Chem 210 Final Flashcards
As pka decreases, acidity
increases
A stronger acid, conj base …
weaker and more stable
Formal charge=
VE - (#of bond lines and individual LP e)
Octet rule
Atoms prefer to have 8 electrons in valence shell
Thermodynamics
predicts the most energetically stable product
Kinetics
determines what product will form the fastest
The e rich reactant uses its ___ in a reaction
HOMO electrons
electrons can move to ___ in response
sp2 and neighboring double bond
Unsaturated bond
double/triple bond
saturated
single bond
Polar covalent bonds
C-O
C-Br
C-N
C-Cl
O-H
Nonpolar covalent bonds
C-C
C-H
HONC
1 2 3 4 (bonds)
sp
linear
sp2
trigonal planar
sp3
tetrahedral
pi electrons cannot move to a
sp3 atom
prop
3
but
4
pent
5
hex
6
hept
7
oct
8
non
9
substituent-_____
substituent-parent-suffix
Alkene/alkyne always in ___
suffix
Resonance must maintain
conservation of charge
Best forms of resonance have
neutral atoms (or minimum charge), does not violate octet, never move e towards sp3 atom
EDG- e poor
Stabilizing
EDG - e-rich
Destabilizing
EWG e poor
Destabilizing
EWG e rich
Stabilizing
Electrophile
e poor, LUMO, full positive charge
Nucleophile
e rich, HOMO, full negative charge
To have a geometric isomer, a molecule needs
alkane
To have an enantiomer, a molecule needs
1 chiral center
To have a diastereomer, a molecule needs
2 chiral centers
Good LG
Weak base
ARIO
Atom
Resonance
Induction
Orbital
Explain atom in ARIO
Higher electronegativity -> better acid
Explain resonance in ARIO
More resonance, better acid
Explain orbital in ARIO
sp better than sp2 or sp3
Explain induction in ARIO
EWG stabilize - charge, EDG destabilize - charge
Constitutional isomer
same mf, diff connectivity
Enantiomers
Diff shape and spatial location
Mirror image (both change)
Diastereomer
Not mirror image (1 change)
at least 2 chiral centers
Alkene diastereomer
Highest priority groups on same side of alkene, (Z)
Higher priority group
higher atomic number
Acid catalysts make electrophilic atoms better
electrophiles
Bases make nucleophilic atoms better
nucleophiles
Acidic conditions form
positively charged intermediates
Basic conditions form
negatively charged intermediates
Acid/base rxns
proton transfer
Electrophile/nucleophile rnx
nucleophilic attack
Higher pka side is
favored
Higher LUMO, less
reactivity
Acids are electron
poor
Bases are electron
rich
Best LG, lowest
pkah
Oxidants
Cro3
Reductants
LiAlH4, NaBH4
Low energy base to high energy base
endothermic
SN1 will use H20, but
SN2 will not
Anion
negative charge
Cation
positive charge
tertiary cannot undergo
SN2
3 main reaction categories
Addition, substitution, elimination
When a molecule with a good LG interacts with a base,
elimination occurs
In order for elim to work, there must be a neighboring
H to protonate to form the pi bond and push out the LG
pka favors formation of
weaker acid
Good nuc, high
pkaH
Common acid catalysts
H2SO4
H3PO4
HCl
Common bases
NaOH, NaH, RMgBr
Nucleophiles
NaCN, NaN3, NaBH4, LiALH4
Bimolecular
SN2 and E2
Unimolecular
SN1 and E1
SN1 and E1 form
carbocation intermediate
Polar protic solvents
H20
methanol
ethanol
acetic acid
Polar aprotic solvents
acetone
DMSO
DMF
acetonitrile
Polar aprotic reaction
SN2 or E2
Polar protic reaction
SN1 or E1
SN1 reactions form
racemic mixture 50/50
Consider _____ of electrophile
LUMO
Consider ____ of nuc
HOMO
PCC
1 alc -> Aldehyde
2 alc -> Ketone
KMnO4
1 alc -> carboxylic acid
2 alc -> ketone
CrO3
1 alc-> carboxylic acid
2 alc -> ketone
3 alc -> NO RXN
H2 (lindlar)
alkyne to cis alkene
H2 (PD/C)
alkyne to alkane
LiAlH4
aldehyde -> 1 alc
ketone -> 2 alc
amide -> amine
NaBH4
Aldehyde -> 1 alc
Ketone -> 2 alc
Wedge up, dash
down
Wedge right, dash
left
Eclipsed conformation is least
stable and highest energy
Anti-staggered conformation is
most stable bc 180 apart
Most stable alkene
Most substituted (tetra)
cis
Z
trans
E
H and LG need to be in the same
plane for E2 to work and both must be axial
Axial
up or down
Equatorial
left or right
SN2 cannot do
3 carbon
Any 1 alkyl halide,
SN2 major
Only ever base
NaH and KoTbut
H on wedge cannot be
elim
Oxidants perform
oxidation
Oxidants are
reduced
Reductants perform
reduction
Reductants are
oxidized
sp hybridized atom has a total of ___ electron domains
2
True or false: Resonance movement can occur in a saturated molecule
false
True or false: A good leaving group is also a stable conjugate base
True
The pka of an acid is ________ the pkaH of its conjugate base
equal to
The ______ the conjugate base, the more stable the conjugate base
weaker
The ________ the pka-H, the weaker the conjugate base
lower
Consider the nucleophile’s
HOMO
Consider the electrophile’s
LUMO
A nucleophilic reactant _____ be incorporated into the structure of the product
will
A base (sometimes/always) deprotonates a proton from a molecule
always
An acid makes a molecule a more reactive
electrophile
A strong base has a ________ pkaH
high
A proton bonded to an atom that has more s character is
more acidic
An atom with a higher electronegativity will typically have a ________ nucleophilicity due to a _______ _________
lower, lower, HOMO
A low pka corresponds to a ____ acid
strong
Strong acids and bases have a _______ potential energy
high
A nucleophile uses its LP electrons to attack electrophiles. Electrophiles are attacked in their
LUMO
Constitutional isomers
Same molecular formula, different connectivity of atoms
Stereoisomers
Same connectivity but different spatial arrangement (enantiomers or diastereomers)
Enantiomers
Non-superimposable mirror images (Hands)
Identical physical properties
Diastereomers
Not mirror images
2 chiral centers
Chiral center
A carbon atom bonded to four different groups
sp2 atoms typically draw electrons
to themselves
sp3 atoms typically give
give away electrons
electron rich regions
negatively charged O, sp3 atom
electron poor regions
pi/weak bonds, positive charges, sp2 atoms
Broad peaks typically indicate
O-H (hydrogen bonding)
Double bonds usually give what signals
strong, sharp
EWG
Pull e density away from a molecule
Typically, electroneg atoms or groups with pi-accepting characterisitics
Stabilizing negative charges
Increase acidity by stabilizing the conjugate base
Common EWG’s
NO2
CN
CF3
C=O
EDG
Donate e density through resonance or induction
Often groups with LP or alkyl chains
Stabilize positive charges or e-deficient systems
Decrease acidity by destabilizing the conjugate base
Common EDGs
OH
OR
NH2
R (alkyl groups)
Elimination pi bonds
increase
Addition pi bonds
Decrease
A molecule that takes up more space will be a better
acid
Most basic molecule will NOT have
resonance
Most nucleophile will have a charge
negative
GOOD LG, high
pkaH
A favored reaction will have the pkaH of the LG ________ than the pkaH of the base
lower
Smaller pkaH, stronger
base
OTS pkaH
-1
2^n =
of possible stereoisomers
n= # of chiral centers
Lower pka= acid
Stronger acid (more likely to donate protons)
Lower pkaH= conjugate acid
Stronger conjugate acid (more likely to donate protons)
Low pkaH = base
Stronger base
Strong acid —> conjugate base
weak
Low pkaH = conjugate acid
Strong
Acid donates
protons
Base accepts
protons
Electrophile is charged
positive
Nucleophile is charged
negative
Electron pushing arrows etiquette
Originate from lone pair or middle of bond
Never from H
Antistaggered
Largest groups are 180 apart. most stable conformation
Gauche staggered
Largest groups are 60 apart. Less stable due to steric strain
Eclipsed
All groups aligned, highest energy due to torsional strain
A hydrogen or substituent must be anti-periplanar to a LG for
E2 reaction to occur
Anti-periplanar
Groups are in the same place but opposite sides of the bond axis (180)
For SN2 reactions, primary substrates and strong nucleophiles favor a
single-step (NaOH, NaCN)
For SN1 reactions, tertiary substrates stabilize the
carbocation intermediate, so weak nucleophiles work well (H20, ROH)
Primary carbons favor a ________ attack, but tertiary favor _____
backside, carbocation formation
Polar aprotic
DMSO
Acetone
DMF
Polar protic
H20
Alcohols
Polar aprotic solvents cause
SN2 and E2
Polar protic solvents cause
E1 and SN1
SN1 will cause a mixture
racemic
E2 eliminations favor
strong bases and crowded alkyl halides
E1 elims prefer
weak bases with tertiary substrates, forming a carbocation intermediate
KOtBu as a base typically yields (elimination)
less-substituted alkene
NaOH or NaOEt often yields (elimination)
more substituted alkene
Tosylation coverts OH into
OTS, which is a better LG than OH
NaBH4 is generally used for
ketones and aldehydes only
LiAlH4 is generally used for
carboxylic acids, esters, ketones, and aldehydes
PCC
stops at aldehydes for 1 alc
CrO3 or H2CrO4 can form
carboxylic acids from 1 alc
Secondary alcohols oxidize to
ketones
Hydrogenation of alkenes and alkynes
Alkenes/alkynes are reduced to alkanes (or alkenes)
H2 with Pd/Pt reduces alkenes or alkynes to
alkanes
H2 with Lindlar or Li/NH3 reduce alkynes to
cis alkene, trans alkene
O3/Zn splits alkenes to form
aldehydes/ketones
KMnO4 fully oxidizes alkenes to
carboxylic acids
OH is added to the _______ alkene in markovnikov hydration of alkenes
most-substituted carbon
OH is added to the _______ alkene in anti-markovnikov hydration of alkenes
less-substituted carbon (typically cis)
Bromination of alkenes
Each double bonded carbon gains one bromine atom
Downfield
ppm increases, deshielded protons (near electroneg atoms or pi-systems)
Upfield
ppm decreases, shielded protons (far from electroneg groups)
N+1 rule to find splitting group
n= number of equivalent neighboring protons
Singlet splitting pattern
0 neighbors
Doublet splitting pattern
1 neighbor
Triplet splitting pattern
2 neighbors
Quartet splitting pattern
3 neighbors
Nieghboring non-equivalent protons
split each other’s signals
Protons attached to the same atom
do not split each other
Oxidation #
increases when oxidation
Oxidation # decreases when
reduction
Reduction is the same as
addition and hydration
Oxidation is the same as
elimination and dehydration
A tri-sub alkene is ______ stable than a mono-sub alkene
more
Bulky groups on chair cyclohexanes prefer to be on _______ bonds
equatorial
Tertiary cannot undergo
SN2
NaCN only functions asa
nucleophile
The LG and H should be _______ on chair cyclohexane
both be axial
Stereocenters that undergo SN2 will ______ its stereochemical configuration
invert
In an E2 reaction, the major product orients the bulkiest group trans (true/false)
true
The LG and H must be
anti for E2 to perform
Tertiary and 2 alkyl bromide can readily undergo
E2
An anion with large steric bulk cannot function as a
nucleophile
An oxidant ______ an organic compound
oxidizes
An oxidant is _____ in an organic reaction
reduced
CrO3 will react with
1 alc and 2 alc, NOT 3 alc
