Theoretical Analysis of Substituted Diels - Alder Reagents to Determine the Polar or Non Polar Character of the Reaction

Pérez, Patricia; Chamorro, Eduardo

doi:10.2174/157017811794697520

Cited by 6 publications

(5 citation statements)

References 27 publications

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“…The global electrophilicity of cyclopentadiene (CPD) is equal to 0.83eV, 12 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 whereas the global electrophilicity of butadiene is equal to 1.17eV. 13 In consequence, the interactions between CPD and BD have practically non-polar character. Next, small difference between global eletrophilicities is a source of weak reaction drive power, which results in the reaction conditions that require both high temperature and high pressure.…”

Section: Introductionmentioning

confidence: 99%

“…Although the electron withdrawing group on the C atom of ethylene can lower the activation barriers considerably, − the negative inductive effect of CC on ethylene is so weak that the matching energy gap between the orbits of CPD is still large. The global electrophilicity of cyclopentadiene (CPD) is equal to 0.83 eV, whereas the global electrophilicity of butadiene is equal to 1.17 eV . As a consequence, the interactions between CPD and BD have practically nonpolar character.…”

Section: Introductionmentioning

confidence: 99%

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Insights into the Diels–Alder Reactions between Cyclopentadiene and 1,3-Butadiene with High Temperature and High Pressure

Cao

Zhang

et al. 2015

Ind. Eng. Chem. Res.

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Synthesis of 5-vinyl-2-norbornene based on the Diels-Alder reactions of cyclopentadiene(CPD) generated from dicyclopentadiene(DCPD) and 1,3-Butadiene(BD) have been investigated in a continuous tube reactor under high temperature and high pressure. The experimental results show that the concentration of main product 5-vinyl-2-norbornene(VNB) increases with the increasing of reaction time at low reaction temperature. The elevated temperature greatly promotes the synthesis rate of both product VNB and its isomer cis-3a,4,7,7a-tetrahydroindene(THI)and tricyclopentadiene(TCPD), resulting in a mountain-shape curve of VNB concentration versus the reaction time. Particularly, it has been confirmed that the trimer (4,4a,4b,5,8,8a,9,9a-octahydro-1H-1,4-methanofluorene(OMF) should be prepared by direct reaction of BD with DCPD rather than by the reaction of CPD with VNB or THI. This comprehensive study can laid a solid foundation for the process optimization of VNB synthesis.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Insights into the Diels–Alder Reactions between Cyclopentadiene and 1,3-Butadiene with High Temperature and High Pressure

Cao

Zhang

et al. 2015

Ind. Eng. Chem. Res.

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“…3,[8][9][10][11][12][13][14][15][16][17][18] The intimate nature of the electronic rearrangement driving this type of transformations remains certainly unknown. Our main goal is the characterization of the electronic patterns governing cyclic transition states, [19][20][21][22][23][24][25][26][27][28] therefore we will focus on the nature of bonding of the thermal decomposition of 1-chlorohexane reaction mechanism as a benchmark of this type of reactivity in gas phase. 2,4,9,10 Our discussion will be based on results from local measures of the same spin pair density distribution as given through the topological analysis of the electron localization function (ELF), 29,30 i.e., a relative but proper measure of Pauli repulsion at the local level.…”

Section: Introductionmentioning

confidence: 99%

Understanding the thermal dehydrochlorination reaction of 1-chlorohexane. Revealing the driving bonding pattern at the planar catalytic reaction center

et al. 2015

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The nature of bonding along the gas-phase thermal decomposition of 1-chlorohexane to produce 1-hexene and hydrogen chloride has been examined at the DFT M05-2X/6-311+G(d,p) level of theory. Based on results both from energetical and topological analysis of the electron localization function (ELF), we propose to rationalize the experimental available results not in terms of a decomposition via a four-membered cyclic transition structure (TS), but properly as a two stage one step reaction mechanism featuring a slightly asynchronous process associated to the catalytic planar reaction center at the TS. In this context, the first electronic stage corresponds to the ‫ܥ‬ ఋା ••• ‫݈ܥ‬ ఋି bond cleavage, which take place on the activation path earlier the transition structure be reached. There is no evidence of a Cl-C bond at the TS configuration. The second stage, associated to the top of the energy barrier, includes the TS and extends beyond on the deactivation pathway towards the products. The existence of both bonding and nonbonding non covalent interactions (NCI) are also revealed for the first time for the TS configuration. 17 47 to point -9 along the IRC reaction pathway. Arbitrarily the second stage concerning main electronic changes will be associated to points -9 to +9. Both stages refer to regions where key electronic changes driving the transformation take place. Note that from point -34 to point -5, the population associated to the disynaptic basin V(C α ,C β ) increases from 1.99e to 2.20e, whereas the population integrated in the disynaptic protonated basin V(H β ,C β ) decreases from 1.98e to 1.72e. The attractor corresponding to the forming double bond localizes out of the line connecting the carbon center cores. This topology for the C  -C  region remains unchanged until point 12 in region g. At the top of the energy barrier, within the entire interval IRC=(-0.97962,+0.97971), i.e., point -9 to point 9, we observe an isolated electron localization region integrating to 7.64e which is associated to the migrating chlorine center. This picture, on the top of the barrier, corresponds to a lonely chlorine atom bearing an electronic charge of -0.64 while evolving to the encounter of the H β center.Thereafter, within the tiny region d four valence monosynaptic basins V(Cl) associated to the negatively charged chlorine center adopt a tetrahedral conformation, with an increasing in the population from 7.64e to 7.70e. In this region the valence basins populations for V(C α ,C β ) and V(H β ,C β ) varies from 2.41e to 2.34e, and from 1.81e to 1.51e, respectively. The migrating chlorine center develops thus a maximum charge of -0.71 at the transition structure (point 0). ELF picture of bonding reveals that activation events are mainly associated to conformational changes in preparation of the reaction center (region a), followed by the breaking of the Cl-C α bond (regions b and c), and the start of the migration of H  atom with the associated bonding changes at C α -C β -H β moiety (regions c and d). Regarding t...

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“…Given these findings, it seemed appropriate to perform a similar study involving an organic dienophile and cyclopentadienes (Scheme ) and to examine whether substituent effects in such reactions were additive. More limited studies of substituent additivity in organic Diels–Alder reactions have appeared, − but none explored all possible substitution permutations, refined additivity parameters, or explored dienes containing mixtures of electronically varied substituents. We, therefore, in this work computationally determined barrier and product energetics for all permutations of the reaction between Me 2 CCMe 2 , 1 , and substituted cyclopentadienes c -C 5 R 1 R 2 R 3 R 4 R 5a R 5b (R = H, CH 3 , CF 3 , F).…”

Section: Introductionmentioning

confidence: 99%

Additivity of Diene Substituent Gibbs Free Energy Contributions for Diels–Alder Reactions between Me₂C═CMe₂and Substituted Cyclopentadienes

2023

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ΔG ASC# values for each substituent in each position appeared to be additive. Substituent effects on barriers showed interesting contrasts. Methyl substitution at positions 5a and 5b increased barriers significantly, while substitution at all other positions had essentially no impact. In contrast, fluoro substitution at positions 5a and 5b lowered barriers more than substitution at other positions. Trifluoromethyl substitution mixed these effects, in that substitution at positions 5a and 5b increased barriers, but substitution at other positions lowered them. Despite the variances, ΔG ASC# ‡ /ΔG ASC# values allowed reliable prediction of barriers and exergonicities for reactions between 1 and highly substituted cyclopentadienes, and between 1 and cyclopentadienes with random mixtures of CH 3 /CF 3 /F substituents. ΔG ASC# ‡ /ΔG ASC# values were correlated with steric considerations and quantum theory of atoms in molecules (QTAIM) calculations. Overall, the ASC values provide a resource for predicting which Diels−Alder reactions of this type should occur at rapid rates and/or give stable bicyclic products.

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Theoretical Analysis of Substituted Diels - Alder Reagents to Determine the Polar or Non Polar Character of the Reaction

Cited by 6 publications

References 27 publications

Insights into the Diels–Alder Reactions between Cyclopentadiene and 1,3-Butadiene with High Temperature and High Pressure

Insights into the Diels–Alder Reactions between Cyclopentadiene and 1,3-Butadiene with High Temperature and High Pressure

Understanding the thermal dehydrochlorination reaction of 1-chlorohexane. Revealing the driving bonding pattern at the planar catalytic reaction center

Additivity of Diene Substituent Gibbs Free Energy Contributions for Diels–Alder Reactions between Me₂C═CMe₂and Substituted Cyclopentadienes

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Theoretical Analysis of Substituted Diels - Alder Reagents to Determine the Polar or Non Polar Character of the Reaction

Cited by 6 publications

References 27 publications

Insights into the Diels–Alder Reactions between Cyclopentadiene and 1,3-Butadiene with High Temperature and High Pressure

Insights into the Diels–Alder Reactions between Cyclopentadiene and 1,3-Butadiene with High Temperature and High Pressure

Understanding the thermal dehydrochlorination reaction of 1-chlorohexane. Revealing the driving bonding pattern at the planar catalytic reaction center

Additivity of Diene Substituent Gibbs Free Energy Contributions for Diels–Alder Reactions between Me2C═CMe2and Substituted Cyclopentadienes

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Additivity of Diene Substituent Gibbs Free Energy Contributions for Diels–Alder Reactions between Me₂C═CMe₂and Substituted Cyclopentadienes