kev taw qhia
Nyob rau hauv lub ntiaj teb no ntawm organic chemistry,Lithium Aluminium Hydride(LAH) sawv tawm raws li tus neeg sawv cev muaj zog. Txawm li cas los xij, nws cov txiaj ntsig thiab kev nyab xeeb feem ntau nyob ntawm qhov hnyav siv. Niaj hnub no, peb tab tom dhia mus rau vim li cas tetrahydrofuran (THF) feem ntau yog qhov hnyav ntawm kev xaiv thaum ua haujlwm nrog ntau yam sib xyaw. Txawm hais tias koj yog tus kws kho mob tshwj xeeb lossis cov tub ntxhais kawm xav paub, phau ntawv qhia no yuav qhia txog qhov tseem ceeb ntawm kev xaiv cov kuab tshuaj zoo rau LAH cov tshuaj tiv thaiv.
nkag siab txog lithium aluminium hydride thiab nws cov khoom
Ua ntej peb delve rau hauv cov laj thawj ntawm kev siv THF, cia peb nkag siab txog dab tsi nws yog thiab yog vim li cas nws thiaj li tseem ceeb nyob rau hauv cov organic chemistry.
Lithium Aluminium Hydride, feem ntau abbreviated li LAH lossis LiAlH4, yog ib tug haib txo tus neeg sawv cev dav siv nyob rau hauv cov organic synthesis. Nws muaj txiaj ntsig tshwj xeeb hauv kev txo qis carbonyl tebchaw, xws li aldehydes thiab ketones, rau cawv. LAH tseem tuaj yeem txo cov carboxylic acids, esters, thiab txawm tias qee qhov kev ua haujlwm tsis zoo xws li nitriles.
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Lub reactivity ntawm LAH yog los ntawm nws cov qauv. Nws yog ib qho inorganic compound nrog cov tshuaj formula LiAlH4, qhov twg lithium thiab aluminium atoms yog txuas los ntawm hydrogen atoms. Cov qauv tshwj xeeb no ua rau nws muaj zog hydride pub, tso cai rau nws kom txo tau ntau yam ntawm cov organic tebchaw.
Txawm li cas los xij, LAH's siab reactivity kuj txhais tau tias nws rhiab heev rau ya raws thiab huab cua. Thaum raug dej, nws reacts vigorously, ua hydrogen gas. Qhov reactivity no yuav tsum tau ua tib zoo tuav thiab khaws cia, suav nrog kev xaiv cov kuab tshuaj tsim nyog rau cov tshuaj tiv thaiv.
lub luag haujlwm ntawm cov kuab tshuaj hauv lAH cov tshuaj tiv thaiv
Cov kuab tshuaj ua lub luag haujlwm tseem ceeb hauv cov tshuaj tiv thaiv, thiab qhov no yog qhov tseeb tshwj xeeb rau cov tshuaj tiv thaiv nrog Lithium Aluminium Hydride. Kev xaiv cov kuab tshuaj tuaj yeem cuam tshuam rau cov tshuaj tiv thaiv kev ua tau zoo, kev nyab xeeb, thiab qhov tshwm sim. Nov yog vim li cas:
Solubility
Cov kuab tshuaj yuav tsum tau yaj LAH kom zoo kom muaj cov tshuaj tiv thaiv homogeneous sib xyaw.
Kev ruaj ntseg
Muab LAH's reactivity, cov kuab tshuaj yuav tsum ruaj khov thiab tsis hnov mob nrog cov compound.
Cov tshuaj tiv thaiv kinetics
Cov kuab tshuaj tuaj yeem cuam tshuam qhov nrawm thiab cov txheej txheem ntawm cov tshuaj tiv thaiv.
Kev nyab xeeb
Qee cov kuab tshuaj yuav ua rau muaj kev pheej hmoo ntxiv thaum siv nrog LAH, xws li kev kub nyhiab lossis rov ua haujlwm.
Nrog rau cov xwm txheej hauv siab, cia peb tshawb nrhiav vim li cas THF feem ntau yog qhov hnyav ntawm kev xaiv rau LAH cov tshuaj tiv thaiv.
vim li cas tHF yog qhov nyiam hnyav rau lithium aluminium hydride
Tetrahydrofuran, lossis THF, tau tshwm sim los ua cov kuab tshuaj rau ntau tus kws tshuaj thaum ua haujlwm nrogLithium Aluminium Hydride. Nov yog cov laj thawj tseem ceeb vim li cas:
Solubility zoo heev
THF yog ib qho kuab tshuaj ethereal uas yaj LAH zoo. Qhov kev solubility siab no ua kom ntseeg tau tias LAH tau zoo sib cais hauv cov tshuaj tiv thaiv sib xyaw, ua rau muaj txiaj ntsig zoo thiab ua tiav cov tshuaj tiv thaiv. Qhov zoo solubility kuj tso cai rau ntau dua LAH, uas tuaj yeem muaj txiaj ntsig zoo rau qee qhov kev cuam tshuam.
Ntuj Aprotic
THF yog cov kuab tshuaj aprotic, txhais tau tias nws tsis muaj cov kua qaub hydrogen atoms uas tuaj yeem ua rau LAH. Cov cuab yeej no tseem ceeb heev vim tias LAH yog qhov muaj zog heev rau cov kuab tshuaj protic (cov uas muaj acidic hydrogens, xws li dej los yog cawv). Qhov aprotic xwm ntawm THF tso cai rau nws los ua ib qho inert nruab nrab rau LAH cov tshuaj tiv thaiv, khaws cia cov reagent lub reactivity rau lub npaj substrate.
Nruab Nrab Boiling Point
Nrog rau qhov kub ntawm 66 degree, THF muab qhov sib npaug zoo rau ntau LAH cov tshuaj tiv thaiv. Nws yog tsawg txaus kom yooj yim tshem tawm tom qab cov tshuaj tiv thaiv, tab sis siab txaus tso cai rau ib tug ntau yam ntawm cov tshuaj tiv thaiv kub. Qhov kev ua tau zoo no ua rau THF haum rau ob qho tib si hauv chav sov thiab cov uas xav tau cua sov me me.
Stability nrog LAH
Tsis zoo li lwm cov ethers, THF kuj ruaj khov nyob rau hauv lub xub ntiag ntawm LAH. Thaum lub sij hawm ntev cia ntawm LAH hauv THF tuaj yeem ua rau qee qhov degradation, nws tsis tshua muaj kev cuam tshuam rau cov teebmeem tshwm sim piv rau cov kuab tshuaj xws li diethyl ether.
Kev sib koom tes muaj peev xwm
THF tuaj yeem koom tes nrog cov hlau ions, suav nrog lithium hauv LAH. Qhov kev sib koom tes no tuaj yeem pab txhim kho cov tshuaj tiv thaiv intermediates thiab cuam tshuam rau cov tshuaj tiv thaiv. Qee qhov xwm txheej, qhov kev sib koom tes no tuaj yeem ua rau muaj kev xaiv zoo dua lossis tawm los ntawm LAH txo.
Kev xav txog kev nyab xeeb
Thaum THF yog nplaim taws thiab yuav tsum tau ua tib zoo tuav, nws feem ntau pom tias muaj kev nyab xeeb dua los siv nrog LAH piv rau qee qhov kev xaiv. Piv txwv li, diethyl ether, lwm cov kuab tshuaj rau LAH, yog ntau volatile thiab tsim peroxides yooj yim dua, ua rau muaj kev pheej hmoo ntawm tawg.
Txawm tias muaj txiaj ntsig zoo, nws tseem ceeb heev uas yuav tsum nco ntsoov tias THF tsis yog qhov kev xaiv zoo tshaj plaws rau txhua qhov LAH cov tshuaj tiv thaiv. Qee cov tshuaj tiv thaiv yuav tau txais txiaj ntsig los ntawm cov kuab tshuaj sib txawv lossis cov kuab tshuaj sib tov. Raws li nrog rau txhua yam ntawm chemistry, kev xaiv cov kuab tshuaj yuav tsum ua tib zoo txiav txim siab raws li cov xwm txheej tshwj xeeb thiab cov txiaj ntsig xav tau.
Cov kev coj ua zoo tshaj plaws rau kev siv THF nrog lithium-saluminium hydride
Thaum THF yog cov kuab tshuaj zoo heev rau LAH cov tshuaj tiv thaiv, nws yog ib qho tseem ceeb kom ua raws li cov txheej txheem kev nyab xeeb thiab kev tuav pov hwm. Nov yog qee qhov kev coj ua zoo tshaj plaws kom nco ntsoov:
Siv THF anhydrous
Muab LAH qhov rhiab heev rau cov dej noo, nws yog ib qho tseem ceeb uas yuav tau siv THF qhuav. Kev lag luam anhydrous THF lossis freshly distilled THF tshaj sodium / benzophenone feem ntau yog siv.
01
Kov nyob rau hauv inert cua
LAH cov tshuaj tiv thaiv yuav tsum tau ua nyob rau hauv ib qho inert roj xws li nitrogen los yog argon los tiv thaiv cov tshuaj tiv thaiv nrog atmospheric noo noo thiab oxygen.
02
Kev tswj qhov kub thiab txias
Thaum THF tso cai rau ntau qhov kub thiab txias, nws yog ib qho tseem ceeb uas yuav tsum tswj qhov kub kom zoo, tshwj xeeb tshaj yog thaum ntxiv LAH lossis substrate.
03
Quenching
Tom qab cov tshuaj tiv thaiv, ceev faj quenching yog qhov tseem ceeb heev. Qhov no feem ntau yog ua los ntawm kev sib ntxiv ntawm cov dej qeeb, ua raws li cov dej aqueous sodium hydroxide thiab dej ntau dua.
04
Kev pov tseg
Kev pov tseg LAH pov tseg kom raug yog qhov tseem ceeb. LAH uas tsis muaj kev cuam tshuam yuav tsum tsis txhob muab pov tseg ncaj qha tab sis yuav tsum ua tib zoo quenched ua ntej.
05
Los ntawm kev ua raws li cov kev coj ua no, chemists tuaj yeem siv tag nrho cov peev txheej ntawm cov khoom thaum ua kom muaj kev nyab xeeb thiab ua haujlwm zoo hauv lawv cov kev cuam tshuam.
xaus
Kev xaiv ntawm THF ua cov kuab tshuaj rauLithium Aluminium HydrideCov tshuaj tiv thaiv yog ib qho pov thawj rau qhov tseem ceeb ntawm kev xaiv cov kuab tshuaj hauv cov organic synthesis. Nws lub peev xwm los yaj LAH, nws qhov xwm txheej aprotic, thiab nws txoj kev ruaj ntseg ua rau nws yog qhov nruab nrab zoo tshaj plaws rau cov kev txo qis no. Txawm li cas los xij, zoo li txhua yam ntawm chemistry, tsis muaj ib qho loj- haum-txhua qhov kev daws teeb meem. Cov kuab tshuaj zoo tshaj plaws yuav ib txwm nyob ntawm cov tshuaj tiv thaiv tshwj xeeb, cov substrates koom nrog, thiab cov txiaj ntsig xav tau.
Raws li peb txuas ntxiv thawb cov ciam teb ntawm cov organic synthesis, nkag siab txog cov nuances ntawm reagents zoo li LAH thiab cov kuab tshuaj zoo li THF ua qhov tseem ceeb. Txawm hais tias koj tab tom ua kev tshawb fawb hauv tsev kawm qib siab lossis tsim cov txheej txheem tshiab hauv kev lag luam, qhov kev paub no tsim lub hauv paus rau kev tsim kho tshiab hauv organic chemistry.
Nco ntsoov, thaum THF feem ntau yog qhov kev xaiv mus rau LAH cov tshuaj tiv thaiv, nws ib txwm tsim nyog xav txog lwm txoj hauv kev thiab ua kom zoo rau koj cov kev xav tau tshwj xeeb. Zoo siab synthesizing!
cov ntaub ntawv
Seyden-Penne, J. (1997). Kev txo qis los ntawm Alumino- thiab Borohydrides hauv Organic Synthesis. Wiley-VCH.
Krishnamurthy, S., & Brown, HC (1980). Kev xaiv txo qis. 27. Cov tshuaj tiv thaiv ntawm alkyl pawg nrog lithium aluminium hydride-aluminium chloride. Ib txoj kev yooj yim rau kev hloov pauv ntawm alkyl halides rau alkanes. Phau ntawv Journal of Organic Chemistry, 45(5), 849-856.
Yoon, NM, & Brown, HC (1968). Kev xaiv txo qis. XII. Kev tshawb nrhiav hauv qee cov ntawv thov sawv cev ntawm aluminium hydride rau kev xaiv txo qis. Phau ntawv Journal of the American Chemical Society, 90(11), 2927-2938.
Balduzzi, S., Brook, MA, & McGlinchey, MJ (2005). Lub ligand pauv kev cuam tshuam ntawm lithium aluminium hydride: Kev kawm kinetic. Canadian Journal of Chemistry, 83(6-7), 929-936.
Ashby, EC, & Prather, J. (1966). Cov muaj pes tsawg leeg ntawm "lithium aluminium hydride" hauv ether tov. Phau ntawv Journal of the American Chemical Society, 88(4), 729-733.