Qhov sib txawv tseem ceeb ntawm electrocyclic thiab cycloaddition cov tshuaj tiv thaiv yog tias cov tshuaj tiv thaiv electrocyclic yog cov tshuaj tiv thaiv rov qab, qhov kev tawm tsam cycloaddition yog cov tshuaj tiv thaiv ntxiv.
Ob qho kev tawm tsam electrocyclic thiab cycloaddition cov tshuaj tiv thaiv yog cov ntaub ntawv ntawm cov tshuaj lom neeg cov tshuaj tiv thaiv uas tseem ceeb hauv cov organic synthesis ntawm cov tshuaj sib xyaw. Lawv muaj qhov sib txawv ntawm kev ua haujlwm; Yog li ntawd, peb tuaj yeem faib cov tshuaj tiv thaiv electrocyclic thiab cycloaddition cov tshuaj tiv thaiv rau hauv ob pawg sib txawv raws li kev hloov pauv thiab cov tshuaj tiv thaiv ntxiv, feem.
Dab tsi yog Electrocyclic Reaction?
Ib qho tshuaj tiv thaiv electrocyclic yog ib hom kev hloov pauv ntawm pericyclic hauv cov organic chemistry uas muab cov txiaj ntsig zoo raws li kev hloov pauv ntawm daim ntawv cog lus pi rau hauv daim ntawv cog lus sigma lossis rov ua dua. Muaj ntau hom tshuaj tiv thaiv electrocyclic vim nws yog ib ceg dav ntawm cov organic chemistry. Qee pawg suav nrog cov tshuaj tiv thaiv photochemical, cov tshuaj tiv thaiv thermal, lub nplhaib qhib lossis lub nplhaib kaw, thiab lwm yam.
Ib qho piv txwv classic ntawm cov tshuaj tiv thaiv electrocyclic yog lub nplhaib qhib qhov cua sov ntawm cis-isomer ntawm 3, 4-dimethylcyclobutene. Cov tshuaj tiv thaiv no yields cis, trans-hexa-2, 4-diene. Ib yam li ntawd, yog peb siv cov trans-isomer ntawm cov reactant molecule, ces qhov kawg tshwm sim kuj yog ib tug trans diene. Cov tshuaj tiv thaiv yog raws li nram no:
Daim duab 01: Ib qho piv txwv Classic ntawm Kev Tiv Thaiv Electrocyclic
Cov tshuaj tiv thaiv saum toj no tshwm sim los ntawm txoj kev frontier-orbital. Ntawm no, lub sigma daim ntawv cog lus nyob rau hauv lub reactant qhib, tsim p orbitals uas muaj tib symmetry li HOMO ntawm cov khoom, hexadiene. Qhov kev hloov dua siab tshiab no tshwm sim los ntawm txoj kev qhib lub nplhaib conrotatory uas ua rau muaj cov cim qhia rau lub davhlau ya nyob twg lobes. Qhov kev hloov pauv ntawm orbitals no tau qhia hauv qab no.
Feem ntau, cov tshuaj tiv thaiv electrocyclic qhia tau hais tias muaj qhov tshwj xeeb. Qhov ntawd txhais tau tias, peb tuaj yeem kwv yees qhov cis-trans geometry ntawm cov khoom kawg. Raws li thawj kauj ruam ntawm qhov kev twv ua ntej no, peb yuav tsum txiav txim siab seb cov tshuaj tiv thaiv puas ua tiav zoo los yog tsis sib haum xeeb. Tom qab qhov kev txiav txim siab no, peb tuaj yeem tshuaj xyuas qhov pib molecule los txiav txim seb qhov khoom kawg yog cis-isomer lossis trans-isomer.
Cycloaddition Reaction yog dab tsi?
Cycloaddition cov tshuaj tiv thaiv yog ib hom tshuaj tiv thaiv hauv cov organic chemistry qhov twg ob los yog ntau tshaj cov molecules unsaturated ua ke nrog ib leeg los ua ib tug cyclic adduct. Cov tshuaj tiv thaiv no ua rau kev txo qis ntawm daim ntawv cog lus ntau. Peb tuaj yeem hu ua qhov kev tshwm sim no ua cov tshuaj tiv thaiv cyclization. Feem ntau, cycloadditions yog concerted. Yog li ntawd, peb tuaj yeem faib lawv ua cov tshuaj tiv thaiv pericyclic. Ib yam li ntawd, tsis muaj kev sib txuas lus cycloadditions tsis yog pericyclic. Cycloaddition cov tshuaj tiv thaiv yog ib hom kev sib txuas ntxiv uas tso cai rau carbon-carbon daim ntawv cog lus tsis siv electrophile lossis nucleophile.
Muaj ntau hom cycloadditions, xws li thermal cycloaddition, photochemical cycloaddition, Diels-Alder cov tshuaj tiv thaiv, Huisgen cycloaddition, Cheletropic cov tshuaj tiv thaiv, thiab lwm yam. Feem ntau, Diels-Alder cov tshuaj tiv thaiv yog cov tshuaj tiv thaiv cycloaddition tseem ceeb.
Qhov txawv ntawm Electrocyclic thiab Cycloaddition Reaction yog dab tsi?
Ob qho kev tawm tsam electrocyclic thiab cycloaddition cov tshuaj tiv thaiv tseem ceeb hauv cov organic synthesis ntawm cov tshuaj sib xyaw. Qhov sib txawv tseem ceeb ntawm electrocyclic thiab cycloaddition cov tshuaj tiv thaiv yog tias cov tshuaj tiv thaiv electrocyclic yog cov tshuaj tiv thaiv rov qab, thaum cov tshuaj tiv thaiv cycloaddition yog cov tshuaj tiv thaiv ntxiv.
Ntxiv mus, cov tshuaj tiv thaiv electrocyclic cuam tshuam nrog kev hloov pauv ntawm daim ntawv cog lus pi rau hauv daim ntawv cog lus sigma lossis rov ua dua, thaum cov tshuaj tiv thaiv cycloaddition cuam tshuam nrog kev sib xyaw ntawm ob lossis ntau dua cov tshuaj tsis txaus ntseeg los ua ib qho kev sib txuas cyclic.
Cov infographic hauv qab no qhia qhov txawv ntawm electrocyclic thiab cycloaddition cov tshuaj tiv thaiv hauv daim ntawv teev npe.
Summary – Electrocyclic vs Cycloaddition Reaction
Ob qho kev tawm tsam electrocyclic thiab cycloaddition cov tshuaj tiv thaiv tseem ceeb hauv cov organic synthesis ntawm cov tshuaj sib xyaw. Qhov sib txawv tseem ceeb ntawm electrocyclic thiab cycloaddition cov tshuaj tiv thaiv yog tias cov tshuaj tiv thaiv electrocyclic yog cov tshuaj tiv thaiv rov qab thaum cov tshuaj tiv thaiv cycloaddition yog cov tshuaj tiv thaiv ntxiv.
