Thiohydantoins. VII. Ionization and ultraviolet spectra of 4-thiohydantoins and 2,4-dithiohydantoins

1969 ◽  
Vol 47 (7) ◽  
pp. 1117-1122 ◽  
Author(s):  
J. T. Edward ◽  
J. K. Liu
Keyword(s):  
Sulfuric Acid ◽  
Acid Solution ◽  
Dissociation Constants ◽  
Acid Media ◽  
Ultraviolet Spectra ◽  
Aqueous Sulfuric Acid ◽  
Different Types ◽  
Acid And Base ◽  
Methyl Derivatives ◽  
Acidity Functions

The acid and base dissociation constants of 5,5-pentamethylene-4-thiohydantoin, 5,5-pentamethylene-2,4-dithiohydantoin, and their 1-methyl derivatives, have been determined by ultraviolet studies in basic and acid media. In aqueous sulfuric acid the 4-thiohydantoins are protonated on oxygen at the 2-position, so that the extent of protonation varies with the HA function of the acid solution, while the 2,4-dithiohydantoins are protonated on sulfur at the 2-position, so that the extent of their protonation varies with H0′′′. The importance of using acidity functions appropriate to the different types of compounds when comparing their basicities is emphasized.

Highly gas permselective polyetherketone hollow fibre membranes using aqueous sulfuric acid solution as coagulant

e-Polymers ◽  
2007 ◽  
Vol 7 (1) ◽  
Author(s):  
Jiping Yang ◽  
Philip J Brown
Keyword(s):  
Mechanical Properties ◽  
Sulfuric Acid ◽  
Acid Solution ◽  
Gas Separation ◽  
Sulfuric Acid Solution ◽  
Hollow Fibre ◽  
Injection Rate ◽  
Fluid Injection ◽  
Aqueous Sulfuric Acid ◽  
Membrane Morphology

AbstractHollow fibre membranes with more sponge-like morphology and improved gas permeation performance were spun from 20% polyetherketone (PEK) /sulfuric acid (H2SO4) dope solution with aqueous sulfuric acid solution as coagulant using dry-jet wet spinning process. The membrane morphology, mechanical properties and gas separation performance (hydrogen, methane and carbon dioxide) of as-spun PEK hollow fibres have been measured using SEM, Instron and gas test rig. Better cross section structures and mechanical properties in as-spun PEK hollow fibres were observed when aqueous sulfuric acid solution replaced water as coagulant (internal and external). The hydrogen/methane selectivity of up to 40 and hydrogen permeation rate of 3.65 GPU obtained in PEK hollow fibre membranes using 30% sulfuric acid solution as internal and external coagulant simultaneously at the bore fluid injection rate of 30 ml/h are higher than those reported in literatures. Furthermore the effects of bore fluid injection rate and various coagulants on the membrane morphology, mechanical properties and gas separation properties were investigated, as well.

scholarly journals RATE ENHANCEMENTS DUE TO AQUEOUS SULFURIC ACID IN Mn (III) OXIDATION OF CERTAIN PURINE ALKALOIDS - KINETIC ANALYSIS OF ACIDITY FUNCTIONS

2021 ◽  
Vol 14 (03) ◽  
Author(s):  
A. Ramakrishna Reddy ◽  
J. Prasad ◽  
M. Bhooshan ◽  
K. C. Rajanna ◽  
A. Panasa Reddy ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Kinetic Analysis ◽  
Aqueous Sulfuric Acid ◽  
Purine Alkaloids ◽  
Acidity Functions

Acidity Dependence of the Tautomeric Equilibrium Between the First Conjugated Acids of 4-Aminoazobenzenes

1979 ◽  
Vol 32 (1) ◽  
pp. 41 ◽  
Author(s):  
S Yamamoto ◽  
Y Tenno ◽  
N Nishimura
Keyword(s):  
Sulfuric Acid ◽  
Tautomeric Equilibrium ◽  
Acid Solutions ◽  
Substituted Anilines ◽  
Aqueous Sulfuric Acid ◽  
Acidity Functions ◽  
Sulfuric Acid Solutions

Acidity functions based upon primary anilines which have no ortho substituents have been established in 20% ethanol-80% aqueous sulfuric acid solutions, and compared with those based upon o-substituted anilines and azobenzenes. It was found that the tautomeric equilibrium between azonium and anilinium forms in 4-aminoazobenzene derivatives invariably shifts to the azonium form with increase in acidity. This observation has been interpreted in terms of acidity functions.

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