Qhov sib txawv tseem ceeb ntawm isovalent thiab sacrificial hyperconjugation yog lawv daim ntawv tseem ceeb thiab daim ntawv canonical. Isovalent hyperconjugation tshwm sim hauv cov dawb radicals thiab carbocations qhov twg daim ntawv canonical qhia tsis muaj kev sib cais, tab sis daim ntawv tseem ceeb muaj kev sib cais, qhov kev txi hyperconjugation yog lub xeev uas daim ntawv canonical tsis muaj daim ntawv cog lus resonance, tab sis daim ntawv tseem ceeb tsis muaj nqi faib.
Ua ntej nkag siab qhov sib txawv ntawm isovalent thiab sacrificial hyperconjugation, nws yog ib qho tseem ceeb kom to taub dab tsi yog hyperconjugation. Hyperconjugation yog kev sib cuam tshuam ntawm σ-bonds nrog pi bond network.
Hyperconjugation yog dab tsi?
Lub sij hawm hyperconjugation yog hais txog kev sib cuam tshuam ntawm σ-bonds nrog pi network. Hauv qhov kev cuam tshuam no, cov khoom siv hluav taws xob hauv daim ntawv cog lus sigma cuam tshuam nrog ib feem ntawm qhov chaw nyob ib sab (lossis tag nrho) puv p orbital lossis nrog pi orbital. Hom kev sib cuam tshuam no tshwm sim los ua kom muaj kev ruaj ntseg ntawm cov molecule.
Daim duab 01: Hyperconjugation
Feem ntau, hyperconjugation tshwm sim vim qhov sib tshooj ntawm cov khoom siv hluav taws xob hauv C-H sigma daim ntawv cog lus nrog p orbital lossis pi orbital ntawm cov pa roj carbon atom. Ntawm no, hydrogen atom nyob ze ze li ib tug proton. Tus nqi tsis zoo uas tsim los ntawm cov pa roj carbon atom yog delocalized vim qhov sib tshooj ntawm p orbital lossis pi orbital.
Isovalent Hyperconjugation yog dab tsi?
Isovalent hyperconjugation yog hais txog hyperconjugation uas tshwm sim hauv cov dawb radicals thiab carbocations qhov twg daim ntawv canonical qhia tsis muaj nqi sib cais, tab sis daim ntawv tseem ceeb muaj kev sib cais. Peb tuaj yeem piav qhia txog hom hyperconjugation no raws li kev teeb tsa ntawm cov khoom siv tshuaj lom neeg nyob rau hauv ib qho hyperconjugated molecule qhov twg cov naj npawb ntawm cov ntawv cog lus zoo ib yam li ob lub qauv resonance thaum tus qauv thib ob tsis tshua muaj txiaj ntsig los ntawm lub zog dua li thawj cov qauv. Ib qho piv txwv zoo ntawm hom hyperconjugation no yog H3C-CH2 thiab H3C-C+H 2
Dab tsi yog Sacrificial Hyperconjugation?
Kev txi nyiaj txiag hyperconjugation yog hais txog qhov hyperconjugation qhov twg daim ntawv canonical tsis cuam tshuam nrog kev sib raug zoo, tab sis hauv daim ntawv tseem ceeb tsis muaj kev faib tawm. Hom hyperconjugation no tseem hu ua "tsis muaj daim ntawv cog lus hyperconjugation". Qhov no yog vim hais tias, nyob rau hauv cov qauv resonance ntawm cov txheej txheem hyperconjugation, peb tuaj yeem pom ib daim ntawv cog lus uas ploj lawm los ntawm cov qauv resonance (qhov kev sib cog lus ntawm hydrogen atom thiab alpha-carbon atom). Yog li ntawd, ib qho ntawm hydrogen atoms ploj lawm los ntawm cov qauv, tab sis nws tseem tshwm sim nyob ze li proton. Qhov no ua rau peb muaj peev xwm muab alpha carbon atom nws daim ntawv cog lus raws li 1.5 kwv yees. Txij li thaum muaj ib daim ntawv cog lus uas ploj lawm los ntawm tus qauv, nws yog lub npe hu ua sacrificial hyperconjugation.
Qhov txawv ntawm Isovalent thiab Sacrificial Hyperconjugation yog dab tsi?
Lub sij hawm hyperconjugation yog hais txog kev sib cuam tshuam ntawm σ-bonds nrog pi network. Muaj ob hom loj ntawm hyperconjugation uas peb tuaj yeem sib tham: isovalent thiab sacrificial hyperconjugation. Qhov sib txawv tseem ceeb ntawm isovalent thiab sacrificial hyperconjugation yog tias isovalent hyperconjugation tshwm sim hauv cov dawb radicals thiab carbocations qhov twg daim ntawv canonical qhia tsis muaj nqi sib cais, tab sis daim ntawv tseem ceeb muaj. Meanwhile, lub sacrificial hyperconjugation yog hais txog lub xeev uas canonical daim ntawv koom nrog tsis muaj daim ntawv cog lus resonance tab sis nyob rau hauv daim ntawv tseem ceeb tsis muaj nqi tis.
Summary – Isovalent vs Sacrificial Hyperconjugation
Lub sij hawm hyperconjugation yog hais txog kev sib cuam tshuam ntawm σ-bonds nrog pi network. Muaj ob hom loj ntawm hyperconjugation: isovalent thiab sacrificial hyperconjugation. Qhov sib txawv tseem ceeb ntawm isovalent thiab sacrificial hyperconjugation yog tias isovalent hyperconjugation tshwm sim hauv cov dawb radicals thiab carbocations qhov twg daim ntawv canonical qhia tsis muaj kev sib cais, tab sis daim ntawv tseem ceeb ua, qhov kev fij hyperconjugation yog hais txog lub xeev uas daim ntawv canonical tsis cuam tshuam nrog kev sib raug zoo, tab sis. lub ntsiab tsis muaj kev faib tawm.
