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56 Cards in this Set
- Front
- Back
sp hybridization |
1s and 1p, |
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sp2 hybridization
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1 s, 2 p
33%s character, 67% p character trigonal planar, 120 degree angles, 3 attached atoms/lone pairs |
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sp3 hybridization
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1s 3 p
25% s character, 75%p character, tetrahedral, 109.5 degree angles, 4 attached atoms/lone pairs |
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saturated molecule
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no pi bonds, no rings
2n+ 2 H atoms (n = number of C) |
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degree of unsaturation
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2n+2-x/2
n= number of carbons, x=H or (F,Cl,Br,I), subtract N from x, ignore O |
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resonance
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delocalized electrons
delocalization of the electrons stables the molecule due to electrons moving between nonhybridized p-orbitals |
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acidity and s character
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acidity increases with more s character
sp3 < sp2 < sp |
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acidity and resonance
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If the conjugate base has resonance, the molecule is more acidic
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Induction
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Electronegativity of nearby atoms causes electrons to shift. The shifts occur through sigma bonds
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Types of reaction intermediates
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1. Carbocations
2. Alkyl Raidicals 3. Carbanions |
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carbocations
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reaction intermediate, positively charged species with a full positive charge on carbon.
Will be sp2 hybridized with an empty p orbital |
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carbocation stability
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tertiary > secondary > primary > methyl
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alkyl radicals
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reaction intermediates that contain one unpaired electron, electron deficient. Will be sp2 hybridized with an unpaired electron in an unhybridized p orbital
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alkyl radical stability
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tertiary > secondary > primary > methyl
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carbanions
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reaction intermediates with a full negative charge on carbon,
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carbanion stability
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methyl > primary > secondary > tertiary
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electron withdrawing groups
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groups that are more electronegative than carbon pull electron density toward them through sigma bonds. Tend to stabilize electron rich intermediates (carbanions)
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electron donating groups
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groups that are less electronegative than carbon tend to donate electrons. Tend to stabilize electron-deficient intermediates (carbocations, radicals). On the MCAT: alkyl substituents.
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homolytic cleavage
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one electron of the bond broken goes to each fragment of the molecule creating 2 radicals
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heterolytic cleavage
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both electrons go to the same atom forming a cation and anion
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Isomers
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different compounds having the same molecular formula
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Structural/constitutional Isomers
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Different connectivity (same molecular formula),
different physical and chemical properties |
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Conformational Isomers
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Different rotation about a sigma bond (same connectivity, same molecular formula),
Same physical and chemical properties, cannot be isolated, NEWMAN projections (anti/gauche) |
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Stereoisomers
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Differ in spatial arrangement (same molecular formula and connectivity)
Two types of stereoisomers: diasteriomers, enantiomers |
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Enantiomers
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type of stereoisomer (different spatial arrangement),
1. Have at least one chiral center, 2. Each isomer has opposite configuration (R,S), inversion of every stereocenter in molecule, 3. Each isomer has equal optical rotation but opposite sign (+/-), 5. All other chemical properties are the same |
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Racemic mixture
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50:50 mixture of enantiomers,
achiral, no optical activity, process of separating enantiomers is called resolution |
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Diastereomers
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type of stereoisomer, nonsuperimposable, non mirror-images,
differ in absolute configuration of at least one (but not all) carbons, physical and chemical properties can be very different, specific rotation is different but there is no relationship |
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Epimers
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Subclass of diastereomers,
inversion of only ONE stereocenter, all epimers are diastereomers (not all diastereomers are epimers) |
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Absolute configuration
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R or S assignment of chiral centers
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Relative configuration
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D or L assignment based on hydroxyl (-OH) group on the highest numbered chiral center in a Fischer projection.
D: hydroxyl group is on the right, L: hydroxyl group is on the left |
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Anomers
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Epimers that form as a result of ring closure.
Only with regards to sugar chemistry, New stereocenter is formed at anomeric carbon, named alpha (OH group down) or beta (OH group up) |
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Meso compound
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An internal plane of symmetry in a molecule that contains chiral centers.
Not optically active, type of stereoisomer |
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Geometric Isomer
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Diastereomers that differ in orientation of substituents around a ring or double bond, |
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Ortho-Para Directors are |
Activating (except for Halide Deactivators) * -NH2 (amino) * -OH (hydroxy) * NHCOCH3 (acetamide) * OCOCH3 (acetoxy) * OR (alkoxy) * CH3 (methyl) * C6H5 (phenyl) |
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Meta Directors are |
Deactivators * -NO2 (nitro) * -NR3 (ammonium) * -CX3 (trihalomethyl) * -CN (cyano or nitrile) * -SO3H (sulfonic acid) * -CHO (aldehyde) * -COR (ketone) * -COOH (carboxyl) |
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Ortho-Para Directors Strong Activators |
* NH2 (amino)
* -OH (hydroxy) |
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Ortho-Para Directors Moderate Activators |
* NHCOCH3 (acetamide)
* OCOCH3 (acetoxy) * OR (alkoxy) |
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Ortho-Para Directors Weak Activators |
* CH3 (methyl)
* C6H5 (phenyl) |
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Ortho-Para directors Weak Deactivators |
-I -Br -Cl -F |
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Meta Directors Strong Deactivators |
* -NO2 (nitro)
* -NR3 (ammonium) * -CX3 (trihalomethyl) |
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Meta Directors Moderate Deactivators |
* -CN (cyano or nitrile)
* -SO3H (sulfonic acid) * -CHO (aldehyde) * -COR (ketone) * -COOH (carboxyl) |
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An Activating Group |
Groups which lower the rate of electrophilic substitution. Activators activate the ring, making it more reactive. |
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A Deactivating Group |
Any substituent that lowers the rate (from benzene) of substitution. Deactivators make the ring less reactive. |
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TLC |
Separates compounds based on polarity -Used to separate small amounts of solids or high boiling point liquids -Uses silica gel |
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TLC |
Stationary Phase:
Mobile phase: a polar, silica gel plate -Non-polar migrate faster, high Rf -Polar, slower, low Rf
Rf (Retention Factor): spot solvent front Rf can never be smaller than 1 or negative. |
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Column Choromatography |
Separates large amounts of solids or high bp liquids. Separates based on polarity differences.
Mobile phase: a polar, silica gel plate -Non-polar migrate faster, high Rf -Polar, slower, low Rf
Rf (Retention Factor): spot solvent front Rf can never be smaller than 1 or negative. |
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HPLC |
Separates based on polarity Are 2 phases.
Can be done in reverse.
Again: non-polar Mobile phase: a non-polar, migrate faster -Polar, slower, low Rf This flips in Reverse HPLC, with a polar plate and polar molecules traveling more quickly. .
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Ion Exhange Chrom. |
Separates compounds based on differences in charge.
Cation-exhange resin: retains cations Anion-exhange resin: retains anions
-Separates mixtures of charged amino acids, proteins, or nucleotides
Stationary phase: resin containing anionic/cationic groups with counter ions.
Mobile phase: buffered solution |
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Affinity Chrom. |
Separates biochemical mixtures based on highly specific lock-&-key interactions
Used to separate proteins from blood serum or a cell lysate.
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Immuno-Affinity hrom. |
Stationary phase: small particles of resin linked to anti-body-binding proteins -Magnetic beads may serve as an alternative stationary phase. |
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Metal ion Affinity Chrom |
Uses recombinant proteins: proteins grafted with a tag at its C or N terminus.
Have a resin that will attract the protein, elute everything else, then elute it out |
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Gas Chrom. |
Separates based on diffs in volatility or bpt. -Used to separate small amounts of low bpt compounds.
-Low bpt compounds elute first. -High bpt compounds elute last.
Volatility is the tendency of a molc to convert to gas.
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Gas Chromatogram |
The no. of compounds = the no. of peaks
The relative quantity of each compound from each peak area
The volatility/bpt of the compuonds can be read from the time axis. |
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Distillation |
Only one phase, seperates based on bpt differences.
Used to separate large amounts of low bpt compounds.
Are a measure of intermolecular forces between liquid molcs. |
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Chromotagraphy |
Uses 2 phases |
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Bpt and Volatility are: |
Inversely related to one another. |