Humic Acid as a Substrate for Alkylation

Kolla, Santha; Paciolla, Mark D.; Sein, Lawrence T.; Moyer, J. Bird.; Walia, D.S.; Heaton, H.L.; Jansen, Susan A.

doi:10.1016/b978-1-85573-806-5.50022-8

Cited by 5 publications

(10 citation statements)

References 7 publications

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“…The relative configurations determined in this modeling work are identical to those anticipated from biosynthesis (29). This HA model hints at propagation mechanisms and metal binding functions of HA important for plant biochemistry and biomineralization This extensive conformational analysis of a humic acid building block yielded a single low-energy isomer, RSSRSSR, significantly stabilized by van der Waals interaction between two stacked rings (Figure 3).…”

Section: Figure 6 Net Energy Of Tnb Ha Monomer From Simultaneous Rotmentioning

confidence: 73%

“…Table 1 compares the energy of the low-energy Steelink structures to those of TNB. Stereochemical assignments for the TNB and Steelink models are consistent with a biosynthesis from tyrosine, phenylalanine, or tryptophan (29). The fundamental differences between the Steelink and TNB models relate to basic chemical considerations (Figure 1).…”

Section: Figure 6 Net Energy Of Tnb Ha Monomer From Simultaneous Rotmentioning

confidence: 74%

“…Some appear so random that they cannot be easily linked to common biological raw materials (23,25). Since humic-like materials are found in living plants (2,3,(26)(27)(28), it is anticipated that their structure(s) will be well-defined, having resulted from controlled biosynthesis from a limited number of components (29) or from abiotic reactions involving biological degradation products. Our HA models possess multiple chiral centers.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Conformational Modeling of a New Building Block of Humic Acid: Approaches to the Lowest Energy Conformer

Sein

Varnum

Jansen

1998

Environ. Sci. Technol.

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145

112

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Multiple structural models of humic acid (HA) building blocks have been reported. In this work, the modeling is based on two structural motifs: (i) the Steelink structure and (ii) a new humic acid [TNB] building block, which incorporates more fully the results of experimental data and retro-biosynthetic analyses. Both have significant conformational freedom complicated by their stereochemistry. A molecular modeling approach for the analysis of complex molecules with significant conformational freedom is described as it relates to the newly proposed humic acid building block. A potential energy surface for various conformers of the low-energy stereoisomer has been generated. Included in this discussion is the relationship of the stereochemistry to conformation and secondary structure.

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Section: Figure 6 Net Energy Of Tnb Ha Monomer From Simultaneous Rotmentioning

confidence: 73%

Section: Figure 6 Net Energy Of Tnb Ha Monomer From Simultaneous Rotmentioning

confidence: 74%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Conformational Modeling of a New Building Block of Humic Acid: Approaches to the Lowest Energy Conformer

Sein

Varnum

Jansen

1998

Environ. Sci. Technol.

Self Cite

145

112

View full text Add to dashboard Cite

show abstract

“…The building block structure used here for humic acid was described previously [22,23] and was used to examine thoroughly the conformation by Sein et al [24]. Sein et al [24] indicated that multiple structural models of humic acid building blocks were in agreement with the experimental conditions of the studies.…”

Section: Structural Modelmentioning

confidence: 99%

Molecular dynamic simulations of the sorption of toluene in a dry humic acid model: A preliminary study

Shih

Lin

et al. 2006

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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“…Todas las geometrías iniciales fueron dibujadas usando el programa Gaussview y los cálculos descritos anteriormente fueron realizados usando el programa Gaussian 09. 19,20 …”

Section: Metodologíaunclassified

Estudio teorico de las interacciones de dos modelos de ácidos húmicos con los cationes Al3+, Ca2+, Mg2+, Zn2+, K+ y NH4+ a un nivel de calculo DFT y un modelo de solvatación PCM

Espinosa-Fuentes¹,

Colpas-Castillo²,

Fuentes³

2017

Quim. Nova

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. In this paper, two models of humic acids, the Temple-NortheasternBirmingham (TNB) and Kolla models, were studied. Also, the complexation reaction of the structures formed by the interaction of the TNB and Kolla models with Al 3+ , Ca 2+ , Mg 2+ , Zn 2+ , K + and NH 4 + cations, common in agricultural soils, was studied. These calculations were made for the complexes, at PM6 and DFT / LANL2DZ level of theory, both in vacuum and in aqueous medium. We found a strong affinity between Kolla and TNB models, and Al 3+ , Ca 2+ , Mg 2+ , Zn 2+ , K + and NH 4 + cations, influenced by the solvent that affected the interaction sites; the solvent increased the rate of reactivity and affinity for the cations in nucleophilic regions and decreased it in electrophilic regions of the structures. Calculations of molecular electronic potential, MEP and atomic charges, the local smoothness, Fukui functions and the HSAB principle adequately described the HA/cations interactions which were affected by the number of hydrogen bonds. The most reactive sites were the hydroxyl, phenolic, carbonyls oxygens and nitrogens at both vacuum and aqueous medium, especially carbonyl oxygens. These results are consistent with the properties of HA that make them attractive as components of agricultural soils.Keywords: TNB; Kolla HA models; reactivity descriptors; DFT; HSAB; PCM; metal cations. INTRODUCCIÓNLas ácidos húmicos (HA) aumentan la fertilidad, la retención de minerales, la acidez del agua adsorbida y el transporte de contaminantes a través del suelo, también afectan la química de la atmósfera a través del ciclo del carbono. 1-3 La gran mayoría de los estudios realizados con sustancias húmicas y fúlvicas se han enfocado en suelos 4 debido a la propiedad que tienen estas sustancias para recuperar suelos erosionados e infértiles; otro aspecto positivo son sus propiedades ambientales, bioquímicas, y terapéuticas. Aunque existen discrepancias entre las estructuras propuestas para los HA, estas poseen semejanzas en cuanto al número y tipo de grupos funcionales presentes. 5 Los estudios reportados sobre sustancias húmicas son relativamente escasos, debido a su gran diversidad y ambigüedad estructural. Asimismo, las interpretaciones de las propiedades químicas teóricas de dichas sustancias han sido muy sesgadas en cuanto a predicción de su utilidad e interacción con los principales cationes metálicos de interés vital. Entre los estudios más sobresalientes encontramos: En el año 2007 a Troul y colaboradores, los cuales estudiaron las interacciones de acidos fulvicos con benceno y Al (III). 6 En el mismo año, De Castro y colaboradores reportaron un estudio teórico de la complejación de Zn (II) y Cd (II) con ácidos fulvicos. 7 En el 2008, André y colaboradores estudiaron la regioselectividad de Al (III) frente a sustancias con grupos catecol. 8 En el año 2009, Burk y colaboradores estudiaron las interacciones de cesio con sustancias orgánicas de naturaleza aniónica provenientes del suelo. 9 En el año 2014, Aquino y colaboradores reportaron las regione...

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Humic Acid as a Substrate for Alkylation

Cited by 5 publications

References 7 publications

Conformational Modeling of a New Building Block of Humic Acid: Approaches to the Lowest Energy Conformer

Conformational Modeling of a New Building Block of Humic Acid: Approaches to the Lowest Energy Conformer

Molecular dynamic simulations of the sorption of toluene in a dry humic acid model: A preliminary study

Estudio teorico de las interacciones de dos modelos de ácidos húmicos con los cationes Al3+, Ca2+, Mg2+, Zn2+, K+ y NH4+ a un nivel de calculo DFT y un modelo de solvatación PCM

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