Menene hankula halayen ga alkanes

Kowane aji na sinadaran mahadi iya nuna Properties saboda su lantarki tsarin. Domin alkanes hankula canzawa dauki, tsakiyan nonon ko kwayoyin hadawan abu da iskar shaka. All sunadarai matakai suna da nasu musamman kwarara, wanda za a kara tattauna.

Mene ne alkanes

Wannan cikakken hydrocarbon mahadi, wanda aka fi sani da paraffin. Wadannan kwayoyin kunshi kawai Carbon da hydrogen atoms, ne mikakke ko branched acyclic sarkar a cikinsa akwai guda ɗaya kawai fili. Ganin halaye na aji, za ka iya lissafta abin da dauki halayyar alkanes. Su yi biyayya da dabara domin dukan aji: H _{2n + 2} C _n.

sinadaran tsarin

Paraffin kwayoyin qunshi carbon atoms exhibiting sp ³ hybridization. Su duk hudu valence orbitals da wannan siffar, makamashi da kuma shugabanci a sarari. A size daga cikin kwana tsakanin makamashi matakan na 109 ° da kuma 28 '.

A gaban guda shaidu a cikin kwayoyin kayyade abin da halayen ne halayyar alkanes. Sun ƙunshi σ-fili. Sadarwa a tsakanin carbons ne nonpolar kuma weakly polarizable, shi ne dan kadan fiye C-H. Har ila yau, electron yawa daga wani motsi zuwa carbon zarra ne mafi electronegative. A sakamakon fili ne halin da C-H low polarity.

canzawa dauki

Abubuwa aji paraffins da low sinadaran aiki. Wannan za a iya bayyana ta da ƙarfin da shaidu tsakanin C-C da kuma C-H, wanda yake da wuya a warware saboda ba polarity. Dalili na halaka su ne homolytic inji, cikinsa da free m irin hannu. Wannan shi ne dalilin da ya sa alkanes halin canzawa dauki. Irin wannan abubuwa suna iya hulɗa tare da ruwa kwayoyin ko ions na cajin yan dako.

Su matsayi free m canzawa a cikin abin da hydrogen atoms an maye gurbinsu da halogen abubuwa ko wasu aiki kungiyar. Wadannan halayen hada da matakai da suka shafi halogenation, sulfochlorination da nitration. Wadannan kai ga shiri na alkane Kalam. Tamkar canzawa halayen via wani free m inji ne babban irin matakai uku:

1. Tsari zai fara ne da wani nucleation qaddamarwa, ko sarkar, a cikin abin da free radicals suna kafa. A catalysts ne kafofin na riskar hasken ultraviolet da kuma dumama.
2. Sa'an nan tasowa sarkar a cikin abin da m aiki barbashi za'ayi hulda da m kwayoyin. Shin su hira cikin kwayoyin da radicals, bi da bi.
3. A karshe mataki zai karya jerin. Akwai recombination ko bacewar na aiki barbashi. Kamar wancan kare ci gaban da sarkar dauki.

Kan aiwatar da halogenation

Ya dogara ne a kan hanyar m irin. Alkane halogenation dauki faruwa ta sakawa a iska mai guba da riskar hasken ultraviolet da dumama da wata cakuda halogens da hydrocarbons.

Duk matakai na aiwatar ne batun mulkin abin da ya bayyana Markovnikov. Ya furta cewa, shigarsu canzawa da halogen, musamman hydrogen, wanda nasa ne da hydrogenated carbon. Halogenation faruwa a cikin wadannan jerin: daga primary zuwa manyan carbon zarra.

A tsari daukan sanya mafi alhẽri a cikin alkane kwayoyin tare da dogon babban hydrocarbon sarkar. Wannan shi ne saboda da rage na ionizing makamashi a cikin wannan shugabanci, da abu sauki cleaved electron.

An misali ne chlorination na methane kwayoyin. A mataki na ultraviolet radiation sa wani tsagawa chlorine m jinsunan cewa gudanar da wani hari a kan alkane. Rabuwa ta auku, kuma samuwar atomic hydrogen H ₃ C · ko wani methyl m. Irin wannan barbashi, bi da bi, kai farmaki da kwayoyin chlorine, abu don halakar da tsarin da kuma samuwar wani sabon sinadaran.

A kowane mataki da aka canza tsari ne da za'ayi daya kawai hydrogen zarra. A halogenation dauki na alkanes take kaiwa zuwa sauka a hankali samuwar hlormetanovoy, dichloromethane, kuma trihlormetanovoy tetrahlormetanovoy kwayoyin.

Schematically, da tsari ne kamar haka:

H ₄ C + CL: CL → H ₃ CCl + HCI,

H ₃ CCl + CL: CL → H ₂ CCl ₂ + HCI,

H ₂ CCl ₂ + CL: CL → HCCl ₃ + HCI,

HCCl ₃ + CL: CL → CCl ₄ + HCI.

A bambanci ga chlorination na methane kwayoyin dauke da irin wannan tsari tare da sauran alkanes halin samu abubuwa da ciwon hydrogen canzawa ba daya carbon zarra, kuma a cikin 'yan. Su gwada yawa rabo dangantawa da yawan zafin jiki Manuniya. A sanyi yanayi, da rage a cikin kudi na samuwar Kalam tare da manyan, na biyu kuma primary tsarin.

Tare da kara yawan zafin jiki manufa gudun samuwar irin wannan mahadi da aka baje. A halogenation tsari akwai rinjayar da rikicewar factor wanda ya nuna wani daban-daban Yiwuwar karo na m tare da carbon zarra.

Tsari halogenation tare da aidin ba ya faruwa a karkashin al'ada yanayi. Wajibi ne a haifar da yanayi na musamman. Lokacin da fallasa su methane ya auku bisa halogen aukuwa hydrogen iodide. Shi yana da wani sakamako a kan methyl iodide a sakamakon tsaya daga na farko reactants methane da aidin. Irin wannan dauki da aka dauke su reversible.

Wurtz dauki na alkanes

Yana da wani hanya domin samun hydrocarbons da cikakken tsakaitã tsarin. Kamar yadda reactants ana amfani da sodium karfe, alkyl bromides ko alkyl chlorides. Tare da su hulda shirya sodium halide, kuma Ya ƙãra hydrocarbon sarkar wanda yake da Naira Miliyan Xari biyu hydrocarbon radicals. Schematically, da kira ne kamar haka: R-CL + CL-R + 2Na → R-R + 2NaCl.

Wurtz dauki na alkanes ne kawai zai yiwu idan halogens a cikin kwayoyin ne a makarantun firamare carbon zarra. Msl, CH ₃ -CH ₂ -CH ₂ Br.

Idan a lokacin wasa na galogenuglevodorododnaya cakuda biyu mahadi, a cikin sandaro na uku daban-daban sarƙoƙi kafa samfurin. Wani misali na wannan dauki iya zama sodium alkane hulda da chloromethanes da hloretanom. The fitarwa ne cakuda hada da butane, propane da ethane.

Bayan sodium, zai yiwu a yi amfani da sauran Alkali karafa, da suka hada da lithium ko potassium.

aiwatar sulfochlorination

Haka kuma an kira da Reed dauki. Yana gudanar a kan manufa na free sauyawa. Wannan irin dauki hankula na alkanes zuwa mataki na cakuda sulfur dioxide da kwayoyin chlorine a gaban ultraviolet radiation.

A tsari fara da kafuwa na sarkar inji, cikinsa da chlorine samu daga biyu radicals. Daya hari alkane cewa ya ba Yunƙurin zuwa wani alkyl barbashi da kuma kwayoyin na hydrogen chloride. By hydrocarbon m a haɗe ta samar da sulfur dioxide hadaddun barbashi. Don dattako kama auku daya chlorine zarra daga wani sunadarin. A karshe abu ne mai alkane sulfonyl chloride, shi da ake amfani a cikin kira na surface-aiki mahadi.

Schematically, da aiwatar da kama da wannan:

CLCL → ^hv ∙ CL + ∙ CL,

HR + ∙ CL → R ∙ + HCI,

R ∙ + OSO → ∙ RSO _2,

∙ RSO ₂ + ClCl → RSO ₂ CL + ∙ CL.

The matakai hade da nitration

Alkanes amsa tare da nitric acid a cikin wani bayani 10% da kuma tare da tetravalent nitrogen oxide a gaseous jihar. Yanayin da ya faru shi ne babban dabi'u na zazzabi (game da 140 ° C) da kuma low matsa lamba dabi'u. A fitarwa samar nitroalkanes.

Kan aiwatar da free-m irin mai suna bayan da masanin kimiyyar Konovalov, ya bude nitration kira: CH ₄ + HNO ₃ → CH ₃ NO ₂ + H ₂ O.

Ginshikai na tsakiyan nonon

Domin hankula alkane dehydrogenation da fatattaka. Methane kwayoyin shigarsu cikakken thermal bazuwar.

Ainihin inji na sama halayen ne tsakiyan nonon na kwayoyin halitta daga alkanes.

dehydrogenation tsari

Lokacin da raba da hydrogen atoms a kan carbon kwarangwal na paraffins, fãce methane da samu unsaturated mahadi. Irin wannan sinadaran halayen na alkanes gwada a high zafin jiki (400 to 600 ° C) da kuma karkashin mataki accelerators kamar yadda platinum, nickel, chromium oxides da aluminum.

Idan shiga a dauki na ethane ko propane kwayoyin, sa'an nan da kayayyakin da za su ethene ko propene da daya biyu bond.

A dehydrogenation na hudu ko biyar-carbon kwarangwal samu diene fili. Daga kafa butane-1,3 butadiene da 1,2-butadiene.

Idan ba a dauki abubuwa da 6 ko fiye carbon atoms, da benzene da aka kafa. Shi yana da wani aromatic zobe da uku biyu shaidu.

A tsari hade tare da bazuwar

Karkashin high zazzabi dauki na alkanes iya wuce tare da wata rata carbon shaidu da kuma samuwar aiki jinsunan m irin. Irin wannan tafiyar matakai an kira a matsayin fatattaka ko pyrolysis.

Dumama da reactants ga yanayin zafi wucewa 500 ° C, sakamakon a cikin bazuwar na kwayoyin a cikin abin da aka kafa hadaddun gaurayawan na alkyl-type radicals.

Dauke da fitar karkashin karfi da dumama da pyrolysis na alkanes da carbon sarkar tsawon saboda samu cikakken kuma unsaturated mahadi. Shi ne ake kira thermal fatattaka. Wannan tsari ne da amfani har cikin tsakiyar karni na 20th.

A drawback ya zuwa samu hydrocarbons da low Octane lamba (kasa da 65), don haka shi aka maye gurbinsu fatattaka kara kuzari. A tsari faruwa a yanayin zafi da suke a kasa 440 ° C, da kuma matsin lamba na kasa da 15 atmospheres, a gaban wani aluminosilicate totur saki alkanes ciwon branched tsarin. An misali ne pyrolysis na methane: 2Tar ₄ → ^{t °} C ₂ H ₂ + 3H _2. The kafa acetylene da kwayoyin hydrogen a lokacin da dauki.

Jigidar halittar iya hõre methane hira. Don wannan dauki bukatar ruwa da kuma wani nickel kara kuzari. The fitarwa ne cakuda carbon monoxide da hydrogen.

hadawan abu da iskar shaka matakai

A sinadaran halayen da suke da hankula alkane dangantawa da electron tasiri.

Akwai auto-hadawan abu da iskar shaka na paraffins. Ta unshi free m inji na hadawan abu da iskar shaka na cikakken hydrocarbons. A lokacin da dauki, ruwa lokaci alkane hydroperoxide samu. Da farko paraffin kwayoyin reacts tare da oxygen a cikin kasaftawa aiki radicals. Next, alkyl barbashi interacts wani sunadarin ya _2, samu ∙ ROO. Tun da peroxy m na wani m acid da aka tuntube alkane DNA, sa'an nan kuma sake hydroperoxide. An misali ne autooxidation na 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.

Domin alkane halin da dauki na konewa cewa su ne yafi sinadaran Properties, a kayyade da abun da ke ciki na wani man fetur. Su ne oxidative a cikin yanayi tare da watsi da zafi: 2C ₂ H ₆ + 7O ₂ → 4CO ₂ + 6H ₂ O.

Idan tsari ne ya lura a cikin wani karamin adadin oxygen, karshen samfurin iya zama wani divalent carbon ko carbon monoxide, wanda aka ƙaddara da taro na Yã _2.

A hadawan abu da iskar shaka na alkanes ƙarƙashin rinjayar catalytic abubuwa kuma mai tsanani zuwa 200 ° C an samu barasa DNA, aldehyde ko carboxylic acid.

MISALI ethane:

C ₂ H ₆ + O ₂ → C ₂ H ₅ OH (ethanol),

C ₂ H ₆ + O ₂ → CH ₃ Cho + H ₂ Ya (ethanal da ruwa)

2C ₂ H ₆ + 3O ₂ → 2Tar ₃ COOH + 2h ₂ Ya (ethanoic acid da ruwa).

Alkanes za a iya oxidized karkashin mataki na cyclic peroxides trinomial. Wadannan sun hada da dimethyl dioxirane. A sakamakon haka ne da hadawan abu da iskar shaka na paraffins barasa kwayoyin.

Wakilai paraffins ba su karɓa KMnO ₄ ko potassium permanganate, kazalika da bromine ruwa.

isomerization

A alkanes halin canzawa irin dauki tare da wani electrophilic inji. Wannan ake isomerization na carbon sarkar. Catalyzes wannan tsari da aluminum chloride, wanda aka mayar da martani tare da wani cikakken paraffin. An misali ne isomerization na butane kwayoyin, wanda shi ne 2-methylpropane: C ₄ H ₁₀ → C ₃ H ₇ CH _3.

aiwatar daɗin ci

Cikakken abubuwa a cikinsa babban carbon sarkar ƙunshi shida ko fiye carbon atoms, iya gudanar da dehydrocyclization. Ga gajeren kwayoyin ba halayyar wannan dauki. A sakamakon haka ne ko da yaushe wani shida-membered zobe a matsayin cyclohexane kuma Kalam daga gare ta.

A gaban dauki accelerators, da kuma wuce da kara dehydrogenation na hira cikin wani more barga benzene zobe. Yana faruwa a mayar acyclic hydrocarbons zuwa aromatics ko fagen fama. An misali ne dehydrocyclization na 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).