Chemistry 241 Exam #3 Summer 2009
The third exam will be given on Wed, June 23. The test will cover material in Chapters 6 - 9 of the text.
The focus of the exam will be on the properties and reactions of alkenes and on the concept of
stereochemistry. See pages 235-237 of the text for a good summary of alkene reactions.
The following sections of the text will NOT be covered on the exam:
6.1 7.1 7.6 7.9 7.10 9.10, 9.12 – 9.14, 9.17
It is particularly important to study and do the problems for the following sections:
6.2 6.8 6.9 6.10 7.2 7.4 7.5 7.7 9.2 9.5 9.6 9.11
Know how the following reagents react with alkenes:
HCl or HBr + inert solvent (CH2Cl2, Et2O)
Cl2 or Br2 + inert solvent (CH2Cl2, CCl4) Cl2 or Br2 + reactive solvent (H2O, ROH)
H2SO4/H2O (Markovnikov, rearr.) Hg(OAc)2 /H2O; reduction (Markovnikov, mild)
BH3/THF; oxidation (Anti-Markov.) H2/catalyst (for catalytic hydrogenation, syn addn.)
OsO4; reduction (make diol) O3; reduction (alkene cleavage)
NBS (used in place of Br2) deuterium (D2, an isotope of H2)
Topics that will likely be covered on this test:
Electron pushing using curved arrows to show the flow of electrons in a reaction
Hybridization and geometry of carbocations and alkenes
cis/trans, E/Z, and R/S nomenclature
Carbocation stability and rearrangement
Selectivity in alkene reactions: Markovnikov vs. Anti-Markov. syn vs. anti
Definitions for : isomer, stereoisomer, enantiomer, diastereomer,
chiral, achiral, optically active, racemic, meso
Identifying chiral molecules and other objects – use plane of symmetry test
Naming enantiomers – assign priority to each group and determine R or S designation
Meso compounds – contain chiral centers but also posses a plane of symmetry
Number of possible stereoisomers – use the 2n rule (but check for meso cmpds!)
Nitrogen inversion and chirality at other heteroatoms.
Physical, chemical, and biological properties of enantiomers and diastereomers.
Reaction Mechanisms: transition states, intermediates, flow of electrons
Questions that may appear on the exam:
What is the degree of unsaturation for a molecular formula?
Draw valid structures for a given molecular formula.
How do you name this alkene? Which alkene is more stable? Why?
Which carbocation is more stable? Which is stabilized by resonance?
What is the stereochemistry of Br2 addition to a double bond? (anti)
What is the effect of a catalyst on alkene hydrogenation reactions?
How would you make the following alcohol from an alkene? Give reagents and solvents
What is the orientation (cis or trans) of substituents after catalytic hydrogenation of an alkene?
Circle the chiral centers in the molecules shown.
Which compounds are: identical, enantiomers, diastereomers, constitutional isomers?
Draw the proper structure for (R)-2-bromopentane.
Draw examples of: a meso compound with 7 carbons a chiral compound containing bromine