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- Beta-silicon_effect abstract "The beta-silicon effect also called silicon hyperconjugation in organosilicon chemistry is a special type of hyperconjugation and describes the stabilizing effect of a silicon atom placed in a position one removed (β) from a carbocation. A prerequisite is an antiperiplanar relationship between the two groups. Silicon hyperconjugation explains specific observations regarding chemical kinetics and stereochemistry of organic reactions with reactants containing silicon. The effect is understood in terms of classical hyperconjugation depicted in structure 3 in scheme 1 or in terms of molecular orbital overlap 1 which is a stabilizing overlap between the empty p-orbital of the carbocation and the filled sigma molecular orbital of the silicon to carbon bond.The alpha-silicon effect is the destabilizing effect of a silicon atom next to a reaction center with a partial positive charge.In a pioneering study by Frank C. Whitmore ethyltrichlorosilane (scheme 2) was chlorinated by sulfuryl chloride as chlorine donor and benzoyl peroxide as radical initiator in a radical substitution resulting in chloride monosubstitution to some extent in the α-position (28%, due to steric hindrance of the silyl group) and predominantly in the β-position. By adding sodium hydroxide to the α-substituted compound only the silicon chlorine groups are replaced but not the carbon chlorine group. Addition of alkali to the β-substituted compound on the other hand leads to an elimination reaction with liberation of ethylene.In another set of experiments (scheme 3) the chlorination is repeated with n-propyltrichlorosilane The α-adduct and the γ-adduct are resistant to hydrolysis but the chlorine group in the β-adduct gets replaced by a hydroxyl group.The silicon effect is also manifest in certain compound properties. Trimethylsilylmethylamine (Me3SiCH2NH2) is a stronger base with a pKa of 10.96 for the conjugate acid than the carbon analogue neopentyl amine with pKa 10.21. In the same vein trimethylsilylacetic acid (pKa 5.22) is a poorer acid than trimethyl acetic acid (pKa 5.00).".
- Beta-silicon_effect thumbnail SiliconHyperconjugation.png?width=300.
- Beta-silicon_effect wikiPageID "4739376".
- Beta-silicon_effect wikiPageLength "3548".
- Beta-silicon_effect wikiPageOutDegree "28".
- Beta-silicon_effect wikiPageRevisionID "680836672".
- Beta-silicon_effect wikiPageWikiLink Acid_dissociation_constant.
- Beta-silicon_effect wikiPageWikiLink Alkane_stereochemistry.
- Beta-silicon_effect wikiPageWikiLink Antiperiplanar.
- Beta-silicon_effect wikiPageWikiLink Atomic_orbital.
- Beta-silicon_effect wikiPageWikiLink Base_(chemistry).
- Beta-silicon_effect wikiPageWikiLink Benzoyl_peroxide.
- Beta-silicon_effect wikiPageWikiLink Carbocation.
- Beta-silicon_effect wikiPageWikiLink Category:Physical_organic_chemistry.
- Beta-silicon_effect wikiPageWikiLink Chemical_kinetics.
- Beta-silicon_effect wikiPageWikiLink Conjugate_acid.
- Beta-silicon_effect wikiPageWikiLink Elimination_reaction.
- Beta-silicon_effect wikiPageWikiLink Ethylene.
- Beta-silicon_effect wikiPageWikiLink Frank_C._Whitmore.
- Beta-silicon_effect wikiPageWikiLink Halogenation.
- Beta-silicon_effect wikiPageWikiLink Hydroxyl.
- Beta-silicon_effect wikiPageWikiLink Hyperconjugation.
- Beta-silicon_effect wikiPageWikiLink Molecular_orbital.
- Beta-silicon_effect wikiPageWikiLink Neopentane.
- Beta-silicon_effect wikiPageWikiLink Neopentyl.
- Beta-silicon_effect wikiPageWikiLink Organosilicon.
- Beta-silicon_effect wikiPageWikiLink P-orbital.
- Beta-silicon_effect wikiPageWikiLink PKa.
- Beta-silicon_effect wikiPageWikiLink Radical_initiator.
- Beta-silicon_effect wikiPageWikiLink Radical_substitution.
- Beta-silicon_effect wikiPageWikiLink Sigma_bond.
- Beta-silicon_effect wikiPageWikiLink Sigma_molecular_orbital.
- Beta-silicon_effect wikiPageWikiLink Silicon.
- Beta-silicon_effect wikiPageWikiLink Sodium_hydroxide.
- Beta-silicon_effect wikiPageWikiLink Stereochemistry.
- Beta-silicon_effect wikiPageWikiLink Sulfuryl_chloride.
- Beta-silicon_effect wikiPageWikiLink File:BetaSiliconEffectI.png.
- Beta-silicon_effect wikiPageWikiLink File:SiliconHyperconjugation.png.
- Beta-silicon_effect wikiPageWikiLink File:SiliconHyperconjugationWhitmore.png.
- Beta-silicon_effect wikiPageWikiLinkText "Beta-silicon effect".
- Beta-silicon_effect wikiPageWikiLinkText "beta-silicon effect".
- Beta-silicon_effect wikiPageWikiLinkText "β-silicon effect".
- Beta-silicon_effect hasPhotoCollection Beta-silicon_effect.
- Beta-silicon_effect wikiPageUsesTemplate Template:Reflist.
- Beta-silicon_effect subject Category:Physical_organic_chemistry.
- Beta-silicon_effect hypernym Type.
- Beta-silicon_effect comment "The beta-silicon effect also called silicon hyperconjugation in organosilicon chemistry is a special type of hyperconjugation and describes the stabilizing effect of a silicon atom placed in a position one removed (β) from a carbocation. A prerequisite is an antiperiplanar relationship between the two groups. Silicon hyperconjugation explains specific observations regarding chemical kinetics and stereochemistry of organic reactions with reactants containing silicon.".
- Beta-silicon_effect label "Beta-silicon effect".
- Beta-silicon_effect sameAs m.0cksnq.
- Beta-silicon_effect sameAs Бета-кремнієвий_ефект.
- Beta-silicon_effect sameAs Q4897231.
- Beta-silicon_effect sameAs Q4897231.
- Beta-silicon_effect sameAs Β-硅基效应.
- Beta-silicon_effect wasDerivedFrom Beta-silicon_effect?oldid=680836672.
- Beta-silicon_effect depiction SiliconHyperconjugation.png.
- Beta-silicon_effect isPrimaryTopicOf Beta-silicon_effect.