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38 Cards in this Set
- Front
- Back
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What is the order of priority for naming mixed functional group compounds? |
1) Carb acids 2) Aldehydes 3) Ketones 4) Alcohols |
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What is the difference between a benzyl and a phenyl group? |
A benzyl group is a benzene with one methyl coming off it
A phenyl group is just the benzene ring |
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When is ortho, para, meta used? |
Only when there are two substituents on a benzene ring
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How is E/Z designated? |
By priority of atomic number. If the two highest atomic number groups are on the same side of the double bond, it is Z If there are on opposite sides of the double bond, it is E |
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Which functional group does a peptide bond contain? |
Amides |
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What does neo- designate? |
An isomer of that molecule Ex. neopentane is an isomer of pentane |
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What are the 4 criteria for picking out the major contributor between resonance forms |
1) Has as many octets as possible on each atom2) Has as many bonds as possible on each atom3) Has the negative charge on the most electronegative atom 4) Has as little charge separation as possible |
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How to count an octet on an atom in a lewis structure |
Count ALL electrons surrounding that atom, including the ones it's sharing in bonds Counting just the electrons possessed by that atom gives formal charge |
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What is a lewis acid and base? |
Lewis acids accept electrons -> electrophiles Lewis bases donate electrons -> nucleophiles |
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What are the three most important factors of high acidity? |
1) High electronegativity 2) Resonance 3) Induction |
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How does electronegativity affect acidity? What 3 things about electronegativity must be taken into account? |
Electronegative atoms pull electrons away from a H, so that it can be released to the base more easily Must take into account: 1) The proximity of these atoms to an acidic H 2) The quantity of eneg atoms in a molecule 3) The level of electronegativity |
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What are the three most important factors of high basicity? Why? |
1) Lower electronegativity 2) Lack of resonance Both allows electrons to be more readily available to accept a proton |
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What are isomers? |
Different compounds with the same molecular formula |
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What are constitutional isomers? |
Isomers that have a different atom connectivity |
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What are stereoisomers? |
Isomers that have the same connectivity but differ in the arrangement of their atoms in space S/R |
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What are enantiomers? |
Stereoisomers that are non-superimpossible mirror reflections of each other b/c all chiral centers have been inverted |
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What are diastereomers? |
Stereoisomers that are not mirror reflections of one another b/c only some of the chiral centers have been inverted |
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What are mess compounds? |
Stereoisomers which ARE superimposable upon one another They have a plane of symmetry, image could be folded onto itself Has a chiral center and but ISN'T chiral b/c of its symmetry and superimposability |
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What are conformations? |
Different stereochemical representations of the same molecule that can be interconverted by rotation around single bonds |
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What are configurations? |
Different stereoisomers that can only be interconverted by breaking and reforming bonds |
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Specific rotation vs. observed rotation
What is the symbol of each? |
Specific rotation = a constant that is unique to each compound under std conditions
• symbol = [α] Observed rotation = angle of rotation of polarized light which is found experimentally • dependent upon the concentration of molecules in the polarimeter cell and the length of the polarimeter cell • symbol = α |
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What is the equation that relates specific rotation to observed rotation, concentration, and cell length? |
[α] = α / (c • l) [α] = specific rotation α = observed rotation c = concentration of molecules in polarimeter cell (std = 1g/ml) l = length of polarimeter cell (std = 1 dm) |
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How is optical purity calculated?
What is another name for it? |
AKA enantiomeric excess (e.e.)
α / [α] x 100 = e.e [α] = specific rotation α = observed rotation |
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How is the percent composition of an enantiomeric mixture calculated? |
% of major enantiomer found first: % major = (e.e. x 50) + 50 % minor = 100 - % major |
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What does axial and equatorial denote? Which is more stable |
Configuration of substituents on a cyclohexane chair conformation Axial = vertical Equatorial = horizontal Equatorial gives more stable configuration |
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What does it mean for two molecules to be identical? |
This means that in some conformation, these two will be superimposable |
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How can stereoisomers be separated out from one another? |
Enantiomers have the same physical properties, but diastereomers have different physical properties. Diastereomers can be separated out by distillation or recrystallization, and then turned into their enantiomers |
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First 2 things to look at when considering a nucleophilic attack question! |
What degree is the C of the leaving group? 1° = Sn2 2° = any depending on nuc 3° = Sn1 / E1/ E2 Is the nucleophile strong or weak? Strong = Sn2 / E2 Weak = Sn1 / E1 |
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What symbol at the arrow denotes that elimination should be occurring? |
∆ heat!
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What 4 things make for a stronger nucleophile? |
1) The higher the electronegativity, the better the nuc 2) If they're in the same row, higher polarizability (larger atom size) trumps electronegativity 3) A lone pair -> can either be neutral or negative 4) Not streakily hindered |
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Mechanism of Sn1 and Sn2 reactions What is the product stereochemistry mixture? |
Sn1:
1) LG leaves on it's own, producing a carbocation 2) Nuc attacks carbocation - forms a racemic mixture Sn2: 1) Nuc back side attacks LG, expelling and replacing it all in one step - gives inversion of stereochemistry (if was S, now is R) |
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Mechanism of E1 and E2 reactions |
E1: 1) LG leaves on it's own, producing a carbocation 2) Base takes a β H, and a double bond forms from this β C to the carbocation E2: 1) Base takes a β H, a double bond forms expelling the LG |
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How to form a markovnikov alcohol 2 methods |
Alkene + 1) Hg(OAc)₂ , H₂O / 2) NaBH₄ Alkene + H₃O⁺ |
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How to form an anti-markovnikov alcohol |
Alkene + 1) BH₃ • THF / 2) H₂O₂, NaOH BH₃ • THF can also be B₂D₂ |
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What is a hydrate? On what type of molecule to they most easily form? Why? |
A compound that contains water Can be deprotonated to become an alcohol Hydrates most easily form on aldehydes because these and the most reactive carbonyls |
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From a group of ketones, what are the facts which impact which is most reactive? |
1) Withdrawing groups / electronegative atoms ↑ reactivity 2) Donating groups ↓ reactivity 2) Steric hinderance |
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What effect does conjugation have on an absorption? Worded 3 ways |
It brings it downfield = shifts it to a lower frequency = longer wavelength |
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IR of: Amides Esters |
Amides = 2 bands of medium strength near 3400
Esters = 2+ bands of medium strength in 1000-1300 region |
