Organic Chemistry Flashcards
Suffixes for Functional groups alkane alkenes alkynes alcohols aldehydes ketones carboxylic acids esters amides anhydrides dicarboxylic acids
- ane= alkane
- ene
- yne
- ol or hydroxy-
- al or oxo-
- one or oxo-
- oic acid
- oate or alkoxycarbonyl-, lactone if cyclic
- amide or carbomoyl-, amido- or lactam if cyclic
- anhydride
- dioic acid
Order of lowest to highest priority
alkane alkenes alkynes alcohols ketones aldehydes amides esters anhydrides carboxylic acids
Fischer diagram rules
into plane/dashes= vertical lines
out of plane/wedges= horizontal lines
switching one pair/rotate 90= invert stereochem
switching two pairs/rotate 180= retains stereochem
lowest priority group should be vertical. If not:
-swap one pair, find R/S and take opp
OR
-find R/S normally and take opp
Factors that affect nucleophillicity
Increase:
- negative charged
- low electronegativity
- low sterics
protic solvent= weak base is better nuc (I>Br?Cl>F)
aprotic solvent= strong base better nuc (F->Cl>Br>I)
Sn1 vs Sn2
Sn1- two steps, formation of carbocation is RDS, next attack of nuc. More hindered electrophile better. Racemic usually formed. Rate dependant only on elec.
Sn2- concerted, rate dependant on both nuc and elec., less hindered electrophile better, inversion of stereochem
oxidation reactions and common reagants
feature increase in number of bonds to oxygen
PCC, CrO3/pyridine, H2CrO4, KMnO4, O3, mCBPA,
reduction reactions and common reagants
feature increase in number of bonds to H
LiAlH4, NaBH4
Properties of Alcohols and Phenols
alcohols= hydrogen bonding= high MP/BP
weakly acidic but phenols more acidic due to resonance stabilization of CB
Oxidation of Alcohol rxns
PCC
Primary to aldehydes
secondary to ketones-
Na2Cr2O7 + K2Cr2O7 and Jones Oxidation (CrO3+ H2SO4+ acetone)
primary to carboxylic acids
secondary to ketones
Mesylates and tosylates
make alcohols better LV
protect alcohol from reaction- especially oxidization
ROH+ MsCl/TsCl= ROMs or ROTs and when nuc attacks= R-nuc +MsOH
look up strructure of mesylate/tosylate
Acetal/ketal formation + purpose
HO-R_OH (diol) + aldehyde/ketone= acetal/ketal
protection from LiALH4!!!!!
deprotection with acid
Quinone, hydroxyquinone, ubiquinone
PLEASE REMEMBER STRUCTURES! ADD TO ANKI OR SOMETHING
Oxidized phenol= quinone (double bond O vs OH)— vitamins K1 and K2
hydroxyquinone= quinone with additional hydroxyl groups on ring
ubiquinone= coenzyme Q- electron carrier on Complex 1,2,3, lipid soluble so e- carrier in bilayer
Ketone, Aldehyde- properties/reactivity compared to eachother
aldehyde more reactive to nucs (less steric)
good electrophiles
high BP (dipole) but no H-bonding so less than ROH
alpha H= acidic— ketones have less acidic since donating alkyl groups destabalize carbanion
From aldehydes and ketones,
how are acetals, hemiacetals, and geminal diols formed
how are imines, enamines, and cyanohydrins formed
nucleophillic substitution
hemiacetal- ROH attack (nuc sub)
acetal- OH protonated, water lost, and then ROH attack again (ike Sn1)
geminal diol= water attack, O- pulls H from water
cyanohydrin= OH and CN present on molecule following nuc substitution
imines=NH3, NH2OH, H2N_NH2 react via nuc sub under acidic conditions. OH protonated, water lost and double bond with N formed
enamine= double bond between Cs instead of CN. tautomerization of imine (not thermo favored)
Oxidation of aldehydes
Go to carboxylic acids
KMnO4, CrO3, Ag2O H2O2
Reduction of ketones/aldehydes
LiAlH4 or NaBH4– go to respective alcohol
Keto vs Enol and enolate formation
keto= more favored/common enol= CC double bond. tautomerization. Racemization if chiral carbon enonate= nuc= formed by deprotonation of alpha C by strong base= LDA, OH, KH
alpha C in between two carbonyls= highly acidic
Michael rxn
review!!!!!! alpha-beta unsaturated carbonyl attacked y enolate
Kinetic vs thermo enolates
thermodynamic= enolate formed on more substituted alpha carbon.
high temps, slow reversible rxns, weak small bases
kinetic= enolate formed on less substituted alpha c (less steric- good intermediate)
low temps, fast irreversible rxns, strong sterically hindered base
Aldol condensation
Aldol formation.
enolate formed by deprotonation. Enolate acts as nuc and attacks carbonyl (nuc addition)
strong base, high temps= dehydration
alpha H removed and double bond formed with C that was an electrophile during nuc sub, kicking off the OH
retro aldol condensation
split alphabeta unsaturated carbonyl into two carbonyls
base added, heat applied
properties of carboxylic acids
H-bonding (both O)— higher BP than ROH
acidity of hydroxyl OH
e-withdawing groups like NO2 increase acidicty, aklkyl groups decease, electron donating like NH2 and OCH3- decrease
dicarboxylic acids
first H- more acidic
second H- less acidic (repulsion of -)
alpha H in beta dicarboxylic acids are less acidic than hydroxyl H
synthesis of carboxylic acids
oxidation of primary alcohols and aldehydes
KMnO4, CrO3, NaCr2O7
Nuc acyl substitution to form amides,esters, anhydrides
RCOOH+ RNH2 (NH3, primary, secondary amines)—– amide
RCOOH + ROH (primary)- ester
protonate double bond O to make more electrophillic (acidic conditions)- Fischer esterification
look up mech.
anhydride+ alcohol= ester
triacylgyclerols= esters of fatty acids and glycerol
RCOOH + RCOOH- anhydride
Reduction of carboxylic acids
only by LiAlH4 to alcohol , not NaBH4
nuc acyl sub with addition of H- to form aldehyde. Then nuc addition of H-
Saponification
long chain carboxylic acid (fatty acid) + NaOH/KOH= polar head, nonpolar tail. micelles
B keto acid decarboxylation
intramolecular rxn - sponatenous under heat
enol formation, keto tuatomeriztion
CO2 release
please!!!!!! image
rank reactivity (electrophillicity) of carboxylic acid derivatives for nucleophillic acyl substitution
acid chloride > anhydride> esters> amides
Anhydride cleavage
nuc acyl substitution
anhydryide + amine= carboxylic acid + amide
anhydride + alcohol= carboxylic acid+ ester
anhydride + water= two carboxylic acids
transesterification
ester + alcohol- replace OR group in ester
amide hydrolysis
need strong acid or base— get carboxylic acid + amine
acidic conditions - protonate carbonyl O, nuc acyl sub, nuc=water
basic conditions= nuc=OH-
IR wavenumber
1/wavelength
Which stretches do not show up on IR spectra?
Symmetric stretches do not show up in IR spectra- no net change in dipole moment
O2, Br2- silent
IR spectras to know for MCAT
OH
NH
C double bond O
C triple bond O or N
alkane
alkene
alkynes
OH- broad peak around 3300 and around 3000 for carboxylic acids
NH- sharp peak 3300
C=O - 1700-1750
1900-2200
2800-3000
3000-3150
3300
UV spectroscopy - which compounds is it useful for studying. How are HOMO and LUMO related
most useful for studying compounds with double bonds or with lone pairs (pi or nonbonding electrons and conjugated systems)
smaller the difference between HOMO and LUMO, longer the wavelengths that can be absorbed by the molecule
NMR spectroscopy
deshielding and what makes proton deshielded
chemical shifts to know
Deshielded- higher chemical shift- occurs when protons electron density being pulled away (e-withdrawing groups)
e- donating groups= shielding= lower chemical shift
remember splitting
chemical shifts to know- alkyl (0-3) alkynes (2-3) alkene( 4.6-6) aromatics (6-8.5) aldehydes (9-10) carboxylic acids (10.5-12)
Extraction
like dissolves in like. used to get product and separate out impurites (wash).
aqueous and organic layer- density determines order on top to bottom
add water and shake and extract etc. multiple times= better yield.
Use rotovap to remove solvent
if acid product:
- add base= acid extracted into aqueous phase.
- anion goes in aqueous phase
When to use gravity vs vacumn filtration
gravity= product is in filtrate (liquid)
vacuum- product is the solid
recrystallization
solvent chosen- product only soluble at high temps so desired product recrystallizes upon cooling, exlcuding impurities
distillate
liquid with lower BP evaporates and condenses and collects- called distillate
simple vs fractional vs vacuum distillation
vacuum- high BP liquid distillation
fractional- too similar BPs
TLC/Paper Chromatography
TLC- use silica gel
Paper- use cellulose
after spotting and set up in beaker, eluent climbs the plate (capillary action)
polar and hydrophilic stationary phase
mobile phase is weak polarity
polar samples stick to the plate- move up less (low rf)
nonpolar samples move further up plate (high rf)
Reverse phase chromatography
stationary phase nonpolar
polar move up plate quickly (high rf)
nonpolar sample stick and move up less (low rf)
Column chromatography
Ion exchange
size- exclusion
affinity
Used to separate compounds- including macromolecules
Stationary phase= column with silica or alumina beads-adsorbent
Mobile phase= nonpolar solvent- travels through column down by gravity
Ion-exchange chromatography= beads coated with charges substances to bind compounds with opp charges. (DNA ex)
Size exclusion chromatography=beads have small pores to trap small compounds and allow larger compounds to pass through fast
Affinity chromatography=beads coated with receptor or antibody to compound to have high affinity for it
Gas chromatography
separates vaporizable compounds according to how well they adhere to absorbent in column
stationary phase= coil of metal/polymer
mobile phase= nonreactive gas
can be combined with mass spectrometry= determines molecular weight
High performance liquid chromatography (HPLC)
computer mediated solvent and temperature gradients used
used is small sample size or forces like capillary action will effect results
Synthesis of AA- Strecker Synthesis
- start with aldehyde (protonated). R group is r of AA., NH4Cl, KCN. Ammonia attacks, form imine (keep this amine) CN attack, form nitrile (eventually kicked off)
Molecule formed is aminonitrile - Nitrile protonated. Water attacks, forming imine with hydroxyl. Water attacks again. Form carbonyl again, deprotnonate, and lose NH3. Amino acid formed.
L and D amino acids generated.
Gabriel Synthesis
malonic ester synthesis
potassium phthalimide (acidic, nucleophillic anion) attacks diethyl bromomalonate (Br is LV)
base deprotonates, leaving compound to act as nuc and attack R-Br, attaching R group.
molecule hydrolyzed with strong base and heat- separaton. U need pics.
dicarboxylic acid with R group and amine group formed. Then dexocarboxylated via acid + heat.
Formation of amino acid
L and D AA generated
Inorganic phosphate
H2PO4-2 and HPO4-2 = Pi inorganic phosphates
Pyrophosphate
PPi (p2O7-4) released when phosphdiester bonds formed. Later hydrolyzed to two inorganic phosphate (Pi)
Reason why phosphate bonds high energy
adjacent negative charges, resonance stabilization of phosphates
Phosphoric acid
3 hydrogens. Acts as buffer over large range of pH values since varying pKas
