Video: Puas yog beta tshem tawm e1 lossis e2?
2024 Tus sau: Miles Stephen | [email protected]. Kawg hloov kho: 2023-12-15 23:36
Hauv E2 tshem tawm mechanism, tshem tawm hydrogen los ntawm ua β carbon los ntawm lub hauv paus (alkoxide ion) thiab halogen los ntawm α carbon ntawm alkyl halides tshwm sim ib txhij los tsim alkene. Hauv E1 mechanism, thawj kauj ruam, halogen los ntawm α carbon tau raug tshem tawm los ua carbocation.
Ua li no, yog Hofmann tshem tawm e1 lossis e2?
Cov ammonium (NR3) + yog pab pawg tawm zoo. Kev kho mob nrog lub hauv paus yuav ua rau E2 cov tshuaj tiv thaiv, qhov twg peb tsim ib qho alkene. Qhov no yog hu ua Kev tshem tawm Hofmann . Qhov ntawd yog qhov txawv, vim hais tias Zaitsev feem ntau nyiam vim muaj kev hloov pauv alkenes ntau dua.
Tsis tas li ntawd, puas cua sov nyiam e1 lossis e2? Cov kab hauv qab no yog tias koj tau nug koj tus kheej txog cov substrate, nucleophile, thiab cov kuab tshuaj thiab tseem tsis muaj lus teb txog SN1 / SN2 / E1 / E2 , ces saib qhov kub thiab txias. Yog muaj kub , nws yog ib qho kev tshem tawm cov tshuaj tiv thaiv. Yog kub tsis siv, nws zoo li hloov pauv.
Kuj Paub, puas e1 thiab e2 muab tib yam khoom?
Nrog nws E1 thiab SN1 cov tshuaj tiv thaiv zoo sib xws, tsuas yog nuances txiav txim siab qhov twg ntawm ob qho no cov khoom yuav tswj hwm. Cov E1 khoom yog nyiam los ntawm qhov kub thiab txias. Hauv E2 react, peb muaj ib yam pib compound uas yog tawm tsam los ntawm lub hauv paus hauv thawj kauj ruam.
Dab tsi yog qhov txawv ntawm sn1 sn2 e1 thiab e2 cov tshuaj tiv thaiv?
Qhov "loj barrier" rau lub SN2 cov tshuaj tiv thaiv yog steric hindrance. Tus nqi ntawm SN2 cov tshuaj tiv thaiv mus rau thawj > theem nrab > tertiary. Qhov "loj barrier" rau lub SN1 thiab E1 cov tshuaj tiv thaiv yog carbocation stability. Cov E2 cov tshuaj tiv thaiv tsis muaj "kev cuam tshuam loj", per se (txawm tias tom qab ntawd peb yuav tau txhawj xeeb txog kev siv tshuaj stereochemistry)
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