The complete ionization scheme for citric acid

1975 ◽  
Vol 28 (11) ◽  
pp. 2409 ◽  
Author(s):  
KN Pearce ◽  
LK Creamer
Keyword(s):  
Aqueous Solution ◽  
Citric Acid ◽  
Substituent Effect ◽  
Reasonable Agreement ◽  
Methyl Esters ◽  
Careful Consideration ◽  
Acidity Constants ◽  
Complete Ionization ◽  
Ionization Scheme

The microacidity constants for citric acid have been redetermined from pH titrations of citric acid and selected methyl esters in aqueous solution at 25�C and at two ionic strengths. The results obtained differ from those previously published. Calculated acidity constants, derived from a careful consideration of the empirical substituent effect, are also given and are in reasonable agreement with the experimental acidity constants.

ChemInform Abstract: COMPLETE IONIZATION SCHEME FOR CITRIC ACID

1976 ◽  
Vol 7 (5) ◽  
pp. no-no
Author(s):  
KEVIN N. PEARCE ◽  
LAWRENCE K. CREAMER
Keyword(s):  
Citric Acid ◽  
Complete Ionization ◽  
Ionization Scheme

A COMPLETE IONIZATION SCHEME FOR CITRIC ACID

1961 ◽  
Vol 65 (11) ◽  
pp. 2053-2055 ◽  
Author(s):  
R. Bruce Martin
Keyword(s):  
Citric Acid ◽  
Complete Ionization ◽  
Ionization Scheme

Solvent effect on preferred protonation sites in nicotinate and isonicotinate anions

1996 ◽  
Vol 74 (4) ◽  
pp. 613-620 ◽  
Author(s):  
Jean-Claude Hallé ◽  
Jacques Lelievre ◽  
François Terrier
Keyword(s):  
Dimethyl Sulfoxide ◽  
Molecular Form ◽  
Tautomeric Equilibrium ◽  
Benzoic Acids ◽  
Acidity Constants ◽  
Pyridinium Ring ◽  
Substituted Pyridines ◽  
Complete Ionization ◽  
Ionization Scheme ◽  
Pyridinium Cations

Potentiometric determinations of the two successive acidities of nicotinic and isonicotinic acids (AH2+) have been carried out in aqueous dimethyl sulfoxide mixtures containing up to 95% Me2SO by volume. In both systems, the results reveal that the addition of Me2SO induces a proton transfer from the pyridinium ring to the carboxylate group, the tautomeric equilibrium between the neutral forms of the two acids being displaced toward the zwitterionic form (AH±) in aqueous solution, but toward the molecular form (AH°) in Me2SO. An analysis of the data by means of Hammett relationships previously established for benzoic acids over the whole range of H2O/Me2SO mixtures allowed the four microscopic acidity constants as well as the tautomeric equilibrium constant KT pertaining to the complete ionization scheme of the two acids to be determined. At 20 °C, there are equal populations of the tautomeric AH° and AH± species in the mixtures containing 38 and 47% Me2SO for the nicotinic and isonicotinic systems, respectively. Hammett relationships describing the ionization behaviour of a number of substituted pyridinium cations in H2O/Me2SO mixtures are also discussed. Possible reasons accounting for the peculiar effects exerted by the NH2, CONH2, and COOH substituents on the process are suggested. Key words: nicotinic and isonicotinic acids, substituted pyridines, acidities, tautomeric equilibrium, protonation sites, water – dimethyl sulfoxide mixtures.

Citric acid modified waste cigarette filters for adsorptive removal of methylene blue dye from aqueous solution

2021 ◽  
pp. 50655
Author(s):  
Aafia Tehrim ◽  
Min Dai ◽  
Xiange Wu ◽  
Malik Muhammad Umair ◽  
Imran Ali ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Methylene Blue ◽  
Citric Acid ◽  
Blue Dye ◽  
Methylene Blue Dye ◽  
Adsorptive Removal

Inerte Amminkomplexe als mehrwertige Kationsäuren in wäßriger Lösung / Inert Ammine Complexes as Multivalent Cationic Acids in Aqueous Solution

1980 ◽  
Vol 35 (9) ◽  
pp. 1096-1103 ◽  
Author(s):  
Matthias Kretschmer ◽  
Lutwin Labouvie ◽  
Karl-W. Quirin ◽  
Helmut Wiehn ◽  
Ludwig Heck
Keyword(s):  
Aqueous Solution ◽  
Ionic Strength ◽  
Spectrophotometric Method ◽  
Complex Cation ◽  
Aqua Ligand ◽  
Second Step ◽  
Acidity Constants ◽  
Ammine Complexes ◽  
Temperature Variations ◽  
Enthalpy Changes

Acidity constants of ammine complexes of tetravalent platinum in aqueous solutions have been determined by a spectrophotometric method at very low ionic strengths and extrapolated to zero ionic strength. Temperature variations of pK-values (25 °C and 50 °C) yield thermodynamic parameters for two successive deprotonation steps of hexaammineplatinum(IV), pentaamminechloroplatinum(IV), and tris(ethylenediamine)pla- tinum(IV) complexes and for the deprotonation of pentaammineaquacobalt(III) ion.The enthalpy changes for the first and second steps are similar and range from 50 to 75 kJ/mole while for the aqua ligand of Co(III) 33 kJ/mole are found. The very large dif­ference in the entropy changes (about 70 to 80 J/K mole for the first step and -10 to + 20 J/K mole for the second step) is interpreted by a model of solvation change. The primary hydration sphere of strongly oriented and immobilized water dipoles around the highly charged complex cation is transformed to a hydrogen-bonded solvation sheath when the electric field of the complex is weakened upon release of the first proton.

scholarly journals Adsorption of heavy metals and methylene blue from aqueous solution with citric acid modified peach stone

2018 ◽  
Vol 53 (11) ◽  
pp. 1678-1688 ◽  
Author(s):  
Junhua Yan ◽  
Guihong Lan ◽  
Haiyan Qiu ◽  
Chao Chen ◽  
Yongqiang Liu ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Aqueous Solution ◽  
Methylene Blue ◽  
Citric Acid

scholarly journals Citric Acid Capped CdS Quantum Dots for Fluorescence Detection of Copper Ions (II) in Aqueous Solution

Nanomaterials ◽  
2018 ◽  
Vol 9 (1) ◽  
pp. 32 ◽  
Author(s):  
Zhezhe Wang ◽  
Xuechun Xiao ◽  
Tong Zou ◽  
Yue Yang ◽  
Xinxin Xing ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Quantum Dots ◽  
Citric Acid ◽  
Limit Of Detection ◽  
Copper Ions ◽  
High Sensitivity ◽  
Fluorescence Sensor ◽  
Cds Quantum Dots ◽  
Detection Range ◽  
Cds Qds

Citric acid capped CdS quantum dots (CA-CdS QDs), a new assembled fluorescent probe for copper ions (Cu2+), was synthesized successfully by a simple hydrothermal method. In this work, the fluorescence sensor for the detection of heavy and transition metal (HTM) ions has been extensively studied in aqueous solution. The results of the present study indicate that the obtained CA-CdS QDs could detect Cu2+ with high sensitivity and selectivity. It found that the existence of Cu2+ has a significant fluorescence quenching with a large red shifted (from greenish-yellow to yellowish-orange), but not in the presence of 17 other HTM ions. As a result, Cu2S, the energy level below the CdS conduction band, could be formed at the surface of the CA-CdS QDs and leads to the quenching of fluorescence of CA-CdS QDs. Under optimal conditions, the copper ions detection range using the synthesized fluorescence sensor was 1.0 × 10‒8 M to 5.0 × 10‒5 M and the limit of detection (LOD) is 9.2 × 10‒9 M. Besides, the as-synthesized CA-CdS QDs sensor exhibited good selectivity toward Cu2+ relative to other common metal ions. Thus, the CA-CdS QDs has potential applications for detecting Cu2+ in real water samples.

Prediction of acidity constants of some important selenium oxoacids in aqueous solution by computational techniques

RSC Advances ◽  
2014 ◽  
Vol 4 (10) ◽  
pp. 5206 ◽  
Author(s):  
Mostafa Abedi ◽  
Hossein Farrokhpour ◽  
Solaleh Farnia
Keyword(s):  
Aqueous Solution ◽  
Computational Techniques ◽  
Acidity Constants

Parameters Influences during Biodiesel Production

2010 ◽  
Vol 44-47 ◽  
pp. 4167-4175
Author(s):  
Anita Kovač Kralj ◽  
Davorin Kralj
Keyword(s):  
Aqueous Solution ◽  
Sodium Hydroxide ◽  
Diesel Engines ◽  
Renewable Resources ◽  
Batch Reactor ◽  
Methyl Esters ◽  
Alternative Fuel ◽  
Biodiesel Production ◽  
Compression Ignition ◽  
Diesel Production

Bio-diesel is a clean burning alternative fuel, produced from domestic, renewable resources. Bio-diesel can be blended at any level with petroleum diesel to create a bio-diesel blend. It can be used in compression-ignition (diesel) engines with little or no modification. Bio-diesel is simple to use, biodegradable, non-toxic, and essentially free of sulphur and aromatics. This paper presents the two following identifiable topic areas as key themes: 1. preparation of an aqueous solution of sodium hydroxide – as a catalyst, which can be activated by the most MeO- active groups, and can therefore be converted to methyl esters (biodiesel) from triglyceride. Methoxide (MeO-) was produced from sodium hydroxide (NaOH) and methanol (MeOH) in a batch reactor: NaOH + MeOH = H2O + Na+ + MeO-. During bio-diesel production, methoxide is incorrectly referred to as the product of mixing methanol and sodium hydroxide. An aqueous solution of sodium hydroxide – was prepared as a catalyst, by using different amounts of water at the same temperature. The reaction with lower water took place at the highest and quickest degrees of NaOH conversion and thus more MeO- active groups. The water was effective as an inhibitor.

Sign in / Sign up

Export Citation Format

Share Document