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Journal article

Buttressing Effects on Haloarene Deprotonation: A Merely Kinetic or Also Thermodynamic Phenomenon?

(2,6-Dichlorophenyl)- and (2,6-dibromophenyl)trialkylsilanes undergo hydrogen/metal interconversion preferentially at the 4- rather than 3-position. However, the organometallic species generated by such a "meta metalation" are thermodynamically less stable (i.e., more basic) than those that would result from an ordinary "ortho metalation". This was demonstrated by equilibration expts. based on permutational halogen/metal interconversion. A new buttressing effect can explain the unprecedented regioselectivity. It is supported by X-ray structures that reveal marked deformations of the benzene ring in halophenylsilanes. [on SciFinder (R)]

    Keywords: Deprotonation; Steric effects (buttressing effects on haloarene deprotonation kinetics or thermodn. phenomenon); Aromatic hydrocarbons Role: CPS (Chemical process) ; FMU (Formation ; unclassified) ; PEP (Physical ; engineering or chemical process) ; PRP (Pro ; buttressing effect haloarene deprotonation kinetic thermodn phenomenon

    Note:

    CAN 142:22985

    22-12

    Physical Organic Chemistry

    Institute of Chemical Sciences and Engineering (ISIC),Ecole Polytechnique Federale,Lausanne,Switz.

    Journal

    1523-7060

    written in English.

    17989-28-5; 121412-28-0 ((2,4-Dichlorophenyl)lithium); 802984-56-1; 802984-57-2 Role: CPS (Chemical process), FMU (Formation, unclassified), PEP (Physical, engineering or chemical process), RCT (Reactant), FORM (Formation, nonpreparative), PROC (Process), RACT (Reactant or reagent) (buttressing effects on haloarene deprotonation kinetics or thermodn. phenomenon); 19752-55-7 (3,5-Dichloro-1-bromobenzene); 650598-50-8 (4-Triethylsilyl-3,5-dichloro-1-bromobenzene) Role: FMU (Formation, unclassified), FORM (Formation, nonpreparative) (buttressing effects on haloarene deprotonation kinetics or thermodn. phenomenon); 802984-55-0P Role: FMU (Formation, unclassified), PRP (Properties), SPN (Synthetic preparation), FORM (Formation, nonpreparative), PREP (Preparation) (buttressing effects on haloarene deprotonation kinetics or thermodn. phenomenon); 1193-72-2 (1-Bromo-2,4-dichlorobenzene) Role: FMU (Formation, unclassified), RCT (Reactant), FORM (Formation, nonpreparative), RACT (Reactant or reagent) (buttressing effects on haloarene deprotonation kinetics or thermodn. phenomenon); 802984-53-8P; 802984-54-9P Role: PRP (Properties), SPN (Synthetic preparation), PREP (Preparation) (buttressing effects on haloarene deprotonation kinetics or thermodn. phenomenon); 108-18-9 (Diisopropylamine); 3032-81-3; 29898-32-6; 650598-44-0 Role: RCT (Reactant), RACT (Reactant or reagent) (buttressing effects on haloarene deprotonation kinetics or thermodn. phenomenon); 650598-42-8 (3,5-Dibromo-4-triethylsilylbenzoic acid) Role: PRP (Properties) (crystal structure; of 3,5-dibromo-4-triethylsilylbenzoic acid); 650598-41-7 (3,5-Dichloro-4-triethylsilylbenzoic acid) Role: PRP (Properties) (crystal structure; of 3,5-dichloro-4-triethylsilylbenzoic acid)

    Reference

    Record created on 2006-03-03, modified on 2016-08-08

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