Kinetics and mechanism of protection of thymine from sulphate radical anion under anoxic conditions

Swaraga, M. Sudha; Adinarayana, M.

doi:10.1007/bf02716979

Cited by 8 publications

(10 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The results obtained in the present study (Table IV) indicate that adenosine radicals are efficiently repaired by caffeic acid to the extent of 69% at about 20 μM of caffeic acid concentration. This type of repair reactions by caffeic acid has been reported 18 in the oxidation of adenine by SO •− 4 . It is known that caffeic acid can repair the transient oxidizing radicals efficiently 19.…”

Section: Resultssupporting

confidence: 63%

“…Hence, we propose that the excited states of caffeic acid and adenosine act as sensitizers to transfer energy to t ‐BuOOH to produce radical species. This type of sensitizing effect has been proposed in similar systems earlier 16. Therefore, the light intensity at 254 nm has been used to calculate the quantum yields of oxidation of adenosine as well as caffeic acid under different experimental conditions.…”

Section: Methodsmentioning

confidence: 89%

See 1 more Smart Citation

Kinetics of oxidation of adenosine by t‐butoxyl radical: Protection and repair by caffeic acid

Charitha

Adinarayana

2005

Int J of Chemical Kinetics

Self Cite

View full text Add to dashboard Cite

The kinetics of oxidation of adenosine and caffeic acid by t-BuO • has been studied by the photolysis of t-BuOOH in the presence of t-BuOH. The rates and the quantum yields (ϕ) of oxidation of caffeic acid by t-BuO • radicals have been determined in the absence and presence of varying concentrations of adenosine. An increase in the concentration of adenosine has been found to decrease the rate of oxidation of caffeic acid suggesting that adenosine and caffeic acid compete for t-BuO • radicals. From competition kinetics, the rate constant of t-BuO • -caffeic acid reaction has been calculated to be 8.15 × 10 8 dm 3 mol −1 s −1 . The results of experimentally determined quantum yield (ϕ exptl ) values of oxidation of caffeic acid and the quantum yield values calculated (ϕ cal ) by assuming that caffeic acid reacts only with t-BuO • radicals suggest that caffeic acid not only protects adenosine from t-BuO • radicals but also repairs adenosine radicals formed by the reaction of t-BuO • radicals. C 2005 Wiley Periodicals, Inc. Int J Chem Kinet 37: [515][516][517][518][519][520][521] 2005

show abstract

Section: Resultssupporting

confidence: 63%

Section: Methodsmentioning

confidence: 89%

Kinetics of oxidation of adenosine by t‐butoxyl radical: Protection and repair by caffeic acid

Charitha

Adinarayana

2005

Int J of Chemical Kinetics

Self Cite

View full text Add to dashboard Cite

show abstract

“…This method has been used to determine the K app for various organic pollutants such as carbamazepine (Matta et al 2011) and caffeic acid (Swaraga and Adinarayana 2003). The concept of this method is based on the simultaneous oxidation of the reference compound and the selected b-blockers.…”

Section: Kinetics Studymentioning

confidence: 99%

Degradation of β-blockers in water by sulfate radical-based oxidation: kinetics, mechanism and ecotoxicity assessment

Tay

Ismail

2016

Int. J. Environ. Sci. Technol.

View full text Add to dashboard Cite

This study investigated the kinetics and degradation pathway of acebutolol, metoprolol and sotalol in a sulfate radical-based advanced oxidation process. The selected pharmaceuticals were b-blockers which have been used to treat cardiovascular diseases. Due to its frequent use, the presence of these pharmaceuticals in the environment has been regularly reported. In this study, sulfate radicals were generated using peroxymonosulfate with cobalt (II) as activator. At pH 7 and 25°C, the secondorder rate constant for the reaction between SO 4 Á-with metoprolol, acebutolol and sotalol was (1.0 ± 0.1) 9 10 10 , (2.0 ± 0.1) 9 10 10 and (3.0 ± 0.2) 9 10 10 M -1 s -1 , respectively. Sixteen transformation by-products were identified from the selected b-blockers. These transformation by-products were mainly formed through the hydroxylation, aromatic ring-opening reaction and aliphatic chain oxidation. The decomposition of b-blockers by sulfate radicals was found to start from the formation of hydroxylated b-blockers followed by an aromatic ring-opening reaction. In general, this study showed that b-blockers reacted favorably with sulfate radicals, and various transformation by-products could be produced. The result from the ecotoxicity assessment showed that almost all of the transformation by-products were less toxic than its parent compound. Therefore, a sulfate radical-based advanced oxidation process could be an effective method for the treatment of b-blockers in water.

show abstract

“…The competition kinetics method has also been used to determine the rate constant for the reaction between SO 4 -Á with caffeic acid (Swaraga and Adinarayana 2003) and carbamazepine (Matta et al 2011). Basically, this method is based on the simultaneous oxidation of benzene (reference compound), whose rate constant for the reaction with SO 4 -Á is known, and DEET (target compound), whose rate constant for the reaction with SO 4 -Á is to be determined.…”

Section: Chemical Oxidation Of Deet In Different Water Matricesmentioning

confidence: 99%

Chemical oxidation of N,N-diethyl-m-toluamide by sulfate radical-based oxidation: kinetics and mechanism of degradation

Tay

Rahman

Abas

2012

Int. J. Environ. Sci. Technol.

View full text Add to dashboard Cite

A study was undertaken in order to understand the kinetics and mechanism of the chemical oxidation of N,N-diethyl-m-toluamide, an insect repellent, by sulfate radical. In this experiment, sulfate radical was generated using peroxymonosulfate with iron(II) and cobalt(II) as activator. The second-order rate constant for the reaction of the sulfate radical with N,N-diethyl-m-toluamide was found to be (1.9 ± 0.1) 9 10 9 M -1 s -1 at pH 7 and a temperature of 25°C. Experiments for the chemical oxidation of N,N-diethyl-m-toluamide in river water and secondary wastewater revealed that the percentage of the removal of N,N-diethyl-m-toluamide was slightly influenced by the water matrices. However, the selected oxidation systems are not effective for the removal of N,N-diethyl-mtoluamide in seawater. Transformation by-products of N,N-diethyl-m-toluamide generated using peroxymonosulfate/iron(II) sulfate, peroxymonosulfate/iron(II) chloride, peroxymonosulfate/cobalt(II) sulfate and peroxymonosulfate/cobalt(II) chloride systems were identified. The results indicated that there are slight differences in the distributions of the transformation by-products detected depending on the activator. The common transformation by-products detected in all selected oxidation systems areMonohydroxylated N,N-diethyl-m-toluamide were detected only when the peroxymonosulfate/iron(II) system was applied. For the peroxymonosulfate/cobalt(II) systems, additional isomers of monohydroxylated N-ethyl-m-toluamide were detected. Peroxymonosulfate/cobalt(II) also transformed 2-(diethylamino)-1-m-tolylethanone into N-ethyl-N-(2-oxo-2-m-tolylethyl)acetamide and monohydroxylated 2-(ethyl(vinyl)amino)-1-m-tolylethanone as transformation by-products.

show abstract

Kinetics and mechanism of protection of thymine from sulphate radical anion under anoxic conditions

Cited by 8 publications

References 7 publications

Kinetics of oxidation of adenosine by t‐butoxyl radical: Protection and repair by caffeic acid

Kinetics of oxidation of adenosine by t‐butoxyl radical: Protection and repair by caffeic acid

Degradation of β-blockers in water by sulfate radical-based oxidation: kinetics, mechanism and ecotoxicity assessment

Chemical oxidation of N,N-diethyl-m-toluamide by sulfate radical-based oxidation: kinetics and mechanism of degradation

Contact Info

Product

Resources

About