19 Oct 2011

GTF 312: Practice problems for Carbohydrates 1

You may like to solve these five problems:

1.  Draw the mirror images of glucose and fructose.  Are glucose and fructose chiral?  Do you expect them to be optically active?


2.  How many asymmetric carbon atoms are there in an aldotetrose?  Draw all the aldotetrose stereoisomers.

3.  How many asymmetric carbons are there in a ketotetrose?  Draw all the ketotetrose stereoisomers.

4.  How many asymmetric carbons and stereoisomers are there for an aldohexose?  For a ketohexose?
  
5.  Like glucose, galactose shows mutarotation when it dissolves in water.  The specific rotation of α-D-galactopyranose is +150.7°, and that of the β anomer is +52.8°.  When either of the pure anomers dissolves in water, the specific rotation gradually changes to +80.2°.  Determine the percentages of the two anomers present at equilibrium.

Answers will be provided few days after the second lecture on carbohydrates.  Happy trying!!! 

No comments:

Post a Comment