The Removal of Hydrogen and Acid Radicals from Organic Compounds by Means of Bases. I. The Removal of Hydrogen Chloride from Ald-chlorimines by Sodium Hydroxide. Rates of Reaction in Alcoholic Solution<sup>1</sup>

Hauser, Charles R.; LeMAISTRE, J. W.; Rainsford, A. E.

doi:10.1021/ja01309a023

Cited by 11 publications

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“…The increasing ratio of Nac-Lys-aldehyde/Nac-Lys-nitrile peak areas with increasing pH concurs with expectations that increasing pH should promote hydrolysis of the chlorinated imine intermediate. However, previous research has demonstrated that HCl elimination from organic chloramines and chlorinated imines is general base-catalyzed. , Indeed, the higher Nac-Lys-nitrile yields at pH 9.0 vs 7.4 (Figure C) concur with base catalysis of HCl elimination from the chlorinated imine, while the simultaneous increase in Nac-Lys-aldehyde peak areas indicates that chlorinated imine formation via HCl elimination from the dichloramine is also enhanced with increasing pH. The decrease in Nac-Lys-nitrile yields at pH 11 (Figure C) suggests faster hydrolysis of Nac-Lys-nitrile at basic pH, as observed for other nitriles and aldehydes. − In a separate experiment, 10 μM Nac-Lys-nitrile decreased by 10 and 70% when held for 48 h at pH 7.0 and 11.0, respectively (Figure S14).…”

Section: Resultsmentioning

confidence: 67%

“…However, previous research has demonstrated that HCl elimination from organic chloramines and chlorinated imines is general base-catalyzed. 33,34 Indeed, the higher Nac-Lys-nitrile yields at pH 9.0 vs 7.4 (Figure 1C) concur with base catalysis of HCl elimination from the chlorinated imine, while the simultaneous increase in Nac-Lysaldehyde peak areas indicates that chlorinated imine formation via HCl elimination from the dichloramine is also enhanced with increasing pH. The decrease in Nac-Lys-nitrile yields at pH 11 (Figure 1C) suggests faster hydrolysis of Nac-Lys-nitrile at basic pH, as observed for other nitriles and aldehydes.…”

Section: Chlorination Of N-acetylmentioning

confidence: 99%

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Lysine and Arginine Reactivity and Transformation Products during Peptide Chlorination

Shi

Mitch

2023

Environ. Sci. Technol.

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Chlorine reactions with peptide-bound amino acids form disinfection byproducts and contribute to pathogen inactivation by degrading protein structure and function. Peptide-bound lysine and arginine are two of the seven chlorine-reactive amino acids, but their reactions with chlorine are poorly characterized. Using N-acetylated lysine and arginine as models for peptide-bound amino acids and authentic small peptides, this study demonstrated conversion of the lysine side chain to mono-and dichloramines and the arginine side chain to mono-, di-, and trichloramines in ≤0.5 h. The lysine chloramines formed lysine nitrile and lysine aldehyde at ∼6% yield over ∼1 week. The arginine chloramines formed ornithine nitrile at ∼3% yield over ∼1 week but not the corresponding aldehyde. While researchers hypothesized that the protein aggregation observed during chlorination arises from covalent Schiff base cross-links between lysine aldehyde and lysine on different proteins, no evidence for Schiff base formation was observed. The rapid formation of chloramines and their slow decay indicate that they are more relevant than the aldehydes and nitriles to byproduct formation and pathogen inactivation over timescales relevant to drinking water distribution. Previous research has indicated that lysine chloramines are cytotoxic and genotoxic to human cells. The conversion of lysine and arginine cationic side chains to neutral chloramines should alter protein structure and function and enhance protein aggregation by hydrophobic interactions, contributing to pathogen inactivation.

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