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Download CARBOHYDRATES PROBLEMS Label the chiral centers as `R` or `S
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CARBOHYDRATES PROBLEMS 1. Label the chiral centers as ‘R’ or ‘S’ in each of the following molecules. Do not guess as wrong answers will be subtracted from the correct answers. CH3 HO NH2 OHC CHO NH2 OH CH3 OH H3C NH2 2. Draw the following structures a) D-arabinose (Fischer) b) L-talose (Fischer) NH2 CHO HO CHO CH3 c) the C-4 epimer of D-glucose (Fischer) and give its name d) -D-mannopyranose (Haworth) 3. Draw the Haworth projection of -D-xylofuranose. Page 1 CARBOHYDRATES PROBLEMS 4. Draw the structures of the products you would expect to obtain from the following reactions. Name the products where required. a) -D-ribofuranose + CH3I, Ag2O ..................................................... (no name required) b) D-threose + Tollens reagent (Ag+ in NH3) .............................................. (name) c) -D- altrofuranose + isopropyl alcohol, HCl ....................................................... (name) d) -D- arabinofuranose + acetic anhydride (CH3CO)2O in pyridine solvent (no name) Page 2 CARBOHYDRATES PROBLEMS e) D- idose + NaBH4, then H2O .............................................................. (name required) f) D- lyxose in Kiliani Fischer Synthesis ...........................................(name both products) g) D- glucose in Wohl Degradation ......................................................... (name product) 5. Draw the following structures ... a) cellobiose b) any deoxyribose c) any amino sugar Page 3 CARBOHYDRATES PROBLEMS 6. Write the correct name of each of the following ... a) polysaccharide in potatoes and digestible by humans ....................................................... b) polysaccharide stored in the liver and muscles of humans ................................................ c) polysaccharides in grass ……………………………………………………………………… d) the disaccharide produced when starch is metabolized …………………………………….. e) water soluble form of starch ............................................................................................. f) pulverized with hot water ................................................................................................. g) the 2 monosaccharides which make up sucrose ............................................................... h) the polysaccharide imparting strength and rigidity to plants ............................................ i) textile fiber made from wood pulp, CS2, and NaOH ........................................................ j) milk sugar ....................................................................................................... k) carbohydrate which yields 3 to 10 monosaccharides on hydrolysis ................................ l) general name for a 5 carbon aldehydic monosaccharide ............................................... m) general name for a 7 carbon ketonic monosaccharide .................................................. n) general name for the 2 diastereomers produced when an open chain monosaccharide cyclicizes to its hemiacetal form .................................................................................. o) Name the 2 reagents which are combined to produce ‘acetate rayon’. …………………………………………………………………………………………………… p) Explain the difference between an epimer and an anomer. …………………………….. ………………………………………………………………………………………………….. …………………………………………………………………………………………………… 7. Identify all chiral centers as (R) or (S) in the following and give their IUPAC and common names. a) b) O OH HO H H O H OH OH OH H HO H OH H OH OH Page 4 CARBOHYDRATES PROBLEMS 8. Explain in words or by a drawing, the structural difference between cellobiose and maltose. Be sure to identify which is which Page 5
