Orgo: Organic Chemist's Toolbox Flashcards

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1
Q

Formula for units of unsaturation

A

(2C+2+N-H-X)/2

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2
Q

Carbocations are most stable when… vs Carbanions are most stable when (opposites)

A

Carbocations (most to least stable) - 3º, 2º, 1º, methyl

Carbanions - methyl, 1º, 2º, 3º

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3
Q

Are alkyl groups, nitro groups, methoxy groups, NH2 e- donating or e- withdrawing groups?

A

Alkyl - e- donating
Nitro - e- withdrawing groups (increases acidity when attached to a phenol)
Methoxy - e- donating (decreases acidity of phenol ring bc adds charge in and neg charges go on carbons)
NH2 - e-donating group

Online: Electron donating groups generally have a lone pair on the atom directly bonded to the aromatic ring.

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4
Q

If have nucleophile and electrophile, who gets attacked?

A

Electrophile attacked by nucleophile (lewis base)

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5
Q

What increases Nucleophilicity?

A

Nucleophilicity increases with:

a) more neg charge
b) going down periodic table (FOR THE SAME GROUP), increasing size so increase polarizability
c) going left across periodic table (FOR THE SAME ROW), increasing EN bc better able to support the neg charge but we want something that is super unstable with their neg charge and wants to give it away
d) increasing basicity (after all it is a lewis base)

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6
Q

Good LGs are:

A

Resonance stabilize, weak bases (LG ability increases with size), Neutral LG (H2O, ROH - a whole ass alcohol)
If you protonate strong base (bad LG such as HO-, RO-, NH2-, etc) then it becomes a good LG (H2O)

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7
Q

We love anti periplanar except for when…

A

there are two groups that are not too large that can have hydrogen bonding within the molecule - then gauche is preferred

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8
Q

MCAT’s fav nucleophile:

A

H2O (MCAT’s fav nucleophile!)

Cl-/Br-, NH3 (ammonia), CH3- (carbanion)

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9
Q

Periodic trend for nucleophilicity, basicity, and acidity

A

Nuc -> increase left and down
Basicity -> increase left and up (makes sense bc think about how uncomfy the molecule is now and how much more stable it would be with added H)

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10
Q

Examples of common electrophiles - can read to refresh

A

Carbocation, carbonyl compounds, alkyl halides (bc for last two that O or X is really pulling e- density away from that carbon

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11
Q

Molecule is chiral if…
____ compounds are achiral
A chiral center has….

A

It is not superimposable over mirror image
meso achiral
four different groups attached

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12
Q

Periodic trend for nucleophilicity, basicity, and acidity

Acidity neumonic and trends

A

Nuc -> increase left and down
Basicity -> increase left and up (makes sense bc think about how uncomfy the molecule is now and how much more stable it would be with added H)
Acidity neumonic = RAI a.k.a. really angry idiots
Resonance, atom (increase across row, increase down column), Inductive

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13
Q

Molecule is chiral if…
____ compounds are achiral
A chiral center has….
If a molecule is achiral, we cannot assign a absolute configuration

A

It is not superimposable over mirror image or conformer of mirror image
meso achiral
four different groups attached

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14
Q

*Optical activity - clockwise represented by ____, counter clockwise represented by ______
Optical activity value of racemic mixture/pair of enantiomers?
Do they tell you about R or S?

A

+ clockwise, dextrorotary (d)
- counterclockwise, levorotary (l)

racemic mixture/pair of enantiomers -> optical activity value is 0
Tells you nothing about R and S and you can’t determine optical activity without experiment

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15
Q

*Optical activity - clockwise represented by ____, counter clockwise represented by ______
Optical activity value of racemic mixture/pair of enantiomers?
Do they tell you about R or S?
Is there a connection b/w diastereomers and optical activity?

A

+ clockwise, dextrorotary (d)
- counterclockwise, levorotary (l)
Must have a chiral center
racemic mixture/pair of enantiomers -> optical activity value is 0
Tells you nothing about R and S and you can’t determine optical activity without experiment
No connection b/w diastereomers and optical activity

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16
Q

*Geometric isomers

A

Do not require chiral centers
cis/trans alkenes
5 membered rings

17
Q

*Geometric isomers

A

Diastereomers that differ in orientation of substituents around ring or a double bond.
Do not require chiral centers bc can’t rotate around double bond or ring
cis/trans alkenes
rings

18
Q

*Resolution

A

separate racemic mixture

19
Q

*Resolution

A

separate racemic mixture by adding a probe and resulting products will be diastereomers, capable of separation due to different physical properties

20
Q

Anomers

A

Epimers that form as a result of ring closure

Remember anomeric carbon after sugar closes it can have substituent face up or down

21
Q

Meso compounds:

characteristics, optically active?

A

Must contains chiral centers, internal plane of symmetry, symmetrical chiral centers must have opposite configurations
NOT optically active (achiral) - the optical activity of one side of the molecule cancels out the other side

22
Q

*For optical activity you need…

A

CANNOT BE MESO

Must have a chiral center (4 different groups attached)

23
Q

Isomers

Stereoisomers and examples of two types

A

General term for same molecular formula Stereoisomers - same bond connectivity, different spatial arrangement of atoms ex. enantiomers and diastereomers