Covalent Binding of Aniline to Humic Substances

Thorn, Kevin A.; Goldenberg, Wayne S.; Younger, Steven J.; Weber, Eric J.

doi:10.1021/bk-1996-0651.ch019

Cited by 32 publications

(11 citation statements)

References 22 publications

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“…Therefore, the nitrogens observed in the liquid phase spectra of the reacted fulvic and humic acids represent only the labeled aniline nitrogens incorporated into the samples. Naturally abundant nitrogens were observed in solid state CP/MAS 15 N NMR spectra recorded on the unreacted samples (20,38). Amide nitrogens (amino acid nitrogens involved in peptide linkages) were observed in the Suwannee River and IHSS soil fulvic and humic acids; additionally, heterocyclic nitrogens were observed in the Suwannee River fulvic and humic acids and in the IHSS soil fulvic acid.…”

Section: Resultsmentioning

confidence: 99%

“…The effect of anoxic conditions, treatment with sodium borohydride and hydroxylamine prior to reaction with aniline under oxic conditions, and the chemical exchangeability by ammonia of aniline incorporated under oxic conditions were examined in the Suwannee River fulvic acid. A comparison of the nucleophilic addition, peroxidase, and birnessite-catalyzed reactions of aniline with the soil samples, and a study of the uptake of aniline by the organic matter of the whole soil are the subject of our next paper (20). We use the same approach in applying liquid phase 15 N NMR to the aniline-reacted fulvic and humic acids as in our previous studies (21,22), wherein the rationale behind our choice of pulse sequences was explained.…”

Section: Introductionmentioning

confidence: 99%

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Covalent Binding of Aniline to Humic Substances. 2. ¹⁵N NMR Studies of Nucleophilic Addition Reactions

Thorn

Pettigrew

Goldenberg

et al. 1996

Environ. Sci. Technol.

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186

204

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Aromatic amines are known to undergo covalent binding with humic substances in the environment. Although previous studies have examined reaction conditions and proposed mechanisms, there has been no direct spectroscopic evidence for the covalent binding of the amines to the functional groups in humic substances. In order to further elucidate the reaction mechanisms, the Suwannee River and IHSS soil fulvic and humic acids were reacted with 15 N-labeled aniline at pH 6 and analyzed using 15 N NMR spectrometry. Aniline underwent nucleophilic addition reactions with the quinone and other carbonyl groups in the samples and became incorporated in the form of anilinohydroquinone, anilinoquinone, anilide, imine, and heterocyclic nitrogen, the latter comprising 50% or more of the bound amine. The anilide and anilinohydroquinone nitrogens were determined to be susceptible to chemical exchange by ammonia. In the case of Suwannee River fulvic acid, reaction under anoxic conditions and pretreatment with sodium borohydride or hydroxylamine prior to reaction under oxic conditions resulted in a decrease in the proportion of anilinohydroquinone nitrogen incorporated. The relative decrease in the incorporation of anilinohydroquinone nitrogen with respect to anilinoquinone nitrogen under anoxic conditions suggested that inter-or intramolecular redox reactions accompanied the nucleophilic addition reactions.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Covalent Binding of Aniline to Humic Substances. 2. ¹⁵N NMR Studies of Nucleophilic Addition Reactions

Thorn

Pettigrew

Goldenberg

et al. 1996

Environ. Sci. Technol.

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186

204

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“…Catechol can easily reduce Fe(III) to Fe(II), which is then converted to oxidized species, quinone and semiquinone radicals. It has been reported that quinones and semiquinone radicals can promote the nucleophilic addition of the nitrogen atom in glycine to form humic-like substances [37,38]. The nitrogen-carbon adducts (a and b in Fig.…”

Section: Elution Behaviors Of Iron From Slag Surfacesmentioning

confidence: 99%

Effects of surface Fe(III) oxides in a steel slag on the formation of humic-like dark-colored polymers by the polycondensation of humic precursors

Nishimoto

Fukuchi

et al. 2013

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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Carbonated furnace steel slag is effective in enhancing polycondensation reactions of humic precursors such as quinones, amino acids and saccharides. To obtain more detailed information concerning the nature of the catalytic sites on the surface of slag, a pristine slag sample was treated with HNO 3 , HF and NH 2 OH to alter the surface states.The catalytic activities for the formation of humic-like dark-colored polymers were significantly decreased for the samples treated with HNO 3 or HF compared to untreated slag. Because substantial amounts of iron were eluted as the result of the HNO 3 and HF treatments, the minerals remaining on the surface of steel slag were characterized by XRD and SEM, and the results were compared with untreated slag. XRD patterns indicated the significant decrease in Fe(III) oxide content, including magnetite and hematite, as the result of the HNO 3 and HF treatment. In addition, when untreated slag 2 was reacted with humic precursors, the hematite and magnetite were largely eluted as a result of the reaction. These results support the conclusion that Fe(III)-oxides on the surface of steel slag, such as hematite and magnetite, serve as catalytic sites for enhancing catalytic activity for the formation of humic-like dark colored-polymers from humic precursors.

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“…The products of tyrosinase-catalyzed reactions are o-quinones which are electrophilic and can undergo a variety of reactions with nucleophilic groups. Reactions between enzyme-generated quinones and nucleophiles have been extensively studied because of their relevance to melanization (Korner and Pawelek, 1982;Sugumaran and Semensi, 1991;RodriguezLopez et al, 1992), the enzymatic browning of foods (Richard-Forget et al, 1992;Friedman, 1996), the binding of agricultural chemicals to the humic fractions of soil (Parris, 1980;Simmons et al, 1989;Tatsumi et al, 1994;Thorn et al, 1996), the sclerotization (hardening) of insect and crustacean integuments (''shells'') (Christensen et al, 1991;Sugumaran, 1988;Peter, 1989;Anderson et al, 1996), and the ''setting'' of adhesive mussel proteins (Holl et al, 1993;Hansen et al, 1998). Despite the studies cited above, quinone chemistry remains poorly characterized because of its complexity.…”

Section: Introductionmentioning

confidence: 99%

Enzymatic grafting of a natural product onto chitosan to confer water solubility under basic conditions

Kumar

Smith

Payne

1999

Biotechnol. Bioeng.

183

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Chitosan is a natural biopolymer whose rich amine functionality confers water solubility at low pH. At higher pH's (greater than 6.5), the amines are deprotonated and chitosan is insoluble. To attain water solubility under basic conditions we enzymatically grafted the hydrophilic compound chlorogenic acid onto chitosan. Despite its name, chlorogenic acid is a nonchlorinated phenolic natural product that has carboxylic acid and hydroxyl functionality. The enzyme in this study was tyrosinase, which converts a wide range of phenolic substrates into electrophilic o‐quinones. The o‐quinones are freely diffusible and can undergo reaction with the nucleophilic amino groups of chitosan. Using slightly acidic conditions (pH = 6), it was possible to modify chitosan under homogeneous conditions. When the amount of chlorogenic acid used in the modification reaction exceeded 30% relative to chitosan's amino groups, the modified chitosan was observed to be soluble under both acidic and basic conditions, and to have a pH window of insolubility at near neutral pH. 1H NMR spectra confirmed that chitosan was chemically modified, although the degree of modification was low. © 1999 John Wiley & Sons, Inc. Biotechnol Bioeng 63: 154–165, 1999.

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Covalent Binding of Aniline to Humic Substances

Cited by 32 publications

References 22 publications

Covalent Binding of Aniline to Humic Substances. 2. ¹⁵N NMR Studies of Nucleophilic Addition Reactions

Covalent Binding of Aniline to Humic Substances. 2. ¹⁵N NMR Studies of Nucleophilic Addition Reactions

Effects of surface Fe(III) oxides in a steel slag on the formation of humic-like dark-colored polymers by the polycondensation of humic precursors

Enzymatic grafting of a natural product onto chitosan to confer water solubility under basic conditions

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Covalent Binding of Aniline to Humic Substances

Cited by 32 publications

References 22 publications

Covalent Binding of Aniline to Humic Substances. 2. 15N NMR Studies of Nucleophilic Addition Reactions

Covalent Binding of Aniline to Humic Substances. 2. 15N NMR Studies of Nucleophilic Addition Reactions

Effects of surface Fe(III) oxides in a steel slag on the formation of humic-like dark-colored polymers by the polycondensation of humic precursors

Enzymatic grafting of a natural product onto chitosan to confer water solubility under basic conditions

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Covalent Binding of Aniline to Humic Substances. 2. ¹⁵N NMR Studies of Nucleophilic Addition Reactions

Covalent Binding of Aniline to Humic Substances. 2. ¹⁵N NMR Studies of Nucleophilic Addition Reactions