Kinetics and mechanism of the bromination of phenols and phenoxide ions in aqueous solution. Diffusion-controlled rates

Tee, Oswald S.; Paventi, Martino; Bennett, Janice M.

doi:10.1021/ja00188a044

Cited by 42 publications

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“…Among various DBPs, the 44 most recognized compounds are trihalomethanes (THMs) and haloacetic acids (HAAs). [2][3][4][5][6][7] In the 45 presence of bromide (Br − ), HOCl can rapidly oxidize naturally occurring Br − to hypobromous 46 acid (HOBr). 8 Upon the reaction between HOCl/HOBr and DOM, four THMs (i.e., THM4, sum 47 of CHCl 3 , CHBrCl 2 , CHBr 2 Cl, and CHBr 3 ) and nine HAAs (i.e., HAA9, sum of monochloro-, 48 dichloro-, trichloro-, monobromo-, dibromo-, bromochloro-, bromodichloro-, dibromochloro-, 49 and tribromo-acetic acids (MCAA, DCAA, TCAA, MBAA, DBAA, BCAA, BDCAA, DBCAA, 50 and TBAA, respectively)) can be formed.…”

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Formation of Bromate and Halogenated Disinfection Byproducts during Chlorination of Bromide-Containing Waters in the Presence of Dissolved Organic Matter and CuO

Liu

Croué

2015

Environ. Sci. Technol.

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Previous studies showed that significant bromate (BrO 3 − ) can be formed via the CuO-catalyzed disproportionation of hypobromous acid (HOBr) pathway. In this study, the influence of CuO on the formation of BrO 3 − and halogenated disinfection byproducts (DBPs) (e.g., trihalomethanes, THMs and haloacetic acids, HAAs) during chlorination of six dissolved organic matter (DOM) isolates was investigated. Only in the presence of slow reacting DOM (from treated Colorado River water, i.e., CRW-BF-HPO), significant BrO 3 − formation is observed, which competes with bromination of DOM (i.e., THM and HAA formation). Reactions between HOBr and 12 model compounds in the presence of CuO indicates that CuO-catalyzed HOBr disproportionation is completely inhibited by fast reacting phenols, while it predominates in the presence of practically unreactive compounds (acetone, butanol, propionic, and butyric acids). In the presence of slow reacting di-and tricarboxylic acids (oxalic, malonic, succinic, and citric acids), BrO 3 − formation varies, depending on its competition with bromoform and dibromoacetic acid formation (i.e., bromination pathway). The latter pathway can be enhanced by CuO due to the activation of HOBr. Therefore, increasing CuO dose (0−0.2 g L −1 ) in a reaction system containing chlorine, bromide, and CRW-BF-HPO enhances the formation of BrO 3 − , total THMs and HAAs. Factors including pH and initial reactant concentrations influence the DBP formation. These novel findings have implications for elevated DBP formation during transportation of chlorinated waters in copper-containing distribution systems.

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“…In the presence of CuO, less oxidant (7. HOBr consumption (≤ 4.6%) was observed and CHBr 3 was the only DBP formed at 2 h (Table 355 1 and thus they are included as fast reacting compounds, [44][45][46][47][48] …”

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Formation of Bromate and Halogenated Disinfection Byproducts during Chlorination of Bromide-Containing Waters in the Presence of Dissolved Organic Matter and CuO

Liu

Croué

2015

Environ. Sci. Technol.

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“…In the latter case, the combination of the two types of catalysis results in an overall rate enhancement of about 12 million (9 solution follow second-order rate laws: first-order in substrate and in bromine ( 3 , 4 , 1 1 , 12). For the present work rates were measured as the first-order disappearance of bromine, in the presence of an excess of the substrate and a large excess of bromide ion.3 In some cases observed first-order rate constants (klobsd) were converted to second-order constants (k20bsd), assuming there is no reaction with tribromide ion (l3), which is true for phenols but not always true for very reactive phenoxide anions (4). For comparative purposes, we also studied the rates of bromination of anisole (methoxybenzene) and of 2-pyridone, which also show second-order kinetics in their reactions with bromine (14, 15).…”

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confidence: 99%

“…Several recent studies in this laboratory have been concerned with the mechanism of bromination of phenol derivatives in I aqueous solution (3)(4)(5)(6)(7)(8)(9). Some of these studies dealt mainly with electrophilic bromine attack (3,4), while others were devoted to the enolization or debromination of transient bromocyclohexadienones (5-9).…”

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Kinetics and mechanism of the bromination of phenols in aqueous solution. Evidence of general base catalysis of bromine attack

Tee¹,

Iyengar²

1990

Can. J. Chem.

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This paper is dedicated to Professor Ross Stewart ot1 tlze occasion of his 65th birthda!.OSWALD S. TEE and N. RANI IYENGAR. Can. J. Chem. 68, 1769 (1990).The reactions of bromine with phenol, 4-bromophenol, and 4-methylphenol (p-cresol) in aqueous solution are catalyzed by carboxylate anions, confirming the suggestions of earlier work. The results are consistent with deprotonation of the phenol hydroxyl group by a general base occurring at more or less the same time as electrophilic attack by molecular bromine. 1769 (1990) Les rCactions du brome avec le phenol, le 4-bromophCno1 et le 4-mCthylphCno1 (p-cresol), en solution aqueuse, sont catalyskes par les anions carboxylates; cette observation confirme les suggestions faites anter~eurement. Les resultats sont en accord avec un mCcanisme impliquant une dCprotonation du groupement hydroxyle du phCnol par une base gCnCrale qui se produirait pratiquement en m&me temps que I'attaque Clectrophile par le brome moleculaire. On d~scute des origines possible de la catalyse basique gCnCrale. Si I'on combine les rCsultats actuels avec ceux obtenus antkrieurement, on peut suggerer qu'une I cyclohexadi&none protone'e n'est pas un intermediaire nCcessaire dans la bromation du phCnol; cet intermidiaire peut &tre evite par la formation et par l'enolisation de l'intermediaire cyclohexadi6none par une catalyse gCnCrale.Mots cle's : bromation, phenol, mkcanisme, catalyse, cinktique.[Traduit par la revue]The importance of acid-base catalysis for a large number of reactions occurring in aqueous solution is firmly established (1). Many reactions which are sluggish or non-existent in other media are facilitated by the ease of proton transfers in water, 1 thereby allowing highly unfavorable intermediates to be stabil-I ized or avoided (1,2). As reported herein, such may be the case I with phenol bromination in aqueous solution. ISeveral recent studies in this laboratory have been concerned with the mechanism of bromination of phenol derivatives in I aqueous solution (3-9). Some of these studies dealt mainly with electrophilic bromine attack (3, 4), while others were devoted to the enolization or debromination of transient bromocyclohexadienones (5-9). Three studles, in particular, suggested that bromine attack may be catalyzed by general bases.Firstly, we found that salicylate (o-hydroxybenzoate) anions (1) have an enhanced reactivity towards bromine and a reduced selectivity (less negative p+), when compared to analogous, monosubstituted phenols (36). As a result, we argued that the attack of bromine on 'salicylate anions is intramolecularly catalyzed by their ortho carboxylate groups (reaction [l]). Complementary to these conclusions, we also found that debromination of the ipso-dienone 5 by bromide ion is strongly catalyzed by the internal carboxyl group (reaction [3]) (36, 6,9).'Since three, quite distinct studies strongly suggested that the attack of bromine on phenols is catalyzed by general bases, we have looked for buffer catalysis in the aqueous bromination of phenol and tw...

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Formation of Carbon–Halogen Bonds (Cl,Br,I)

Sasson

2009

Patai's Chemistry of Functional Groups

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Introduction Halogenation in Presence of Solid Supports or Catalysts Halogen Exchange and Transhalogenation Reactions Oxyhalogenations Cohalogenation and Mixed Halogenation Halogen–Halogen Reagents Carbon–Halogen Reagents Nitrogen–Halogen and Phosphorus–Halogen Reagents Oxygen–Halogen Reagents Sulfur–Halogen Reagents Silicon–Halogen Reagents Halogenation with Metal Halides and Halodemetallation Halogenation in Special Environments Carbon–Halogen Bond Formation by Extrusion of CO , CO 2 or SO 2 Ring Opening of Oxiranes

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Kinetics and mechanism of the bromination of phenols and phenoxide ions in aqueous solution. Diffusion-controlled rates

Cited by 42 publications

References 3 publications

Formation of Bromate and Halogenated Disinfection Byproducts during Chlorination of Bromide-Containing Waters in the Presence of Dissolved Organic Matter and CuO

Formation of Bromate and Halogenated Disinfection Byproducts during Chlorination of Bromide-Containing Waters in the Presence of Dissolved Organic Matter and CuO

Kinetics and mechanism of the bromination of phenols in aqueous solution. Evidence of general base catalysis of bromine attack

Formation of Carbon–Halogen Bonds (Cl,Br,I)

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