Oxidation of 2-propanol by bromine and by hypobromous acid in aqueous solution

Perlmutter-Hayman, Berta; Weissmann, Yael

doi:10.1021/ja01031a025

Cited by 15 publications

(5 citation statements)

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“…However, when 50 mM isopropanol was added, no HOBr was detected above its lowest standard concentration (13 μM) (pH 7, 2 h, 80 °C, Figure S5). Since isopropanol reacts very slowly with HOBr (i.e., k isopropanol, HOBr < 3.9 × 10 −4 M −1 s −1 ), 64 HOBr generated in the absence of isopropanol was attributed to halogen radical recombination rather than the nonradical pathway. Consequently, halogenation of cinnamaldehyde most likely occurs only via a radicalmediated pathway under physicochemical conditions relevant to hydraulic fracturing.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Halogen Radicals Contribute to the Halogenation and Degradation of Chemical Additives Used in Hydraulic Fracturing

Chen

Rholl

et al. 2021

Environ. Sci. Technol.

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In hydraulic fracturing fluids, the oxidant persulfate is used to generate sulfate radical to break down polymer-based gels. However, sulfate radical may be scavenged by high concentrations of halides in hydraulic fracturing fluids, producing halogen radicals (e.g., Cl•, Cl2 •–, Br•, Br2 •–, and BrCl•–). In this study, we investigated how halogen radicals alter the mechanisms and kinetics of the degradation of organic chemicals in hydraulic fracturing fluids. Using a radical scavenger (i.e., isopropanol), we determined that halogenated products of additives such as cinnamaldehyde (i.e., α-chlorocinnamaldehyde and α-bromocinnamaldehyde) and citrate (i.e., trihalomethanes) were generated via a pathway involving halogen radicals. We next investigated the impact of halogen radicals on cinnamaldehyde degradation rates. The conversion of sulfate radicals to halogen radicals may result in selective degradation of organic compounds. Surprisingly, we found that the addition of halides to convert sulfate radicals to halogen radicals did not result in selective degradation of cinnamaldehyde over other compounds (i.e., benzoate and guar), which may challenge the application of radical selectivity experiments to more complex molecules. Overall, we find that halogen radicals, known to react in advanced oxidative treatment and sunlight photochemistry, also contribute to the unintended degradation and halogenation of additives in hydraulic fracturing fluids.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Halogen Radicals Contribute to the Halogenation and Degradation of Chemical Additives Used in Hydraulic Fracturing

Chen

Rholl

et al. 2021

Environ. Sci. Technol.

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“…Although equilibrium constants for the hydrolysis of aqueous bromine (eq 1) have been measured by many investigators − over the past 85 years, considerable disagreement exists about the value of K 1 (Table ). A few investigators 2,7,8 have reported the temperature dependence for this hydrolysis with Δ H ° values of 48−56 kJ mol -1 .…”

Section: Introductionmentioning

confidence: 99%

Equilibrium and Kinetics of Bromine Hydrolysis

1996

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Equilibrium constants for bromine hydrolysis, K(1) = [HOBr][H(+)][Br(-)]/[Br(2)(aq)], are determined as a function of ionic strength (&mgr;) at 25.0 degrees C and as a function of temperature at &mgr; approximately 0 M. At &mgr; approximately 0 M and 25.0 degrees C, K(1) = (3.5 +/- 0.1) x 10(-)(9) M(2) and DeltaH degrees = 62 +/- 1 kJ mol(-)(1). At &mgr; = 0.50 M and 25.0 degrees C, K(1) = (6.1 +/- 0.1) x 10(-)(9) M(2) and the rate constant (k(-)(1)) for the reverse reaction of HOBr + H(+) + Br(-) equals (1.6 +/- 0.2) x 10(10) M(-)(2) s(-)(1). This reaction is general-acid-assisted with a Brønsted alpha value of 0.2. The corresponding Br(2)(aq) hydrolysis rate constant, k(1), equals 97 s(-)(1), and the reaction is general-base-assisted (beta = 0.8).

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“…To test this hypothesis, we repeated our experiments in solutions including 50 mM isopropanol, a known scavenger of both • OH (i.e., k isopropanol, • OH = 1.9 × 10 9 M –1 s –1 ) and halogen radicals (e.g., k isopropanol,Cl 2 •– = 1.2 × 10 5 M –1 s –1 , k isopropanol,Br • = 6.6 × 10 6 M –1 s –1 ) . In addition, isopropanol is not expected to quench hypohalous acids directly due to slow reported rate constants (e.g., k isopropanol,HOBr < 3.9 × 10 –4 M –1 s –1 ), which we confirmed by demonstrating that isopropanol did not impact para -hydroxybenzoate degradation by hypohalous acids added directly as HOCl to halide-containing solutions (Figure S12). The addition of isopropanol to halide-containing solutions decreased the degradation rate of para -hydroxybenzoate to 0.20 ± 0.02 μM/min, which was 6-fold lower than the rate measured in halide-containing solutions without isopropanol (Figure c).…”

Section: Resultsmentioning

confidence: 99%

Effects of Halides on Organic Compound Degradation during Plasma Treatment of Brines

Chen,

Moher,

Rogers

et al. 2024

Environ. Sci. Technol.

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Plasma has been proposed as an alternative strategy to treat organic contaminants in brines. Chemical degradation in these systems is expected to be partially driven by halogen oxidants, which have been detected in halide-containing solutions exposed to plasma. In this study, we characterized specific mechanisms involving the formation and reactions of halogen oxidants during plasma treatment. We first demonstrated that addition of halides accelerated the degradation of a probe compound known to react quickly with halogen oxidants (i.e., para-hydroxybenzoate) but did not affect the degradation of a less reactive probe compound (i.e., benzoate). This effect was attributed to the degradation of para-hydroxybenzoate by hypohalous acids, which were produced via a mechanism involving halogen radicals as intermediates. We applied this mechanistic insight to investigate the impact of constituents in brines on reactions driven by halogen oxidants during plasma treatment. Bromide, which is expected to occur alongside chloride in brines, was required to enable halogen oxidant formation, consistent with the generation of halogen radicals from the oxidation of halides by hydroxyl radical. Other constituents typically present in brines (i.e., carbonates, organic matter) slowed the degradation of organic compounds, consistent with their ability to scavenge species involved during plasma treatment.

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Oxidation of 2-propanol by bromine and by hypobromous acid in aqueous solution

Cited by 15 publications

References 0 publications

Halogen Radicals Contribute to the Halogenation and Degradation of Chemical Additives Used in Hydraulic Fracturing

Halogen Radicals Contribute to the Halogenation and Degradation of Chemical Additives Used in Hydraulic Fracturing

Equilibrium and Kinetics of Bromine Hydrolysis

Effects of Halides on Organic Compound Degradation during Plasma Treatment of Brines

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