Qhov sib txawv tseem ceeb ntawm Woodward thiab Prevost cov tshuaj tiv thaiv yog Woodward cov tshuaj tiv thaiv tshwm sim nyob rau hauv lub xub ntiag ntawm iodine thiab silver acetate whereas Prevost cov tshuaj tiv thaiv tshwm sim nyob rau hauv muaj cov nyiaj ntsev ntawm benzoic acid.
Woodward thiab Prevost cov tshuaj tiv thaiv tseem ceeb hauv kev tsim cov vicinal diols los ntawm alkenes. Lub sij hawm vicinal yog hais txog qhov tseeb tias cov pab pawg ua haujlwm ntawm diol (hydroxyl pawg) txuas nrog cov pa roj carbon atoms los yog cov atoms uas nyob ib sab. Thaum xav txog geometry, lawv tuaj yeem yog cis lossis trans-isomers. Txawm li cas los xij, Woodward cov tshuaj tiv thaiv tsuas yog tsim cov cis isomer.
Woodward Reaction yog dab tsi?
Woodward cov tshuaj tiv thaiv yog ib hom tshuaj tiv thaiv uas cis diol tsim los ntawm alkene. Cov tshuaj tiv thaiv muaj npe tom qab tus kws tshawb fawb Robert Burns Woodward. Cov tshuaj tiv thaiv no tshwm sim thaum muaj iodine thiab nyiaj acetate reagent. Tsis tas li ntawd, cov tshuaj tiv thaiv no yuav tsum tau ntub dej acetic acid nruab nrab. Tsis tas li ntawd, qhov no yog ib hom tshuaj tiv thaiv ntxiv hauv cov organic chemistry.
Daim duab 01: Ib qho Kev Sib Txuas Sib Txuas rau Woodward Reaction
Ntxiv mus, Woodward cov tshuaj tiv thaiv muaj cov ntawv thov hauv thaj chaw ntawm steroid synthesis. Thaum xav txog cov tshuaj tiv thaiv ntawm Woodward cov tshuaj tiv thaiv, nws thawj zaug siv iodine, uas cuam tshuam nrog alkene. Thiab, cov kauj ruam no tshwm sim yog txhawb los ntawm nyiaj acetate. Cov khoom ntawm cov kauj ruam no yog iodonium ion. Tom qab ntawd, cov tshuaj tiv thaiv SN2 tshwm sim; iodonium ion qhib vim qhov kev txiav txim ntawm acetic acid lossis silver acetate thiab muab thawj qhov nruab nrab ntawm cov tshuaj tiv thaiv, iodo-acetate. Tom qab ntawd, lwm cov tshuaj tiv thaiv SN2 tshwm sim - nws ua rau iodine hloov chaw, muab oxonium ion. Tom qab ntawd, cov khoom no hydrolyzes muab ib tug monoester.
Yuav Ua Li Cas Ua Ntej Ua Ntej?
Cov tshuaj tiv thaiv Prevost yog ib hom tshuaj tiv thaiv uas alkene hloov mus rau hauv vicinal diol. Cov tshuaj tiv thaiv no tau qhia los ntawm Fab Kis tus kws chemist Charles Prevost. Cov tshuaj tiv thaiv tshwm sim nyob rau hauv lub xub ntiag ntawm iodine thiab nyiaj ntsev ntawm benzoic acid. Tsis tas li ntawd, cov vicinal diol uas tsim los ntawm cov tshuaj tiv thaiv no muaj kev tiv thaiv stereochemistry.
Daim duab 02: Kev sib luag dav dav rau kev tshwm sim ua ntej
Thaum xav txog cov tshuaj tiv thaiv ntawm Prevost cov tshuaj tiv thaiv, nws suav nrog cov tshuaj tiv thaiv ntawm cov nyiaj benzoate thiab iodine (ib qho tshuaj tiv thaiv sai heev), ua rau cov tshuaj tiv thaiv iodonium benzoate nruab nrab. Qhov nruab nrab no ces reacts nrog cov alkene muab lwm luv luv iodonium ntsev. Tom qab ntawd, cov tshuaj tiv thaiv SN2 tshwm sim, uas muab cov ester nyob rau hauv lub xub ntiag ntawm benzoate ntsev. Tom qab ntawd lwm cov nyiaj ion ua rau benzoate ester muab oxonium ntsev. Qhov thib ob SN2 cov tshuaj tiv thaiv tshwm sim, ua rau lub siab xav tau. Thaum kawg, hydrolysis tshwm sim kom tau txais cov tshuaj tiv thaiv diol los ntawm pawg ester hauv cov khoom kawg.
Qhov txawv ntawm Woodward thiab Prevost Reaction yog dab tsi?
Cov tshuaj tiv thaiv Woodward thiab Prevost cov tshuaj tiv thaiv yog qhov tseem ceeb hauv kev tsim cov diol los ntawm alkene. Qhov sib txawv tseem ceeb ntawm Woodward thiab Prevost cov tshuaj tiv thaiv yog tias Woodward cov tshuaj tiv thaiv tshwm sim nyob rau hauv muaj iodine thiab nyiaj acetate whereas Prevost cov tshuaj tiv thaiv tshwm sim nyob rau hauv lub xub ntiag ntawm cov nyiaj ntsev ntawm benzoic acid.
Hauv qab infographic qhia ntau cov ntsiab lus ntawm qhov sib txawv ntawm Woodward thiab Prevost cov tshuaj tiv thaiv.
Summary – Woodward vs Prevost Reaction
Woodward cov tshuaj tiv thaiv thiab cov tshuaj tiv thaiv Prevost yog qhov tseem ceeb hauv kev tsim cov diol los ntawm alkene. Ob hom tshuaj tiv thaiv no txawv ntawm ib leeg, raws li cov reagents siv thaum lub sij hawm cov txheej txheem tshuaj tiv thaiv. Qhov sib txawv tseem ceeb ntawm Woodward thiab Prevost cov tshuaj tiv thaiv yog tias Woodward cov tshuaj tiv thaiv tshwm sim nyob rau hauv muaj iodine thiab nyiaj acetate whereas Prevost cov tshuaj tiv thaiv tshwm sim nyob rau hauv muaj cov nyiaj ntsev ntawm benzoic acid.
Image Courtesy:
1. "Woodward Cis-Hydroxylation Scheme" Los ntawm Tsis muaj lub tshuab nyeem nyeem tau muab. ~K xav. Tus kheej ua haujlwm xav tias (raws li kev thov kev cai lij choj) (Public Domain) ntawm Commons Wikimedia
2. "Prevost Reaction Scheme" Los ntawm ~ K - Tus kheej ua haujlwm. Kev daws teeb meem siab PNG; ChemDraw / The GIMP (Public Domain) ntawm Commons Wikimedia
