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Nulakani NVR, Ali MA. Unveiling the chemical kinetics of aminomethanol (NH 2CH 2OH): insights into O . H and O 2 photo-oxidation reactions and formamide dominance. Front Chem 2024; 12:1407355. [PMID: 38873406 PMCID: PMC11169873 DOI: 10.3389/fchem.2024.1407355] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2024] [Accepted: 05/08/2024] [Indexed: 06/15/2024] Open
Abstract
Aminomethanol is released into the atmosphere through various sources, including biomass burning. In this study, we have expounded the chemical kinetics of aminomethanol in the reaction pathways initiated by the hydroxyl radical (O ˙ H) with the aid of ab initio//density functional theory (DFT) i.e., coupled-cluster theory (CCSD(T))//hybrid-DFT (M06-2X/6-311++G (3df, 3pd). We have explored various possible directions of theO ˙ H radical on aminomethanol, as well as the formation of distinct pre-reactive complexes. Our computational findings reveal that the H transfer necessitates activation energies ranging from 4.1 to 6.5 kcal/mol from the -CH2 group, 3.5-6.5 kcal/mol from the -NH2 group and 7-9.3 kcal/mol from the -OH group of three rotational conformers. The H transfer from -CH2, -NH2 and -OH exhibits an estimated total rate constant (k OH) of approximately 1.97 × 10-11 cm3 molecule-1 s-1 at 300 K. The branching fraction analysis indicates a pronounced dominance of C-centered NH2C ˙ HOH radicals with a favorability of 77%, surpassing the N-centeredN ˙ HCH2OH (20%) and O-centered NH2CH2O ˙ (3%) radicals. Moreover, our investigation delves into the oxidation of the prominently favored carbon-centered NH2C ˙ HOH radical through its interaction with atmospheric oxygen molecules. Intriguingly, our findings reveal that formamide (NH2CHO) emerges as the predominant product in the NH2C ˙ HOH + 3O2 reaction, eclipsing alternative outcomes such as amino formic acid (NH2COOH) and formimidic acid (HN = C(H)-OH). At atmospheric conditions pertinent to the troposphere, the branching fraction value for the formation of formamide is about 99%, coupled with a rate constant of 5.5 × 10-12 cm3 molecule-1 s-1. Finally, we have scrutinized the detrimental impact of formamide on the atmosphere. Interaction of formamide with atmospheric hydroxyl radicals could give rise to the production of potentially perilous compounds such as HNCO. Further, unreactedN ˙ HCH2OH radicals may initiate the formation of carcinogenic nitrosamines when reacting with trace N-oxides (namely, NO and NO2). This, in turn, escalates the environmental risk factors.
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Affiliation(s)
| | - Mohamad Akbar Ali
- Department of Chemistry, Khalifa University of Science and Technology, Abu Dhabi, United Arab Emirates
- Center for the Catalyst and Separations, Khalifa University of Science and Technology, Abu Dhabi, United Arab Emirates
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Tomczyk I, Kalek M. Electrochemical Dearomatizing Methoxylation of Phenols and Naphthols: Synthetic and Computational Studies. Chemistry 2024; 30:e202303916. [PMID: 38315289 DOI: 10.1002/chem.202303916] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2023] [Revised: 02/05/2024] [Accepted: 02/05/2024] [Indexed: 02/07/2024]
Abstract
The electrochemical oxidative dearomatizing methoxylation of phenols and naphthols was developed. It provides an alternative route for the preparation of methoxycyclohexadienones, important and versatile synthetic intermediates, that eliminates the need for stoichiometric high-energy chemical oxidants and generates hydrogen as a sole by-product. The reaction proceeds in a simple constant current mode, in an undivided cell, and it employs standardized instrumentation. A collection of methoxycyclohexadienones derived from various 2,4,6-tri-substituted phenols and 1-substituted-2-naphthols was obtained in moderate to excellent yields. These include a complex derivative of estrone, as well as methoxylated dearomatized 1,1'-bi-2-naphthols (BINOLs). The mechanism of the reaction was subject to profound investigations using density functional theory calculations. In particular, the reactivity of two key intermediates, phenoxyl radical and phenoxenium ion, was carefully examined. The obtained results shed light on the pathway leading to the desired product and rationalize experimentally observed selectivities regarding a side benzylic methoxylation and the preference for the functionalization at the para over the ortho position. They also uncover the structure-selectivity relationship, inversely correlating the steric bulk of the substrate with its propensity to undergo the side-reaction. Moreover, the loss of stereochemical information from enantiopure BINOL substrates during the reaction is rationalized by the computations.
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Affiliation(s)
- Ireneusz Tomczyk
- Centre of New Technologies, University of Warsaw, Banacha 2C, 02-097, Warsaw, Poland
| | - Marcin Kalek
- Centre of New Technologies, University of Warsaw, Banacha 2C, 02-097, Warsaw, Poland
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Exploring Interaction Dynamics of Designed Organic Charge Transfer Complex of 6-Aminoindole and Chloranilic Acid: Spectrophotometric, Characterization, Computational, Antimicrobial, and DNA Binding Properties. J Mol Struct 2022. [DOI: 10.1016/j.molstruc.2022.132666] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Sun Y, Xu F, Li X, Zhang Q, Gu Y. Mechanisms and kinetic studies of OH-initiated atmospheric oxidation of methoxyphenols in the presence of O 2 and NO x. Phys Chem Chem Phys 2019; 21:21856-21866. [PMID: 31553018 DOI: 10.1039/c9cp03246k] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Methoxyphenols, as the main products and tracers of biomass burning, have been demonstrated to play an important role in the formation of secondary organic aerosols. However, their chemical transformation and migration in the atmosphere haven't been well characterized. In this study, detailed gas-phase reaction mechanisms and kinetics of three representative methoxyphenols (guaiacol, creosol and syringol) with OH radicals were investigated by using density functional theory (DFT). The initial reactions of methoxyphenols with OH radicals proceed via two different patterns, including OH-addition and H-atom abstraction. Subsequent reaction schemes of the active intermediates in the presence of O2/NOx are thoughtfully modeled. Catechol, methyl glyoxylate, malealdehyde and carbonyl or carboxyl compounds were confirmed as the dominant oxidation products for guaiacol. As a supplementary study, the formation pathways for the expected products nitroguaiacol and nitrocatechol were presented in high-NO2 conditions. Total and individual rate coefficients are calculated using the MESMER program at 294 K and 1 atm. The lifetimes of guaiacol, creosol and syringol were estimated to be 4.27, 3.56 and 2.98 hours, respectively, which are strongly competitive with the solar photolysis of methoxyphenols.
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Affiliation(s)
- Yanhui Sun
- College of Environment and Safety Engineering, Qingdao University of Science and Technology, Qingdao 266042, P. R. China.
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An Z, Sun J, Han D, Mei Q, Wei B, Wang X, He M. Theoretical study on the mechanisms, kinetics and ecotoxicity assessment of OH-initiated reactions of guaiacol in atmosphere and wastewater. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 685:729-740. [PMID: 31234135 DOI: 10.1016/j.scitotenv.2019.06.229] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Revised: 05/31/2019] [Accepted: 06/15/2019] [Indexed: 06/09/2023]
Abstract
The OH-initiated transformation mechanisms, kinetics and ecotoxicity assessment of guaiacol (2-methoxyphenol) in the presence of O2/NOx were investigated both in atmosphere and wastewater. The solvent effect lowers the energy barriers of initial OH-addition reactions more than H-abstraction reactions, leading to much higher addition branching ratio (Γadd) of 0.92 in aqueous solution than that of 0.42 in gas-phase. At 298 K, the overall rate constants of the title reactions in atmosphere and wastewater are 5.56 × 10-12 and 1.41 × 10-11 cm3 molecule-1 s-1 with corresponding half-lives of 34.6 h and 0.82 s, respectively. In atmosphere, all the proposed favorable products including nitroguaiacols, methoxybenzoquinone, 2-hydroxyphenyl formate, 2-methoxybenzene-1, 3-diol and dialdehyde could contribute to secondary organic aerosols (SOAs). In wastewater, NO2 addition reactions lead to higher toxicity of products (nitroguaiacols and 2-methoxybenzene-1, 4-diol) than that of parental guaiacol. However, O2/NO addition pathways may generate less harmful products except for methoxybenzoquinone (P3) which is with higher toxicity than guaiacol. Therefore, more attention should be focused on the products formed from OH-initiated reactions of guaiacol both in atmosphere and wastewater.
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Affiliation(s)
- Zexiu An
- Environment Research Institute, Shandong University, Qingdao 266237, PR China
| | - Jianfei Sun
- Environment Research Institute, Shandong University, Qingdao 266237, PR China
| | - Dandan Han
- School of Chemistry and Chemical Engineering, Heze University, Heze 274015, PR China
| | - Qiong Mei
- Environment Research Institute, Shandong University, Qingdao 266237, PR China
| | - Bo Wei
- Environment Research Institute, Shandong University, Qingdao 266237, PR China
| | - Xueyu Wang
- Environment Research Institute, Shandong University, Qingdao 266237, PR China
| | - Maoxia He
- Environment Research Institute, Shandong University, Qingdao 266237, PR China.
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He L, Schaefer T, Otto T, Kroflič A, Herrmann H. Kinetic and Theoretical Study of the Atmospheric Aqueous-Phase Reactions of OH Radicals with Methoxyphenolic Compounds. J Phys Chem A 2019; 123:7828-7838. [PMID: 31397571 DOI: 10.1021/acs.jpca.9b05696] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Methoxyphenols, which are emitted through biomass burning, are an important species in atmospheric chemistry. In the present study, temperature-dependent aqueous-phase OH radical reactions of six methoxyphenols and two related phenols have been investigated through laser flash photolysis and the density functional theory. The rate constants obtained were in a range of (1.1-1.9) × 1010 L mol-1 s-1 with k(3-MC) > k(Cre) ≈ k(Syr) ≈ k(MEP) > k(Res) > k(3-MP) > k(2-EP) ≈ k(2-MP). We derived the parameters of these reactions from the obtained T-dependent rate constants and found a mean Arrhenius activation energy of 16.9 kJ mol-1. The diffusion rate constants were calculated for each case and compared to the measured ones. Generally, the rate constants are found to be close to fully diffusion-controlled (kdiff = (1.4-1.5) × 1010 L mol-1 s-1 for all reactions). A structure-function relationship was established through the measurement result, which could be used for predicting unknown rate constants of other phenolic compounds. All of these findings are expected to enhance the predictive capabilities of models, such as the chemical aqueous-phase radical mechanism.
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Affiliation(s)
- Lin He
- Atmospheric Chemistry Department (ACD) , Leibniz-Institute for Tropospheric Research (TROPOS) , Permoserstrasse 15 , 04318 Leipzig , Germany
| | - Thomas Schaefer
- Atmospheric Chemistry Department (ACD) , Leibniz-Institute for Tropospheric Research (TROPOS) , Permoserstrasse 15 , 04318 Leipzig , Germany
| | - Tobias Otto
- Atmospheric Chemistry Department (ACD) , Leibniz-Institute for Tropospheric Research (TROPOS) , Permoserstrasse 15 , 04318 Leipzig , Germany
| | - Ana Kroflič
- Atmospheric Chemistry Department (ACD) , Leibniz-Institute for Tropospheric Research (TROPOS) , Permoserstrasse 15 , 04318 Leipzig , Germany.,Department of Analytical Chemistry , National Institute of Chemistry , Hajdrihova 19 , SI-1000 Ljubljana , Slovenia
| | - Hartmut Herrmann
- Atmospheric Chemistry Department (ACD) , Leibniz-Institute for Tropospheric Research (TROPOS) , Permoserstrasse 15 , 04318 Leipzig , Germany.,School of Environmental Science and Engineering , Shandong University , Binhai Road 72 , 266237 Qingdao , China
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Zare M, Norouzi Sarkati M, Tashakkorian H, Partovi R, Rahaiee S. Dextran-immobilized curcumin: An efficient agent against food pathogens and cancer cells. J BIOACT COMPAT POL 2019. [DOI: 10.1177/0883911519863074] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Curcumin–dextran conjugate was synthesized by free radical grafting reaction between curcumin and dextran. The chemical characterization of the conjugate was obtained by Fourier-transform infrared and 1H-NMR (proton nuclear magnetic resonance) spectroscopy analysis, while the functionalization degree was determined by the Folin–Ciocalteu assay, finding a 22.93 mg of curcumin/g of dextran conjugate. Antioxidant activity of curcumin and curcumin–dextran conjugate was investigated employing DPPH• radical method, and IC50 (the half maximal inhibitory concentration) values of curcumin and the curcumin–dextran conjugate (Cur equivalents) were 86.6 ± 0.1 and 17.4 ± 1 µM, respectively. The presence of dextran into the curcumin–dextran conjugate improved radical scavenging activities of the curcumin. In addition, antimicrobial effect of curcumin and curcumin–dextran conjugate was evaluated against gram-positive ( Listeria monocytogenes and Staphylococcus aureus) and gram-negative ( Escherichia coli O157:H7 and Salmonella typhimurium) bacteria. According to our experiments, gram-positive microorganisms are more sensitive to these compounds than gram-negative ones. Curcumin–dextran is a more potent bacteriostat ( S. aureus (minimum inhibitory concentration = 0.008 µg/mL), E. coli O157:H7 (minimum inhibitory concentration = 250 µg/mL), and S. typhimurium (minimum inhibitory concentration = 500 µg/mL)) and also a more potent bacteriosid against S. aureus and S. typhimurium than curcumin. The cytotoxic effects of the curcumin–dextran conjugate toward AGS, MCF-7, and normal fibroblast cell lines were determined at 48 and 72 h using an MTT assay. The results revealed the considerable antiproliferative effects of the curcumin–dextran conjugate in both AGS and MCF-7 cancer cells in comparison with fibroblast cells. This study shows that dextran as a versatile scaffold develops the biological activities of curcumin by covalent grafting and can be regarded in further bioapplications.
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Affiliation(s)
- Mahboobeh Zare
- Faculty of Medicinal Plants, Amol University of Special Modern Technologies, Amol, Mazandaran, Iran
| | | | - Hamed Tashakkorian
- Cellular and Molecular Biology Research Center (CMBRC), Health Research Institute, Babol University of Medical Sciences, Babol, Mazandaran, Iran
- Department of Pharmacology, School of Medicine, Babol University of Medical Sciences, Babol, Mazandaran, Iran
| | - Razieh Partovi
- Faculty of Veterinary Medicine, Amol University of Special Modern Technologies, Amol, Mazandaran, Iran
| | - Somayeh Rahaiee
- Department of Biotechnology, Amol University of Special Modern Technologies, Amol, Mazandaran, Iran
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Krupa J, Pagacz-Kostrzewa M, Wierzejewska M. UV laser-induced photolysis of matrix isolated o-guaiacol. J Mol Struct 2018. [DOI: 10.1016/j.molstruc.2018.05.098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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9
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Aazaad B, Lakshmipathi S. Reaction of Pentanol isomers with OH radical – A theoretical perspective. Mol Phys 2017. [DOI: 10.1080/00268976.2017.1414966] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- Basheer Aazaad
- Department of Physics, Bharathiar University, Coimbatore, India
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