Qhov sib txawv tseem ceeb ntawm EDG thiab EWG yog tias EDG (sawv cev rau Electron Donating Groups) tuaj yeem ua rau cov khoom siv hluav taws xob ntau ntxiv ntawm qhov sib txuas ntawm pi system whereas EWG (sawv cev rau Electron Withdrawing Groups) txo cov electron ceev ntawm ib qho conjugated. pi system.
EDG thiab EWG yog cov pab pawg tswj hwm electrophilic aromatic. Ob qho no yog cov ntawv hloov pauv uas peb tuaj yeem pom hauv cov organic tebchaw.
EDG yog dab tsi?
EDG sawv cev rau cov pab pawg pub dawb electron. Peb hu lawv "electron tso tawm pawg (ERG)" ib yam nkaus. Cov no yog cov hloov pauv hauv cov organic tebchaw uas tuaj yeem pub qee yam ntawm nws cov electron ntom ntom rau hauv qhov system conjugated pi. Qhov no yog ua los ntawm cov nyhuv resonance lossis inductive effect. Qhov no ua rau pi electron system ntau nucleophilic.
Piv txwv li, EDG, thaum txuas nrog lub nplhaib benzene, lub nplhaib benzene tuaj yeem raug hloov pauv cov tshuaj electrophilic. Qhov no yog vim EDG ua rau kom cov electron ceev ntawm lub nplhaib benzene. Txawm li cas los xij, benzene feem ntau ua rau cov tshuaj tiv thaiv electrophilic hloov pauv. Yog li EDG tuaj yeem ua rau cov tshuaj tiv thaiv nce ntxiv. Yog li ntawd, peb hu cov neeg hloov pauv no ua pab pawg rau cov nplhaib uas muaj ntxhiab. Qee qhov piv txwv ntawm EDG suav nrog phenoxide, thawj, theem nrab thiab qib amines, ether, phenols, thiab lwm yam.
EWG yog dab tsi?
EWG sawv cev rau pawg tshem tawm hluav taws xob. Nws muaj qhov cuam tshuam rau ntawm EDG ntawm lub nplhaib uas muaj ntxhiab. Yog li ntawd, nws tshem tawm electron ceev ntawm lub pi-electron system. Qhov no ua rau pi electron system ntau electrophilic. Li no thaum cov pab pawg no txuas rau benzene rings, lawv yuav txo qis cov tshuaj tiv thaiv ntawm electrophilic hloov cov tshuaj tiv thaiv.
Daim duab 01: Nitrobenzene muaj ib pawg nitro li EWG
Ntxiv mus, EWG tuaj yeem ua rau lub nplhaib uas muaj ntxhiab tsw. Qhov no yog ua los ntawm resonance rho tawm los yog inductive thim nyhuv. Rau benzene, cov pab pawg no tuaj yeem ua rau ortho thiab para txoj haujlwm tsawg dua nucleophilic. Yog li ntawd, lub nplhaib benzene nyhav dhau los ua cov tshuaj electrophilic ntxiv ntawm cov haujlwm meta. Qee qhov piv txwv ntawm EWG suav nrog trihalides, sulfonates, ammonium, aldehydes, ketones, esters, thiab lwm yam.
Qhov txawv ntawm EDG thiab EWG yog dab tsi?
EDG sawv cev rau cov pab pawg pub dawb electron thaum EWG sawv cev rau cov pab pawg rho tawm hluav taws xob. Ob leeg no yog "electrophilic aromatic directing pawg". Raws li qhov sib txawv tseem ceeb ntawm EDG thiab EWG, peb tuaj yeem hais tias EDG tuaj yeem ua kom cov electron ceev ntawm lub conjugated pi system whereas EWG txo cov electron ceev ntawm conjugated pi system. Yeej, EDG tuaj yeem pub cov khoom siv hluav taws xob thaum EWG tuaj yeem tau txais hluav taws xob. Ntxiv mus, EDG tuaj yeem ua rau cov nucleophilicity ntawm cov nplhaib uas muaj ntxhiab, uas yog qhov ua haujlwm ntawm EWG; nws txo cov nucleophilicity ntawm aromatic rings. Ob qho tib si hloov pauv no qhia txog qhov cuam tshuam tseem ceeb ntawm kev hloov pauv hluav taws xob ntawm cov kab ke pi xws li benzene nplhaib; EDG tuaj yeem nce cov tshuaj tiv thaiv ntawm electrophilic hloov pauv cov tshuaj tsw qab ntawm cov nplhaib uas muaj ntxhiab thaum EWG tuaj yeem txo cov tshuaj tiv thaiv ntawm electrophilic hloov cov tshuaj tsw qab.
Cov hauv qab no infographic teev tawm cov ntsiab lus ntxiv ntawm qhov sib txawv ntawm EDG thiab EWG.
Summary – EDG vs EWG
Ob qho tib si EDG thiab EWG yog cov pab pawg electrophilic aromatic directing. Lawv qhia cov haujlwm sib txawv thaum txuas nrog cov nplhaib uas muaj ntxhiab. Yog li ntawd, peb tuaj yeem pom qhov sib txawv tseem ceeb ntawm EDG thiab EWG li; EDG tuaj yeem ua kom cov electron ceev ntawm lub conjugated pi system whereas EWG txo cov electron ceev ntawm conjugated pi system.
