Influence of polar .alpha.-substituents in the gas-phase pyrolysis kinetics of tertiary chlorides. Correlation of alkyl and polar groups

Chuchani, Gabriel; Rotino, Alexandra; Martín, Ignació; Avila, Irama; Domínguez, Rosa M.

doi:10.1021/j100265a042

Cited by 9 publications

(20 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…2,4,[9][10] to be independent of the initial pressure, and the derived Arrhenius activation parameters, i.e., ‫ܣ‬ = 9.84 ± 1.08 s -1 and ‫ܧ‬ = 177.25 ± 3.35 kJ mol -1 , have been claimed to be consistent with the suggested heterolytic mechanism depicted in Scheme 1. 2,4,[9][10] to be independent of the initial pressure, and the derived Arrhenius activation parameters, i.e., ‫ܣ‬ = 9.84 ± 1.08 s -1 and ‫ܧ‬ = 177.25 ± 3.35 kJ mol -1 , have been claimed to be consistent with the suggested heterolytic mechanism depicted in Scheme 1.…”

Section: Introductionsupporting

confidence: 68%

“…1,2 Indeed, experimental analysis of the reaction occurring in deactivated static reaction vessels and in the presence of free radical suppressors, suggests the existence of large electric charge separations in the transition region. 2,4,[9][10] The catalytic substituent effects on the rates, 2,4,[9][10] including both inductive and resonance effects on the centers ‫ܥ‬ ఈ and ‫ܥ‬ ఉ , have been rationalized on the basis of 3 favouring a heterolytic transition structure (1) or a completely concerted alternative (2). [3][4][5][6][7][8] Extensive work, both experimental 2, 4, 9-10 and theoretically oriented 3,[9][10][11] have pointed out to the polarization of the ‫ܥ‬ ఋା ••• ܺ ఋି bond as the key chemical event associated to the rate determining step of the dehydrohalogenation process (See Scheme 1).…”

Section: Introductionmentioning

confidence: 99%

“…1 In the case of decomposition of alkyl chlorides, a syn-elimination with the active participation of a nonbonding pair of the chlorine atom has been considered the driving factor allowing a highly concerted decomposition in the gas-phase. 3,[9][10][11] However, and not free from controversy, mechanisms in the gas phase implying a polar nature of the transition state have been also related to the consideration of very polar intimate ion pair interactions (3), or even semi-ion pair transition structures (4). 1 Scheme 1.…”

Section: Introductionmentioning

confidence: 99%

“…[3][4][5][6][7][8] Extensive work, both experimental 2, 4, 9-10 and theoretically oriented 3,[9][10][11] have pointed out to the polarization of the ‫ܥ‬ ఋା ••• ܺ ఋି bond as the key chemical event associated to the rate determining step of the dehydrohalogenation process (See Scheme 1). 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. Thermal decomposition of alkyl chlorides in the gas phase via a four-membered planar transition structure (TS), including polar (1), concerted (2), ion pair (3) or semi ion pair alternatives (4).…”

Section: Introductionmentioning

confidence: 99%

“…Thermal decomposition of alkyl chlorides in the gas phase via a four-membered planar transition structure (TS), including polar (1), concerted (2), ion pair (3) or semi ion pair alternatives (4). 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. The thermal decomposition of 1-chlorohexane (R = n-C 4 H 8 ) is examined in this work as test representative example.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

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

et al. 2015

View full text Add to dashboard Cite

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...

show abstract

Section: Introductionsupporting

confidence: 68%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

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

et al. 2015

View full text Add to dashboard Cite

show abstract

Homogeneous, unimolecular, gas-phase elimination of leaving groups at the alkoyl side of carboxylic acids

Chuchani

Rotinov

Domínguez

et al. 1996

J. Phys. Org. Chem.

View full text Add to dashboard Cite

The molecular gas-phase elimination kinetics of the series CI (CH,).COOH (n = 1-4), show changes in mechanisms from polar five-centered intramolecular displacement of the CI leaving group by the acidic hydrogen of the COOH to neighboring group participation of the oxygen carbonyl of the COOH group. The mechanisms for the series 2-, 3-and 4-chlorobutyric acids are explained similarly as above. The leaving chloride at the 2-position of acetic, propionic, and butyric acids is displaced by the hydrogen of the COOH group through a prevaling path of a five-centered cyclic transition-state mechanism. This type of mechanism is also described for the pyrolysis of 2-hydroxy-, 2-alkoxy-, 2-phenoxy-, and 2-acetoxycarboxylic acids. The ease with which the groups at the 2-position of acetic and propionic acids are displaced by the H of COOH give rise theThese two sequences differ only in the OH leaving group position. Additional work on glycolic acid pyrolysis is needed to explain the above differences.

show abstract

Pyrolysis of Organic Halides

Chuchani

2009

Patai's Chemistry of Functional Groups

View full text Add to dashboard Cite

Introduction Organic Fluoro Compounds Organic Chloro Compounds Organic Bromo Compounds Organic Iodo Compounds Competitive Dehydrohalogenation Five‐Membered Transition State Six‐Membered Transition State Neighboring Group Participation Rearrangements Acid Halides Chloroformates Acknowledgment

show abstract

Influence of polar .alpha.-substituents in the gas-phase pyrolysis kinetics of tertiary chlorides. Correlation of alkyl and polar groups

Cited by 9 publications

References 0 publications

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

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

Homogeneous, unimolecular, gas-phase elimination of leaving groups at the alkoyl side of carboxylic acids

Pyrolysis of Organic Halides

Contact Info

Product

Resources

About