Canzawa halayen: description, lissafi misalai

Mutane da yawa canzawa dauki bude hanya ga shiri na daban-daban mahadi da ciwon mai amfani da aikace-aikacen. A babbar rawar a sinadaran kimiyya da masana'antu ne ba electrophilic da nucleophilic canzawa. A kwayoyin kira, wadannan matakai na da yawan siffofin da ya kamata a lura.

A iri-iri da sunadarai mamaki. canzawa dauki

Chemical canje-canje hade da canji na al'amarin, a dama daban-daban fasali. Iya zama daban-daban sakamakon, thermal effects. wasu matakai da za a gama, ya zo a cikin wasu sinadaran ma'auni. Gyaggyarawa jamiái shi ne sau da yawa tare da kara ko ragewa mataki na hadawan abu da iskar shaka. A cikin rarrabuwa da sunadarai mamaki a wasan karshe da sakamakon jawo hankali ga ingantaccen da kuma gwada yawa bambance-bambance tsakanin reactants daga kayayyakin. Wadannan siffofin za a iya bambanta 7 iri sinadaran halayen, ciki har da canzawa, a ci gaba bisa ga makirci: A-B-C A + C + B. A Saukake rikodi na dukan aji na sinadaran mamaki ba da wani ra'ayin cewa, daga cikin farawa kayan ne da ake kira "attacker "barbashi substituent a reagent zarra, ion aikin kungiyar. A canzawa dauki halayyar cikakken kuma aromatic hydrocarbons.

canzawa dauki iya faruwa a cikin nau'i na biyu-musayar: A-B-C + E C + A-B-E. Daya subspecies - hijirar, msl, jan, da baƙin ƙarfe daga wani bayani na jan karfe sulphate: CuSO ₄ + Fe = FeSO ₄ + Cu. Kamar yadda "kai hare hare" barbashi za su iya aiki kwayoyin halitta, ions ko aikin kungiyoyin

Homolytic canzawa (m, SR)

Lokacin da ginshikai na m katsewa covalent electron biyu ne na kowa da daban-daban abubuwa za a proportionally rarraba tsakanin ", niƙaƙƙun gaɓãɓuwa" na kwayoyin. Samuwar free radicals. Wannan m barbashi karfafawa wanda ya auku a sakamakon m halayen. Alal misali, a cikin shirye-shiryen da ethane daga methane nuna free radicals da hannu a cikin canzawa dauki: CH ₄ CH ₃ • + • H; CH ₃ • + • CH ₃ → C2H5. H • + • H → H2. Homolytic bond tsakiyan nonon a kan aiki inji na canzawa ne halayyar alkanes, da dauki wata sarkar hali. A methane H atoms iya jẽre maye gurbinsu da chlorine. Hakazalika ya amsa tare da bromine, aidin amma ya kasa kai tsaye maye gurbin hydrogen alkanes, sunadarin flourine reacts ma vigorously tare da su.

Heterolytic bond tsakiyan nonon Hanyar

Lokacin da ginshikai na ion kwarara canzawa halayen, electrons suna unevenly rarraba a tsakanin barbashi sabuwar taso. A dauri biyu daga electrons kara duk hanyar zuwa daya daga cikin "wani ɓaɓɓake", mafi sau da yawa, to da sadarwa da abokin tarayya, da gefen wanda ya biya diyya korau yawa a cikin iyakacin duniya kwayoyin. By canzawa halayen hada da dauki samuwar methyl barasa CH ₃ OH. A brommetane CH3Br rata kwayoyin ne heterolytic hali, da cajin barbashi ne barga. Methyl yakan mallaki wani m cajin, kuma bromo - korau: CH ₃ Br → CH ₃ ^{+ +} Br ^-. NaOH → Na ^{+ +} OH ^-. CH ₃ ^{+ +} OH ^- → CH ₃ OH. Na ^{+ +} Br ^- ↔ NaBr.

Electrophiles da nucleophiles

Barbashi cewa rasa electrons da zai iya yarda da su, suna kira "electrophiles." Wadannan su ne carbon atoms bonded da halogens a haloalkanes. Nucleophiles da high electron yawa, su ne "wadanda" wata biyu daga electrons don ƙirƙirar wani covalent bond. A canzawa halayen arziki korau zargin an kai hari ta hanyar nucleophiles electrophiles, gaira na electrons. Wannan sabon abu ne hade da motsi na atoms ko wasu barbashi - barin kungiyar. Wani iri-iri na canzawa halayen - kai farmaki da electrophile nucleophile. Wani lokacin wuya a rarrabe tsakanin biyu matakai, kira zuwa ga maye da daya ko wasu irin, saboda yana da wuya a saka daidai da abin da irin kwayoyin - substrate, da kuma wanda - reagent. Yawancin lokaci a irin haka ne, wadannan dalilai suna dauke:

• da yanayi na barin kungiyar.
• da reactivity na nucleophile.
• da yanayin da sauran ƙarfi.
• da alkyl rabo daga tsarin.

Nucleophilic canzawa (SN)

A kan aiwatar da hulda a cikin kwayoyin kwayoyin da aka kara rabuwa. A lissafai na m tabbatacce ko korau cajin da aka nuna ta wasika daga cikin Girkanci haruffa. Rabuwa sadarwa yana mai nuni da yanayin da katsewa da kuma nan gaba hali na ", niƙaƙƙun gaɓãɓuwa" na kwayoyin. Alal misali, a carbon zarra a iodomethane yana da wani m m cajin, shi ne wani electrophilic cibiyar. Yana janyo hankalin da dipole na ruwa, inda da oxygen yana da wani wuce haddi na electrons. A dauki na electrophile da nucleophile aka kafa methanol: CH ₃ I + H ₂ Ya → CH ₃ OH + HI. nucleophilic canzawa halayen dauki wuri tare da sa hannu na wani barnatar da cajin ion ko kwayoyin ciwon free electron biyu, wanda ba ya shiga a cikin halittar wani sinadaran bond. Gudummawar iodomethane a SN _2-dauki saboda da gaskiya, nucleophilic hari da aidin motsi.

Electrophilic canzawa (SE)

A kwayoyin kwayoyin iya zama ba nucleophilic cibiyar, wanda aka halin wani wuce haddi na electron yawa. Yana reacts tare da rashin korau zargin electrophilic reagent. Irin wannan barbashi ne kwayoyin halitta da ciwon free orbital kwayoyin da rabo na rage yawan electron yawa. A sodium formate carbon da ciwon cajin "-", an mayar da martani tare da m ɓangare na ruwa dipole - hydrogen: CH ₃ Na + H ₂ Ya → CH ₄ + NaOH. A samfurin wannan dauki, electrophilic canzawa - methane. Lokacin da heterolytic halayen mu'amala oppositely cajin cibiyoyin kwayoyin kwayoyin, wanda ya ba su damar kusantar ions a inorganic abubuwa sunadarai. Ya kamata ba za a saba shukawa cewa hira da gudanar da mahadi yana da wuya tare da samuwar wadannan cations da anions.

Unimolecular da bimolecular halayen

A nucleophilic canzawa ne monomolecular (SN1). By wannan ginshiki, wani muhimmin samfurin gudana hydrolysis na Organic kira - manyan butyl chloride. A mataki na farko shi ne jinkirin, shi ake dangantawa da m dissociation cikin carbonium cation da wani chloride anion. A mataki na biyu ne a sauri dauki auku carbonium ion da ruwa. A lissafi na dauki na canzawa daga halogen a alkane ya sami hydroxy da primary barasa: (CH _{3) 3} C-CL → (CH _{3) 3} C ^{+ +} CL ^-. (CH _{3) 3} C ^{+ +} H ₂ Ya → (CH _{3) 3} C-OH ⁺ H +. Ga daya-mataki hydrolysis na firamare da kuma sakandare alkyl halides halin da lokaci daya halakar carbon saboda halogen da kuma samuwar biyu C-OH. Wannan nucleophilic bimolecular canzawa inji (SN2).

Heterolytic inji na canzawa

canzawa inji unshi da electron canja wuri, halittar matsakaici gidaje. A dauki fitowa mafi hanzari, da sauki shi ne domin hankula tsaka-tsakin mata. Sau da yawa kan aiwatar da yake faruwa a inda da dama a lokaci guda. A amfani yawanci samun hanyar da barbashi an yi amfani da, bukata da kalla kashe kudi na makamashi domin da samuwar. Alal misali, a gaban wata biyu bond qara da alama na wani allyl cation CH 2 = CH-CH ₂ ^+, idan aka kwatanta da _CH3 ⁺ ion. Dalilin ta'allaka a electron yawa daga cikin mahara bond, wanda rinjayar da delocalization na tabbatacce cajin, tarwatsa kan gaba daya.

benzene canzawa dauki

A rukunin na gudanar da mahadi, wanda aka halin da electrophilic canzawa - fagen fama. Benzene zobe - dace abu ga electrophilic hari. A tsari fara sadarwar da biyu rabuwa reagent, game da shi, kafa electrophile electron girgije m da benzene zobe. A sakamakon haka ne wani hadadden miƙa mulki. M sadarwa electrophilic barbashi tare da daya daga cikin carbon atoms ba tukuna, shi ne janyo hankalin ga dukan korau cajin "aromatic shida" electrons. A cikin uku mataki na aiwatar electrophile da daya zobe carbon zarra ta ɗaure na kowa biyu daga electrons (covalent bond). Amma a wannan yanayin, shi ne halakar da "aromatic shida", wanda yake shi ne disadvantageous cikin sharuddan cimma wata barga ci makamashi jihar. Akwai wani al'amari da cewa za a iya kira a "saki wani proton." An raba kashe H ^+, murmurewa a barga sadarwa tsarin, hankula arenes. Side abu qunshi hydrogen cation na wani benzene zobe da anion daga na biyu reagent.

Misalai na canzawa halayen kwayoyin sunadarai

Domin alkanes musamman hankula canzawa dauki. Misalan electrophilic da nucleophilic halayen zai iya kai ga cycloalkanes da arenes. Similar a cikin halayen da kwayoyin kwayoyin abubuwa ne karkashin al'ada yanayi, amma yawanci - da kuma ta dumama a gaban catalysts. By kowa da kyau karatu matakai sun hada da electrophilic aromatic canzawa. A mafi muhimmanci dauki na da irin wannan:

1. Nitration na benzene tare da nitric acid a gaban H ₂ SO ₄ - haka makirci: C ₆ H ₆ → C ₆ H ₅ -NO _2.
2. A catalytic halogenation na benzene, musamman chlorination, da lissafi: C ₆ H ₆ + CL ₂ → C ₆ H ₅ CL + HCI.
3. Aromatic sulfonation na benzene Saide da "fuming" sulfuric acid, benzenesulfonic acid suna kafa.
4. Alkylation - sauyawa daga cikin hydrogen zarra daga benzene zobe don alkyl.
5. Acylation - da samuwar ketones.
6. Formylation - maye gurbin wani hydrogen a kan wani rukuni Cho da kuma samuwar aldehydes.

By canzawa halayen hada da dauki a alkanes da cycloalkanes, cikinsa da halogens kai farmaki samuwa C-H bond. Derivatization iya hade tare da sauyawa na daya, biyu ko duk abin da hydrogen atoms a cikakken hydrocarbons da cycloparaffins. Mutane da yawa na galogenoalkanov na low kwayoyin nauyi aka yi amfani da a samar da karin hadaddun abubuwa na daban-daban azuzuwan. Nasarorin cimma a cikin binciken na sunadaran da canzawa halayen, ya ba da wani iko impetus ga ci gaban syntheses a kan tushen da alkanes, cyclo-mataki da halogenated hydrocarbons.