Ketose vs Aldose
Carbohydrates yog ib pawg ntawm cov tebchaw uas txhais tau tias "polyhydroxy aldehydes thiab ketones lossis cov khoom uas hydrolyze kom tawm los polyhydroxy aldehydes thiab ketones." Carbohydrates yog hom ntau tshaj plaws ntawm cov organic molecules hauv ntiaj teb. Lawv yog lub hauv paus ntawm chemical zog rau cov kab mob nyob. Tsis tas li ntawd xwb, lawv ua haujlwm tseem ceeb ntawm cov ntaub so ntswg. Carbohydrate tuaj yeem muab faib ua peb yam xws li monosaccharides, disaccharides thiab polysaccharides. Monosaccharides yog hom carbohydrate yooj yim tshaj plaws. Monosaccharide muaj cov qauv ntawm Cx(H2O)x Cov no tsis tuaj yeem hydrolyzed rau hauv cov carbohydrates yooj yim. Lawv qab zib hauv saj. Tag nrho cov monosaccharides txo cov suab thaj. Yog li, lawv muab cov txiaj ntsig zoo nrog cov txiaj ntsig 'lossis Fehling's reagents. Monosaccharides raug cais raws li,
- Tus naj npawb ntawm cov pa roj carbon atoms nyob hauv cov molecule
- Txawm tias lawv muaj aldehyde lossis keto pawg
Yog li ntawd, ib qho monosaccharide nrog rau 6 carbon atoms hu ua hexose. Yog hais tias muaj tsib carbon atoms, ces nws yog ib tug pentose. Cov no tau muab faib ntxiv raws li seb lawv puas muaj pawg aldehyde lossis pawg ketone.
Ketose
Raws li tau piav qhia saum toj no, ib txoj hauv kev ntawm kev faib cov monosaccharides yog siv cov pab pawg ua haujlwm muaj nyob hauv cov molecule. Yog li ntawd, yog tias monosaccharide muaj ketone pawg, nws yog hu ua ketose. Piv txwv li, fructose yog ketose. Nws muaj cov qauv hauv qab no.
Carbon nrog pawg ketone ib txwm tau txais tus lej thib ob. Thaum tsim lub nplhaib, fructose tsim tau tsib lub nplhaib, uas yog hemiketal. Cov monosaccharides no tau muab faib ntxiv raws li tus naj npawb ntawm carbon atoms tam sim no. Yog tias muaj tsib carbon atoms, nws yog hu ua ketopentose thiab, yog tias muaj rau carbon atoms, nws yog hu ua ketohexose. Fructose, sorbose, tagtose thiab psicose yog qee qhov ketohexoses. Lawv muaj peb lub chaw chiral thiab, yog li ntawd, yim stereoisomers. Ribulose thiab xylulose yog ketopentoses, thiab lawv tsuas muaj ob lub chaw chiral.
Aldose
A monosaccharide nrog ib pawg aldehyde hu ua aldose. Piv txwv li, qabzib muaj ib pawg aldehyde thiab nws muaj cov qauv hauv qab no.
Cov pa roj carbon atom nrog cov pab pawg aldehyde ib txwm muab tus lej ib. Thiab muaj tsib lwm pawg hydroxyl hauv cov molecules. Rau monosaccharides, peb tuaj yeem kos ib kab qauv zoo li saum toj no lossis cov qauv cyclic. Hauv kev daws, feem ntau ntawm cov molecules yog nyob rau hauv cov qauv cyclic. Piv txwv li, thaum lub cyclic qauv tsim nyob rau hauv qabzib, lub -OH ntawm carbon 5 yog hloov dua siab tshiab rau hauv lub ether linkage, kaw lub nplhaib nrog cov aldehyde pab pawg neeg carbon 1. Qhov no tsim ib tug rau lub nplhaib qauv. Lub nplhaib tseem hu ua lub nplhaib hemiacetal, vim muaj cov pa roj carbon monoxide uas muaj ether oxygen thiab ib pawg cawv. Lwm yam tshaj li qabzib muaj lwm cov molecules nrog rau 6 carbon atoms thiab ib pawg aldehyde. Allose, altrose, qabzib, mannose, gulose, idose, thiab talose yog lwm hom aldohexoses. Tag nrho cov no muaj plaub lub chaw chiral, thiab yog li muaj 16 stereoisomers. Ribose, xylose, arabinose, thiab lyxose, yog aldopentoses nrog tsib carbon atoms thiab ib pawg aldehyde.
Qhov txawv ntawm Ketose thiab Aldose yog dab tsi?
• Ketoses yog monosaccharides nrog pawg ketone. Aldoses yog monosaccharides nrog ib pawg aldehyde.
• Ketoses form hemiketal rings thiab aldoses form hemiacetal rings.
• Hauv aldoses, pawg carbonyl yog nyob rau hauv tus naj npawb ib txoj haujlwm. Hauv ketoses, carbonyl carbon muaj tus lej ob.
