Lithium aluminium hydride(LAH) yog ib qho kev ntxim nyiam uas yog qhov tseem ceeb hauv kev tshawb fawb ntuj. Paub txog nws cov khoom muaj zog txo qis, cov khoom siv no tau sau cov kev xav rau nws txoj kev yooj yim thiab rau nws ib qho zoo ntawm kev ua pyrophoric. Hauv qhov kev nkag blog no, peb yuav dhia tob rau hauv lub ntiaj teb ntawm cov khoom, tshawb xyuas nws cov khoom, kev siv, thiab tshwj xeeb, vim li cas nws qhia txog kev coj cwj pwm pyrophoric.
Peb muabLithium aluminium hydride, thov xa mus rau lub vev xaib hauv qab no kom paub meej cov lus qhia tshwj xeeb thiab cov ntaub ntawv khoom.
Nkag siab txog Lithium Aluminium Hydride: Cov Qauv thiab Cov Khoom
Ua ntej peb delve rau hauv cov pyrophoric xwm ntawm cov khoom, cia peb xub to taub dab tsi cov compound no thiab nws cov yam ntxwv.Lithium aluminium hydride, nrog rau cov tshuaj formula LiAlH4, yog ib tug complex hlau hydride. Nws yog ib qho dawb, crystalline khoom uas tau siv dav hauv cov organic synthesis ua tus neeg sawv cev muaj zog.
Cov qauv ntawm cov khoom yog qhov nthuav heev. Nyob rau hauv nws cov khoom, nws tshwm sim raws li ib tug complex ntsev, qhov twg cov lithium cation (Li +) yog txuam nrog tetrahedral aluminohydride anion (AlH4-). Cov qauv tshwj xeeb no pab txhawb rau nws cov peev xwm txo qis thiab nws cov reactivity nrog ntau yam khoom.
Qee qhov tseem ceeb ntawm cov khoom muaj xws li:
High reactivity nrog dej thiab cawv
Muaj zog txo tus neeg sawv cev hauv cov organic synthesis
Muaj peev xwm txo tau ntau yam ntawm pawg ua haujlwm
rhiab heev rau huab cua thiab noo noo
Pyrophoric xwm
Nws yog cov cuab yeej kawg no - nws qhov xwm txheej pyrophoric - uas peb yuav tsom mus rau hauv kab lus no. Tab sis ua ntej, cia peb tshawb nrhiav cov kev siv ntawm no ntau yam compound.
Kev siv ntawm Lithium Aluminium Hydride hauv Chemistry
Txawm hais tias nws qhov xwm txheej zoo li cas, cov khoom lag luam taug qab siv dav hauv kev sib txawv ntawm cov khoom sib txawv, tshwj xeeb tshaj yog nyob rau hauv natural union. Nov yog ib feem ntawm cov kev siv tseem ceeb:
Kev txo qis ntawm Utilitarian Gatherings:
LAH yog qhov zoo ntawm kev txo qis kev sib sau ua ke hauv kev sib xyaw ntuj. Nws tuaj yeem ua tiav txo qis aldehydes, ketones, carboxylic acids, esters, thiab, xav tsis thoob, ob peb amides rau lawv piv cov cawv lossis amines.
Union ntawm Complicated Atoms:
Hauv kev lag luam tshuaj, LAH suav tias yog ib feem tseem ceeb hauv kev sib xyaw ntawm cov tshuaj atom nyuaj. Hauv ntau cov txheej txheem organic syntheses, nws lub peev xwm los xaiv txo cov kev ua haujlwm tshwj xeeb ua rau nws muaj nuj nqis.
Hydrogen Peev Xwm:
Hlau hydrides, xws li cov khoom, tam sim no yog cov kev tshawb fawb rau cov roj cell hydrogen cia cov ntaub ntawv.
Kev tsim cov Reducers Ntxiv:
LAH tuaj yeem siv los tsim lwm tus kws kho mob txo qis, piv txwv li, sodium borohydride, uas tsis tshua txais thiab yooj yim dua los daws.
Qhov tseem ceeb ntawmlithium aluminium hydridehauv chemistry yog ua kom pom tseeb los ntawm cov ntawv thov no. Txawm li cas los xij, nws txoj kev yooj yim nrog rau kev sim ntawm nws cov pyrophoric xwm, uas yuav tsum tau ceev faj saib xyuas thiab khaws cia.
Pyrophoric xwm ntawm Lithium Aluminium Hydride: Ua rau thiab cuam tshuam
Tam sim no, yuav ua li cas hais txog qhov kev nug focal ntawm kab lus no: Vim li cas cov khoom lag luam pyrophoric? Yuav kom nkag siab txog qhov no, peb yuav tsum xub qhia qhov "pyrophoric" signifies.
Ib yam khoom raug suav hais tias yog pyrophoric ntawm qhov kev tawm tsam uas nws teeb tsis tau xav txog thaum qhib rau huab cua ntawm lossis hauv qab 54 degree (130 degree F). Ib qho hluav taws xob hluav taws xob sab nraud zoo li lub txim taws lossis nplaim taws tsis tas yuav tsum muaj rau qhov hluav taws kub tsis zoo no. Vim tias cov cuab yeej no, cov khoom lag luam yog cov khoom txaus ntshai los daws yam tsis muaj kev ceev faj kom raug.
Ntau yam ua rau cov khoom pyrophoric xwm:
High Oxygen Reactivity:
LAH muaj cov tshuaj tiv thaiv zoo nrog cov pa oxygen. Cov lus teb no yog exothermic profoundly, xa txaus siv los teeb lub compound.
01
Teb nrog Dampness:
LAH tseem teb emphatically nrog dej los yog dampness hauv huab cua. Hydrogen gas yog tsim los ntawm cov tshuaj tiv thaiv no, thiab nws yog heev flammable thiab yooj yim rau ignite.
02
Tsawg kub pib:
Lithium aluminium hydrideQhov kub tsis tshua muaj hluav taws kub ua rau nws yooj yim rau cov cua sov uas tsim los ntawm nws cov kev cuam tshuam nrog huab cua thiab noo noo kom ncav cuag qhov no.
03
ntau qhov chaw ntawm qhov chaw:
LAH thaj chaw siab hauv cov hmoov ua rau nws muaj zog dua nrog cov dej noo thiab huab cua, txhim kho nws tus cwj pwm pyrophoric.
04
Kev tuav thiab khaws cia ntawm cov khoom raug cuam tshuam los ntawm nws qhov xwm txheej pyrophoric:
Nws yuav tsum tau khaws cia rau hauv ib qho chaw inert, feem ntau qhuav nitrogen los yog argon.
Thaum LAH siv rau hauv cov tshuaj tiv thaiv, yuav tsum tau ceev faj tshwj xeeb, xws li siv cov pa cua tsis zoo thiab qhuav, cov kuab tshuaj tsis muaj oxygen.
Tsim nyog tus neeg tiv thaiv kho vajtse (PPE) yog qhov tseem ceeb thaum saib xyuas LAH kom tsis txhob muaj hluav taws kub los yog tawg.
Kev tshem tawm LAH yuav tsum tau ceev faj cov txheej txheem kom deb ntawm qhov pib tsis muaj kev txwv.
Kev nkag siab txog lub tswv yim pyrophoric ntawm cov khoom yog qhov tseem ceeb rau physicists thiab cov kws tshawb fawb ua haujlwm nrog cov khoom sib xyaw no. Nws hais txog qhov tseem ceeb ntawm kev ntsuas kev noj qab haus huv raug cai thiab ua haujlwm nrog cov txheej txheem hauv cov chaw tshawb fawb sib xyaw thiab cov chaw niaj hnub.
Xaus
Cov khoom pyrophoric xwm, thaum nyuaj, tsis txo nws cov nqi hauv chemistry. Nws lub zog txo cov khoom ua rau nws yog ib qho cuab yeej tseem ceeb hauv cov organic synthesis thiab lwm cov txheej txheem tshuaj. Los ntawm kev nkag siab tias yog vim li cas nws yog pyrophoric - nws cov reactivity siab nrog oxygen thiab ya raws, qis ignition kub, thiab qhov chaw siab - chemists tuaj yeem ua raws li kev ceev faj kom siv tau nws cov txiaj ntsig zoo.
Raws li peb txuas ntxiv tshawb nrhiav thiab siv cov khoom sib txuas zoo li cov khoom, nws yog ib qho tseem ceeb kom sib npaug lawv cov txiaj ntsig nrog kev ntsuas kev nyab xeeb kom raug. Daim teb ntawm chemistry yog hloov zuj zus mus tas li, thiab leej twg paub? Kev tshawb fawb yav tom ntej tuaj yeem ua rau kev txhim kho ntawm cov neeg muaj zog sib npaug nrog kev txhim kho kev ruaj ntseg thiab kev ruaj ntseg profiles.
Txawm hais tias koj yog ib tus neeg nyiam chemistry, tub ntxhais kawm, lossis tus kws tshaj lij hauv kev ua haujlwm, nkag siab txog cov khoom sib txuas xws lilithium aluminium hydrideenriches peb txaus siab rau qhov nyuaj thiab xav tsis thoob ntawm cov tshuaj tiv thaiv. Nws yog ib qho kev ceeb toom ntawm kev ua tib zoo sib npaug ntawm kev siv lub zog ntawm cov tshuaj tiv thaiv thiab ua kom muaj kev nyab xeeb hauv kev tshawb fawb.
Cov ntaub ntawv
Finholt, AE, Bond Jr, AC, & Schlesinger, HI (1947). Lithium aluminium hydride, aluminium hydride thiab lithium gallium hydride, thiab qee qhov ntawm lawv cov kev siv hauv cov organic thiab inorganic chemistry. Phau ntawv Journal of the American Chemical Society, 69(5), 1199-1203.
Seyden-Penne, J. (1997). Kev txo qis los ntawm Alumino-thiab Borohydrides hauv Organic Synthesis. John Wiley & Tub.
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.
Ashby, EC, & Prather, J. (1966). Cov muaj pes tsawg leeg ntawm "mixed hydride" txo cov neeg ua haujlwm. Phau ntawv Journal of the American Chemical Society, 88(4), 729-733.
Hydrogen Cia|Department of Zog.