Download Final Exam Review

Chem 241
Final Exam Practice
1. For these compounds, give proper Lewis structure and molecular shape. Also indicate hybridization
of the central atom (shown in bold). Show all lone pairs of electrons on each Lewis structure.
Electron Pair
Lewis Structure
Orbital
Geometry
Molecular Shape
Hybridization
HNCH2
H2C=CH2
2. Give proper IUPAC name or structure for the following compounds.
structure:
cis -1-tert-butyl-3bromo cyclopentane
_______________________________________
Cl
H
_________________________________________
_________________________________________
3. Circle all compounds that are Lewis acids. (Don’t include compounds that can act only as Bronsted
acids.) Underline compounds that may act as a Lewis base.
HPMe2
+CH
3
MgEt2
CH3CH2CH3
AlBr3
4. a. Draw a ketone (any number of C’s and H’s) containing one tertiary carbon and two chlorine atoms.
Circle all the primary carbons in the structure.
b. Draw valid skeletal structures for three different isomers of C7H16.
1
5. For each pair of compounds below, indicate whether the structures are identical (I), stereoisomers (S),
Cl
or constitutional isomers (C).
Me
Cl
O
OH
6. Give the expected products of the following acid-base reactions.
.. _
Me2N:
OH
+
Et2O
O
+
AlCl3
CH2Cl2
7. Draw the most stable Newman projection for 2,4-dimethylheptane, looking at the C3-C4 bond, then
draw the most stable eclipsed conformation. Label your two structures as staggered or eclipsed.
8. Draw the substituted cyclohexane shown in the two possible chair conformations, and underline the
most stable chair. Calculate the relative energy of each chair using the table at the end of the exam.
On one of the chair structures, include all axial and equatorial bonds and atoms.
Et
HO
C=N
2
9. a. For the compounds below, circle individual atoms that can act as nucleophiles.
O
(CH3)4N
CH3-O
CH3
..
Cl
..
NH2
H
S
CH3
b. For the compounds below, circle individual atoms that can act as electrophiles.
O
Cl
(CH3)4N
CH3
Cl
NH2
H
H
S
CH3
10. For these reactions, draw arrows to indicate the flow of electrons from starting materials to products,
using a regular arrow (
) or “fishhook” as appropriate. For the last two reactions, identify the
nucleophiles (Nu), electrophiles (E), and leaving groups (LG).
O
O
Cl
R
THF
HH
Cl.
H
+
+
Cl
+
H-Cl
Me
R
Me
.
CCl4
+
+
H2O
+
H2O
H+
OH
11. Indicate the geometry of the following double bonds using the E / Z nomenclature.
O
OEt
O
Cl
3
12. Give products for the following reactions. Think about the flow of electrons!
+
HBr
CCl4
O
HO
+
:CH3
+
H Cl
Et2O
H2O
13. Give the major product for each reaction below.
H
Ra Ni
+
H2
+
HBr
Et2O
CCl4
1) O3 / CH2Cl2
2) Red
14. Calculate the “Degree of Unsaturation” for the molecular formulas shown. For one of the formulas,
draw out three valid organic structures (isomers).
a. C5H8PCl _________
b. C7H14Cl2 _________
4
c. C4H9NO
_________
15. How would you complete the following transformations? Fill in the starting material or give reagents
above the arrow for each of the reactions.
O
+
SOCl2
Cl
OH
Cl
OH
H
16. Starting with an alkene or alkyne, prepare these compounds. Show starting materials AND reagents.
Cl
HO
OH
Et
5
17. Given an SN1 reaction between t-butyl bromide and water, decide how the following changes effect
the rate of the reaction? (Do not consider the yield of product.)
Br
OH
+
+
H2O
Change
changing t-butyl bromide to isopropyl bromide
changing t-butyl bromide to t-butyl fluoride
doubling the molar concentration of H2O
doubling the molar concentration of t-butyl bromide
Rate
faster
faster
faster
faster
HBr
of Reaction
slower
no effect
slower
no effect
slower
no effect
slower
no effect
18. For the SN2 reaction of bromomethane and ammonia (NH3), draw out starting materials, transition
state, and product. Sketch a potential energy diagram for the reaction. Also do this for an E2 reaction.
H
H3N:
+
Br
H
H
E
19. Designate each chiral center below as either R or S.
Me
H
O
Br
CH2OH
Me
NMe2
20. For each pair of compounds, indicate whether they are identical (I), enantiomers (E), diastereomers
(D), or constitutional isomers (C),
O
O
H
SH
OH
H
OH
SH
H
OMe
C
Et
OMe
6
CH3
CH3
NMe2
C
Me2N
Et
H
21. Give the major product for these reactions of alcohols.
OH
+
PBr3
THF
Et
+
OH
HCl
Et2O
22. Propose a synthesis of each compound shown, using a substitution reaction or elimiation reaction.
Show the starting material and the reagent (nucleophile or base).
a.
+
Me
b.
+
23. Draw the expected major product, or write NR if no reaction.
R
+
O
Br
Me2N
+
Ph
Et2O
Cl
Et2O
7
O