Video: Dab tsi yog pKa ntawm amide?
2024 Tus sau: Miles Stephen | [email protected]. Kawg hloov kho: 2023-12-15 23:36
Lub hauv paus. Piv rau amines, amides yog lub hauv paus tsis muaj zog heev. Thaum lub conjugate acid ntawm amine muaj pKib ntawm 9.5, conjugate acid ntawm ib amide muaj pkib los ntawm -0.5. Yog li ntawd, amides tsis muaj qhov pom tseeb ntawm cov kua qaub-puag hauv dej.
Kuj nug, pKa ntawm ib qho amine yog dab tsi?
Tus nqi ntawm 10.63 tiag tiag yog hais txog tus pKa ntawm conjugate acid ntawm methyl amine , Tsis yog methylamine nws tus kheej. Nws yog tus nqi pKaH. Ib yam li ntawd, tib lub rooj teev cov trimethylamine muaj ib pKa ua 9.8.
Tsis tas li ntawd, amides tuaj yeem raug protonated? A protonated amide muaj tsawg kawg acidic pab pawg ntawm lawv tag nrho (CONH +), pov thawj tias daim ntawv blinking resonance muaj nyob rau hauv cov ntaub ntawv no ib tug yooj yim pab. Lub electron ib leeg khub ntawm NH2 yog heev delocalized rau carbonyl pawg nyob rau hauv amides . Qhov tseeb, C = O. group ib amide yog qhov yooj yim dua li NH2.
Ib yam li ntawd, koj tuaj yeem nug, pKa ntawm hydroxide yog dab tsi?
Hydroxide ion, HO(-) tsis nyob rau sab laug ntawm tus pKa lub rooj, tab sis nws yog nyob rau ntawm "inverse" pKa lub rooj - nws yog lub hauv paus conjugate dej, H2O. Dej muaj ib pKa ntawm ~ 15, thiab CH4 muaj ib pKa ntawm 50. Peb cov khoom yog ib tug muaj zog acid. Los ntawm inverse pKa lub rooj, peb kuj nco ntsoov tias CH3(-) yog lub hauv paus muaj zog dua HO(–).
Vim li cas amides yog qhov yooj yim?
Tsis zoo li amines, uas yog cov hauv paus zoo, amides yog lub hauv paus tsis muaj zog. Lub conjugate acids ntawm amides muaj pKa tus nqi nyob ib ncig ntawm -0.5. Yog vim li cas amides tsis yog li yooj yim yog vim muaj cov pab pawg carbonyl. Amides tuaj yeem ua tau hydrogen daim ntawv cog lus vim tias lawv muaj N-H daim ntawv cog lus.
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