Hauv cov tshuaj tiv thaiv, ntau yam khoom tuaj yeem ntxiv rau ntawm qhov chaw ntawm kev puas tsuaj ntawm ob daim ntawv cog lus hauv alkenes thiab triple daim ntawv cog lus hauv alkynes. Cov kev cai lij choj tswj cov txheej txheem no yog dab tsi? Tus cwj pwm ntawm asymmetric ethylene homologues thaum hydrohalogenation thiab hydration tau kawm los ntawm Lavxias tus kws tshawb fawb VV Markovnikov. Nws pom tias cov txheej txheem ntawm cov tshuaj tiv thaiv nyob ntawm tus naj npawb ntawm hydrogen carbon yog sib koom ua ke hauv ob daim ntawv cog lus. Qhov kev xav tau muab tso rau los ntawm tus kws tshawb fawb tau lees paub tom qab kev tshawb pom hauv thaj chaw ntawm cov qauv ntawm lub atom. Markovnikov txoj cai nteg lub hauv paus rau lub creation ntawm ib tug scientific txoj kev xav uas muaj tswv yim siv. Nws tso cai rau koj los tsim kom muaj kev sib koom ua ke ntawm cov khoom siv polymers, lubricating roj, cawv.
Markovnikov txoj cai
Tus kws tshawb fawb Lavxias tau siv sijhawm ntau los kawm txog cov txheej txheem ntawm kev sib ntxiv ntawm asymmetric reagents rau unsaturated hydrocarbons. Hauv nws tsab xov xwm luam tawm hauv GermanNyob rau hauv 1870, V. V. Markovnikov tau txais kev mloog ntawm lub zej zog scientific rau kev xaiv ntawm kev sib cuam tshuam ntawm hydrogen halides nrog carbon atoms uas yog nyob rau hauv ob daim ntawv cog lus nyob rau hauv unsymmetrical alkenes. Tus kws tshawb fawb Lavxias tau hais txog cov ntaub ntawv uas nws tau txais empirically hauv nws chav kuaj. Markovnikov tau sau tias halogen yuav tsum txuas rau cov pa roj carbon atom uas muaj tsawg tshaj plaws ntawm hydrogen atoms. Cov hauj lwm ntawm tus kws tshawb fawb tau txais txiaj ntsig zoo thaum pib ntawm lub xyoo pua 20th. Lub tswv yim ntawm kev sib cuam tshuam mechanism tau thov los ntawm nws tau hu ua "Markovnikov txoj cai".
Lub neej thiab kev ua haujlwm ntawm tus kws tshawb fawb organic
Vladimir Vasilievich Markovnikov yug rau lub Kaum Ob Hlis 25 (13 raws li cov qauv qub) Lub Kaum Ob Hlis 1837. Nws kawm hauv University of Kazan, tom qab ntawd qhia ntawm lub tsev kawm ntawv no thiab hauv Moscow University. Markovnikov tau kawm txog tus cwj pwm ntawm unsaturated hydrocarbons thaum cuam tshuam nrog hydrogen halides txij li xyoo 1864. Txog rau xyoo 1899, cov kws tshawb fawb los ntawm lwm lub tebchaws tsis tau muab qhov tseem ceeb rau cov lus xaus ntawm Lavxias tus kws tshuaj. Markovnikov, ntxiv rau txoj cai muaj npe tom qab nws, tau ua ntau qhov kev tshawb pom:
- tau txais cyclobutanedicarboxylic acid;
- tshawb nrhiav cov roj ntawm Caucasus thiab pom nyob rau hauv nws cov organic tshuaj ntawm ib qho tshwj xeeb muaj pes tsawg leeg - naphthenes;
- tsim qhov sib txawv ntawm qhov kub thiab txias ntawm cov tebchaw nrog cov ceg ntoo thiab cov saw ncaj;
- ua pov thawj cov isomerism ntawm fatty acids.
Kev ua haujlwm ntawm tus kws tshawb fawb tau pab txhawb kev tsim kho tshuaj hauv tsev thiab kev lag luam.
Qhov tseem ceebQhov kev xav tau muab los ntawm Markovnikov
Tus kws tshawb fawb tau mob siab rau ntau xyoo los kawm txog kev sib ntxiv ntawm cov tshuaj reagents rau unsaturated hydrocarbons nrog ib daim ntawv cog lus ob (alkenes). Nws pom tias yog hydrogen muaj nyob rau hauv cov tebchaw, ces nws mus rau cov pa roj carbon atom uas muaj ntau yam ntawm hom no. Lub anion txuas nws tus kheej mus rau cov pa roj carbon nyob sib ze. Qhov no yog Markovnikov txoj cai, nws cov ntsiab lus. Tus kws tshawb fawb ingeniously kwv yees tus cwj pwm ntawm cov khoom, cov qauv ntawm lub sijhawm ntawd tseem tsis tau meej meej. Raws li txoj cai, complex tshuaj muaj cov muaj pes tsawg leeg HX yog ntxiv rau ethylene hydrocarbons, qhov twg X:
- halogen;
- acid residue ntawm sulfuric acid;
- lwm yam.
Yhydroxyl;
Lub suab niaj hnub ntawm Markovnikov txoj cai txawv ntawm cov kws tshawb fawb cov qauv: cov hydrogen atom los ntawm HX molecule txuas los ntawm alkene mus rau cov pa roj carbon hauv ob daim ntawv cog lus uas twb muaj ntau dua hydrogen, thiab X particle mus rau qhov tsawg kawg nkaus. hydrogenated atom.
Mechanism rau txuas ntawm electrophilic hais
Cia peb xav txog cov tshuaj hloov pauv uas Markovnikov txoj cai siv. Piv txwv:
- Cov tshuaj tiv thaiv ntawm qhov sib ntxiv ntawm hydrogen chloride rau propene. Nyob rau hauv chav kawm ntawm kev sib cuam tshuam ntawm cov khoom, qhov kev puas tsuaj ntawm ob daim ntawv cog lus tshwm sim. Cov tshuaj chlorine anion mus rau qhov tsawg dua hydrogenated carbon uas nyob hauv ob daim ntawv cog lus. Hydrogen cuam tshuam nrog feem ntau hydrogenated ntawm cov atoms. 2-chlorine yog tsimpropane.
- Nyob rau hauv qhov sib ntxiv cov tshuaj tiv thaiv ntawm cov dej molecule, cov hydroxyl los ntawm nws cov muaj pes tsawg leeg mus txog qhov tsawg hydrogenated carbon. Hydrogen txuas rau feem ntau hydrogenated atom ntawm ob daim ntawv cog lus.
Muaj kev zam rau txoj cai tau thov los ntawm Markovnikov nyob rau hauv cov kev tshwm sim uas cov reactants yog alkenes, uas cov pa roj carbon nyob rau hauv ob daim ntawv cog lus twb muaj ib tug electronegative pawg nyob ze. Nws ib nrab xaiv cov electron ceev, uas feem ntau zoo them hydrogen yog nyiam. Txoj cai tseem tsis tau pom nyob rau hauv cov kev tshwm sim tshwm sim raws li ib tug radical es tsis yog ib tug electrophilic mechanism (cov nyhuv Harish). Cov kev zam no tsis cuam tshuam los ntawm qhov zoo ntawm txoj cai tsim los ntawm tus kws tshaj lij Lavxias teb sab organic chemist V. V. Markovnikov.
