Ukudakwa kwamanzi kotywala

Igama elithi "ukungcoliswa kwamanzi" lisetyenziselwa unyango (oko kuthetha intsholongwane yomzimba), kwinqwelo-moya (oku kulahlekelwa kwamanzi ngomoya ngexesha lokuhamba), kwi-chemistry (impendulo eyahlula amanzi kwi-molecule yezinto eziphilayo). Ukusabela kokungcoliswa kwamanzi e-alcohols kubonisa izixhobo ezibizwa ngokuba yi-alcohol. Inkqubo iyaqhubeka xa ithukuthele phambi kwamagunya okususa amanzi, ayenziwe yi-sulfuric acid, i-zinc chloride, i-aluminium oxide okanye i- phosphoric acid. Ngokuxhomekeke kwiimeko zokusabela, i-hydrocarbons okanye i-ethers engabonakaliyo ingabunjwa, kwaye ihlukaniswe ngokufanelekileyo kwi-intramolecular and intermolecular dehydration.

Ama-Ethere akhiwa xa ukuphendulwa kwenzeni kwinqanaba elisezantsi kwaye utywala kakhulu. Isigaba sokuqala senza i-sulfuric acid ester: C2H5OH + HO-SO2OH ↔ C2H5O-SO2OH + H2O. Ukuba umxube wempendulo uyashushu, i-acid ethylsulfuric ephumela ekubeni uphuze ngokweqile: C2H5O-SO2OH + C2H5OH → C2H5-O-C2H5 + H2SO4. Ngenxa yoko, i-diethyl (okanye isulfure) ether ifunyanwa. Ngokwale cwangciso, i-interhylrate dehydration of alcohols. Ngenxa yoko, ngenxa yokuhlukana kwamatyeli e-alcohol, i-athomu ezimbini ze-hydrogen kunye ne-athomu ye-oksijini (iyenzayo ilamleksi enye yamanzi), i-ethers yenziwa. Kwimashishini, i-diethyl ether iveliswa ngokugqithisa iimbini zobunxila ngaphezu kwe-alumina kwiqondo lokushisa lama-250 ° C. Iskimu sokuphendula sisilandelayo: 2C2H5-OH → C2H5-O-C2H5 + H2O.

Ukunyuka kwamanzi e-intramolecular kungenziwa kuphela kwiqondo eliphezulu. Kule meko, kwi-molecule yiselo yotywala (kunokuba ibini, njengoko kwimeko yangaphambili), i-molecule yamanzi iyahlula, kwaye phakathi kwee-athomu ze-khabhoni ezimbini, ukuhlanganiswa kabini kuyakha. Le ndlela isetyenziselwa ukuvelisa i-hydrocarbons engasetshenziswanga. Kusetyenziswa kuphela i-monohydric alcohols. Ngokomzekelo, ukwahlukana kwamanzi kwi-ethyl yotywala kwintlawulo kwiqondo lokushisa lama-500 ° C ngaphezu kwe-catalyst yokususwa kwamanzi, umzekelo, i-aluminium oxide i-Al2O3 okanye i-zinc chloride i-ZnCl2.

Ukuchithwa kwamanzi kotywala yindlela elula yokufumana i-alkenes inkunkuma kwiimeko zebhubhoratri. Isetyenziselwa ukuvelisa i-ethylene kwi-ethanol: CH3-CH2-OH → CH2 = CH2 + H2O. Ukuxhatshazwa kwamanzi kungenziwa phambi kobuchopho, obunobumba. Imiphunga ye-ethyl yotywala idluliselwa phezu kompu we-aluminium oxide. Amanzi ahlukanisiweyo ngesimo se-steam ayangena, ngelixa i-ethylene ecocekileyo ikhutshwa. Njengoko i-catalyst yale nkqubo, i-acid concentrated, umzekelo we-sulfuric okanye i-phosphoric, ingasetyenziswa. Bona, njenge-aluminium oxide, banokukhupha amanzi. Kodwa ekubeni i-sulfuric acid nayo i-oxidizer enamandla, i-product-products (ewe, utywala i-oxidized carbon dioxide kwaye i-asidi iyancitshiswa ibe yi-sulfur dioxide), ngoko ke igesi ephumayo idinga ukuhlanjululwa okongeziweyo.

Ukunyanzeliswa kwamanzi atywala, umzekelo, ukutshatyalaliswa kwe-cyclohexanol, kunokuthi kwenzeke phambi kwe-phosphoric acid. Ngokuqhelekileyo kukhethwa ukuba kusetyenziswe i-sulfuric, kuba oko, ukuba neendawo ezintle zokukhupha amanzi, akunakunceda ukubunjwa kwemveliso, kwaye ukhuseleko. Ngenxa yolu mpendulo, i-cyclohexene yenziwa. Inyaniso yokuba iathom e-carbon idibeneyo ibe yindandatho ayitshintshi i-chemistry yokusabela: C6H11-OH → C6H10 + H2O. I-Cyclohexanol ishushu i-phosphoric (V) acid. I-hydrocarbon ye-cyclic eyabangela i-bond ephindwe kabini kwindandatho yintsimbi yamanzi, ngoko i-distilled ukususa ukungcola.

Kwakhona kunokwenzeka ukuba utyilise utywala obunamaqela amaninzi e-hydroxyl kwi-molecule. Njengomzekelo we-polyhydric alcohols, umntu unokuqwalasela impendulo eyenza ukuhlukana kwamamolekyuli emibini yamanzi kwii-molecule ze-ethylene glycol, kunye nokwakhiwa kwe-ether e-cyclic ye-dioxane: 2OH-CH2-CH2-OH → (C2H4O) 2. Ukuxhatshazwa kwamanzi kuyenzeka ngexesha le-distillation ye-ethylene glycol phambi kwe-acid ye-sulfuric. Le ngenye yezobuchwepheshe bezoshishino zokuvelisa i-dioxane.

Ngaloo ndlela, kunokuthi ukutyhelwa kwamanzi e-alcohols kunezixhobo zombane kunye neelabhoratri. Ngenxa yoko, iimveliso zeekhemikhali zenziwe, ezisetyenziselwa uphando, kwaye nazo zixhobo okanye izinto ezincedisayo kwiikhemikhali.