Predicting the reactivity of phenolic compounds with formaldehyde under basic conditions: Anab initio study

Conner, Anthony H.

doi:10.1002/1097-4628(20001010)78:2<355::aid-app150>3.0.co;2-3

Cited by 10 publications

(3 citation statements)

References 24 publications

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“…10.6 and 11.6, respectively [55]. This suggests that these disubstituted phenols should be more reactive towards electrophilic substitution than the tyrosine phenol [56,57]. For instance, it can be expected that thymol and 2,4-ditert-butylphenol would react faster with the imine electrophile than the phenol moiety of tyrosine and limit the self-condensation of tyrosine.…”

Section: L1 L2mentioning

confidence: 99%

Enhancement of the Antioxidant and Antimicrobial Activities of Porphyran through Chemical Modification with Tyrosine Derivatives

et al. 2021

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The chemical modification of porphyran hydrocolloid is attempted, with the objective of enhancing its antioxidant and antimicrobial activities. Sulfated galactan porphyran is obtained from commercial samples of the red algae Porphyra dioica using Soxhlet extraction with water at 100 °C and precipitation with isopropyl alcohol. The extracted porphyran is then treated with modified L-tyrosines in aqueous medium in the presence of NaOH, at ca. 70 °C. The modified tyrosines L1 and L2 are prepared through a Mannich reaction with either thymol or 2,4-di-tert-butylphenol, respectively. While the reaction with 2,4-di-tert-butylphenol yields the expected tyrosine derivative, a mixture of products is obtained with thymol. The resulting polysaccharides are structurally characterized and the respective antioxidant and antimicrobial activities are determined. Porphyran treated with the N-(2-hydroxy-3,5-di-tert-butyl-benzyl)-L-tyrosine derivative, POR-L2, presents a noticeable superior radical scavenging and antioxidant activity compared to native porphyran, POR. Furthermore, it exhibited some antimicrobial activity against S. aureus. The surface morphology of films prepared by casting with native and modified porphyrans is studied by SEM/EDS. Both POR and POR-L2 present potential applicability in the production of films and washable coatings for food packaging with improved protecting characteristics.

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Section: L1 L2mentioning

confidence: 99%

Enhancement of the Antioxidant and Antimicrobial Activities of Porphyran through Chemical Modification with Tyrosine Derivatives

et al. 2021

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“…Thus, to remove the harmful chlorinated organic compounds efficiently, including CPs which are the by-products of industrial processes, a variety of experimental [3][4][5][6][7] and theoretical [8][9][10][11][12][13][14][15][16] studies are being carried out. To evaluate the photo degradation characteristics of chlorinated organic compounds, several studies using the density functional theory (DFT) method have been reported.…”

Section: Introductionmentioning

confidence: 99%

“…Until recently, there have merely been studies predicting the reaction of formaldehyde with alkaline phenol among phenol compounds based on the calculation of the atomic charges. [12][13][14] Thus, to understand the ·OH substitution reaction of phenols, CPs and CNB at the molecular level, it is important to predict what products are made in radical reaction by Fenton or ozone. A deep comprehension of the ·OH reaction mechanism of these harmful chlorinated organic compounds is also important.…”

Section: Introductionmentioning

confidence: 99%

Prediction of Hydroxyl Substitution Site(s) of Phenol, Monochlorophenols and 4-Chloronitrobenzene by Atomic Charge Distribution Calculations

Lee¹,

Lee

2009

Bulletin of the Korean Chemical Society

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The predictions of the radical reaction sites for phenol, 2-, 3-and 4-chlorophenols (CPs) and 4-chloronitrobenzene (CNB) were studied by atomic charge distribution calculations. The atomic charge distributions on each atom of these molecules were obtained using the CHelpG and MK (Merz-Kollman/Singh) methods with the optimized structural parameters determined by DFT calculation at the level of BLYP/6-311++G(d,p). By comparing the experimentally obtained hydroxyl addition site(s) and the calculated atomic charges on carbon atoms of phenol and CPs, we found that hydroxyl substitution by oxidation reaction mainly occurred to the carbon(s) with high atomic charges. With these results, we were easily able to predict the position(s) of the ·OH reaction site(s) of phenol, CPs and CNB through atomic charge distribution calculations.

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Predicting the reactivity of phenolic compounds with formaldehyde. II. Continuation of an ab initio study

Mitsunaga

Conner

Hill

2002

J of Applied Polymer Sci

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Phenol-formaldehyde resins are important adhesives used by the forest products industry. The phenolic compounds in these resins are derived primarily from petrochemical sources. Alternate sources of phenolic compounds include tannins, lignins, biomass pyrolysis products, and coal gasification products. Because of variations in their chemical structures, the reactivities of these phenolic compounds with formaldehyde vary in quite subtle ways. Previously, it was demonstrated that the reactivity of a number of phenols with formaldehyde in nonaqueous conditions could be correlated with charges calculated for reactive sites on the aromatic ring (Conner, A. H. J Appl Polym Sci 2000, 78, 355-363). We studied the reactivity of a larger number of phenolic compounds with formaldehyde in an aqueous solution using sodium hydroxide as the catalyst. Reaction rates were determined from measurements of the concentrations of the phenolic compounds and formaldehyde as functions of time. The reaction rate constants varied over a wide range (approximately 10 Ϫ2 to 10 4 L mol Ϫ1 h Ϫ1 ). An estimate of the reactivity per reactive site on the phenolic ring was determined by dividing the rate by the number of reactive sites. Atomic charges for each phenolic compound were calculated by ab initio methods at the RHF/6-31ϩ G level of theory using the CHelpG method. The charge per reactive site was estimated by summing the charges at all the reactive sites on the phenolic ring and dividing by the number of reactive sites. A strong correlation was observed between the reactivity per reactive site and the average charge per reactive site.

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Predicting the reactivity of phenolic compounds with formaldehyde under basic conditions: Anab initio study

Cited by 10 publications

References 24 publications

Enhancement of the Antioxidant and Antimicrobial Activities of Porphyran through Chemical Modification with Tyrosine Derivatives

Enhancement of the Antioxidant and Antimicrobial Activities of Porphyran through Chemical Modification with Tyrosine Derivatives

Prediction of Hydroxyl Substitution Site(s) of Phenol, Monochlorophenols and 4-Chloronitrobenzene by Atomic Charge Distribution Calculations

Predicting the reactivity of phenolic compounds with formaldehyde. II. Continuation of an ab initio study

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