Electrophilic Kuwonjezera pa Chemistry Organic

Pakuti zochita Kuwonjezera yodziwika ndi mapangidwe mankhwala kuchokera ku zipangizo awiri kapena kuposa poyambira. Taganizirani limagwirira wa Kuwonjezera electrophilic chitsanzo yachidule alkenes - unsaturated acyclic chimasanduka ndi chomangira umodzi awiri. Kuwonjezera iwo, mu kusinthika chonchi chimasanduka zina ndi zomangira angapo, kuphatikizapo ozungulira.

Masiteji yatikhudza mamolekyulu kuyambira

Electrophilic Kuwonjezera chikuchitika mu magawo angapo. Electrophile kukhala zabwino kuyang'anira ntchito ngati ndi elekitironi acceptor, ndipo chomangira iwiri ya alkene molekyulu - monga elekitironi mwiniwake. The mankhwala awiri kupanga loyamba tsa-oyaka zovuta. Ndiye umayamba kusintha kwa π-lovuta ϭ-zovuta. Carbocation mapangidwe panthawi imeneyi ndi kukhazikika ake kudziwa mlingo wa mogwirizana ambiri. Kenako carbocation amachitira mofulumira ndi tsankho nucleophile zoipa mlandu chomaliza kutembenuka mankhwala anapanga.

Mmene substituents pa mlingo zimene

Mlandu delocalization (ϭ +) mu carbocation zimatengera pa koyamba dongosolo maselo. Zabwino inductive zotsatira zomwe kuwawonetsera alkyl gulu, akutitsogolera kuti kuchepa mu mtengo pafupi mpweya atomu. Chifukwa, mu molekyulu ndi elekitironi kupereka substituent kumawonjezera mtendere wa cation π-elekitironi kachulukidwe ndi chifukwa ndi reactivity wa molekyulu wonse. Zotsatira pa reactivity wa acceptors elekitironi adzakhala anzanu.

Limagwirira wa halogens kugwirizana

Tiyeni tione mwatsatanetsatane limagwirira wa electrophilic Kuwonjezera alkene kuti chitsanzo cha mogwirizana ndi halogen.

1. Halogen molekyulu wakudza mgwirizano awiri pakati pa maatomu a carbon ndi magetsi. Chifukwa mtengo pang'ono zabwino pa kumalekezero a halogen molekyulu imakoka ma elekitironi π-muzikondana. Popeza pali mapangidwe ndi wosakhazikika π-zovuta.
2. Mu sitepe yotsatira electrophilic tinthu olumikizidwa kwa maatomu awiri mpweya, n'kupanga mphete. Pali ozungulira "onium" ion.
3. Otsala mlandu tinthu halogen (zabwino mlandu nucleophile) ali anachitira ndi ion onium nkulowa mbali ina ku yapita particles halogen. Zikuoneka chomaliza mankhwala - Trans-1,2-digalogenalkan. Mofananamo, ubwenzi kumachitika mwa halogen cycloalkenyl.

Limagwirira kuphatikana hydrohalic zidulo

Electrophilic Kuwonjezera halides hydrogen ndi asidi sulfuric zimachitika mosiyana. M'madera acidic ndi dissociated mu cation ndi reagent anion. Ndithu mlandu ion (electrophile) akuukira π-chomangira zolumukizidwa mmodzi wa maatomu mpweya. Carbocation aumbike, mmene moyandikana mpweya atomu ndithu mlandu. Kenako carbocation amachitira ndi anion kupanga chomaliza mankhwala zotani.

Malangizo a anachita pakati pa reagents ndi zambiri asymmetrical Markovnikov

Electrophilic Kuwonjezera pakati mamolekyulu awiri asymmetric amapezeka regioselectively. Izi zikutanthauza kuti isomers awiri zotheka aumbike makamaka imodzi yokha. Regioselectivity limafotokoza ulamuliro Markovnikov a, malinga ndi zomwe wa hydrogen amamangiriridwa ku mpweya atomu chikugwirizana ndi ambiri maatomu ena a hydrogen (more hydrogenated).

Kuti timvetse lamulo limeneli, m'pofunika kukumbukira kuti mlingo anachita zimadalira mtendere wa carbocation wapakatikati. Mmene elekitironi mwiniwake ndi acceptor substituents tatchulazi. Choncho, electrophilic Kuwonjezera asidi hydrobromic kuti propene kutsogolera mapangidwe 2-bromopropane. The cation wapakatikati ndi mlandu zabwino chapakati mpweya atomu zambiri khola carbocation ndi mlandu abwino mu atomu kwambiri. Chifukwa, ndi bromine atomu ali anachita ndi wachiwiri mpweya atomu.

Mmene zinthu zosiyanasiyana za pochoka substituents pa njira ya mogwirizana ndi

Ngati molekyulu choyambirira lili elekitironi pochoka substituent amene ali inductive zoipa ndi / kapena zotsatira mesomeric, electrophilic Kuwonjezera ndi malamulo pamwambapa. Zitsanzo za substituents amenewa: CF _3, COOH, CN. Pankhaniyi, wamkulu mtunda wa mtengo zabwino zofunika elekitironi pochoka gulu akupanga carbocation wolimba kwambiri. Chifukwa cha zimenezi, a hydrogen olumikizidwa kwa mpweya atomu zochepa hydrogenated.

Universal buku la malamulo lidzaonekera izi: mogwirizana ya alkene asymmetric ndi asymmetric chimaposa reagent anachita mwa mapangidwe a carbocation khola kwambiri.