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Al-Kwradi M, Ali L, Altarawneh M. Predicting the Decomposition Mechanism of the Serine α-Amino Acid in the Gas Phase and Condensed Media. ACS OMEGA 2024; 9:8574-8584. [PMID: 38405454 PMCID: PMC10882666 DOI: 10.1021/acsomega.3c10496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/29/2023] [Revised: 01/16/2024] [Accepted: 01/22/2024] [Indexed: 02/27/2024]
Abstract
Comprehending the nitrogen combustion chemistry during the thermal treatment of biomass demands acquiring a detailed mechanism for reaction pathways that dictate the degradation of amino acids. Serine (Ser) is an important α-amino acid that invariably exists in various categories of biomass, most notably algae. Based on density functional theory (DFT) coupled with kinetic modeling, this study presents a mechanistic overview of reactions that govern the fragmentation of the Ser compound in the gas phase as well as in the crystalline form. Thermokinetic parameters are computed for a large set of reactions and involved species. The initial decomposition of Ser is solely controlled by a dehydration channel that leads to the formation of a 2-aminoacrylic acid molecule. Decarboxylation and deamination routes are likely to be of negligible importance. The falloff window of the dehydration channel extends until the atmospheric pressure. Bimolecular reactions between two Ser compounds simulate the widely discussed cross-linking reactions that prevail in the condensed medium. It is demonstrated that the formation of the key experimentally observed products (NH3, CO2, and CO) may originate from direct bond fissions in the melted phase of Ser prior to evaporation. A constructed kinetic model (with 24 reactions) accounts for the primary steps in the degradation of the Ser molecule in the gas phase. These steps include dehydration, decarboxylation, deamination, and others. The kinetic model presents an onset decomposition temperature of 700 K with the complete conversion attained at ∼1090 K. Likewise, the model portrays the temperature-dependent increasing yields of CO2 and NH3. The results presented in this work offer a detailed analysis of the intricate chemical processes involved in nitrogen transformations, specifically in relation to amino acids. Amino acids play a crucial role as the primary nitrogen carriers in biomass, such as microalgae and protein-rich biomass.
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Affiliation(s)
- Mubarak Al-Kwradi
- Department of Chemical and Petroleum Engineering, United Arab Emirates University,, Sheikh Khalifa bin Zayed Street, Al-Ain 15551, United Arab Emirates
| | - Labeeb Ali
- Department of Chemical and Petroleum Engineering, United Arab Emirates University,, Sheikh Khalifa bin Zayed Street, Al-Ain 15551, United Arab Emirates
| | - Mohammednoor Altarawneh
- Department of Chemical and Petroleum Engineering, United Arab Emirates University,, Sheikh Khalifa bin Zayed Street, Al-Ain 15551, United Arab Emirates
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Li T, Chen S, Li J, Zhu Q, Li Z. Accurate Kinetics of Cyclization Reactions of the Large-Size Hydroperoxy Methyl-Ester Radicals Investigated by the Isodesmic Reaction Correction Method. J Phys Chem A 2023; 127:10253-10267. [PMID: 38015153 DOI: 10.1021/acs.jpca.3c06089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
The cyclization reactions of hydroperoxymethylester radicals are pivotal in low-temperature methyl-ester combustion but limited experimental and theoretical kinetic data pose challenges. Prior research has drawn upon analogous hydroperoxy alkyl radical cyclization reactions to approximate rate constants and might inaccurately represent ester group-specific behavior. This study systematically investigates these kinetics, accounting for ester group effects and computational complexities in large molecular systems. The reactions are categorized into 11 classes based on cyclic transition state size and -OOH/radical positions. Energy barriers and high-pressure-limit rate constants are calculated using the isodesmic reaction correction method, validated, and applied to 24 subclasses based on carbon sites connected to -OOH and radical moieties. Subclass high-pressure-limit rate rules are derived through averaging rate constants. Analysis reveals uncertainties within acceptable chemical accuracy limits, validating the reaction classification and rate rules. We conduct comparative analyses with values from analogous alkyl reactions in established mechanisms while comparing our results with the high-pressure-limit rate rules for analogous alkane reactions. These comparisons reveal notable disparities, emphasizing the ester group's influence and necessitating tailored ester-specific rate rules. These findings hold promise for improving automatic reaction mechanism generation, particularly for large methyl esters.
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Affiliation(s)
- Tao Li
- School of Chemical Engineering, Sichuan University, Chengdu 610065, P. R. China
- Engineering Research Center of Combustion and Cooling for Aerospace Power, Ministry of Education, Sichuan University, Chengdu, Sichuan 610065, P. R. China
| | - Siyu Chen
- School of Chemical Engineering, Sichuan University, Chengdu 610065, P. R. China
- Engineering Research Center of Combustion and Cooling for Aerospace Power, Ministry of Education, Sichuan University, Chengdu, Sichuan 610065, P. R. China
| | - Juanqin Li
- School of Chemical Engineering, Sichuan University, Chengdu 610065, P. R. China
- Engineering Research Center of Combustion and Cooling for Aerospace Power, Ministry of Education, Sichuan University, Chengdu, Sichuan 610065, P. R. China
| | - Quan Zhu
- School of Chemical Engineering, Sichuan University, Chengdu 610065, P. R. China
- Engineering Research Center of Combustion and Cooling for Aerospace Power, Ministry of Education, Sichuan University, Chengdu, Sichuan 610065, P. R. China
| | - Zerong Li
- Engineering Research Center of Combustion and Cooling for Aerospace Power, Ministry of Education, Sichuan University, Chengdu, Sichuan 610065, P. R. China
- College of Chemistry, Sichuan University, Chengdu 610064, P. R. China
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Viegas LP. A Multiconformational Transition State Theory Approach to OH Tropospheric Degradation of Fluorotelomer Aldehydes. Chemphyschem 2023; 24:e202300259. [PMID: 37326576 DOI: 10.1002/cphc.202300259] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Revised: 06/09/2023] [Accepted: 06/12/2023] [Indexed: 06/17/2023]
Abstract
Experimental work on the OH-initiated oxidation reactions of fluorotelomer aldehydes (FTALs) strongly suggests that the respective rate coefficients do not depend on the size of the Cx F2x+1 fluoroalkyl chain. FTALs hence represent a challenging test to our multiconformer transition state theory (MC-TST) protocol based on constrained transition state randomization (CTSR), since the calculated rate coefficients should not show significant variations with increasing values of x ${x}$ . In this work we apply the MC-TST/CTSR protocol to thex = 2 , 3 ${x={\rm 2,3}}$ cases and calculate both rate coefficients at 298.15 K with a value ofk = ( 2 . 4 ± 1 . 4 ) × 10 - 12 ${k=(2.4\pm 1.4)\times {10}^{-12}}$ cm3 molecule-1 s-1 , practically coincident with the recommended experimental value of kexp =( 2 . 8 ± 1 . 4 ) × 10 - 12 ${(2.8\pm 1.4)\times {10}^{-12}}$ cm3 molecule-1 s-1 . We also show that the use of tunneling corrections based on improved semiclassical TST is critical in obtaining Arrhenius-Kooij curves with a correct behavior at lower temperatures.
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Affiliation(s)
- Luís P Viegas
- Coimbra Chemistry Centre-Institute of Molecular Sciences (CQC-IMS), Department of Chemistry, University of Coimbra, 3004-535, Coimbra, Portugal
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Xu Z, Munyaneza NE, Zhang Q, Sun M, Posada C, Venturo P, Rorrer NA, Miscall J, Sumpter BG, Liu G. Chemical upcycling of polyethylene, polypropylene, and mixtures to high-value surfactants. Science 2023; 381:666-671. [PMID: 37561876 DOI: 10.1126/science.adh0993] [Citation(s) in RCA: 24] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Accepted: 06/16/2023] [Indexed: 08/12/2023]
Abstract
Conversion of plastic wastes to fatty acids is an attractive means to supplement the sourcing of these high-value, high-volume chemicals. We report a method for transforming polyethylene (PE) and polypropylene (PP) at ~80% conversion to fatty acids with number-average molar masses of up to ~700 and 670 daltons, respectively. The process is applicable to municipal PE and PP wastes and their mixtures. Temperature-gradient thermolysis is the key to controllably degrading PE and PP into waxes and inhibiting the production of small molecules. The waxes are upcycled to fatty acids by oxidation over manganese stearate and subsequent processing. PP ꞵ-scission produces more olefin wax and yields higher acid-number fatty acids than does PE ꞵ-scission. We further convert the fatty acids to high-value, large-market-volume surfactants. Industrial-scale technoeconomic analysis suggests economic viability without the need for subsidies.
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Affiliation(s)
- Zhen Xu
- Department of Chemistry, Virginia Tech, Blacksburg, VA 24061, USA
| | | | - Qikun Zhang
- Department of Chemistry, Chemical Engineering and Materials Science, Ministry of Education Key Laboratory of Molecular and Nano Probes, Shandong Normal University, Shandong 250014, PR China
| | - Mengqi Sun
- Department of Chemistry, Virginia Tech, Blacksburg, VA 24061, USA
| | - Carlos Posada
- Department of Chemistry, Virginia Tech, Blacksburg, VA 24061, USA
| | - Paul Venturo
- Department of Chemistry, Virginia Tech, Blacksburg, VA 24061, USA
| | - Nicholas A Rorrer
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO 80401, USA
- BOTTLE Consortium, Golden, CO 80401, USA
| | - Joel Miscall
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO 80401, USA
- BOTTLE Consortium, Golden, CO 80401, USA
| | - Bobby G Sumpter
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Guoliang Liu
- Department of Chemistry, Virginia Tech, Blacksburg, VA 24061, USA
- Department of Chemical Engineering, Department of Materials Science and Engineering, Macromolecules Innovation Institute, Virginia Tech, Blacksburg, VA 24061, USA
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Viegas LP. Gas-phase OH-oxidation of 2-butanethiol: Multiconformer transition state theory rate constant with constrained transition state randomization. Chem Phys Lett 2022. [DOI: 10.1016/j.cplett.2022.139829] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Chen B, Houk KN, Cammi R. High-Pressure Reaction Profiles and Activation Volumes of 1,3-Cyclohexadiene Dimerizations Computed by the Extreme Pressure-Polarizable Continuum Model (XP-PCM). Chemistry 2022; 28:e202200246. [PMID: 35286727 PMCID: PMC9320931 DOI: 10.1002/chem.202200246] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Indexed: 02/05/2023]
Abstract
Quantum chemical calculations are reported for the thermal dimerizations of 1,3‐cyclohexadiene at 1 atm and high pressures up to the GPa range. Computed activation enthalpies of plausible dimerization pathways at 1 atm agree well with the experiment activation energies and the values from previous calculations. High‐pressure reaction profiles, computed by the recently developed extreme pressure‐polarizable continuum model (XP‐PCM), show that the reduction of reaction barrier is more profound in concerted reactions than in stepwise reactions, which is rationalized on the basis of the volume profiles of different mechanisms. A clear shift of the transition state towards the reactant under pressure is revealed for the [6+4]‐ene reaction by the calculations. The computed activation volumes by XP‐PCM agree excellently with the experimental values, confirming the existence of competing mechanisms in the thermal dimerization of 1,3‐cyclohexadiene.
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Affiliation(s)
- Bo Chen
- Donostia International Physics Center, Paseo Manuel de Lardizabal, 4, 20018, Donostia-San Sebastián, Spain.,IKERBASQUE, Basque Foundation for Science, Plaza Euskadi 5, 48009, Bilbao, Spain
| | - K N Houk
- Department of Chemistry and Biochemistry, University of California, 90095, Los Angeles, California, USA
| | - Roberto Cammi
- Department of Chemical Science, Life Science and Environmental Sustainability, University of Parma, Viale Parco Area delle Scienze. 17/a, 43100, Parma, Italy
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