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What is a lactone?
circularized ester
What is a lactam?
circularized amide
What is another word for alkene?
olefin
What is another word for epoxide?
oxirane
What is another cyanohydrin?
carbon bonded to an alcohol and a CN
How are substituents ordered in a compound name?
in alphabetical order, not including the prefixes i.e. di, tri etc
How are compounds named when there is an alcohol in them?
so that lowest priority is given to the alcohol
What is the formula for unsaturation?
(2n + 2 + N - X - H) / 2
What are some general trends for electron donating groups?
alkyl groups i.e. CH3, Et etc
lone pair groups/atoms
What are some general trends for electron withdrawing groups?
halides
no lone pair
ie NO2
When does resonance stabilization occur?
in a conjugated system with 3 or more atoms that each have a p orbital
What are the 3 rules for resonance structures?
1) resonance structures can never be drawn through atoms that are truly spy hybridized
2) usually only involve electrons that are adjacent to a pi bond or an unhybridized p orbital
3) resonance structures of lowest energy are the most important
What 3 main criteria does evaluation of resonance structure rely on?
1) contributors in which the octet rule is satisfied for all toms are more important than for ones in which its not
2) contributors that minimize separation charge (formal charge) are better
3) if there are formal charges negatives should be on the more electronegative atoms and positives on the less electronegative atoms
What is a Bronsted-Lowry acid?
molecule that can donate a proton
Rank the stability of a carbocation from most to least stable
3 > 2 > 1 > Me
Rank the stability of a carbanion from most to least stable
Me > 1 > 2 > 3
What is a Bronstad-Lowry base?
accepts protons
What is a Lewis acid?
electron acceptor
What is a Lewis base?
electron donator
In general what is the order of relative acidity for organic compounds?
strong acids sulfonic acids carboxylic acids phenols alcohols and water aldehydes and ketons sp CH sp2 CH sp3 CH
What are the 6 strong acids (for the MCAT)?
HClO4 H2SO4 HNO3 HCl HBr HI
How do inductive effects affect acidity?
the closer an electron-withdrawing group is to the acidic proton, the greater the stabilizing effect and thus the greater the acidity
closer = better
more electronegative = better
electron-donating groups tend to destabilize and thus decrease acidity
Are nucleophiles Lewis acids or bases?
Lewis bases because they donate electrons
Are electrophiles Lewis acids or bases?
Lewis acids because they accept electrons
What are the general trends for nucelophilicity?
1) increases as negative charge increases
2) increases going down a group (larger, more polarizable)
3) increases going left across a period (less electronegative)
What is polarizability?
how easy it is for the electrons surrounding an atom to be distorted
generally down a group atoms become larger and more polarizable
What are some characteristics of a good leaving group?
weak C-LG bond (electronegative atoms or EWGs)
stable and unreactive products (low basicity, stable from resonance etc, large)
What is a better leaving group R-OH or R-OMs?
R-OMs
What is more reactive, a C-C double bond or a strained carbon ring?
C-C double bond
Do cyclopentane and cyclohexane undergo hydrogenation reactions under normal conditions?
no, they are relatively-strain free compared to smaller hydrocarbon rings
What are constitutional isomers?
same formula, different structure
What are conformational isomers?
same formula, same connectivity, different sigma bond rotation
ie eclipsed and staggered conformations
What are stereoisomers?
same formula, same connectivity, different 3D arrangements that cannot be changed by rotation of sigma bonds
If a compound rotates plane polarized light clockwise what is it classified as?
dextrorotatory
+
If a compound rotates plane polarized light counter clockwise what is it classified as?
levorotatory
-
When assigning absolute configuration how does priority work among isotopes?
assigned based on atomic weight
highest weight = highest priority
What are enantiomers?
non-superimposable mirror images
have the opposite absolute configuration at all chiral centres
have many identical physical properties
rotate plane polarized light in opposite directions (same magnitude)
What are diastereomers?
stereoisomers that aren’t enantiomers
opposite absolute configuration at some chiral centres i.e. only one needs to be the same
physical and chemical properties can vary dramatically
specific rotation is different, but there is no relationship between them
What are mess compounds?
need to have an even number of chiral centres and a line of symmetry
optically inactive
have chiral centres but are achiral
Do stereoisomers include E/Z configurations?
yes
How are enantiomers separated?
resolution
attach chiral probes which make them diasteromers than separate based on their different physical properties then release the probe
What are geometric isomers?
a type of diasteromers
have different orientation around a ring or double bond
cis/trans (for double bonds or rings)
E/Z (only for double bonds)
What are epimers?
diasteromers that are opposite at only one chiral centre
ie L-glucose and D-glucose
What are anomers?
ring formations of epimers (which are diastereomers)
ie alpha-glucose and beta-glucose
What is the mobile phase in chromatography usually for?
it is usually a solvent and the mix to be separated
What is the stationary phase in chromatography usually for?
its usually something that the mix to be separated interacts with
What are the 4 options for the force driving the mobile phase in chromatography?
capillary action
gravity
pressure
magnet
What are the 5 physical properties used to separate compounds in chromatography? Will they work for enantiomer separation?
polarity size charge specific affinity volatility no they won't differ for enantiomers because they are physical properties
What is the stationary phase in thin layer chromatography?
silica (SiO2) coated glass plate (polar)
Which compounds move farthest in thin layer chromatography? Do they have a high or low Rf?
nonpolar compounds move farther than polar ones
they have a higher Rf
Explain column/flash chromatography
kind of like TLC using gravity and a column
column is filled with glass beads coated in silica (SiO2)
mixture of compounds to be separated are poured in and extra solvent is added periodically
compounds are collected at the bottom
nonpolar compounds come out first
polar compounds come out later because they interact with the silica
Explain size-based exclusion chromatography
large porous beads line a column
solvent with mixture is poured into the top
small molecules take a longer path so they come out later
large molecules take a shorter path and therefore come out first
used for separating polymers and monomers etc
Explain ionic exchange chromatography
column is lined with resin that is functionalized with charged groups (entire column is either negative or positive) i.e. Na+SO4-
mobile phase containing the mixture to be separated is put through
as it passes through the positively charged groups will replace the Na+ while the negatively charged and neutral species will pass right through
column can then be eluted with a concentrated sodium-containing solution to displace all the positively charged species
frequently used for separating proteins
Explain affinity chromatography
usually used to purify proteins or nucleic acids from cell lysates etc
large scale: column is packed with resin and sample is poured in
smaller scale: solid phase is mixed with sample in a small tube then centrifuged
solid phase with protein of interest goes to the bottom and supernatant can just be decanted
magnetic beads can also be used instead and held by a magnet while the solution is decanted
How are proteins of interest isolated using affinity chromatography?
either an antibody specific for the protein of interest is added and then protein A, G or L linked to a solid support is added (bind mammalian antibodies)
or an affinity tag can be used
added to the N or C terminus
i.e. His tags are 6-10 histidine AAs and will bind ions of resin such as nickel
done under high pH and His-tagged proteins can then be eluted under low pH conditions
Describe generally how HPLC (high performance liquid chromatography) works
mobile phase is pressurized
it is then injected by a syringe and carried to the column (4 different types)
sample is separated into individual flasks by retention time
components are detected and analyzed by UV/vis or mass spectrometry as the exit the column
increases speed and efficiency
What are the 4 types of HPLC? Which is the most common?
normal phase reverse phase size exclusion ion exchange *reverse phase is the most common (assume if not indicated on mcat)