Breakdown of the Hammett acidity function concept

1973 ◽  
Vol 95 (24) ◽  
pp. 8178-8179 ◽  
Author(s):  
Maurice M. Kreevoy ◽  
Ernest H. Baughman
Keyword(s):  
Acidity Function ◽  
Function Concept ◽  
Hammett Acidity Function

STRONGLY BASIC SYSTEMS: III. THE H− FUNCTION FOR VARIOUS SOLVENT SYSTEMS

1964 ◽  
Vol 42 (7) ◽  
pp. 1681-1693 ◽  
Author(s):  
Ross Stewart ◽  
J. P. O'Donnell
Keyword(s):  
Lithium Hydroxide ◽  
Dimethyl Sulphoxide ◽  
Tetramethylammonium Hydroxide ◽  
Acidity Function ◽  
Function Concept ◽  
Substituted Anilines ◽  
Hammett Acidity Function ◽  
Solvent Systems

The Hammett acidity function concept has been used to determine simultaneously the pKa values of 24 substituted anilines and diphenylamines and the H− values of various solvent systems. The following solvent systems were examined (the most basic H− value obtained for each is shown in parentheses): water containing benzyltrimethylammonium hydroxide (16.20); pyridine–water containing tetramethylammonium hydroxide (18.91); sulpholane–water containing tetramethylammonium hydroxide (19.18); dimethyl sulphoxide–water containing tetramethylammonium hydroxide (18.61); water containing lithium hydroxide (14.31).In addition to these results adjustments have been made to previously published scales for hydrazine–water (15.08) and ethylenediamine–water (15.48).

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.

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.

A Critical Test of the Hammett Acidity Function

1972 ◽  
Vol 50 (4) ◽  
pp. 581-583 ◽  
Author(s):  
Keith Yates ◽  
Stanley A. Shapiro
Keyword(s):  
Sulfuric Acid ◽  
Aromatic Amines ◽  
Acidity Function ◽  
Experimental Uncertainty ◽  
Critical Test ◽  
Hammett Acidity Function ◽  
Primary Aromatic Amines

The applicability of the H0 acidity function to primary aromatic amines in general has been tested by using a set of five aniline indicators bearing no nitro-substituents. Up to 45% sulfuric acid the scale generated by these bases is the same (within experimental uncertainty) as that based entirely on nitro-anilines.

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