Qhov Tseem Ceeb Qhov txawv - Anomers vs Epimers
Anomers thiab epimers yog ob qho tib si diastereomers. Epimer yog ib qho stereoisomer uas txawv hauv kev teeb tsa ntawm ib qho chaw stereogenic nkaus xwb. Ib qho anomer yog ib qho cyclic saccharide thiab kuj yog ib qho epimer uas txawv ntawm qhov kev teeb tsa, tshwj xeeb tshaj yog nyob rau hauv hemiacetal lossis acetal carbon. Cov pa roj carbon no hu ua anomeric carbon. Txawm li cas los xij, anomers yog ib chav tshwj xeeb ntawm epimers. Nov yog qhov sib txawv tseem ceeb ntawm anomers thiab epimers.
Anomers yog dab tsi?
Ib qho anomer yog cyclic saccharide thiab tseem yog ib qho epimer, qhov sib txawv ntawm qhov kev teeb tsa tshwj xeeb tshwm sim ntawm hemiacetal lossis acetal carbon. Cov pa roj carbon no yog hu ua anomeric carbon thiab nws yog muab los ntawm carbonyl carbon (aldehyde los yog ketone functional pab pawg) ntawm qhib-chain daim ntawv ntawm cov carbohydrate molecule. Anomerization yog txheej txheem ntawm kev hloov pauv ntawm ib qho anomer mus rau lwm qhov. Ob tug anomers txawv los ntawm naming lawv alpha (α) los yog beta (β).
Dab tsi yog Epimers?
Epimers pom muaj nyob hauv carbohydrate stereochemistry. Lawv yog ib khub ntawm stereoisomers uas txawv tsuas yog nyob rau hauv lub configuration ntawm ib qho chaw stereogenic. Tag nrho lwm cov stero-centers hauv cov molecules no zoo ib yam li ib leeg. Qee cov epimers muaj txiaj ntsig zoo hauv ntau daim ntawv thov kev lag luam xws li hauv kev tsim tshuaj. Txij li cov epimers muaj ntau tshaj ib qho chaw chiral, lawv yog cov neeg mob ntshav qab zib. Tawm ntawm tag nrho cov chaw chiral, lawv sib txawv ntawm ib leeg nyob rau hauv qhov tseeb configuration ntawm tsuas yog ib qho chaw chiral.
Dab tsi yog qhov txawv ntawm Anomers thiab Epimers?
Definition
Anomers: Anomers yog ib txheej tshwj xeeb ntawm epimers uas txawv hauv kev teeb tsa tsuas yog ntawm cov pa roj carbon monoxide. Qhov no tshwm sim thaum lub molecule xws li qabzib hloov mus rau hauv daim ntawv cyclic.
Epimers: Epimers yog ib khub ntawm stereoisomers pom nyob rau hauv stereochemistry. Lawv yog ob isomers uas txawv hauv kev teeb tsa ntawm ib qho chaw chiral nkaus xwb. Yog hais tias lub molecule muaj lwm yam stereocenters, lawv tag nrho cov tib yam nyob rau hauv ob isomers.
Examples
Anomers:
- α-D-Fructofuranose thiab β-D-fructofuranose
Epimers:
- Doxorubicin thiab epirubicin
- D-erythrose thiab D-threose
Definition:
Stereogenic center:
A stereocenter lossis stereogenic chaw tseem hu ua chiral center. Cov molecules no yog tus yam ntxwv uas muaj daim iav duab daim ntawv, qhov uas lawv tsis superposable rau ib leeg.
Diasteem:
Diasteemers lossis diastereoisomers yog ib pawg ntawm stereoisomer. Qhov no tshwm sim thaum ob lossis ntau lub stereoisomers ntawm ib qho chaw sib txawv ntawm ib lossis ntau dua (tab sis tsis yog tag nrho) ntawm qhov sib npaug (txog) stereocenters. Tab sis, lawv tsis yog daim iav duab ntawm ib leeg.
