 2.25 for Tc (IV) and 2.05 for the less oxidizing Re (IV). The spectrochemical parameter Δ is determined to 28 400 cm-1 in TcF6 and 32 800 cm-1 in ReF6-. The nephelauxetic effect is evaluated from the spin-forbidden intra-sub-shell transitions in all eight species, and from the two spin-allowed bands of TcF6- The vibrational structure of the narrow absorption bands and the possible weak distortion from octahedral symmetry of Tc (IV) hexahalides are discussed.

Preparation and Characterization of a Novel Room Temperature Dicationic Ionic Liquid and its Application in the Synthesis of Xanthenediones Under Solvent-Free Conditions

2018 ◽  
Vol 21 (8) ◽  
pp. 602-608 ◽  
Author(s):  
Zainab Ehsani-Nasab ◽  
Ali Ezabadi
Keyword(s):  
Ionic Liquid ◽  
Room Temperature ◽  
Reaction Times ◽  
Significant Loss ◽  
Solvent Free ◽  
Acidity Function ◽  
Efficient Catalyst ◽  
Solvent Free Conditions ◽  
Hammett Acidity Function ◽  
Dicationic Ionic Liquid

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.

Mechanism of anionic coordination dimerization of isoprene

1981 ◽  
Vol 46 (7) ◽  
pp. 1600-1606 ◽  
Author(s):  
Jan Bartoň ◽  
Karel Volka ◽  
Miroslav Kašpar ◽  
Vlastimil Růžička
Keyword(s):  
Gas Chromatography ◽  
Alkali Metal ◽  
Absorption Spectra ◽  
Visible Radiation ◽  
Absorption Bands ◽  
Absorption Spectrophotometry ◽  
Spectrophotometric Data ◽  
Oligomeric Forms

The mechanism of controlled anionic coordination dimerization of isoprene (i.e. 2-methyl-1,3-butadiene) in the system tetrahydrofuran-isoprene-alkali metal-dialkylamine was investigated by using absorption spectrophotometry in the range of visible radiation and gas chromatography. The effect of the alkali metal (Li, Na, K) and dialkylamine (dicyclohexylamine, N-isopropylcyclohexylamine, N-methylisopropylamine) on the absorption spectra was tested. By comparing chromatographic and spectrophotometric data, the absorption bands in the range of visible radiation were identified with the existence of π-complexes between oligomeric forms of isoprene and alkali metal dialkylamide.

Sign in / Sign up

Export Citation Format

Share Document