Yiziphi ukusabela ejwayelekile alkanes

Ikilasi ngalinye of zamakhemikhali kungaba abonise izakhiwo ngenxa isakhiwo kuma-computer. Ukuze alkanes ejwayelekile esikhundleni ukuphendula, cleavage noma namachibi yamangqamuzana ezinto eziphilayo. Zonke izinqubo zamakhemikhali babe ukugeleza yabo ethile, okuyinto Kuzoxoxwa.

Kuyini alkanes

Lokhu ayegcwele hydrocarbon compounds, ezaziwa ngokuthi ama upharafini. Lezi zinhlayiya aqukethe kuphela carbon ne-hydrogen athomu, kukhona komugqa noma branched acyclic uchungechunge lapho kukhona kuphela ekhuthaza olulodwa. Banikezwe izici isigaba, ungakwazi ukubala ukuthi ukusabela nobuntu alkanes. Balalela ifomula for lonke ikilasi: H _{2N + 2} C _n.

isakhiwo sazo sekhemikhali

Upharafini-molecule yakhiwa ngama-athomu carbon bembonisa sp ³ hybridization. Bonke Valence orbitals ezine ezifanayo ukuma, amandla nesiqondiso emkhathini. Usayizi engela phakathi amazinga zamandla 109 ° 28 '.

Ukuba khona izibopho esisodwa molecule ukuthi yini ukusabela nobuntu alkanes. Ziqukethe σ-kwakwakhe. Ukuxhumana phakathi carbons kuyinto nonpolar futhi wavuma polarizable, kuba kancane isikhathi eside kunaleso C-H. Futhi, ukuminyana electron we shift-athomu carbon iyona electronegative kakhulu. Egcekeni kwaphumela libhekene C-H polarity ongaphakeme.

esikhundleni ukuphendula

Izinto ekilasini paraffins abe ongaphakeme umsebenzi zamakhemikhali. Lokhu zingachazwa ngezinqubo amandla izibopho phakathi C C C-H, okuyinto kanzima ukuze aphule ngenxa non-polarity. Ngesisekelo nokubhujiswa kwabo indlela homolytic, lapho khulula uhlobo olukhulu abathintekayo. Yingakho alkanes zinezikhathi yokusabela esikhundleni. Izinto ezinjalo bayakwazi uxhumana amangqamuzana amanzi noma ion of abathwali kwenkokhelo.

Bona lilinganise khulula esikhundleni olukhulu lapho ama-athomu ye-hydrogen esikhundleni izakhi Halogen noma ezinye iqembu asebenzayo. Lezi indlela esisabela ngayo zihlanganisa izinqubo ezihlobene halogenation, sulfochlorination futhi nitration. Lezi kuholele ukulungiswa alkane nemikhiqizo. Ecashile esikhundleni ukusabela nge khulula indlela olukhulu yinhlobo oyinhloko izigaba ezintathu:

1. Inqubo iqala yokuqala nucleation noma iketanga, lapho akhiwa radicals khulula. I yelikhono kuyimithombo zokukhanya oku-ultraviolet futhi bafudumale.
2. Khona-ke eba uchungechunge lapho izinhlayiyana asebenzayo ngokulandelana kwenziwe ukuxhumana nge-molecule esingasebenzi. Ingabe ukuguqulwa zabo zibe amangqamuzana futhi radicals, ngokulandelana.
3. Isinyathelo sokugcina uyosabalala iketanga. Kube recombination noma ukunyamalala izinhlayiya asebenzayo. sinqanyuliwe Ngakho ukuthuthukiswa ukusabela chain.

Inqubo halogenation

Kusekelwe mshini uhlobo olukhulu. Alkane halogenation ukuphendula senzeka kakhulu ngokuzishisa ngemisebe nge ultraviolet bafudumale ingxube ka halogens hydrocarbon.

Zonke izigaba inqubo zingaphansi kokubusa eyayithi Markovnikov. Lithi asitholayo esikhundleni ngu Halogen, ikakhulukazi e-hydrogen, elingelakwaJuda carbon hydrogenated. Halogenation senzeka ukulandelana elandelayo: ovela ngokuyinhloko carbon athomu ephakeme.

Inqubo isifika kangcono molecule alkane obude main hydrocarbon chain. Lokhu kungenxa Ukwehla ionizing amandla kulesi siqondiso, ketshezi kulula electron wajinge wanamatsela.

Isibonelo salokhu chlorination methane molecule. Isenzo emisebeni ultraviolet kubangela eqhekeza chlorine zinhlobo olukhulu ukuthi afeze nokuhlaselwa kwaleli alkane. Ukwahlukana kwenzeka kanye kumiswa e-athomu ye-hydrogen H ₃ C · noma methyl olukhulu. nezinhlayiya enjalo yena, ukuhlasela-chlorine yamangqamuzana, eziyoholela ekubhujisweni yokulandelana kwayo ngokohlu kanye kumiswa ikhemikhali entsha.

Esigabeni ngasinye senqubo esikhundleni Kwenziwa hydrogen atom eyodwa kuphela. I halogenation ukusabela alkanes kuholela ekwakhekeni kancane kancane hlormetanovoy, dichloromethane, futhi trihlormetanovoy tetrahlormetanovoy-molecule.

Schematically, inqubo simiswe ngalendlela lelandzelako:

H ₄ C + Cl: Cl → H ₃ CCL + HCl,

H ₃ CCL + Cl: Cl → H ₂ CCL ₂ + HCl,

H ₂ CCL ₂ + Cl: Cl → HCCl ₃ + HCl,

HCCl ₃ + Cl: Cl → CCL ₄ + HCl.

Ngokungafani chlorination methane molecule ethwele inqubo enjalo nabanye alkanes libhekene ukuthola izinto kokuba hydrogen esikhundleni akusona esisodwa carbon athomu, futhi abambalwa. isilinganiso sabo ambalwa elihlobene ne lokushisa izinkomba. Ezimweni ezibanda, ukwehla izinga kumiswa nemikhiqizo nge isakhiwo ephakeme, secondary eyinhloko.

Njengoba kwanda lokushisa target ijubane kumiswa compounds enjalo kuqondiswa. Ngo inqubo halogenation kukhona ithonya isici static okhombisa okungenzeka ezehlukene ukushayisana we olukhulu nge-athomu carbon.

Inqubo halogenation iodine ingekho ngaphansi kwezimo ezivamile. Kuyadingeka ukudala izimo ezikhethekile. Lapho wadalula methane kwenzeka ngokusho Halogen nesenzakalo hydrogen iodide. It has an nomthelela methyl iodide ngenxa ivelele reactants kokuqala i-methane ne-iodine. ukusabela okunjalo ubhekwa emuva.

Wurtz ukusabela alkanes

Kuyinto indlela yokuthola hydrocarbon ne elihlale isakhiwo izinhlangothi zazo ziyalingana. Njengoba reactants asetshenziswa sodium metal, alkyl bromides noma alkyl chloride. Nge nokuxhumana uzilungiselele yabo sodium halide futhi ngakhula hydrocarbon uchungechunge okuyinto isamba hydrocarbon ezizivelelayo ezimbili. Schematically, synthesis simiswe ngalendlela lelandzelako: R-Cl + Cl-R + 2Na → R-R + 2NaCl.

Wurtz ukusabela alkanes kungenzeka kuphela uma halogens e-molecule awo ahlangane ngaso eyinhloko carbon athomu. Isb, CH ₃ -CH ₂ -CH ₂ Br.

Uma ngesikhathi sokudlala of galogenuglevodorododnaya ingxube compounds okubili, ukufingqa ngamaketanga amathathu ahlukene umkhiqizo kwakhiwa. Isibonelo salokhu ukuphendula zingakhiqiza sodium alkane nokuxhumana chloromethanes futhi hloretanom. Okuphuma inhlanganisela ehlanganisa i-butane, propane kanye ethane.

Ngaphandle sodium, kungenzeka ukusebenzisa nezinye izinsimbi alikhali, okuhlanganisa lithium noma potassium.

inqubo sulfochlorination

Ibizwa nangokuthi i-Reed ukuphendula. It uyagijima isimiso esikhundleni khulula. Lolu hlobo yokusabela esivamile alkanes ukuze isenzo ingxube ka-sulphur dioxide kanye chlorine yamangqamuzana khona emisebeni ultraviolet.

Inqubo iqala emizameni yokuthuthukisa mshini uchungechunge, lapho-chlorine eyatholakala kusukela ezizivelelayo ezimbili. Kuhlaselwa alkane ukuthi kuphakamisa i izinhlayiya alkyl kanye nama-molecule e-hydrogen chloride. Ngu hydrocarbon olukhulu enamathiselwe yakha i-sulphur dioxide izinhlayiya eziyinkimbinkimbi. Ekulinganiseni bamba kwenzeka omunye chlorine athomu kusuka kwenye i-molecule. Indaba wokugcina kuyinto alkane sulfonyl chloride, isetshenziswa synthesis compounds ebusweni-asebenzayo.

Schematically, inqubo libukeka kanje:

CLCL → ^HV ∙ Cl + ∙ Cl,

HR + ∙ Cl → R ∙ + HCl,

R ∙ + Oso → ∙ RSO _2,

∙ RSO ₂ + ClCl → RSO ₂ Cl + ∙ Cl.

Izinqubo elihlobene ne nitration

Alkanes ukuxubana nitric acid in isixazululo 10% kanye ne-nitrous tetravalent nitrogen isimo gaseous. Imibandela nesenzakalo salo amagugu eliphezulu lokushisa (140 ° C) futhi ingcindezi ongaphakeme amagugu. Ngesikhathi okukhiphayo ekhiqizwa nitroalkanes.

Inqubo khulula-olukhulu uhlobo yaqanjwa usosayensi Konovalov, wavula nitration zamagama: CH ₄ + HNO ₃ → CH ₃ CHA ₂ + H ₂ O.

Lo mshini cleavage

Ukuze ejwayelekile dehydrogenation alkane kwemifantu. Methane-molecule asitholayo ephelele noqhekeko ezishisayo.

Mshini eziyisisekelo ukusabela elingenhla liyindlela cleavage zama-athomu kusukela alkanes.

inqubo dehydrogenation

Lapho uhlukanisa ama-athomu ye-hydrogen kwi-carbon amathambo endoda paraffins, ngaphandle methane etholwe compounds unsaturated. Okunjalo zamakhemikhali ka alkanes ihlolwe ashisa kakhulu (400 kuya kwangu-600 ° C) futhi ngaphansi accelerators senzo njengoba i-platinum, nickel, i-chromium oxides kanye ne-aluminium.

Uma iqhaza ukusabela ethane noma propane molecule ke imikhiqizo yayo ngeke ethene noma propene nomunye isibopho double.

I dehydrogenation we skeleton ezine noma ezinhlanu-carbon etholwe diene kwakwakhe. Kusukela kwamiswa i-butane-1.3 butadiene futhi 1,2-butadiene.

Uma ekhona izinto ukuphendula 6 noma ngaphezulu carbon athomu, kwakheka benzene is. It has an indandatho elimnandi ngezibopho ezintathu double.

Inqubo ephathelene ne-noqhekeko

Ngaphansi lokushisa eliphezulu ukusabela alkanes izophela nge-gap carbon izibopho kanye kumiswa zinhlobo asebenzayo ohlobo olukhulu. izinqubo ezinjalo zibizwa ngokuthi kwemifantu noma pyrolysis.

Amalahle reactants ukuze okushisa eqile 500 ° C, imiphumela noqhekeko yezinhlayiya lapho akhiwa Izingxube eyinkimbinkimbi alkyl-uhlobo ezizivelelayo.

Kuphethe ngaphansi Ukushisa okunamandla pyrolysis ka alkanes nge-carbon chain ubude ngenxa ukuthola compounds te futhi unsaturated. Ibizwa ngokuthi kwemifantu ezishisayo. Le nqubo isetshenziswa kuze kube maphakathi nekhulu le-20.

I ethile kwaba ukuthola hydrocarbon ngenombolo octane ongaphakeme (esingaphansi 65), ngakho-ke salandelwa ngokuhlaziya kulethe. Inqubo yenzeka okushisa ukuthi ingezansi 440 ° C, nezingcindezi angaphansi kuka-15 izikhathi eziphindwe, phambi kwe-aluminosilicate namafutha ukukhululwa alkanes kokuba isakhiwo branched. Isibonelo salokhu pyrolysis methane: 2Kro ₄ → ^{t °} C ₂ H ₂ + 3H _2. I kwakhiwa hydrogen acetylene futhi yamangqamuzana ngesikhathi yokusabela.

I-molecule okufanele abekeke methane ukuguqulwa. Ukuze lesi simo sidinga amanzi kulethe ne-nickel. Okuphuma inhlanganisela carbon monoxide ne-hydrogen.

namachibi izinqubo

I zamakhemikhali eziningi kukhona alkane ejwayelekile ehambisana ne-electron umthelela.

Kukhona ngokuzenzakalela namachibi of paraffins. Kuhilela ukubhekana khulula indlela olukhulu namachibi of hydrocarbon ayegcwele. Phakathi ukuphendula, uketshezi isigaba hydroperoxide alkane etholwe. Ekuqaleni i-molecule upharafini ihlangana oksijini labelwe ezizivelelayo asebenzayo. Ngokulandelayo, alkyl kuyizinhlayiyana kuwuthinta omunye O-molecule _2, etholwe ∙ Roo. Njengoba olukhulu peroxy we acid okunamafutha iyathintwa-molecule alkane, badedelwa hydroperoxide. Isibonelo salokhu autooxidation ka ethane:

C ₂ H ₆ + O ₂ → ∙ C ₂ H ₅ + Hoo ∙,

∙ C ₅ H ₂ + O ₂ → ∙ OOC ₂ H _5,

∙ OOC ₂ H ₅ + C ₂ H ₆ → HOOC ₂ H ₅ + ∙ C ₂ H _5.

Ukuze alkane libhekene ukusabela omlilo nalezo ezikhuluma ikakhulukazi nezakhi ezithile zamakhemikhali, ekunqumeni ukwakheka nophethiloli. Ziyakwazi oxidative ngokwemvelo nge ekushayweni ukushisa: 2C ₂ H ₆ + 7O ₂ → 4CO ₂ + 6H ₂ O.

Uma inqubo ebonwe esincane oksijini, okwaphuma lapho kuyilo kungaba divalent carbon noma i-carbon monoxide, okuyinto kunqunywa lokuhlushwa O _2.

Esikhathini namachibi of alkanes bedle izidakamizwa okhanda amanye amathuba kanye eliwu 200 ° C etholakala utshwala molecule aldehyde noma carboxylic acid.

ISIBONELO ethane:

C ₂ H ₆ + O ₂ → C ₂ H ₅ OH (ethanol),

C ₂ H ₆ + O ₂ → CH ₃ Cho + H ₂ O (ethanal namanzi)

2C ₂ H ₆ + 3o ₂ → 2Kro ₃ COOH + 2H ₂ O (ethanoic acid namanzi).

Alkanes kungenziwa oxidized ngaphansi isenzo peroxides eyindilinga trinomial. Lezi zihlanganisa dimethyl dioxirane. Umphumela uba namachibi of paraffins utshwala-molecule.

Abamele paraffins ungaphenduli KMnO ₄ noma potassium permanganate, kanye namanzi uxhumano lokudlulisa.

isomerization

On alkanes libhekene esikhundleni uhlobo ukuphendula indlela electrophilic. Lokhu kubizwa isomerization we-carbon chain. Catalyzes Kule nqubo amathambo chloride aluminium, okuyinto asabela ngayo nge upharafini ayegcwele. Isibonelo salokhu isomerization ka-butane molecule okuyinto 2-methylpropane: C ₄ H ₁₀ → C ₃ H ₇ CH _3.

inqubo isithokela

izinto ayegcwele lapho main carbon uchungechunge iqukethe ama-athomu eziyisithupha noma ngaphezulu-carbon, uyakwazi kokuqhuba dehydrocyclization. Ukuze amangqamuzana emifushane kungamathuluzi nobuntu okunjena. Umphumela uhlale indandatho ayisithupha membered njengoba cyclohexane nemikhiqizo yalo.

Ephambi kwezinduna ukuphendula accelerators, futhi idlule dehydrogenation obengeziwe ukuguqulwa ibe umuntu omdala ophumelelayo benzene indandatho. Kwenzeka ukuguqulela hydrocarbon acyclic ukuba Aromatics noma enkundleni. Isibonelo salokhu dehydrocyclization ka hexane:

H ₃ C-CH ₂ - CH ₂ - CH ₂ - CH ₂ -CH ₃ → C ₆ H ₁₂ (cyclohexane)

C ₆ H ₁₂ → C ₆ H ₆ + 3H ₂ (benzene).