Nyob rau hauv cov organic chemistry, txo cov tshuaj tiv thaiv ua lub luag haujlwm tseem ceeb hauv kev tsim kho thiab hloov kho ntawm ntau lub tebchaw. Ib qho ntawm cov muaj zog tshaj plaws txo cov neeg sawv cev ntawm kev ua lag luam yog lithium aluminium hydcaije(LAJ). Nws yog nto moo rau nws lub peev xwm los txo cov carbonyl-muaj cov sib tov xws li aldehydes, ketones, esters, thiab carboxylic acids rau lawv cov cawv sib piv. Txawm li cas los xij, nws tseem muaj txiaj ntsig zoo tiv thaiv amides.
Yog lawm, LAH tuaj yeem hloov amides rau hauv lawv cov amines sib xws. Cov lus teb no suav nrog qhov txo qis ntawm carbonyl sib sau ua ke hauv amide rau ib pawg amine. Tshwj xeeb, LAH rhuav tshem C=O daim ntawv cog lus hauv amide, thaum kawg hloov nws mus rau hauv ib qho amine los ntawm kev paub txog hydrogen nrog carbonyl carbon. Cov lus teb no muaj txiaj ntsig zoo hauv kev tshawb fawb txog ntuj tsim, raws li nws txiav txim siab qhov kev hloov pauv ntawm amides, uas nquag siv los ua cov neeg nruab nrab lossis kev sib sau ua ke hauv cov khoom nyuaj, rau hauv amines, uas muaj ntau yam kev siv tshuaj thiab cov ntaub ntawv tshawb fawb.
Yog li ntawd, LAH qhov kev hloov pauv raws li tus kws tshaj lij txo qis kuj tau ua piv txwv ntxiv los ntawm nws lub peev xwm los daws cov amides tiag tiag, nthuav tawm nws cov txiaj ntsig nthuav dav hauv kev sib koom ua ke ntuj.
nkag siab txog lithium aluminium hydride: tus neeg saib xyuas muaj zog
Txij li thaum nws cov lus qhia nyob rau hauv 1940s, lub zog inorganic compound Lithium Aluminium Hydride (LAH), tseem hu ua AlLiH4, tau muaj kev cuam tshuam loj rau thaj tsam ntawm cov organic synthesis. Vim nws lub zog txo qis, cov khoom dawb, crystalline no yog ib qho tseem ceeb heev reagent nyob rau hauv cov chaw kuaj tshuaj. Aldehydes, ketones, esters, carboxylic acids, thiab amides tsuas yog ob peb pawg ua haujlwm uas tuaj yeem txo qis rau lawv cov cawv lossis amines los ntawm LAH. Nws lub siab reactivity thiab adaptability tau nteg tawm LAH raws li lub hauv paus apparatus nyob rau hauv manufactured science, txhawb lub meej tswj thiab zus tau tej cov perplexing atoms rau ntau yam kev siv.
LAH tus qauv muaj cov nqi tsis zoo [AlH4]-ion sib npaug los ntawm qhov zoo them Li+ion. Qhov sib xyaw tshwj xeeb no ua rau nws muaj peev xwm pub dawb hydride ions (H-) rau ntau yam organic tebchaw.
Ua kom zoo txo lawv. Qee qhov tseem ceeb ntawm Lithium Aluminium Hydride suav nrog:
High reactivity nrog dej thiab huab cua
Muaj peev xwm txo qis
Versatility nyob rau hauv cov organic synthesis
Muaj peev xwm txo tau ntau yam ntawm pawg ua haujlwm
Muab nws qhov muaj zog, LAH feem ntau yog siv los txo cov carboxylic acids, esters, aldehydes, thiab ketones rau lawv cov cawv sib xws. Tab sis li cas txog amides? Cia peb tshawb nrhiav qhov no ntxiv.
kev sib tw ntawm kev txo amides nrog lithium aluminium hydride
Amides yog cov organic tebchaw uas muaj cov pab pawg carbonyl (C=O) sib txuas rau nitrogen atom. Lawv paub txog lawv txoj kev ruaj ntseg thiab tsis kam txo qis, ua rau lawv lub hom phiaj nyuaj rau ntau tus neeg txo qis. Lo lus nug yog: ua tauLithium Aluminium Hydridekov yeej qhov kev sib tw no?
Cov lus teb yog yog, tab sis nrog qee qhov caveats. Lithium Aluminium Hydride yog qhov tseeb muaj peev xwm txo cov amides, tab sis cov txheej txheem nyuaj dua nrog rau lwm pab pawg ua haujlwm. Nov yog vim li cas:
Bond zog
CN daim ntawv cog lus hauv amides yog qhov muaj zog tshwj xeeb, xav tau lub zog ntau dua los ua txhaum piv rau lwm cov ntsiab lus carbonyl.
Resonance ruaj khov
Amides tau txais txiaj ntsig los ntawm resonance stabilization, uas ntxiv dag zog rau lawv cov kev tiv thaiv kom txo tau.
Cov xwm txheej tshwm sim
Kev txo cov amides nrog LAH feem ntau yuav tsum muaj zog ntau dua, xws li kub siab dua lossis ntev dua cov tshuaj tiv thaiv.
Txawm hais tias cov kev cov nyom no, Lithium Aluminium Hydride tuaj yeem txo cov amides rau lawv cov amines sib xws. Cov tshuaj tiv thaiv feem ntau pib los ntawm cov kauj ruam hauv qab no:
Thawj qhov kev tawm tsam ntawm hydride ntawm carbonyl carbon
Tsim ib tug intermediate complex
Kev txo qis ntxiv kom tawg CN daim ntawv cog lus
Tsim cov khoom amine kawg
Nws yog ib qho tsim nyog sau cia tias qhov txo qis ntawm amides nrog LAH feem ntau tsis yooj yim dua li lwm cov pab pawg ua haujlwm, thiab cov kws kho mob yuav tsum ua tib zoo xav txog yam xws li cov qauv substrate, cov tshuaj tiv thaiv kab mob, thiab muaj peev xwm tshwm sim.
Cov tswv yim xav txog thiab lwm txoj hauv kev rau kev txo qis
Thaum Lithium Aluminium Hydride tuaj yeem txo cov amides, nws tsis yog qhov kev xaiv zoo tshaj plaws lossis kev xaiv zoo.
Chemists feem ntau xav txog ntau yam thaum xaiv tus neeg sawv cev txo qis rau amides:
Kev xaiv
LAH yog ib tug muaj zog txo tus neeg sawv cev uas tej zaum kuj yuav txo tau lwm yam functional pawg uas muaj nyob rau hauv lub molecule.
Kev txhawj xeeb txog kev nyab xeeb
Vim tias nws muaj kev ua haujlwm siab nrog dej thiab cua, tuav LAH yuav tsum tau ceev faj txog kev nyab xeeb.
Scale-up kev sib tw
Kev siv LAH ntawm cov nplai loj tuaj yeem muaj teeb meem vim nws qhov xwm txheej exothermic thiab muaj peev xwm rau kev khiav tawm.
Kev xav txog tus nqi
LAH tuaj yeem kim dua li qee qhov kev txo cov neeg ua haujlwm.
Muab cov xwm txheej no, chemists feem ntau tshawb nrhiav lwm txoj hauv kev los txo cov amides. Qee qhov kev xaiv nrov muaj xws li:
Borane (BH3) thiab nws cov derivatives
Cov tebchaw no tuaj yeem txo cov amides hauv cov mob me me.
Catalytic hydrogenation
Siv cov roj hydrogen nrog cov hlau catalyst tuaj yeem txo cov amides xaiv.
Sodium borohydride (NaBH4)
Txawm hais tias muaj zog tsawg dua LAH, nws tuaj yeem ua tau zoo rau qee qhov kev txo qis.
Dissolving hlau txo
Cov txheej txheem zoo li Birch txo qis tuaj yeem pab tau rau cov amide substrates tshwj xeeb.
Qhov tshwj xeeb amide substrate, muaj cov pab pawg ua haujlwm ntxiv, thiab qhov xav tau cov tshuaj tiv thaiv tag nrho ua lub luag haujlwm hauv kev xaiv tus neeg sawv cev txo qis.
xaus
Noj txhua yam rau hauv tus account, thaumLithium Aluminium Hydridetuaj yeem tsis muaj kev poob siab amides, nws tsis yog qhov kev xaiv zoo tshaj plaws rau qhov kev hloov pauv tshwj xeeb no. Nws lub peev xwm txo qis qis ua rau nws yog ib qho tseem ceeb hauv cov khoom siv ntuj tsim, tab sis cov kws kho mob yuav tsum ceev faj xav txog qhov upsides thiab downsides thaum siv nws kom txo qis. Chemists yuav tuaj yeem xaiv lub tswv yim zoo tshaj plaws rau lawv cov khoom siv hluavtaws tshwj xeeb yog lawv paub txog LAH qhov kev ua haujlwm thiab tshawb xyuas lwm yam.
Kev ua liaj ua teb ntawm organic chemistry txuas ntxiv nthuav tawm cov kev sib tw zoo siab thiab lub cib fim rau kev tsim kho tshiab, txawm tias koj yog ib tus tub ntxhais kawm kawm txog kev txo qis lossis tus kws paub txog tshuaj lom neeg nrhiav kev txhim kho koj txoj kev hluavtaws. Lub peev xwm ntawm Lithium Aluminium Hydride kom txo qis amides tsuas yog ib qho piv txwv ntawm kev sib hloov ntawm kev sib txuas ntawm kev tsim kho, kev ua haujlwm, thiab kev tsim kho.
cov ntaub ntawv
Seyden-Penne, J. (1997). Kev txo qis los ntawm Alumino- thiab Borohydrides hauv Organic Synthesis. Wiley-VCH.
Clayden, J., Greeves, N., & Warren, S. (2012). Organic Chemistry. Oxford University Press.
Carey, FA, & Sundberg, RJ (2007). Advanced Organic Chemistry: Part B: Reaction and Synthesis. Springer.
Kürti, L., & Czakó, B. (2005). Cov kev siv tswv yim ntawm cov tshuaj muaj npe nyob hauv Organic Synthesis. Elsevier Academic Press.
Smith, MB, & March, J. (2007). Lub Peb Hlis Ntuj Advanced Organic Chemistry: Reactions, Mechanisms, and Structure. John Wiley & Tub.