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Mansouri A, Ghasemi Hamedani N, Zou C, Mousavi S, Khonakdar HA, Bahri-Laleh N, RodrĂguez-Pizarro M, Brotons-Rufes A, Posada-PĂŠrez S, Poater A. Improving Environmental Stress Cracking Resistance of High-Density Polyethylene Grades by Comonomer Addition and Nanocomposite Approach. Chemistry 2024; 30:e202401926. [PMID: 39015026 DOI: 10.1002/chem.202401926] [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: 05/17/2024] [Revised: 07/16/2024] [Accepted: 07/16/2024] [Indexed: 07/18/2024]
Abstract
The aim of this paper is to determine the effect of polymer density, correlated to the comonomer content, and nanosilica addition on the mechanical and Environmental Stress Cracking Resistance (ESCR) characteristics of high-density polyethylene (HDPE). In this regard, five HDPE samples with similar Melt Flow Index (MFI) and molar mass but various densities were acquired from a petrochemical plant. Two polymerization reactors work in series and differ only in the amount of 1-buene comonomer fed to the second reactor. To ascertain the microstructure of the studied samples, GPC and SSA (successive self-nucleation and annealing) analyses were accomplished. All samples resulted having similar characteristics but slightly various SCB/1000â
C=7.26-9.74 (SCB=Short Chain Branching). Consequently, meanwhile studied HDPEs reveal similar notched impact and stress at yield values, the tensile modulus, stress-at-break, and elongation-at-break tend to demonstrate different results with the SCB content. More significantly, ESCR characteristic varied considerably with SCB/1000â
C extent, so that higher amount of SCB acknowledged advanced ESCR. Notably, blending HDPE sample containing higher amount of SCB/1000â
C, with 3â
wt.% of chemically modified nanosilica enhanced ESCR characteristic by 40â%. DFT (Density Functional Theory) calculations unveiled the role of the comonomer, quantitatively by binding energies and qualitatively by Non Covalent Interaction (NCI) plots.
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Affiliation(s)
| | | | - Chen Zou
- Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei, 230026, China
| | | | | | - Naeimeh Bahri-Laleh
- Iran Polymer and Petrochemical Institute (IPPI), P.O. Box 14965/115, Tehran, Iran
- Institute for Sustainability with Knotted Chiral Meta Matter (WPI-SKCM2), Hiroshima University, Hiroshima, 739-8526, Japan
| | - Montserrat RodrĂguez-Pizarro
- Institut de QuĂmica Computacional i CatĂ lisi, Departament de QuĂmica, Universitat de Girona, c/ MÂŞ Aurèlia Capmany 69, 17003, Girona, Catalonia, Spain
| | - Artur Brotons-Rufes
- Institut de QuĂmica Computacional i CatĂ lisi, Departament de QuĂmica, Universitat de Girona, c/ MÂŞ Aurèlia Capmany 69, 17003, Girona, Catalonia, Spain
| | - Sergio Posada-PĂŠrez
- Institut de QuĂmica Computacional i CatĂ lisi, Departament de QuĂmica, Universitat de Girona, c/ MÂŞ Aurèlia Capmany 69, 17003, Girona, Catalonia, Spain
| | - Albert Poater
- Institut de QuĂmica Computacional i CatĂ lisi, Departament de QuĂmica, Universitat de Girona, c/ MÂŞ Aurèlia Capmany 69, 17003, Girona, Catalonia, Spain
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Escayola S, Bahri-Laleh N, Poater A. % VBur index and steric maps: from predictive catalysis to machine learning. Chem Soc Rev 2024; 53:853-882. [PMID: 38113051 DOI: 10.1039/d3cs00725a] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2023]
Abstract
Steric indices are parameters used in chemistry to describe the spatial arrangement of atoms or groups of atoms in molecules. They are important in determining the reactivity, stability, and physical properties of chemical compounds. One commonly used steric index is the steric hindrance, which refers to the obstruction or hindrance of movement in a molecule caused by bulky substituents or functional groups. Steric hindrance can affect the reactivity of a molecule by altering the accessibility of its reactive sites and influencing the geometry of its transition states. Notably, the Tolman cone angle and %VBur are prominent among these indices. Actually, steric effects can also be described using the concept of steric bulk, which refers to the space occupied by a molecule or functional group. Steric bulk can affect the solubility, melting point, boiling point, and viscosity of a substance. Even though electronic indices are more widely used, they have certain drawbacks that might shift preferences towards others. They present a higher computational cost, and often, the weight of electronics in correlation with chemical properties, e.g. binding energies, falls short in comparison to %VBur. However, it is worth noting that this may be because the steric index inherently captures part of the electronic content. Overall, steric indices play an important role in understanding the behaviour of chemical compounds and can be used to predict their reactivity, stability, and physical properties. Predictive chemistry is an approach to chemical research that uses computational methods to anticipate the properties and behaviour of these compounds and reactions, facilitating the design of new compounds and reactivities. Within this domain, predictive catalysis specifically targets the prediction of the performance and behaviour of catalysts. Ultimately, the goal is to identify new catalysts with optimal properties, leading to chemical processes that are both more efficient and sustainable. In this framework, %VBur can be a key metric for deepening our understanding of catalysis, emphasizing predictive catalysis and sustainability. Those latter concepts are needed to direct our efforts toward identifying the optimal catalyst for any reaction, minimizing waste, and reducing experimental efforts while maximizing the efficacy of the computational methods.
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Affiliation(s)
- SĂlvia Escayola
- Institut de QuĂmica Computacional i CatĂ lisi and Departament de QuĂmica, Universitat de Girona, c/MÂŞ Aurèlia Capmany 69, 17003 Girona, Catalonia, Spain.
- Donostia International Physics Center (DIPC), 20018 Donostia, Euskadi, Spain
| | - Naeimeh Bahri-Laleh
- Iran Polymer and Petrochemical Institute (IPPI), P.O. Box 14965/115, Tehran, Iran
- Institute for Sustainability with Knotted Chiral Meta Matter (WPI-SKCM), Hiroshima University, Hiroshima, 739-8526, Japan
| | - Albert Poater
- Institut de QuĂmica Computacional i CatĂ lisi and Departament de QuĂmica, Universitat de Girona, c/MÂŞ Aurèlia Capmany 69, 17003 Girona, Catalonia, Spain.
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Monreal-Corona R, SolĂ M, Pla-Quintana A, Poater A. Stereoretentive Formation of Cyclobutanes from Pyrrolidines: Lessons Learned from DFT Studies of the Reaction Mechanism. J Org Chem 2023; 88:4619-4626. [PMID: 36940389 PMCID: PMC10088030 DOI: 10.1021/acs.joc.3c00080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/22/2023]
Abstract
The stereoselective synthesis of cyclobutanes that possess an array of stereocenters in a contiguous fashion has attracted the wide interest of the synthetic community. Cyclobutanes can be generated from the contraction of pyrrolidines through the formation of 1,4-biradical intermediates. Little else is known about the reaction mechanism of this reaction. Here, we unveil the mechanism for this stereospecific synthesis of cyclobutanes by means of density functional theory (DFT) calculations. The rate-determining step of this transformation corresponds to the release of N2 from the 1,1-diazene intermediate to form an open-shell singlet 1,4-biradical. The formation of the stereoretentive product is explained by the barrierless collapse of this open-shell singlet 1,4-biradical. The knowledge of the reaction mechanism is used to predict that the methodology could be amenable to the synthesis of [2]-ladderanes and bicyclic cyclobutanes.
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Affiliation(s)
- Roger Monreal-Corona
- Institut de QuĂmica Computacional i CatĂ lisi and Departament de QuĂmica, Universitat de Girona, C/ Maria Aurèlia Capmany 69, 17003 Girona, Catalonia, Spain
| | - Miquel SolĂ
- Institut de QuĂmica Computacional i CatĂ lisi and Departament de QuĂmica, Universitat de Girona, C/ Maria Aurèlia Capmany 69, 17003 Girona, Catalonia, Spain
| | - Anna Pla-Quintana
- Institut de QuĂmica Computacional i CatĂ lisi and Departament de QuĂmica, Universitat de Girona, C/ Maria Aurèlia Capmany 69, 17003 Girona, Catalonia, Spain
| | - Albert Poater
- Institut de QuĂmica Computacional i CatĂ lisi and Departament de QuĂmica, Universitat de Girona, C/ Maria Aurèlia Capmany 69, 17003 Girona, Catalonia, Spain
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Liu C, Szostak M. Amide N-C Bond Activation: A Graphical Overview of Acyl and Decarbonylative Coupling. SYNOPEN 2023; 7:88-101. [PMID: 38037650 PMCID: PMC10686541 DOI: 10.1055/a-2035-6733] [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] [Indexed: 02/16/2023] Open
Abstract
This Graphical Review provides an overview of amide bond activation achieved by selective oxidative addition of the N-C(O) acyl bond to transition metals and nucleophilic acyl addition, resulting in acyl and decarbonylative coupling together with key mechanistic details pertaining to amide bond distortion underlying this reactivity manifold.
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Affiliation(s)
- Chengwei Liu
- Department of Chemistry, Shanghai University, 99 Shangda Road, Shanghai 200444, China
- Department of Chemistry, Rutgers University, 73 Warren Street, Newark, NJ 07102, USA
| | - Michal Szostak
- Department of Chemistry, Rutgers University, 73 Warren Street, Newark, NJ 07102, USA
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Monreal-Corona R, BesalĂş E, Pla-Quintana A, Poater A. Photoredox catalysis leading to triazolo-quinoxalinones at room temperature: selectivity of the rate determining step. Org Biomol Chem 2022; 20:9330-9336. [PMID: 36254586 DOI: 10.1039/d2ob01587k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The interest in the fusion product of quinoxalinone skeletons and 1,2,3-triazole units has greatly increased in recent years since they are known to be agonists of G-protein-coupled Niacin receptor 109A and inhibitors of the benzodiazepine and adenosine receptors. Here, we unveil the mechanism for the photoredox catalyzed synthesis of those scaffolds by means of DFT calculations. The calculations indicate that the rate determining step of this transformation is the attack of the in situ generated radical intermediate on the CîN bond of the quinoxalinone species to form a new C-C bond. Predictive chemistry here reveals that the energy difference is so subtle, and gives the recipe of which substituents, sterically and electronically, can fit to perform the reaction at room temperature.
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Affiliation(s)
- Roger Monreal-Corona
- Institute of Computational Chemistry and Catalysis and Department of Chemistry, University of Girona, c/Maria Aurèlia Capmany 69, 17003 Girona, Catalonia, Spain.
| | - Emili BesalĂş
- Institute of Computational Chemistry and Catalysis and Department of Chemistry, University of Girona, c/Maria Aurèlia Capmany 69, 17003 Girona, Catalonia, Spain.
| | - Anna Pla-Quintana
- Institute of Computational Chemistry and Catalysis and Department of Chemistry, University of Girona, c/Maria Aurèlia Capmany 69, 17003 Girona, Catalonia, Spain.
| | - Albert Poater
- Institute of Computational Chemistry and Catalysis and Department of Chemistry, University of Girona, c/Maria Aurèlia Capmany 69, 17003 Girona, Catalonia, Spain.
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