Qhov sib txawv tseem ceeb ntawm kev sib tham thiab kev sib tham yog qhov kev sib tham sib tham yog cov kev cuam tshuam ib kauj ruam, qhov kev tawm tsam stepwise yog ntau qhov kev tawm tsam.
Cov ntsiab lus hais txog kev sib koom ua ke thiab cov tshuaj tiv thaiv ib ntus tuaj nyob rau hauv thaj chaw ntawm lub cev chemistry qhov twg tus nqi ntawm cov tshuaj tiv thaiv tau txiav txim siab siv qhov kev hloov pauv ntawm cov tshuaj reactant thiab cov khoom lag luam nrog lub sijhawm. Txhua yam tshuaj lom neeg uas peb paub tuaj yeem muab faib ua ob pawg sib txawv raws li kev sib tham sib tham thiab cov tshuaj tiv thaiv ib ntus nyob ntawm cov txheej txheem ntawm cov tshuaj tiv thaiv.
Kev sib tham yog dab tsi?
Cov tshuaj tiv thaiv kev txhawj xeeb yog tshuaj lom neeg uas cuam tshuam nrog ib kauj ruam nkaus xwb. Qhov ntawd txhais tau tias; tag nrho cov kev cuam tshuam ib kauj ruam poob rau hauv qeb ntawm kev sib tham sib tham. Yog li ntawd, daim ntawv cog lus tawg thiab daim ntawv cog lus-kev tawm tsam tshwm sim ib txhij los tsim cov khoom. Nyob rau hauv lwm yam lus, tsis muaj reactive intermediates los yog unstable siab zog complexes tsim thaum lub sij hawm hom tshuaj no.
Daim duab 01: Ib qho piv txwv ntawm Kev Sib Tham Sib Tham (muaj qhov nruab nrab tsis ruaj khov)
Feem ntau, kev sib koom ua ke tsis yog nyob ntawm qhov hnyav polarity, thiab cov txheej txheem ntawm cov tshuaj tiv thaiv yog lub npe hu ua kev sib koom ua ke. Qee qhov piv txwv rau hom kev tshwm sim no suav nrog cov tshuaj tiv thaiv pericyclic, cov tshuaj tiv thaiv SN2 thiab qee qhov kev hloov kho tshiab xws li Claisen rearrangement.
Dab tsi yog qhov cuam tshuam Stepwise?
Cov tshuaj tiv thaiv ib ntus yog cov tshuaj tiv thaiv ntau kauj ruam. Yog li ntawd, muaj cov tshuaj intermediates nyob rau hauv cov tshuaj no. Cov intermediates no feem ntau yog reactive heev vim lub zog siab uas ua rau lawv tsis ruaj khov. Cov tshuaj tiv thaiv ib ntus feem ntau muaj ob lossis ntau qhov tshwm sim hauv theem pib.
Daim duab 02: Ib qho piv txwv ntawm Kev Ua Phem
Nyob rau hauv qhov sib piv rau cov kev xav tsis zoo, kev sib tsoo thiab kev sib koom ua lag luam hauv cov kauj ruam sib txawv tshwm sim hauv cov kauj ruam sib txawv (tsis yog hauv ib kauj ruam). Yog li ntawd, cov reactants tsis tuaj yeem hloov mus rau hauv cov khoom ncaj qha. Lub "tag nrho cov tshuaj tiv thaiv" nyob rau hauv ib tug stepwise cov tshuaj tiv thaiv uas muab hloov dua siab tshiab ntawm reactants rau hauv cov khoom. Peb tuaj yeem tau txais tag nrho cov tshuaj tiv thaiv los ntawm kev sib npaug txhua kauj ruam hauv cov tshuaj tiv thaiv stepwise. Txawm li cas los xij, muaj ib qho tshuaj tiv thaiv theem pib hauv cov tshuaj tiv thaiv stepwise uas txiav txim siab tus nqi ntawm cov tshuaj tiv thaiv. Nws yog cov tshuaj tiv thaiv qeeb tshaj plaws ntawm cov tshuaj tiv thaiv kab mob, thiab nws yuav los yog tsis muaj cov tshuaj reactants lossis cov khoom lag luam koom nrog (nws tsuas yog muaj cov tshuaj tiv thaiv nruab nrab xwb).
Qhov txawv ntawm Concerted thiab Stepwise Reactions yog dab tsi?
Cov ntsiab lus hais txog kev sib koom ua ke thiab cov tshuaj tiv thaiv ib ntus tuaj nyob rau hauv thaj chaw ntawm lub cev chemistry qhov twg tus nqi ntawm cov tshuaj tiv thaiv tau txiav txim siab siv qhov kev hloov pauv ntawm cov tshuaj reactant thiab cov khoom lag luam nrog lub sijhawm. Qhov sib txawv tseem ceeb ntawm kev sib koom ua ke thiab kev sib tw ua ke yog qhov kev sib koom ua ke yog cov kev cuam tshuam ib kauj ruam, qhov kev tawm tsam stepwise yog ntau qhov kev tawm tsam. Tus nqi-txhais kauj ruam ntawm kev sib tham sib tham yog nws tus kheej ib qho kev sib tham. Tab sis, nyob rau hauv cov kev tshwm sim stepwise, qhov qis tshaj cov tshuaj tiv thaiv theem pib yog tus nqi txiav txim siab.
Ntxiv mus, tsis muaj cov tshuaj tiv thaiv intermediates hauv kev sib koom ua ke vim tias cov reactants ncaj qha hloov mus rau hauv cov khoom. Txawm li cas los xij, nyob rau hauv cov tshuaj tiv thaiv stepwise, muaj ib lossis ntau qhov sib txuas nruab nrab uas tsis ruaj khov vim yog lub zog siab ntawm cov compound. Tag nrho cov tshuaj tiv thaiv ntawm cov tshuaj tiv thaiv stepwise muab kev hloov pauv ntawm cov reactants rau hauv cov khoom.
Hauv qab infographic muab cov ntsiab lus ntxiv ntawm qhov sib txawv ntawm kev sib tham thiab kev tawm tsam.
Summary – Concerted vs Stepwise Reactions
Txhua cov tshuaj tiv thaiv uas peb paub tuaj yeem muab faib ua ob pawg raws li kev sib tham sib tham thiab cov tshuaj tiv thaiv ib ntus. Qhov sib txawv tseem ceeb ntawm kev sib koom ua ke thiab kev sib tw ua ke yog qhov kev sib koom ua ke yog cov tshuaj tiv thaiv ib kauj ruam, qhov kev tawm tsam stepwise yog ntau qhov kev tawm tsam.
