Kinetics of Base Hydrolysis of Some Chromen-2-one Indicator Dyes in Different Solvents at Different Temperatures

Abu-Gharib, Ezz A.; El‐Khatib, Rafat M.; Nassr, Lobna A. E.; Abu‐Dief, Ahmed M.

doi:10.5012/jkcs.2011.55.3.346

Cited by 16 publications

(10 citation statements)

References 21 publications

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“…This interaction is expected to increase in a following order water < methanol < acetone and stabilizes the studied compounds in the same direction. Furthermore, the transition state is more polar than the initial state that matches with the decrease in k obs values with increas ing ratios of organic cosolvent [25].…”

Section: Kinetic Results and Reaction Mechanismsupporting

confidence: 65%

“…1) that the initial action on NC and NCC by NaOH takes place in one stage and leads to the rate determining opening of the pyrone ring and the formation of a salt of (2E) 3 (2 hydroxy 5 nitrophenyl) acrylic acid and (2 hydroxy 5 nitrobenzylidene) malonic acid [24,25] as shown in Schemes 1 and 2. …”

Section: Kinetic Results and Reaction Mechanismmentioning

confidence: 98%

“…It is worth mentioning that the activation parameters are important for determination of the reaction rate and mechanism. The high negative values of entropy of activation (Table 3, 4) indicate the role of solvation in the mechanism [25,26].…”

Section: Determination Of Activation Parametersmentioning

confidence: 97%

“…Also the relatively high free energy of transfer (ΔG # ) would indicate that the slow step is the ring opening, and many vibrational degrees of freedom have been transformed into translations. The positive free energy of transfer from water to methanol or acetone reported in Table 3 assumes that the transient species in hand are polar entities [24,25,27,28].…”

Section: Determination Of Activation Parametersmentioning

confidence: 99%

“…The values of the rate con stants (k obs and k 2 ) decrease in the following order water > acetone > methanol with increasing methanol or acetone content. Hydroxy 2H chromen 2 one (HC) and 7 hydroxy 2H chromen 2 one 4 acetic acid (HCA) are taken from ref erence [25].…”

Section: Determination Of Activation Parametersmentioning

confidence: 99%

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Reactivity trends in the base hydrolysis of 6-nitro-2H-chromen-2-one and 6-nitro-2H-chromen-2-one-3-carboxylic acid in binary mixtures of water with methanol and acetone at different temperatures

et al. 2012

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182 1 Chromen 2 one is the parent organic compound of a class of naturally occurring photochemicals found in many plant species such as meliot, tonca beans, lav ender, sweet clover grass and licorice. It occurs in food plants such as strawberries, apricots, cherries, and cin namon. It is thought to work as a pesticide for the plants that produce it. This oxygen heterocycle is best known for its fragrance described as a vanilla like odor or the aroma of freshly mowed hay. It is the odoriferous principle of wood ruff, which led to its wide spread use as a perfumery chemical in industry [1]. Chromen 2 one derivatives have also found applications as fluores cent dyes [2,3], antitumor agents [4], antioxidants [5], antiinflammatory agents [6], antineoplastic agents [7], immunomodulant agents [8] antifungals [9], antico agulants [10], antibacterials [11], antimicrobial [12] and insecticides agents [13], proliferators of HIV [14, 15], and particular human malignant cell lines in vitro [16, 17], as well as affecting tumor activity of several tumor types in vivo [18][19][20]. The synthesis of nitro substituted chromen 2 ones has been undertaken as part of a general scheme of search for physiologically active compounds, in view of the fact that nitro substi tuted compounds have a unique place in the attack against pathogenic microorganisms [21].Rate coefficient for the reaction between organic and inorganic compounds with hydroxide ions in aqueous solutions is sensitive to the nature and molar 1 The article is published in the original. fraction of organic cosolvent. The rate constants in binary aqueous mixtures depend on the composition of the solvent [22,23].In our work, we report here the effects of methanol and acetone, as organic cosolvents, on the kinetics of the base hydrolysis of 6 nitro 2H chromen 2 one (NC) and 6 nitro 2H chromen 2 one 3 carboxylic acid (NCC) at different temperatures to gain more information about the activation parameters of base hydrolysis of these two compounds. EXPERIMENTALMaterials All materials, sodium hydroxide, sodium chloride, sodium nitrate, methanol, and acetone were obtained from "BDH". The stock solutions of NaOH, NaCl O O O 2 N O O O 2 N COOH 6 Nitro 2H chromen 2 one 3 carboxylic acid (NCC) 6 Nitro 2H chromen 2 one (NC)Abstract-Kinetics of the base hydrolysis of 6 nitro 2H chromen 2 one (NC) and 6 nitro 2H chromen 2 one 3 carboxylic acid (NCC) in water-methanol and water-acetone mixtures was studied at temperature range from 283 to 313 K. The activation parameters of the reactions were evaluated and discussed. The change in the activation barrier of the investigated compounds from water to water-methanol and wateracetone mixtures were estimated from the kinetic data. The base hydrolysis of NC and NCC in the watermethanol and water-acetone mixtures follows a rate law with k obs = k 2 [OH -] and k obs = k 1 + k 2 [OH -], respectively. The decrease in the rate constants of NC and NCC hydrolysis, as the proportion of methanol and acetone increases, is accounted for by the destabilizatio...

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Section: Kinetic Results and Reaction Mechanismsupporting

confidence: 65%

Section: Kinetic Results and Reaction Mechanismmentioning

confidence: 98%

Section: Determination Of Activation Parametersmentioning

confidence: 97%

Section: Determination Of Activation Parametersmentioning

confidence: 99%

Section: Determination Of Activation Parametersmentioning

confidence: 99%

See 3 more Smart Citations

Reactivity trends in the base hydrolysis of 6-nitro-2H-chromen-2-one and 6-nitro-2H-chromen-2-one-3-carboxylic acid in binary mixtures of water with methanol and acetone at different temperatures

et al. 2012

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Reactivity Trends and Kinetic Inspection of Hydroxide Ion Attack and DNA Interaction on Some Pharmacologically Active Agents of Fe(II) Amino Acid Schiff Base Complexes at Different Temperatures

Abdel‐Rahman

El‐Khatib

Nassr

et al. 2014

Int J of Chemical Kinetics

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The reactivity of few novel high-spin Fe(II) complexes of Schiff base ligands derived from 2-hydroxynaphthaldehyde and some variety of amino acids with the OH − ion has been examined in an aqueous mixture at the temperature range from 10 to 40°C. Based on the kinetic investigations, the rate law and a plausible mechanism were proposed and discussed. The general rate equation was suggested as follows: rate = k obs [complex], whereBase-catalyzed hydrolysis kinetic measurements imply pseudo-first-order doubly stage rates due the presence of mer-and fac-isomers. The observed rate constants k obs are correlated with the effect of substituent R in the structure of the ligands. From the effect of temperature on the rate base hydrolysis reaction, various thermodynamic parameters were evaluated. The evaluated rate constants and activation parameters are in a good agreement with the stability constants of the investigated complexes. Moreover, the reactivity of the investigated complexes toward DNA was examined and found to be in a good agreement with the reported binding constants. C

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Reactivity Tracers of the Hydrolysis of Fe(II)‐Bis(salicylidene) Complexes: Initial–Transition States Analysis and Enhanced Impact of Tensides on the Kinetic Trends

Nassr

2015

Int J of Chemical Kinetics

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The kinetics of the acid hydrolysis reaction of Fe(II)‐bis(salicylidene) complexes were followed under pseudo–first‐order conditions ([H+] >> [complex]) at 298 K. The ligands of the studied azomethine complexes were derived from the condensation of salicylaldehyde with different five α‐amino acids. The hydrolysis reactions were studied in acidic medium at different ratios (v/v) of aqua–organic mixtures. The decrease in the dielectric constant values of the reaction mixture enhances the reactivity of the reaction. The transfer chemical potentials of the initial and transition states (IS–TS) from water into mixed solvents were determined from the solubility measurements combined with the kinetic data. Nonlinear plots of logkobs versus 1/D (the reciprocal of the dielectric constant) suggest the influence of the solvation of IS–TS on the reaction reactivity. Furthermore, the acid hydrolysis reactions were screened in the presence of different concentrations of cationic and anionic tensides. The addition of surfactants to the reaction mixture accelerates the reaction reactivity. The obtained kinetic data were used to determine the values of δmΔG# (the change in the activation barrier) for the studied complexes when transferred from “water to various ratios (v/v) of water–co‐organic binary mixtures” and from “water to water containing different [surfactant].” It was found that the reactivity of the acid hydrolysis reaction was controlled by the hydrophobicity of the studied chelates.

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Kinetics of Base Hydrolysis of Some Chromen-2-one Indicator Dyes in Different Solvents at Different Temperatures

Cited by 16 publications

References 21 publications

Reactivity trends in the base hydrolysis of 6-nitro-2H-chromen-2-one and 6-nitro-2H-chromen-2-one-3-carboxylic acid in binary mixtures of water with methanol and acetone at different temperatures

Reactivity trends in the base hydrolysis of 6-nitro-2H-chromen-2-one and 6-nitro-2H-chromen-2-one-3-carboxylic acid in binary mixtures of water with methanol and acetone at different temperatures

Reactivity Trends and Kinetic Inspection of Hydroxide Ion Attack and DNA Interaction on Some Pharmacologically Active Agents of Fe(II) Amino Acid Schiff Base Complexes at Different Temperatures

Reactivity Tracers of the Hydrolysis of Fe(II)‐Bis(salicylidene) Complexes: Initial–Transition States Analysis and Enhanced Impact of Tensides on the Kinetic Trends

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