Electrophilic Bugu da kari a Organic Chemistry

Domin Bugu da kari halayen halin da samuwar sinadaran mahadi daga biyu ko fiye da lokacin da na fara kayan. La'akari da ginshikai na electrophilic Baya ga m misali na alkenes - unsaturated acyclic hydrocarbons da daya biyu bond. Bugu da kari a gare su, a cikin irin canje dauki sauran hydrocarbons da ciwon mahara shaidu, ciki har da cyclic.

Akayi maida martani da fara kwayoyin

Electrophilic Bugu da kari faruwa a dama, saukarwa. Electrophile ciwon tabbatacce cajin ayyukan matsayin electron Mai karɓar, da kuma biyu bond na wani alkene kwayoyin - kamar yadda wani electron bayarwa. The biyu mahadi samar da wata farko p-maras tabbas hadaddun. Sa'an nan ya fara da canji na π-hadaddun a ϭ-hadaddun. Carbocation samuwar a wannan mataki, kuma ta zaman lafiya da sanin da kudi na hulda a general. Sa'an nan carbocation reacts hanzari tare da m barnatar da cajin nucleophile da karshe hira samfurin kafa.

Effect na substituents a dauki kudi

Cajin delocalization (ϭ +) a carbocation shi ya dogara da farko kwayoyin tsarin. M inductive sakamako wanda bayyana alkyl kungiyar, take kaiwa zuwa wani karu a cikin cajin m carbon zarra. A sakamakon haka, a cikin kwayoyin da electron donating substituent qara zumunta kwanciyar hankali na cation π-electron yawa ne saboda da reactivity na kwayoyin a matsayin dukan. Sakamako a kan reactivity na electron acceptors zai zama m.

Ginshikai na halogens connection

Bari mu bincika a cikin mafi daki-daki, inji na electrophilic Bugu da kari daga cikin alkene zuwa wani misali na hulda da halogen.

1. Halogen kwayoyin fuskanci biyu bond tsakanin carbon kwayoyin zarra da polarized. Saboda da partially tabbatacce cajin a daya ƙarshen kwayoyin halogen jan da electrons π-bond. Tun da akwai wani samuwar wani m π-hadaddun.
2. A mataki na gaba electrophilic barbashi da alaka da biyu carbon atoms, forming wani zobe. Akwai cyclic "onium" ion.
3. Sauran caje barbashi halogen (lallai cajin nucleophile) ne ya mayar da martani tare da onium ion da kuma shiga a gefen daga baya barbashi halogen. Bayyana karshe samfurin - trans-1,2-digalogenalkan. Hakazalika, abin da aka makala faruwa da halogen cycloalkenyl.

The inji abin da aka makala hydrohalic acid

Electrophilic Bugu da kari na hydrogen halides da sulfuric acid faruwa in ba haka ba. A wani acidic yanayi ne barranta zuwa wani cation da reagent anion. Gaskiya ma cajin ion (electrophile) ya fāɗa cikin π-bond guda biyu zuwa daya daga cikin carbon atoms. Carbocation aka kafa, cikinsa da m carbon zarra ne gaskiya ma da caji. Next carbocation reacts tare da anion samar da karshe samfurin na dauki.

Shugabanci na dauki tsakanin reagents kuma yawanci asymmetrical Markovnikov

Electrophilic Bugu da kari tsakanin biyu asymmetric kwayoyin faruwa regioselectively. Wannan yana nufin cewa biyu yiwu isomers aka kafa zai fi dacewa kawai daya. Regioselectivity bayyana Markovnikov ta mulki, bisa ga abin da hydrogen ne a haɗe zuwa carbon zarra da alaka da wani babban adadin wasu hydrogen atoms (mafi hydrogenated).

Don gane da wannan mulkin, shi wajibi ne don tunawa da cewa dauki kudi ya dogara da zaman lafiyar na tsaka-tsaki carbocation. Effect na electron bayarwa da kuma Mai karɓar substituents da aka ambata a sama. Saboda haka, electrophilic Bugu da kari na hydrobromic acid don propene gubar da samuwar 2-bromopropane. Matsakaiciyar cation tare da wani m cajin a kan tsakiyar carbon zarra more barga carbocation tare da wani m cajin a cikin matsananci zarra. A sakamakon haka, a bromine zarra ne ya mayar da martani tare da wata biyu carbon zarra.

Effect na electron-janye substituents a cikin shakka daga cikin hulda

Idan asali kwayoyin ƙunshi electron janye substituent wanda yana da wani mummunan inductive da / ko mesomeric sakamako, electrophilic Bugu da kari shi ne da na sama dokoki. Misalai na irin wannan substituents: CF _3, COOH, CN. A wannan yanayin, da girma da nisa daga tabbatacce cajin na farko electron janye kungiyar sa a mafi barga carbocation. A sakamakon haka, hydrogen da alaka da carbon zarra kasa hydrogenated.

Universal version daga cikin dokoki za su yi kama da wannan: hulda da wani asymmetric alkene da wani asymmetric reagent dauki Saide ta hanyar samuwar mafi barga carbocation.