Molecular mechanics calculations for dl,meso-2,3-dichlorobutanes and 2-halopropionyl chlorides

Borkar, Nitin; Kingsbury, Charles A.; Rack, E. P.

doi:10.1016/0022-2860(88)85026-9

Cited by 6 publications

(2 citation statements)

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“…This hypothesis was based on results from experimental measurements [11] and on molecular mechanics calculations [12] on the rotational conformer populations for DCB. Recently, these calculations were extended to include DFB, CFB and BFB as well [13], and revealed that the gas-phase distributions for the rotational conformers of these molecules were very similar.…”

Section: Results and Discussiodmentioning

confidence: 99%

Stereochemical Consequences of Recoil Halogen Atom Substitution

et al. 1990

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Hot atom chemistry / Halogen atom substitutions / Stereochemistry SummaryThe stereochemical consequences of recoil ^®Cl-for-X (X = Br, Cl, F) atom substitutions in (2S, 3R)-dl-and (2S, 3S)-dlbromofluorobutanes (BFB's) and in (2S, 3R)-dl-and (2S, 3S)dl-chlorofluorobutanes (CFB's) were investigated in the gas phase as a function of kinetic energy moderator concentration. Results from exothermic ^®Cl-for-Br substitutions in the BPH stereoisomers revealed that the reaction stereochemistry changed from predominant retention of configuration to predominant Inversion of configuration with increasing kinetic energy moderator concentration. An inspection of individual yields revealed that the Channel for Inversion product formation was insensitive to moderator concentration, while the Channel for retention product formation decreased in importance as the moderator concentration was increased. In contrast, results from thermoneutral '®Cl-for-Cl and endothermic ^®Cl-for-F substitutions in the CFB stereoisomers revealed that reaction stereochemistry for both cases was insensitive to changes in the moderator concentration. An inspection of the individual product yields from both reactions revealed that the Channels for retention and Inversion product formation exhibited the same dependence on moderator concentration. Both Channels decreased in importance as the moderator concentration was increased.

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Section: Results and Discussiodmentioning

confidence: 99%

Stereochemical Consequences of Recoil Halogen Atom Substitution

et al. 1990

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“…This interpretation was, in fact, based on earlier experimental work of Vasaros et al [15] which investigated the influence of rotational conformer on hot halogen atom substitutions in liquid dihalobutanes. Later molecular mechanics calculations on the gas-phase rotational conformer populations of DCB's, DFB's, FCB's, as well as BFB's help support these findings [20,21]. However, this conclusion assumed that the hot atom was sufficiently large to feel the effects of any steric repulsions.…”

Section: Exothermic 18 F-for-br Substitutionmentioning

confidence: 79%

Stereochemical Consequences of Recoil Halogen Atom Substitution IV : Effect of Kinetic Energy Moderator Concentration on the ¹⁸F-for-X (X=Br, F) Reactions in Gaseous Diastereomeric 2,3-Bromofluorobutanes

et al. 1997

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Hot atom chemistry / Halogen atom substitution / Stereochemistry SummaryThe stereochemical consequences of recoil ,8 F-for-X (X = Br, F) atom substitutions in (2S,3R)-dl-and (2S,3S)-rf/-bromofluorobutanes (BFB's) were investigated in the gas phase as a function of kinetic energy moderator concentration. Results from exothermic 18 F-for-Br substitutions in the BFB stereoisomers revealed that the reaction stereochemistry changed from high retention of configuration to predominant inversion of configuration with increasing kinetic energy moderator concentration. An inspection of individual yields revealed that the inversion product channel was insensitive to kinetic energy moderator concentration, while the retention product channel decreased in importance as the moderator concentration was increased. In contrast, results from thermoneutral ,8 F-for-F substitutions in BFB's revealed that reaction stereochemistry was insensitive to kinetic energy moderator. An inspection of product yields revealed that channels for retention and inversion product formation exhibited the same moderator dependence.

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Appendix 1: Published Force Field Parameters

Ōsawa

Lipkowitz

1995

Reviews in Computational Chemistry

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Molecular mechanics calculations for dl,meso-2,3-dichlorobutanes and 2-halopropionyl chlorides

Cited by 6 publications

References 9 publications

Stereochemical Consequences of Recoil Halogen Atom Substitution

Stereochemical Consequences of Recoil Halogen Atom Substitution

Stereochemical Consequences of Recoil Halogen Atom Substitution IV : Effect of Kinetic Energy Moderator Concentration on the ¹⁸F-for-X (X=Br, F) Reactions in Gaseous Diastereomeric 2,3-Bromofluorobutanes

Appendix 1: Published Force Field Parameters

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Molecular mechanics calculations for dl,meso-2,3-dichlorobutanes and 2-halopropionyl chlorides

Cited by 6 publications

References 9 publications

Stereochemical Consequences of Recoil Halogen Atom Substitution

Stereochemical Consequences of Recoil Halogen Atom Substitution

Stereochemical Consequences of Recoil Halogen Atom Substitution IV : Effect of Kinetic Energy Moderator Concentration on the 18F-for-X (X=Br, F) Reactions in Gaseous Diastereomeric 2,3-Bromofluorobutanes

Appendix 1: Published Force Field Parameters

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Stereochemical Consequences of Recoil Halogen Atom Substitution IV : Effect of Kinetic Energy Moderator Concentration on the ¹⁸F-for-X (X=Br, F) Reactions in Gaseous Diastereomeric 2,3-Bromofluorobutanes