Kinetics and mechanism of isatin ring opening in aqueous binary mixtures of methanol and acetonitrile cosolvents

Ismail, Amel M.; Zaghloul, Adel

doi:10.1002/(sici)1097-4601(1998)30:7<463::aid-kin2>3.3.co;2-c

Cited by 10 publications

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“…Hydrolysis of isatin and N -methyl isatin and recyclization of isatinates have been studied, 24 but the study of other N-substituted isatins is quite limited. The stability of N -benzylisatins towards base hydrolysis is expected to be better than that of isatin or N-methyl isatin because of the steric protection from the benzyl substitute on the nitrogen atom in the isatin ring.…”

Section: Resultsmentioning

confidence: 99%

[18F]- and [11C]-Labeled N-benzyl-isatin sulfonamide analogues as PET tracers for Apoptosis: synthesis, radiolabeling mechanism, and in vivo imaging study of apoptosis in Fas-treated mice using [11C]WC-98

et al. 2009

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Summary The radiolabeled isatin sulfonamide caspase-3 inhibitor, [18F]2 (WC-II-89), is a potential PET radiotracer for noninvasive imaging of apoptosis. The radiolabeling mechanism was studied by 13C NMR, ESI/MS, and computational calculations. It was found that the high electrophilicity of the C3 carbonyl group in the isatin ring, which served as a trap for [18F]fluoride, was responsible for the failure of the radiolabeling via nucleophilic substitution of the mesylate group in 7a by [18F]fluoride. Once treated with a strong base, 7a opened the isatin ring completely to form an isatinate intermediate 16, which lost the ability to trap [18F]fluoride, thereby allowing the displacement of the mesylate group to afford the 18F-labeled isatinate 17. [18F]17 can be converted to isatin [18F]2 efficiently under acidic conditions. The ring-opening and re-closure of the isatin ring under basic and acidic conditions were confirmed by reversed phase HPLC analysis, ESI/MS and 13C NMR studies. Computational studies of model compounds also support the above proposed mechanism. Similarly, the ring-opening and re-closure method was used successfully in the synthesis of the 11C labeled isatin sulfonamide analogue [11C]4 (WC-98). A microPET imaging study using [11C]4 in the Fas liver apoptosis model demonstrated retained activity in the target organ (liver) of the treated mice. Increased caspase-3 activation in the liver was verified by the fluorometric caspase-3 enzyme assay. Therefore, this study provides a useful method for radio-synthesis of isatin derivative radiotracers for PET and SPECT studies, and [11C]4 is a potential PET radiotracer for noninvasive imaging of apoptosis.

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Section: Resultsmentioning

confidence: 99%

[18F]- and [11C]-Labeled N-benzyl-isatin sulfonamide analogues as PET tracers for Apoptosis: synthesis, radiolabeling mechanism, and in vivo imaging study of apoptosis in Fas-treated mice using [11C]WC-98

et al. 2009

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“…Data of Tables I–V were analyzed by the SESMORTAC model. In the SESMORTAC model 16, a range of solvent composition in which the equation of logarithm of the reaction rate constant, log k , versus a reciprocal of dielectric constant of the solution, D −1 , is linear 27–34, is called a “zone” and a solvent composition in which a zone finishes and another zone starts, is called “ m echanism c hange point” (or abbreviated as the mc point). Considering a mechanism on the basis of point charge on a dielectric continuum suggests that the plots of log k against D −1 should be linear.…”

Section: Resultsmentioning

confidence: 99%

Kinetics of malachite green fading in water–ethanol–2‐propanol ternary mixtures

Samiey

Motamedi

2011

Int J of Chemical Kinetics

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The rate constant of malachite green (MG + ) alkaline fading was measured in waterethanol-2-propanol ternary mixtures. This reaction was studied under pseudo-first-order conditions at 283-303 K. It was observed that the observed reaction rate constants, k obs , were increased in the presence of different weight percentages of ethanol and 2-propanol. The fundamental rate constants of MG + fading in these solutions were obtained by using the SESMOR-TAC model. In each series of experiments, the concentration of one alcohol was kept constant and the concentration of the second one was changed. It was observed that at the constant concentration of one alcohol and variable concentrations of the second one, with an increase in temperature, k 2 values decrease according to the trend of hydroxide ion nucleophilic parameter values and k 1 values increase. C

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“…Data of Tables I–VII were analyzed by using the SESMORTAC model. In the SESMORTAC model 16, a range of solvent composition in which the equation of logarithm of reaction rate constant, log k , versus reciprocal of the dielectric constant of the solution, D −1 , is linear 34–41, is called a “zone” and a solvent composition in which a zone finishes and another zone starts, which is called “ m echanism c hange point” (abbreviated as mc point). Consideration of a mechanism on the basis of point charge on a dielectric continuum suggests that the plots of log k against D −1 should be linear.…”

Section: Resultsmentioning

confidence: 99%

Kinetics of malachite green fading in alcohol–water binary mixtures

Samiey

Toosi

2010

Int J of Chemical Kinetics

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The rate constant of alkaline fading of malachite green (MG + ) was studied in alcohol-water binary mixtures. This reaction was studied under pseudo-first-order conditions at 283-303 K. It was observed that the reaction rate constants were increased in the presence of different weight percentages of methanol, ethanol, 1-propanol, 2-propanol, ethylene glycol, 1,2-propanediol, and glycerol (up to 19.3%). In aqueous glycerol solutions higher than 19.3%, the rate constant of reaction slightly decreases, which is due to high viscosity values of solvent mixtures. The fundamental rate constants of MG + fading in these solutions were obtained by using the SESMORTAC model. Owing to the charged character of activated complex, with an increase in the weight percentage of the used cosolvents or temperature, k 2 values change according to the trend of hydroxide ion nucleophilic parameter values. Also, using MG + solvatochromism, a simple test, called MAGUS, is introduced for measuring the glycerol concentration in its aqueous solutions. C 2010 Wiley Periodicals, Inc. Int J Chem Kinet 42: [508][509][510][511][512][513][514][515][516][517][518] 2010

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Kinetics and mechanism of isatin ring opening in aqueous binary mixtures of methanol and acetonitrile cosolvents

Cited by 10 publications

References 0 publications

[18F]- and [11C]-Labeled N-benzyl-isatin sulfonamide analogues as PET tracers for Apoptosis: synthesis, radiolabeling mechanism, and in vivo imaging study of apoptosis in Fas-treated mice using [11C]WC-98

[18F]- and [11C]-Labeled N-benzyl-isatin sulfonamide analogues as PET tracers for Apoptosis: synthesis, radiolabeling mechanism, and in vivo imaging study of apoptosis in Fas-treated mice using [11C]WC-98

Kinetics of malachite green fading in water–ethanol–2‐propanol ternary mixtures

Kinetics of malachite green fading in alcohol–water binary mixtures

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