Qhov sib txawv tseem ceeb ntawm oxo thiab wacker txheej txheem yog cov txheej txheem oxo yog cov txheej txheem los tsim cov aldehydes los ntawm alkenes, hos cov txheej txheem wacker yog cov txheej txheem los tsim acetaldehyde los ntawm ethylene.
Ob txoj kev oxo thiab wacker yog siv rau aldehydes; oxo txheej txheem tsim aldehydes thaum wacker txheej txheem hloov aldehydes. Ob qho ntawm cov txheej txheem no tseem ceeb heev hauv kev lag luam-teev daim ntawv thov. Ntxiv mus, ob qho tib si oxo thiab wacker txheej txheem xav tau catalysts rau lawv qhov pib thiab kev loj hlob.
Oxo Process yog dab tsi?
Oxo txheej txheem yog txheej txheem kev lag luam uas peb tuaj yeem tsim aldehydes los ntawm alkenes. Qee zaum, peb hu nws hydroformylation. Nws yog ib hom tshuaj tiv thaiv ntxiv vim nws koom nrog qhov sib ntxiv ntawm pawg foryl mus rau C=C pawg ntawm alkene. Ntawm no, ib qho carbon atom ntawm ob daim ntawv cog lus no ntxiv nrog ib pawg formyl (-CHO) thiab lwm cov pa roj carbon atom ntxiv nrog hydrogen atom. Cov txiaj ntsig aldehydes tuaj yeem hloov mus rau ntau yam khoom sib txawv, xws li hloov mus rau hauv cawv thiab lwm yam tshuaj. Yog li ntawd, txoj kev tsim khoom no tseem ceeb heev.
Daim duab 01: Cov qauv dav dav rau txheej txheem Oxo
Ib qho kev txiav txim siab loj txog cov txheej txheem oxo yog kev xaiv. Peb tuaj yeem soj ntsuam qhov "ib txwm" vs "iso" xaiv. Nws yog vim hais tias cov hydroformylation ntawm alkenes tuaj yeem muab ob yam khoom isomeric: qhov qub aldehyde thiab iso-aldehyde. Feem ntau, cov qauv linear ib txwm xav tau ntau dua. Tsis tas li ntawd, cov teebmeem steric thiab cov teebmeem hluav taws xob kuj tseem ceeb hauv cov txheej txheem tsim khoom vim tias cov teebmeem no txiav txim siab qhov kev tso tawm zaum kawg.
Muaj kev hloov pauv ntawm cov txheej txheem oxo. Piv txwv li, BASF-oxo txheej txheem, Exxon txheej txheem, plhaub txheej txheem, union-carbide txheej txheem, thiab lwm yam. Tsis tas li ntawd, peb tuaj yeem siv qee cov reactants uas tsis yog alkenes nrog rau cov catalysts tshwj xeeb. Piv txwv li, formaldehyde thiab ethylene oxide yuav siv tau raws li reactants nyob rau hauv lub xub ntiag ntawm cob alt carbonyl thiab rhodium complexes raws li catalysts, feem. Cov tshuaj tiv thaiv no ua rau muaj txiaj ntsig ntau dua ntawm qhov chaw ib puag ncig.
Txheej txheem Wacker yog dab tsi?
txheej txheem Wacker yog txheej txheem kev lag luam uas peb tuaj yeem tsim acetaldehyde los ntawm ethylene. Ntawm no, cov txheej txheem cuam tshuam nrog oxidation ntawm ethylene. Cov tshuaj tiv thaiv nce nyob rau hauv lub xub ntiag ntawm palladium (II) chloride catalyst. Nws yog homogeneous catalysis tshuaj tiv thaiv.
Daim duab 02: Cov txheej txheem Summary rau Wacker txheej txheem
Cov tshuaj tiv thaiv loj hauv cov txheej txheem no yog raws li hauv qab no:
[PdCl42- + C2H4 + H2O ⟶ CH3CHO + Pd + 2HCl + 2Cl–
Tom qab ntawd, ob peb qhov kev tshwm sim ntxiv tshwm sim txhawm rau rov tsim cov catalyst palladium (II) chloride. Yog li ntawd, nyob rau hauv cov txheej txheem no, tsuas yog oxygen thiab alkene tau noj raws li cov reactants. Txawm li cas los xij, muaj qee qhov kev hloov pauv hauv cov txheej txheem wacker, xws li txheej txheem ib-theem, ob-theem txheej txheem, Tsuji-wacker txheej txheem, thiab lwm yam.
Qhov txawv ntawm Oxo thiab Wacker txheej txheem yog dab tsi?
Oxo thiab wacker txheej txheem yog cov txheej txheem tseem ceeb. Qhov sib txawv tseem ceeb ntawm oxo thiab wacker txheej txheem yog cov txheej txheem oxo yog cov txheej txheem los tsim aldehydes los ntawm alkenes. Lub sijhawm no, cov txheej txheem wacker yog cov txheej txheem los tsim acetaldehyde los ntawm ethylene. Yog li ntawd, cov txheej txheem oxo cuam tshuam nrog kev tsim cov aldehyde, whereas cov txheej txheem wacker koom nrog kev tsim cov aldehyde hloov; acetaldehyde.
Tsis tas li ntawd, cov catalyst ntawm cov txheej txheem oxo yog homogeneous rhodium / cob alt catalyst, thaum lub catalyst ntawm cov txheej txheem wacker yog palladium (II) chloride. Tsis tas li ntawd, lwm qhov sib txawv ntawm oxo thiab wacker txheej txheem yog tias cov reactants rau cov txheej txheem oxo yog alkenes thiab syngas, thaum cov reactants rau cov txheej txheem wacker yog ethylene thiab oxygen.
Summary – Oxo vs Wacker Process
Hauv cov ntsiab lus, cov txheej txheem oxo thiab wacker yog cov txheej txheem tseem ceeb. Qhov sib txawv tseem ceeb ntawm oxo thiab wacker txheej txheem yog cov txheej txheem oxo yog cov txheej txheem los tsim cov aldehydes los ntawm alkenes, hos cov txheej txheem wacker yog cov txheej txheem los tsim acetaldehyde los ntawm ethylene.
