The decomposition of N-chloro amino acids of essential branched-chain amino acids: Kinetics and mechanism

Szabó, Mária; Bíró, Vivien; Simon, Fruzsina; Fábián, István

doi:10.1016/j.jhazmat.2019.120988

Cited by 7 publications

(8 citation statements)

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“…As it was suggested before 7,23,24 , the OH − assisted reaction path is initiated by the formation of a carbanion in an equilibrium step (KOH), which is followed by the dechlorination in a rate determining step (k1), kd OH = KOH k1 (Scheme S2). In the next reaction sequence, the equilibrium is rapidly established between the Schiff base and the final products.…”

Section: The Decomposition Of Alkyl Substituted N-chloro-n-methyl Amimentioning

confidence: 95%

“…In recent studies, we have investigated the formation and decomposition kinetics and mechanisms of several N -chloro amino acids and the decomposition of monochloramine. ,− It was confirmed that the functional group on the α-carbon atom significantly influences the kinetics of the decomposition, and these reactions exhibit distinct mechanistic features. It was shown that N -chloroglycine decomposes in a hydroxide-ion-catalyzed process, and the intermediates as well as the final product of the reaction may have significant biological activities .…”

Section: Introductionmentioning

confidence: 96%

“…For example, the formation of aldehydes from N-chloro amino acids may induce taste and odor issues in drinking water. [7][8][9] The very same reactions are also important in biological systems. During inflammatory processes, hydrogen-peroxide oxidizes chloride ion to HOCl in a myeloperoxidase enzyme catalyzed process.…”

Section: Introductionmentioning

confidence: 99%

“…Their decomposition may lead to the formation of antagonistic intermediates and final products. For example, the formation of aldehydes from N -chloro amino acids may induce taste and odor issues in drinking water. − …”

Section: Introductionmentioning

confidence: 99%

“…The decomposition of N -chloro-BCAAs (branched-chain amino acids) also occurs via competing spontaneous and hydroxide-ion-catalyzed reaction paths. However, regardless of the pH, the final product is always the corresponding aldehyde formed via decarboxylation and subsequent deamination of the parent compounds . In the absence of the bulky alkyl substituents on the α-carbon atom, these steps occur in reverse order under alkaline conditions and yield different products as shown in the case of N -chloroglycine and N -chloro-α-alanine.…”

Section: Introductionmentioning

confidence: 99%

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The Chlorination of N-Methyl Amino Acids with Hypochlorous Acid: Kinetics and Mechanisms

Simon

Kiss

Szabó

et al. 2020

Chem. Res. Toxicol.

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The formation and decomposition kinetics of N-chloro-N-methyl amino acids were studied to predict the fate and impact of these compounds in water treatment technologies and biological systems. These compounds form in fast second order reactions between N-methyl amino acids and hypochlorous acid. The comparison of the activation parameters for the reactions of Nmethyl substituted and non-substituted branched chain amino acids reveals the transition state features less organized structure and stronger bonds between the reactants in the reactions with the N-methyl derivatives. This is due to a combined positive inductive effect of the N-methyl group and the alkyl sidechain, as well as to the steric effects of the substituents. N-methyl-Nchloro amino acids decompose much faster than the non-substituted compounds. The reaction rates do not depend on the pH and the same final product is formed in the entire pH range. Nchlorosarcosine is an exception, it decomposes via competing paths, kd obs = kd + kd OH [OH − ], yielding different final products. This feature is most likely due to the lack of an alkyl substituent on the α-carbon atom. Under physiological pH, aldehydes and methylamine form in these reactions which are not particularly toxic.

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Section: The Decomposition Of Alkyl Substituted N-chloro-n-methyl Amimentioning

confidence: 95%