pH controlled byproduct formation in aqueous decomposition of N-chloro-Α-alanine

Fruzsina Simon, Mária Szabó, I. Fábián

Research output: Contribution to journalArticle

Abstract

N-chloro-amino acids are readily formed in chlorination water treatment technologies. These reactions are also important in biological systems where HOCl plays an important role in the defense mechanism against invading pathogens. The intermediates and the products formed are of primary concern because they may have significant biological activities. In order to clarify intimate details and resolve discrepancies in the literature, the decomposition kinetics of N-chloro-α-alanine (MCA) was studied in the neutral – alkaline pH range by UV–vis spectrophotometry and 1H-NMR method. In contrast to earlier reports, the decomposition reaction proceeds via two distinct reaction paths: kobs1 = kOH[OH] + k, where kOH = (1.38 ± 0.02) × 10−2 M−1s−1 and k = (2.95 ± 0.09) × 10−4 s−1. In slightly alkaline solution, the sole product is acetaldehyde. Under alkaline conditions, the main product is pyruvate ion, however, N-acetyl-α-alanine is also formed in a subsequent reaction sequence. A detailed kinetic model is postulated which involves the rate determining dissociation of MCA into Cl and ethanimine which produces acetaldehyde in further reaction steps. Via the OH assisted path, first a carbanion is formed which undergoes dechlorination and produces iminopropionate ion. This species is transformed into pyruvate ion through hydration and deamination steps.

LanguageEnglish
Pages286-293
Number of pages8
JournalJournal of Hazardous Materials
Volume362
DOIs
Publication statusPublished - Jan 15 2019

Fingerprint

Alanine
Byproducts
Acetaldehyde
acetaldehyde
Ions
decomposition
Decomposition
Pyruvic Acid
ion
kinetics
Dechlorination
Deamination
Kinetics
defense mechanism
Water Purification
Spectrophotometry
Chlorination
Halogenation
dechlorination
Pathogens

Keywords

  • Acetaldehyde
  • Decomposition reaction
  • N-acetyl-α-alanine
  • N-chloro-α-alanine
  • Pyruvate ion
  • Reaction kinetics and mechanism

ASJC Scopus subject areas

  • Environmental Engineering
  • Environmental Chemistry
  • Waste Management and Disposal
  • Pollution
  • Health, Toxicology and Mutagenesis

Cite this

pH controlled byproduct formation in aqueous decomposition of N-chloro-Α-alanine. / Simon, Fruzsina; Szabó, Mária; Fábián, I.

In: Journal of Hazardous Materials, Vol. 362, 15.01.2019, p. 286-293.

Research output: Contribution to journalArticle

@article{1763d826e847481ebe0df0229b7fb65e,
title = "pH controlled byproduct formation in aqueous decomposition of N-chloro-Α-alanine",
abstract = "N-chloro-amino acids are readily formed in chlorination water treatment technologies. These reactions are also important in biological systems where HOCl plays an important role in the defense mechanism against invading pathogens. The intermediates and the products formed are of primary concern because they may have significant biological activities. In order to clarify intimate details and resolve discrepancies in the literature, the decomposition kinetics of N-chloro-α-alanine (MCA) was studied in the neutral – alkaline pH range by UV–vis spectrophotometry and 1H-NMR method. In contrast to earlier reports, the decomposition reaction proceeds via two distinct reaction paths: kobs1 = kOH[OH−] + k, where kOH = (1.38 ± 0.02) × 10−2 M−1s−1 and k = (2.95 ± 0.09) × 10−4 s−1. In slightly alkaline solution, the sole product is acetaldehyde. Under alkaline conditions, the main product is pyruvate ion, however, N-acetyl-α-alanine is also formed in a subsequent reaction sequence. A detailed kinetic model is postulated which involves the rate determining dissociation of MCA into Cl− and ethanimine which produces acetaldehyde in further reaction steps. Via the OH− assisted path, first a carbanion is formed which undergoes dechlorination and produces iminopropionate ion. This species is transformed into pyruvate ion through hydration and deamination steps.",
keywords = "Acetaldehyde, Decomposition reaction, N-acetyl-α-alanine, N-chloro-α-alanine, Pyruvate ion, Reaction kinetics and mechanism",
author = "Fruzsina Simon and M{\'a}ria Szab{\'o} and I. F{\'a}bi{\'a}n",
year = "2019",
month = "1",
day = "15",
doi = "10.1016/j.jhazmat.2018.09.004",
language = "English",
volume = "362",
pages = "286--293",
journal = "Journal of Hazardous Materials",
issn = "0304-3894",
publisher = "Elsevier",

}

TY - JOUR

T1 - pH controlled byproduct formation in aqueous decomposition of N-chloro-Α-alanine

AU - Simon, Fruzsina

AU - Szabó, Mária

AU - Fábián, I.

PY - 2019/1/15

Y1 - 2019/1/15

N2 - N-chloro-amino acids are readily formed in chlorination water treatment technologies. These reactions are also important in biological systems where HOCl plays an important role in the defense mechanism against invading pathogens. The intermediates and the products formed are of primary concern because they may have significant biological activities. In order to clarify intimate details and resolve discrepancies in the literature, the decomposition kinetics of N-chloro-α-alanine (MCA) was studied in the neutral – alkaline pH range by UV–vis spectrophotometry and 1H-NMR method. In contrast to earlier reports, the decomposition reaction proceeds via two distinct reaction paths: kobs1 = kOH[OH−] + k, where kOH = (1.38 ± 0.02) × 10−2 M−1s−1 and k = (2.95 ± 0.09) × 10−4 s−1. In slightly alkaline solution, the sole product is acetaldehyde. Under alkaline conditions, the main product is pyruvate ion, however, N-acetyl-α-alanine is also formed in a subsequent reaction sequence. A detailed kinetic model is postulated which involves the rate determining dissociation of MCA into Cl− and ethanimine which produces acetaldehyde in further reaction steps. Via the OH− assisted path, first a carbanion is formed which undergoes dechlorination and produces iminopropionate ion. This species is transformed into pyruvate ion through hydration and deamination steps.

AB - N-chloro-amino acids are readily formed in chlorination water treatment technologies. These reactions are also important in biological systems where HOCl plays an important role in the defense mechanism against invading pathogens. The intermediates and the products formed are of primary concern because they may have significant biological activities. In order to clarify intimate details and resolve discrepancies in the literature, the decomposition kinetics of N-chloro-α-alanine (MCA) was studied in the neutral – alkaline pH range by UV–vis spectrophotometry and 1H-NMR method. In contrast to earlier reports, the decomposition reaction proceeds via two distinct reaction paths: kobs1 = kOH[OH−] + k, where kOH = (1.38 ± 0.02) × 10−2 M−1s−1 and k = (2.95 ± 0.09) × 10−4 s−1. In slightly alkaline solution, the sole product is acetaldehyde. Under alkaline conditions, the main product is pyruvate ion, however, N-acetyl-α-alanine is also formed in a subsequent reaction sequence. A detailed kinetic model is postulated which involves the rate determining dissociation of MCA into Cl− and ethanimine which produces acetaldehyde in further reaction steps. Via the OH− assisted path, first a carbanion is formed which undergoes dechlorination and produces iminopropionate ion. This species is transformed into pyruvate ion through hydration and deamination steps.

KW - Acetaldehyde

KW - Decomposition reaction

KW - N-acetyl-α-alanine

KW - N-chloro-α-alanine

KW - Pyruvate ion

KW - Reaction kinetics and mechanism

UR - http://www.scopus.com/inward/record.url?scp=85053465379&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85053465379&partnerID=8YFLogxK

U2 - 10.1016/j.jhazmat.2018.09.004

DO - 10.1016/j.jhazmat.2018.09.004

M3 - Article

VL - 362

SP - 286

EP - 293

JO - Journal of Hazardous Materials

T2 - Journal of Hazardous Materials

JF - Journal of Hazardous Materials

SN - 0304-3894

ER -