Topics for Chemistry 321 final.
1. We will cover material through Chapter 10, Section 10.7 (page 414).
Topics you will need to know well are:
1. Bonding and Structure
Lewis structures
draw Lewis structures
assign formal charges where appropriate
resonance
recognize major and minor contributors
allyl systems
delocalization of a lone pair from a heteroatom
aromatic rings, etc.
stabilization increases with number of equivalent contributing structures
molecular orbitals
,  orbitals
assign hybridization to atomic orbitals used to make bonds.
molecular shape and polarity
determine shape at any site in a molecule
determine polarity of bonds in a molwecule
determine molecular polarity
reaction mechanisms
be able to "push arrows" to indicate electron movement
interconvert resonance contributors
show movement of electrons during reaction
2. Acid/Base Chemistry
Lowry-Brønsted acids/bases
Ka, pKa
order of acid strength
strong/weak acids
strong/weak bases
conjugate acids/bases
Lewis acids/bases
electrophiles
nucleophiles
3. Nomenclature
functional groups
know alkanes, alkenes, alkynes, dienes, alcohols, alkyl halides in depth.
main chain vs substituents – endings!!!
4. Shapes of molecules – Stereochemistry
conformations of ethane
staggered, eclipsed
conformations of butane
anti, gauche, eclipsed
conformations of cyclohexane
chair, boat, skew
axial, equatorial
stereochemistry
geometric isomers
cis/trans, E/Z
enantiomers
R/S
diastereoisomers
recognize meso compounds
stereochemistry of newly-introduced chiral centers
when do you get diastereisomers, when do you get a racemate?
5. Alkene Chemistry
reaction energy diagram
reactants and products
reactive intermediates
activated complexes/transition states
reaction coordinate
rate determining steps
electrophilic addition
mechanism
two steps
carbocation intermediate
potential for cation rearrangements
stabilization of carbocations
hyperconjugation
conjugation with a  bond (alkene, alkyne, aromatic ring)
conjugation with a lone pair
Markovnikov's Rule for addition
HCl, HBr, HI, H2O/H+, etc.
effects of lone pairs on electrophilic atom
Markovnikov regiochemistry
anti stereochemistry
absence of free carbocation
Br2/H2O; ICl; IN3; Cl2/H2O; Br2/CH3OH; etc.
free radical addition of HBr – anti-Markovnikov addition.
mechanism for this addition.
hydration
oxymercuration-demercuration
stereospecific anti addition through mercurinium ion in step 1
loss of stereochemistry through free radical in step 2.
Markovniokov regiochemistry
no rearrangements
hydroboration-oxidation
stereospecific syn addition
anti-Markovnikov regiochemistry
catalytic hydrogenation
syn addition of hydrogen
6. Alkyne Chemistry
electrophilic addition
acid-catalyzed hydration
Hg2+ catalyst required
Markovnikov regiochemistry
enol intermediate
keto-enol tautomerization
addition of 1 mole of halogens
anti stereochemistry
addition of 2 moles of electrophile – Markovnikov addition
catalytic hydrogenation
H2/Pt gives alkane
H2/Pd-BaSO4/PbSO4/quinoline ("Lindlar palladium") gives Z alkene
Birch reduction
Na/NH3 or Li/NH3 gives E alkene
acidity of terminal alkynes
RCC—H has pKa ≈ 26
alkynide (acetylide) ions are strong nucleophiles
use as nucleophiles in SN2 reactions.
use of alkynes in synthesis.
7. Diene Chemistry
electrophilic addition
1,2- vs. 1,4-addition
kinetic vs thermodynamic control
Diels-Alder reaction
[4+2] cycloaddition
product is a cyclohexene
diene reacts with dienophile (alkene)
electron-withdrawing groups on alkene accelerate reaction
conjugating groups on alkene accelerate reaction
stereospecific
E alkene gives E cyclohexene product
Z alkene gives Z cyclohexene product
E,E-diene and Z,Z-diene give Z cyclohexene product
E,Z-diene and Z,E-diene give E cyclohexene product
alkynes may be sued as dienophiles in Diels-Alder reactions.
8. Free Radical Chemistry
definition of a radical
species with at least one unpaired electron
stability of radicals
3° > 2° > 1° > Me
allyl, benzyl > 3° (usually)
radical chain reactions
all product is formed in propagation steps
only one product is formed in each propagation step
chain carriers
formed in initiation step
must be present for reaction to continue
are free radicals themselves
"reaction cycle" diagram showing chain carriers
allylic halogenation
N-bromosuccinimide
replacement of allylic hydrogen by halogen
allyl radical intermediate
resonance contributing forms show where reaction will occur
9. Nucleophilic Substitution in Alkyl Halides
mechanism
1-step: SN2
2-step: SN1
carbocation intermediate
rate determining step
stereochemistry:
SN2: inversion
SN1: partial or total racemization
effects of nucleophile strength
strong nucleophiles: RS—, RO—, I—, CN—, N3—; etc.
modest nucleophiles: R3N, Br—; etc.
weak nucleophiles: H2O, ROH, etc.
strong nucleophiles favor SN2, weak nucleophiles favor SN1
effects of solvent
protic solvents favor reactions that go through more ionic states (SN1)
aprotic dipolar solvents favor reactions that go through charge-dispersed transition states
DMF, DMSO, HMPA
aprotic dipolar solvents accelerate SN2 reactions dramatically.
effects of alkyl group structure
SN2: allyl, benzyl > 1° > 2° >> 3°
SN1: allyl, benzyl > 3° > 2° >> 1°
effects of leaving group identity
I > Br > Cl >> F
10. Elimination Reactions of Alkyl Halides
mechanism
1-step: E2
2-step: E1
carbocation intermediate
rate determining step
stereochemistry:
E2: proceeds anti
E1: most stable stereoisomer of alkene usually predominates
regiochemistry
E1: Zaitsev's Rule predicts major product (most substituted alkene predominates)
E2: Zaitsev's Rule predicts stereochemistry if more than one anti path allowed.
effects of alkyl group structure
E1 and E2: 3° > 2° >> 1°
effects of leaving group identity
I > Br > Cl >> F