Monosaccharides

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Monosaccharides

  1. 1. MONOSACCHARIDES <ul><li>Simple sugars. </li></ul><ul><li>Cannot be further hydrolyzed into simple carbohydrates </li></ul><ul><li>catagorized by the number of carbon (typically 3-8) and whether an aldehyde or ketone. </li></ul>
  2. 2. Monosaccharides <ul><li>Aldoses (e.g., glucose) have an aldehyde group at one end. </li></ul>Ketoses (e.g., fructose) have a keto group, usually at C2.
  3. 5. MONOSACCHARIDE STRUCTURES <ul><li>FISHER PROJECTIONS </li></ul><ul><li>HAWORTH PERSPECTIVE FORMULAS </li></ul>
  4. 6. The asymmetric(chiral) carbon atom and D and L monosaccharides <ul><li>Any carbon atom which is connected to four </li></ul><ul><li>different groups will be chiral, and will have two </li></ul><ul><li>nonsuperimposable mirror images; it is a chiral </li></ul><ul><li>carbon or a center of chirality. </li></ul>
  5. 10. <ul><li>When a molecule has more than one chiral carbon, </li></ul><ul><li>each carbon can possibly be arranged in either the </li></ul><ul><li>right-hand or left-hand form, thus if there are n </li></ul><ul><li>chiral carbons, there are 2 n possible stereoisomers. </li></ul><ul><li>Maximum number of possible stereoisomers = 2 n </li></ul>
  6. 11. Isomerism in monosaccharides <ul><li>Compounds that possess the same chemical formula are called isomers. </li></ul><ul><li>Glucose,fructose,mannose and galactose all have the same formula,i.e C6H12O6 and therefore isomers of each other. </li></ul>
  7. 12. <ul><li>1.STERIOISOMERISM </li></ul><ul><li>General term,means two or more monosaccharides having the same structure but differing from each other in that the configuration,i.e the arrangement of their atoms in space differ from each other. </li></ul>
  8. 14. <ul><li>2.ENANTIOMERS. </li></ul><ul><li>Pair of stereoisomerism that are mirror images of each other in regard to asymetric carbon atoms present in their molecules. </li></ul><ul><li>For example glucose occurs as D and L glucose isomers. </li></ul>
  9. 17. <ul><li>3.OPTICAL ISOMERISM </li></ul><ul><li>The enantiomeric monosaccharides by virtue of their content of asymmetric carbon atom can rotate the plane-polarized light either to right or left. </li></ul><ul><li>The monosaccharides that rotate this light to right are called dextrorotatory(+type) </li></ul><ul><li>Those rotating this light to left are called levorotatory(-type). </li></ul><ul><li>Glucose is dextrorotatory(+),while fructose is levorotatory(-) </li></ul>
  10. 18. <ul><li>4.EPIMERS </li></ul><ul><li>Monosaccharides(isomers) which differ in configuration around one specific carbon atom other than the carbon atom of carbonyl group. </li></ul>
  11. 19. Glucose Galactose
  12. 21. <ul><li>5.ANOMERS </li></ul><ul><li>Isomers that differ in configuration around the anomeric carbon i.e the carbon atom of the carbonyl group which is carbon no.1 in aldosed and carbon no.2 in ketoses . </li></ul>
  13. 22. These representations of the cyclic sugars are called Haworth projections.
  14. 23. <ul><li>Cyclization of glucose produces a new asymmetric center at C1 . The 2 stereoisomers are called anomers ,  &  . </li></ul><ul><li>  (OH below the ring) </li></ul><ul><ul><li>  (OH above the ring). </li></ul></ul>
  15. 25. <ul><li>6.PYRANOSE-FURANOSE ISOMERISM </li></ul><ul><li>The ring structures of monosaccharides may be similar to either pyran or furan and accordingly the monosaccharide is said to occur in pyranose or furanose form. </li></ul>
  16. 27. <ul><li>RECEMIC MIXTURE </li></ul><ul><li>Equal amounts of dextro- and levorotatory isomers in solution results no net rotation of plane of polarized light.Such a mixture is called racemic mixture. </li></ul><ul><li>MESOCOMPOUNDS </li></ul><ul><li>Donot rotate the light inspite of asymmetric carbon due to internal compensation. </li></ul>
  17. 28. <ul><li>MUTAROTATION </li></ul><ul><li>Process by which anomers are interconverted. </li></ul>

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