Dehydration ba alcohols

Poleloana e reng "dehydration" le sebelisitsoe ka moriana (e bolelang dehydration), ka lifofane (ho ke ke ho felloa ke metsi ka sefofane nakong sefofane ho), ka k'hemistri (itšoara joang, e leng ka lebaka la ho hlahisa limolek'hule arola theoha metsi). Liphetoho tsa alcohols dehydration bath ya metsoako pele e tsejoang e le ho noa joala. Tsela tsoela ka futhumatsang ka ho ba teng ha metsi a timetsang, tse acid e sulfuric, zinki chloride, aluminium oxide e kapa acid e phosphoric. Ho itšetlehile ka maemo a ho ikutloa ka tsela e ka etsa hydrocarbons unsaturated, kapa ethers, e arotsoe 'me, ka lebaka leo, ho intramolecular le intermolecular dehydration.

Ethers thehoa ha karabelong e khanna ka mocheso ka tlaase le joala feteletseng. Ka mohato oa pele oa sulfuric acid e Ester e ile a fumana: C2H5OH + HO-SO2OH ↔ C2H5O-SO2OH + H2O. Ha motsoako itsoara joang ka nako eo thabisa, ka nako eo ha thehoa acid e ethylsulfuric e ileng a itšoara ka ho feteletseng ea joala: C2H5O-SO2OH + C2H5OH → C2H5O-C2H5 + H2SO4. Phello ke diethyl (kapa sebabole) phenylate. Ho ea ka morero ona o tsoela pele intermolecular dehydration ba alcohols. Ka lebaka leo, ka lebaka la karohano ea limolek'hule tse peli tsa joala ba liathomo tse peli haedrojene le e 'ngoe ea oksijene athomo (ba bōpang molek'hule e' ngoe ea metsi) thehoa ethers. Ho indasteri, diethyl phenylate hlahiswa ka ho fetisa joala fetang para ea oxide e aluminium ka mocheso oa 250 ° C. Ba itšoara joang sekemeng joalo: 2C2H5-OH → C2H5-O-C2H5 + H2O.

Intramolecular dehydration ba alcohols ka etsahala feela ka thempereichara e phahameng. Ka tsela eo ho tswa ho molek'hule le 'ngoe joala (ho ena le ho tse peli joaloka tabeng fetileng) arola molek'hule ea metsi le liathomo tse peli har'a carbon thehoa ke tlamo e' ngoe habeli. Sebelisa mokhoa ona bakeng sa ba lokisetsa ho ea hydrocarbons unsaturated. Sebediswa bakeng sa morero ona monoalcohols feela. Ka mohlala, bokaholimo ba matsoele ya metsi ho ethanol e phethahatsoa ka mocheso oa 500 ° C ka holimo ho sethothetsi ke metsi mmeleng, mohlala, ea alumina Al2O3 kapa zinki chloride ZnCl2.

Dehydration tsa alcohols - ke mokhoa e bonolo bakeng sa ho hlahisa alkenes gaseous ka laboratori ea. E sebediswa bakeng sa tlhahiso ea ethylene tloha ethanol: CH3-CH2-OH → CH2 = CH2 + H2O. Dehydration ka nka sebaka ka ho ba teng ha ka sethothetsi eo ke ea alumina. Lipara tsa ethyl joala e fetela halefile ea alumina phofo. metsi Segregated ananelang e le mouoane, kahoo e emela ka ethylene bo hloekileng. Ka tshebetso ena, boleng ba sethothetsi ka dirisia khobokellane acid, mohlala, sulfuric kapa phosphoric. Ba, joaloka oxide e aluminium, rua thepa ke metsi mmeleng. Empa ha e le asiti sulfuric ke e boetse e oxidant matla, se hlahisa e ngata ka lihlahisoa (ka mohlala, ho noa joala haholo e oxidized ho carbon dioxide, le asiti e fokotsehile ho dioxide e sebabole), e le hore ba khase sephetho le hloka ho itlhoekisa ka ho eketsehileng.

Dehydration tsa alcohols ya sebopeho cyclic, mohlala, dehydration ba cyclohexanol, e se eka li ke li etsahale ka pel'a acid e phosphoric. Hangata e khetha acid e sulfuric, joale, 'na le thepa e ntle ke metsi mmeleng, tlase ho tlatsetsa hore ho thehoe ka lihlahisoa-, hammoho le bo sireletsehileng haholoanyane. Ka lebaka la itšoara joang joalo hlahisa cyclohexene. 'nete ea hore carbon liathomo kopanngoa ka lesale la ha fetola k'hemistri ea kamoo ba ileng ba: C6H11-OH → C6H10 + H2O. Cyclohexanol e halefile ka khobokellane phosphoric (V) acid e. La sephetho cyclic hydrocarbon le 'ngoe habeli tlamo e ka lesale ke ntho mokelikeli, Leha ho le joalo bakeng sa ho itlhoekisa ho tloha litšila e distilled.

Hape, hoa khoneha dehydration ba alcohols nang ka molek'hule lihlopha tse ngata hydroxyl. E le mohlala bakeng sa polyols ho ka nkoa e le ba ikutloa ka tsela eo ho fella ka ho felisoa ha limolek'hule tse peli tsa metsi ho tswa limolek'hule tse peli tsa ethylene glycol, ka tsela eo eaba ba etsa cyclic phenylate dioxane: 2OH-CH2-CH2-OH → (C2H4O) 2. Dehydration ke nakong ea distillation ea ethylene glycol ka ho ba teng ha acid e sulfuric. Ena ke e 'ngoe ea theknoloji e sa liindasteri sa baeti ba fihlelang ho ea dioxane.

Kahoo, re ka bolela hore dehydration ba alcohols le nang le liindasteri le laboratori ea dikopo. Ka lebaka leo, metsoako tsena ho ile ha thehoa, e leng lintho tse neng li sebelisoa bakeng sa ho etsa lipatlisiso, hammoho le e tala thepa kapa ba thusang reagents tsa lik'hemik'hale indasteri.