Chem. 116 EXAM 2 PRACTICE SHEET Summer 2009
1. Name the following compounds put stereochemistry and geometry where appropriate
OH
H3C CH O
CH2 CH2 CH3
Name___(2S)-2-hydroxy-2-methylbutanal_ Name_____1-methoxy-2-butanol_
OH
CH2
Cl CH2 CH3
Do not do R or S on this molecule
Name___4-chloro-2-propylphenol__ Name_____trans-3-iodocycloheptanethiol______
2. Assign priorities to the groups below (1=highest, 4=lowest):
a. –C(CH3)3 –CH2Br –CHO –CH2CH(CH3)2
__3__ ___1__ ___2___ ___4__
3. For the following compound, assign the indicated carbon atoms as R, S, or neither (N) by writing the appropriate
letter on the lines provided
.
___S___A___R____B ___N_____C
4. Consider the two molecules below. On the lines provided, indicate how many stereocenter’s and stereoisomer’s
are present in each molecule.
5. Use the compounds below the answer the questions that follow:
CHO CH3 CHO CHO
HO H HO H H OH HO H
H OH H OH HO H HO H
CH3 CHO CH3 CH3
A B C D
List all pairs of enantiomers. _____A&C __B&C____________________
List all pairs of diasteromers. _A&D__B&D C&D______________________________
List all pairs that are identical _____A&B____________________________
6. Below each of the following structures, write all of the appropriate terms from the list: triose, tetrose, pentose,
hexose, aldose, ketose, pyranose, furanose, “”, “”,deoxy sugar, alditol, aldonic acid, uronic acid
OH
HO OH
Hexose O hexose
O
Ketose furanose
HO H
Uronic Acid
H OH OH
OH OH
HO H
O
OH
7. Draw the ring forms of D-Gulose and the equilibrium it has with the open chain (Haworth projection) give the
proper name of each cyclic form
CHO
H OH
↔ H OH
↔
HO H
H OH
CH2OH
D-Gulose
Name__D-gulopyranose________ Name____D-gulopyranose ___
8. Rank the following compounds in order of increasing boiling point (number them 1-4 from lowest to highest) and
explain reasoning:
The primary and secondary alcohol contain H-bonding which produces a higher boiling point over the aldeydyde and
ether which exhibits a weaker attraction between polar molecules (lower boiling point ) of dipole-dipole forces. The
Primary alcohol is higher boiling then the secondary alcohol due to it not being a branched chain allowing for greater
stack ability and more effective London dispersion to occur in the carbon chain. The aldehyde has a higher boiling point
over the either due to the pi bond allowing it to have greater partial charges and it is more accessible to the molecules
around it.
9. Draw the principal reactant(s) or product(s) of the reactions shown below. If no reaction write NR.
10. Does propanal hydrogen bond with other propanal molecules? If so show the hydrogen bonding if not explain
No, hydrogen bond results from a dipole-dipole force with a hydrogen atom bonded to nitrogen, oxygen or
fluorine. Propanal does not contain a hydrogen off its oxygen atom and does not have nitrogen or flourine so
it is unable to hydrogen bond to other propanal molecles
b. Does propanal hydrogen bond with water molecules? If so show the hydrogen bonding if not explain.
11. The following structure represents, an oligosaccharide. (12 pts)
a. Write the fisher projection and identify the individual saccharide groups in the structure below
b. Point an arrow to each glycosidic bond and identify its type (example β1,4)
c. Is this a reducing sugar? Explain your answer
It is a reducing sugar. The fructofuranose and galactopyranose are locked in their ring form by the glycosidic bonds
(ketal) but the mannopyranose contains a hemiacetal which allows this ring to open into its chain form which contains a
free aldehyde that can be oxidized to a carboxylic acid thus making the sugar a reducing sugar.
12. Label the three functional groups on this molecule including acetals, hemiacetals, ketals and hemiketals as well
as primary, secondary and tertiary where appropriate.
The following tables may be useful for some of the questions above
O O O O O O O O OH OH OH OH
H OH HO H H OH HO H H OH HO H H OH HO H O O O O
H OH H OH HO H HO H H OH H OH HO H HO H H OH HO H H OH HO H
H OH H OH H OH H OH HO H HO H HO H HO H H OH H OH HO H HO H
H OH H OH H OH H OH H OH H OH H OH H OH H OH H OH H OH H OH
OH OH OH OH OH OH OH OH OH OH OH OH
D-Allose D-Altrose D-Glucose D-Mannose D-Gulose D-Idose D-Galactose D-Talose D-Psicose D-Fructose D-Sorbose D-Tagatose