Qhov txawv ntawm Kev tshem tawm thiab hloov pauv qhov tshwm sim

2024 Tus sau: Alex Aldridge | [email protected]. Kawg hloov kho: 2023-12-17 13:40

Qhov Tseem Ceeb Qhov Sib Txawv - Kev Tshem Tawm vs Hloov Kev Tawm Tsam

Kev tshem tawm thiab hloov cov tshuaj tiv thaiv yog ob hom tshuaj tiv thaiv feem ntau pom hauv cov tshuaj lom neeg. Qhov sib txawv tseem ceeb ntawm kev tshem tawm thiab hloov cov tshuaj tiv thaiv tuaj yeem piav qhia tau zoo tshaj plaws los ntawm kev siv lawv cov txheej txheem. Hauv kev tshem tawm cov tshuaj tiv thaiv, rov kho dua ntawm cov ntawv cog lus yav dhau los tshwm sim tom qab cov tshuaj tiv thaiv, qhov kev hloov pauv hloov pauv ib pawg tawm nrog cov nucleophile. Ob qhov kev cuam tshuam no sib tw ua ke thiab cuam tshuam los ntawm ntau yam. Cov xwm txheej no txawv ntawm ib qho tshuaj tiv thaiv mus rau lwm qhov.

Kev Tawm Tsam Tawm Tsam yog dab tsi?

Kev tshem tawm cov tshuaj tiv thaiv muaj nyob hauv Organic Chemistry, thiab cov txheej txheem cuam tshuam nrog kev tshem tawm ob qho kev hloov pauv ntawm cov organic molecule hauv ib kauj ruam lossis ob kauj ruam. Thaum cov tshuaj tiv thaiv tshwm sim hauv ib kauj ruam txheej txheem, nws yog hu ua E2 (bi-molecular cov tshuaj tiv thaiv) cov tshuaj tiv thaiv, thiab thaum nws muaj ob kauj ruam mechanism, nws yog hu ua E1 (unimolecular cov tshuaj tiv thaiv) cov tshuaj tiv thaiv. Feem ntau, feem ntau ntawm kev tshem tawm cov kev cuam tshuam cuam tshuam nrog qhov poob ntawm tsawg kawg ib qho hydrogen atom los ua ob daim ntawv cog lus. Qhov no ua rau kom qhov tsis txaus ntawm cov molecule.

E1 reaction

Kev hloov pauv yog dab tsi?

Kev hloov pauv tshuaj yog ib hom tshuaj tiv thaiv uas cuam tshuam txog kev hloov ntawm ib pawg ua haujlwm hauv cov tshuaj lom neeg los ntawm lwm pab pawg ua haujlwm. Kev hloov pauv cov tshuaj tiv thaiv kuj tseem hu ua 'ib qho kev hloov pauv hloov pauv' lossis 'ib qho kev hloov pauv ib zaug.' Cov tshuaj tiv thaiv no tseem ceeb heev hauv Organic Chemistry, thiab lawv feem ntau muab faib ua ob pawg, raws li cov reagents koom nrog cov tshuaj tiv thaiv: electrophilic hloov pauv cov tshuaj tiv thaiv thiab nucleophilic. hloov cov tshuaj tiv thaiv. Ob hom kev hloov pauv no muaj xws li S_N1 cov tshuaj tiv thaiv thiab S_{N2 cov tshuaj tiv thaiv.}

Kev hloov tshuaj tiv thaiv -Methane Chlorination

Dab tsi yog qhov txawv ntawm Kev Tshem Tawm thiab Kev Hloov Hloov Tawm?

Mechanism:

Kev Tshem Tawm Tawm: Kev tshem tawm cov tshuaj tiv thaiv tuaj yeem muab faib ua ob pawg; Cov tshuaj tiv thaiv E1 thiab E2 cov tshuaj tiv thaiv. Cov tshuaj tiv thaiv E1 muaj ob kauj ruam hauv cov tshuaj tiv thaiv, thiab E1 cov tshuaj tiv thaiv muaj ib kauj ruam txheej txheem.

Kev Sib Hloov Hloov: Cov kev hloov pauv tau muab faib ua ob pawg raws li lawv cov txheej txheem tshuaj tiv thaiv: S_N 1 kev tawm tsam thiabS_{N2 kev tawm tsam.}

Properties:

Kev Tawm Tsam Tawm:

E1 cov tshuaj tiv thaiv: Cov tshuaj tiv thaiv no tsis yog qhov tshwj xeeb, thiab lawv ua raws li txoj cai Zaitsev (Saytseff). Ib qho carbocation intermediate yog tsim nyob rau hauv cov tshuaj tiv thaiv kom cov tshuaj tiv thaiv no tsis-concerted tshua. Lawv yog cov tshuaj tiv thaiv unimolecular txij li cov tshuaj tiv thaiv tus nqi tsuas yog nyob ntawm qhov concentration. Cov tshuaj tiv thaiv no tsis tshwm sim nrog thawj alkyl halides (tawm pawg). Cov kua qaub muaj zog tuaj yeem txhawb nqa qhov poob ntawm OH li H_{2O lossis LOS YOG HOR yog tertiary lossis conjugated carbocation tuaj yeem tsim ua qhov nruab nrab.}

E2 cov tshuaj tiv thaiv: Cov tshuaj tiv thaiv no yog cov yam ntxwv tshwj xeeb; anti-periplanar geometry yog nyiam, tab sis synperiplanar geometry kuj ua tau. Lawv tau sib tham thiab suav tias yog cov tshuaj tiv thaiv bimolecular vim tias cov tshuaj tiv thaiv yog nyob ntawm qhov concentration ntawm lub hauv paus thiab cov substrate. Cov tshuaj tiv thaiv no tau txais kev txhawb nqa los ntawm cov hauv paus muaj zog.

Kev hloov pauv:

S_{N 1 cov tshuaj tiv thaiv: Cov tshuaj tiv thaiv no tau hais tias tsis yog qhov tshwj xeeb vim tias cov nucleophile tuaj yeem tua cov molecule ntawm ob sab. Ib qho carbocation ruaj khov yog tsim nyob rau hauv cov tshuaj tiv thaiv thiab yog li cov tshuaj tiv thaiv no tsis yog-concereted cov tshuaj tiv thaiv. Tus nqi ntawm cov tshuaj tiv thaiv tsuas yog nyob ntawm qhov concentration ntawm substrate, thiab lawv hu ua unimolecular cov tshuaj tiv thaiv.}

S_{N2 kev tshwm sim: Cov tshuaj tiv thaiv no yog qhov tshwj xeeb thiab sib tham. Tus nqi ntawm cov tshuaj tiv thaiv nyob ntawm qhov concentration ntawm nucleophile thiab substrate. Cov tshuaj tiv thaiv no tshwm sim zoo heev, thaum lub nucleophile ntau reactive (ntau anionic los yog yooj yim).}

Definition:

Stereospecific:

Nyob rau hauv cov tshuaj tiv thaiv, kev tsim cov stereomeric daim ntawv ntawm cov khoom, tsis hais lub configuration ntawm cov reactant.

Cov lus pom zoo:

Cov tshuaj tiv thaiv kab mob yog cov tshuaj tiv thaiv uas txhua daim ntawv cog lus tawg thiab tsim hauv ib kauj ruam.