MCAT Organic Chemistry Flashcards

Terms Definitions
acetal
RCH(OR)2
gauche
alkoxy
ester
aniline
antistaggered
benzyl
imine
sec-butyl
vic-dihalide
phosphoric anhydride
Fischer projection
Newman projection
Vinyl
monosubstituted ethylene
lactose
galactose + glu
epoxide
three-membered cyclic ethers
syn-addition
same side addition
propionaldehyde
name for propanal
Haloalkane
compounds with halogen
pyranose
6C sugar, ex: glu
Ketone with NaBH₄
2° Alcohol
alcohols as acids trend
strongest
methyl



weakest
Acetylene
Common name for ethyne
beta lactam
cyclic amide, ex: penicillin
Oxidizing agents and Reducing Agents
O:
K₂Cr₂O₇
KMnO₄
H₂CrO₄
O₂
Br₂
R:
LiAlH₄ --stronger
NaBH₄
H₂ + pressure
reactivity of halogens
most reactive
F
Cl
Br
I
lest reactive
hybridization, bond angles, and shape
achiral
three different substitutents often have plane of symmetry. and rotation of 180 will allow molecule to be superimposed on mirror image
amines
nitrogen containing compound, longest chain attached to nitrogen used in backbone. use e and replace with AMINE. if more complex molecule present, use prefix amino. IF additional group added, use N-
Excluding stereoisomers, how many mono-brominated compounds can be made from 2,5-dimethylhexane?
3
Trigonal-bipyramidal
5 bonds at 120° and 90°
Electron Withdrawing Group
Strong: NO₂, Halogens
Moderate: Carbonyls (Ketone, Aldehyde, Ester, C.A.), Nitrile, Sulfonate
Weak: -X
Ester with LiAlH₄
1° Alcohol + HOR
mesylate
commonly used sulfonate; weak base, great leaving group
Grignard synthesis
*Grignard synthesis of an alcohol
amino acid structure at isoelectric point
electron withdrawing groups direct to which position(s)?
meta
amino acid structure at low pH
covalent bond
sharing of electron between atoms
chiral center
carbon with four different substituents and lack a plane of symmetry
sp3
one s and three p orbitals
What direction does the r configuration take priority?
clockwise
London Dispersion Forces
imfs from 2 instantaneous dipoles
parent peak
mass spectroscopy peak of molecular ions (+1 charge)
Esterification
- Alcohol and C.A. reaction
- they react via Nuke Sub. with a strong acid
- they form an ester + H₂0
Epoxides
- 3 membered cyclic ethers
- more reactive than typical ethers due to ring strain
- react with water in the presence of an acid to form diols.
- this is anti-addition
β-lactams
4 membered cyclic amides that are highly reactive (for amides at least)
ring strain
strain caused by cycloalkanes because bonds get too close to each other
anomers
diasteriomers that exist if a ring closure occurs at the epimeric carbon where two possible diasteriomers may form; the new chiral carbon of the anomer is called the anomeric carbon; ex: glucose
enol
alkenes with a hydroxyl group affixed to one of the carbon atoms composing the double bond
weak bases
what are the best leaving groups?
initiation propagation termination
steps of free radical substitution
carboxylic acid
always receive number one. contain carbonyl and OH group, very oxidized. highest priority functional group.
relative configuration
configuration in relation to another chiral molecule. use it to determine if a molecule is an enantiomer, diastereomer, etc
molecular orbital
when two atomic orbitals combine. obtained mathematically by adding or subtracting wave functions. if sings are the same, make bonding, if different, less stable antibonding.
nonbonded strain
results when nonadjacent atoms or groups compete for space. dominant source of energy in flagpole interactions of the boat conformation. thus it goes in various conformations like chair boat and twist.
Diastereomers that differ at only one chiral carbon are called?
epimers
Carbocation Stability
- same trend as radical stability
3° > 2° > 1° > methyl
- Rearrangement will only occur if a more stable carbocation (C+) can be formed.
Electron Donating Groups
Strong: O-, -O-H, -N-R
-R
Moderate: -O-R
Weak: -R
Saytzeff Rule
- the major product of elimination will be the most substituted
4 > 3 > 2 > 1
Enantiomers
- same molecular formula, but not the same molecule
- same bond to bond connectivity
- mirror images of each other "an ant in a mirror"
- must have opposite absolute configurations of each chiral carbon
- rotate plane polarized light in opposite directions to an equal degree
- same chemical and physical properties except:
1. reaction with other chiral compounds
2. reaction with polarized light
nitrosonium ion
useful ion created from nitrous acid used in many reactions with amines and nitrous acid; notably the diazotization of an amine to make the diazonium ion
pinacol rearrangement
dehydration of an alcohol that results in an unexpected product
dipole moment
occurs when the center of positive charge on a molecule or bond does not coincide with the center of negative charge
C=O in IR spectroscopy
sharp dip at 1700 cm-1
induced dipole
when a dipole moment is induced momentarily in a nonpolar molecule by a polar molecules, ion, or electric field; common dipole in nature
Hofmann degradation
reaction that uses primary amides to create primary amines and CO2 (biproduct)
pyrolysis
occur when a molecule is broken down by heat. used to reduce the avverage molecular weight of heavy oils. c-c- bonds are cleave dand make small chain alkyl radicals that recombine to form different alkanes
gauche conformation
methyl are 60 degrees apart. kinda stable
conformational isomer
most similar. same molecule only at different points in their rotation. show them with newmans projections
If a ring closure occurs at the epimeric carbon, two possible diastereomers may be formed. These are new diastereomers called?
anomers
Dehydrohalogenation
- may proceed by E1 (lack of strong base) or E2 (strong, bulky base)
Phosphoric Acid
- when phosphoric acid is heated it forms phosphoric anhydrides.
- phosphoric acid reacts with alcohols --> esters
Biological example:
- in a living cell at a pH ≈ 7, triphosphates exist as - charged ions, making them less susceptible to nuke attack and relatively stable
- ATP is an important example
Condensation with ketones
- amines react with Aldehydes and Ketones losing water to produce Imines and Enamines
- the amine acts as a nuke attacking the e' deficiency of the C=O C of the ketones
- the ketone undergoes nuke addition
- acid catalyst protonates the product to form an unstable intermediate
- intermediate loses water and a proton to produce either an enamine or an imine
- if the original amine is:
2° --> no proton to give up = enimine
1° --> gives up a proton = imine
Disubstituted Alkene with O₃
Aldehyde
O₃ has excessive O; alkene reactant is being oxidized
haloform reaction
when a methyl ketone reacts with a halogen in the presence of a base and becomes completely halogenated; it then further reacts to produce a carboxylic acid and haloform
stability of carbocations
3° > 2° > 1° > methyl
pi bond
when two p orbitals line up in parallel and electron clouds overlap. it exsits over a single bond.
meso compound
a molecule with an internal plane of symmetry
hot, acidic potassium permanganate
nonterminal alkenes are cleaved to form two molar equivalent of carvoxylic acid ..make keton
cold potassium permanganate
alkenes oxidzed with kmno4, if made with cold, dilue, make OH on each side of double bond, diols or glycol in syn orientation
The number of electrons in the isolate atom, minus the number of electrons assign to the atom in the Lewis structure.
Formal charge
Substituents on Chair conformation
- Most substituent groups are favored in equatorial due to crowding
- Equatorial = projects outward
- Axial = projects upward / downward
Ketone with H₂NNH₂ --> (over) KOH
Alkane + N₂ + H₂O
Iodoform Reaction
- conversion of a methyl ketone into a C.A.
Polar Aprotic Solvents
- can't form H-bonds
- do not form strong bonds with ions and ∴ ⬆ rate of Sn2 reactions while inhibiting Sn1 reactions
- in Sn1: the solvent is often heated to reflux in order to provide energy for the formation of the C+
molecular dipole moment
dipole of a whole molecule due to dipoles within the bonds
optical activity
if a compound is able to rotate plane polarized light.
What does racemic mean?
There are equal concentrations of both mixtures of R and S configurations of the molecule.
Claisen Condensation Reaction
- the aldol reaction with an ester.
- deprotonation of the α-C of an ester and the addition of the anion to the carbonyl carbon of a second ester.
- forms a β-ketoester
- has a biological application in fatty acid synthesis
Diazotization of an Amine
- Nitrous acid is protonated by a strong acid to form the nitrosonium ion.
- nitrosonium ion reacts with the 1° amine --> N-nitrosonium (unstable compound)
- N-nitrosonium tautomerizes to diazenol
- in presence of acid, diazenol dehydrates to diazonium ion.
** Just think diazonium ion when thinking about nitrous acid and 1° amine
O-H in IR spectroscopy
broad dip at 3200 cm-1 to 3600 cm-1
electrophilic addition of free radicals
in presence of peroxide, oxygen or ultraviolet light. antimarkonikov because they want a stable free radical. therefore X ends up on least subsituted carbon
Difference in 1° and 2° Amines
- unlike 1°...2° Amines have an extra R group instead of a tautomeric proton
∴ no tautomer can form
Which is the strongest base? Ammonia, primary amines or secondary amines?
Secondary amines because the carbon alkyl groups act as electron donors and thereby stabilize the conjugate acid.
Carboxylic Acid order of reactivity
Acyl Halide > Acid Anhydride > C.A. > Ester > Amide
Why are alkynes more acidic than alkenes and alkanes?
Alkynes have sp hybridization on the terminal carbon. The resultant negative charge is thus more tightly held due to the greater s character of the hybridization. The great electron density present in the tripple bond also creates sort of an electron-withrawing/inductive effect. Resonance plays no role in its acidity.
Acidities of functional groups in order
C.A > water > alcohol > aldehydes > alkyne > ammonia > deuterium > alkene > alkane
Index of Hydrogen Deficiency
(2n+2) - x / 2
2(#C) + (#N) - H - (#X) + 2 / 2
rule to determine if reduction occurred
1. addition of H2 or H-
2. loss of O or O2
3. loss of X2 (halogens)
sucrose
glu+fruc
alkyne
allyl
phenol
vinylic
toluene
nitro
ketone
mesyl
nitrile
hydroxyl
benzoic acid
1° amine
2° amine
potassium permanganate
kmno4
Ketone + Alcohol
Hemiketal
acetyl
a functional group
amine basicity trend
highest


ammonia
lowest
acetaldehyde
name for ethanal
electrophile
charged, need electrons
diol
two hydroxyl groups
1° Alcohol with PCC
Aldehyde
Aldehyde with NaBH₄
1° Alcohol
formic acid
(aka methanoic acid)
ring flip
when boat flips
character
acts like a certain orbital
Aromatic
4n + 2 π electrons
diastereomers
stereoisomers that are not enantiomers; are not mirror images of each other
UV spectroscopy
(ultraviolet spectroscopy) detects conjugated double bonds (double bonds separated by one single bond) by comparing the intensities of two beams of light from the same monochromatic light source
ethers
functionality is specified by alkoxy-prefix. ROR
enantiomer
nonsuperimposable mirror image of chiral objects, a specific steroisomer.
Square-planar
4 bonds and 2 lone pairs
stereoisomers
same molecular formula, same bond connectivity
Maximum number of optically active isomers
2ⁿ
Tautomerization
equilibrium represented by a proton shift.
ex: ketones tautomerize to enols
isomers
unique molecules with the same molecular formula; are different compounds
intermolecular attractions
attractions between separate molecules that occur solely due to dipole moments; very weak attractions compared to covalent bonds; ex: hydrogen bonding and london dispersion forces
amino acid structure at high pH
isomer
same molecular formula but different structure
nucleophile
nucleus lover. electron rich species that are attracked to charged atoms
anti conformation
most favorable of staggared conformations
alpha hydrogen
H next to carbonyl, unusually acidic
isolectric point
pI, first equivalence point when titrtae with strong B, net charge =0, maximum number of zwitterions
bond energy
energy required to break a bond
carbonyl
a carbon double bonded to an oxygen
crystallization
based upon the principle that pure substances form crystals more easily than impure substances
structural isomers
same molecular formula but different bond-to-bond connectivity
hybridization
formed by mixing different types of orbitals
configuration
spatial arrangement of the atoms or groups of a sterioisomer
basicity
more likely it is to attract positively charged proton. nucleophilic strength decreses: RO->HO>RCO2>ROH>H2O
racemic mixture
rotations cancel each other out therefore no optical activity
hydroboration
diborane add to double bond. boron acts as lewis acid and attaches to less hindered carbon. hydride transferred to adjacent carbon. antimarkonikov, alcohol produced
2^n
how many stereoisomers can a molecule have with n chiral centers
maltose
glu+glu with alpha 1,4 axial O bond polymer
Grignard Reaction
- addition of an alkyl magnesium halide to a carbonyl
- adds one R-group to aldehydes and ketones, forming alcohols
- adds twice to carbonyls with a leaving group, forming a 3° alcohol
Hoffman Elimination
- "less stable alkene (major product), less substituted"
- vs. saytzeff is the minor product in a hoffman
Wittig Reaction
- Ketone to alkene
- phosphorous ylide is used
- ketone behaves normally like a nuke addition from the ylide to form a betaine.
- now unstable and quickly breaks down to trimethylphosphine oxide and the alkene.
- possible to have both cis and trans isomers.
fatty acids
long carbon chains with a carboxylic acid end
hydrogenation
formation of an alkane from an alkene using H2 as a reactant and Ni, Pd, or Pt as catalysts
sp2
one s and two p 120 degree apart
aldehyde
carbonyl located at the end of the chain named by replacing al with e. e.g. butanal
disproportionation
a radical transfers a hydrogen atom to another radical and makes an alkane and alkene
What are isomers?
Different compounds with the same molecular formula.
Electronegativity
- degree to which an atom can attract an electron in a bond that it shares with another atom
three types of spectroscopy
1. nuclear magnetic resonance (NMR)
2. infrared spectroscopy (IR)
3. ultraviolet spectroscopy (UV)
fingerprint region
in IR spectroscopy, it is the range from 600 cm-1 to 1400 cm-1 where many of the complex vibrations that distinguish one compound from a similar compound are found
y-root-en-x-yne
y = position of double bond, x is position of triple bond, root is the prefix representing the length of the principal carbon chain
What is an enantiomer?
Stereoisomers that are mirror images of each other.
Electrophilic Addition
- when you see an alkene, check for Electrophilic addition
- Electrophile ---> electron loving species, so it will have at least a partially + charge, even if it is only from a momentary dipole.
- the double bond is an electron rich environment and it attracts electrophiles.
Breakdown of Alkene + H₂O <---> Alcohol
<-----Concentrated acid and heat
Dilute acid and cold ---------->
Plane polarized light
- resulting light of photons in the same direction
Pi bonds
- Weaker than σ bonds (less energy to break bond), π bonds are always added to an existing σ bond
∴ strengthens the overall bond b/w the atoms
stability of alkyl radicals
3° > 2° > 1° > methyl
clockwise rotation vs. counter-clockwise rotation of plane-polarized light
"+" or "d" and "-" or "l"
Alkane nomenclature
Use the Greek root for the number of carbons followed by the ending, -ane
What does levorotatory mean? Dextrorotatory?
Levorotatory means that the compound rotates plane polarized light to the left. Dextrorotatory rotates the plane polarized light to the right.
Dipole moment formula
u = qd
q = magnitude of charge
d = distance b/w centers of charge
dipole = polar no dipole = nonpolar
halogenation of an alkene
reaction in which a halogen gas adds to (ex: Br2) an alkene or alkyne, removing the double bonds
electrophilic addition of H2O
water can be added to alkenes under acidic conditions. make carbocation. ends with alcohol
Hydrogen Halides added to alkenes
- follow Mark's rule = the hydrogen will add to the least substituted C of a double bond
- (HF, HCl, HBr, HI)
coordinate covalent bond
a bond in which one nucleus of an atom donates both electrons to form a bond with another atom
Alcohol and relation to breaking C-O bond and O-H bond
C-O bond broken: alcohol is behaving like an electrophile
O-H bond broken: alcohol is behaving like a nuke
rules to determine if neither oxidation or reduction occurred
addition or loss of H+, H2O, or HX
What does a Tollen's reagent tell us?
The Ag+ becomes reduced to elemental silver in the presence of reducing sugar to yield a silver "mirror". If the sugar is non-reducing, no silver comes out of solution and we can conclude that it is a polysaccharide or includes an ether.
C3H8 + 5O2 = 3CO2 + 4H2O + heat
combustion reaction occurs through a radical process
Relationship between acidity and conjugate base
- any EWG attached to the α C or the carbonyl tend to stabilize the conjugate base
∴ ⬆ acidity
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Term:
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