O-chem 1 Flashcards

0
Q

How do you calculate ring strain?

A

Angle strain+torsional strain

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1
Q

Between two substituents what determines the degree of steric hindrance?

A

The size or bulkiness of the ELECTRON CLOUD, not just the mass

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2
Q

What is torsional strain?

A

The strain due to groups on adjacent carbons

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3
Q

What is non-bonding strain?

A

Strain due to groups that are more than one carbon away

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4
Q

What are the Fischer projection conventions?

A

Horizontal=wedge (out of screen)

Vertical=dashes (into page)

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5
Q

Should you redraw things in the exam?

A

99% of the time try to AVOID redrawing.

–Work with what they give you for times sake

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6
Q

What is required to classify something as an enantiomer?

A

All chiral centers must be opposite

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7
Q

What is required to classify something as an diasteromer?

A

At least one chiral center (but not all) must be switched

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8
Q

Can meso compounds have an enantiomer

A

NO, b/c the mirror image of a meso compound is the same molecule

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9
Q

What is a good way to remember the E and Z confirmations?

A

E-enemies , therefore opposite sides

Z-zame side

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10
Q

What affects boiling point?

A

Strength of intermolecular forces, molecular weight, and POLARITY (a net dipole moment will increase boiling point)

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11
Q

What does a geometric isomer refer to?

A

Cis or trans

E or Z

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12
Q

How can you make a leaving group better in the beginning?

A

Protonate it

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13
Q

Can protic solvents hydrogen bond?

A

YES, remember hydrogen bonds with FON

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14
Q

What is the Zaitsev’s rule?

A

In a beta elimination, the most highly substituted alkene will be the major product

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15
Q

Does I2 react in a radical reaction?

A

NO

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16
Q

What are the four components in the IUPAC system for naming an organic molecule?

A

Locants–Substituents prefixes–Parent–Suffix

Locants: the numbers that tell where the principal functional groups are located on the main chain or ring
Suffix: identifies the compounds principal functional group

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17
Q

What is the IUPAC suffix for carboxylic acid?

A

-oic acid

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18
Q

What is the IUPAC suffix for an Ester?

A

-oate

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19
Q

What is the IUPAC suffix for an Acyl halide?

A

-oyl halide

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20
Q

What is the IUPAC suffix for a Nitrile?

A

-nitrile

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21
Q

What is the IUPAC suffix for an Amine?

A

-amine

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22
Q

What is the IUPAC suffix for a Ketone?

A

-one

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23
Q

What is the IUPAC suffix for an Amide?

A

-amide

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24
Q

What is the IUPAC prefix for an Amine?

A

amino-

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25
Q

What is the IUPAC prefix for Carboxylic acid?

A

carboxy-

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26
Q

What is the IUPAC prefix for an Amide?

A

amido-

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27
Q

What is the IUPAC prefix for an Aldehyde?

A

oxo-

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28
Q

What is the IUPAC prefix for an Alcohol?

A

hydroxy-

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29
Q

What is the IUPAC prefix for a Ketone?

A

oxo- / keto-

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30
Q

What is the IUPAC prefix for a Nitrile/Cyanide?

A

cyano-

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31
Q

What is the IUPAC prefix for an Acyl halide?

A

halocarbonyl-

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32
Q

What is the IUPAC prefix for an Ester?

A

alkoxycarbonyl-

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33
Q

What is the name of a 12-carbon parents chain?

A

dodecane

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34
Q

What type of solvent favors an E1 reaction?

A

Polar protic solvents (these solvents stabilize the carbocation intermediate)

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35
Q

What conditions favor E1 reactions?

A
  • -Protic solvents
  • -Highly substituted carbons
  • -Good L.G.
  • -Weak Nu
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36
Q

What conditions favor E2 reactions?

A
  • -Strong, bulky base
  • -Highly substituted carbons
  • -Temperature
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37
Q

What is the Hoffman rule?

A

When the LESS substituted double bond is created in an elimination reaction
–E2 usually favors the formation of the MORE substituted double bond, but under certain conditions (very bulky base and highly substituted carbons

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38
Q

In what order do alcohols most easily undergo dehydration elimination reactions?

A

Tertiary > Secondary > Primary

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39
Q

What types of conditions or substances produce free radicals, and what type of addition reaction do molecules with the radicals undergo?

A

–Light
–Peroxide
Anti-markovnikov

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40
Q

What is the difference between the Hoffman rule and Zaitsev’s rule?

A

??

41
Q

What does Huckle’s rules about aromatic compounds system?

A

The number of pi electrons in an aromatic compound will equal (4n+2), where n is any non-negative integer (n can’t be a fraction, but it can be zero)

42
Q

Stronger intermolecular forces do what to boiling point and melting point?

A

Increase it

43
Q

What is the order of decreasing boiling point?

A
1-Covalent (diamond, Quartz)
2-Ionic (between polar molecules)
3-Hydrogen bonding
4-Dipole-dipole
5-London Dispersion
44
Q

What is the nucleophilic strength trend in an APROTIC solvent?

A

Increases UP a column
Increases from right to left across a row

Same as basicity trend

45
Q

What is the nucleophilic strength trend in a PROTIC solvent?

A

Increases DOWN
Increases right to left

Remember that protic solvents capable of hydrogen bonding are SUPER POLAR (ion dipole interactions, comparable in strength to hydrogen bonding. Protic solvents stabilize Nu)

46
Q

Every two hydrogens you are missing from the saturation number [CnH*(2n+2)] is how many degrees of unsaturation?

A

1 degree of unsaturation for every two hydrogens missing

47
Q

Does adding oxygen change the degrees of unsaturation?

A

NO

48
Q

Does adding a halogen change the degrees of unsaturation?

A

They are counted just like hydrogens

49
Q

Does adding nitrogen change the degrees of unsaturation?

A

For every nitrogen add an extra hydrogen for the saturated formula. Then calculate how many hydrogens are missing for degrees of unsaturation

50
Q

For every pi bond or ring that a molecule has how many degrees of unsaturation does it have?

A

1 degree of unsaturation (2 hydrogens missing) for every pi bond or ring

51
Q

What are the five rules used to rank BASES?

A

Remember CARDiO
1-Charge, negative charge is more basic typically
2-Atoms (same column look at size, the smaller atom is more basic. Same row then compare electronegativity, the more electronegative the weaker the base)
3-Resonance (the greater number and quality of resonance structures is a weaker base)
4-Dipole Induction (all about electronegativity, also look at proximity)
5-Orbitals (sp3 > sp2 > sp)

52
Q

How do you rank acids?

A

First right the conjugate bases

Then use the base rules

53
Q

Which is more acidic, a Carboxylic acid or ammonium?

A

Carboxylic acid

–The rules don’t help you with this one, just memorize it

54
Q

Between a phenol and a Carboxylic acid which acid is stronger?

A

The Carboxylic acid

–look at the quality of your resonance structures. Two oxygens are better than one oxygen and four carbons

55
Q

What is a stronger base NH2- or C2H- ?

A

NH2-

This you just need to memorize. It will come up again in the alkyne reactions

56
Q

What are constitutional isomers (structural isomers)?

A

Same chemical formula but different bond connectivity

57
Q

What is a stereoisomer?

A

Same bond connectivity

Different 3-D arrangement of the atoms

58
Q

What are cis and trans isomers called?

A

Diastereomers, remember that cis trans isomers are stereoisomers also

59
Q

Any compound that is different than its mirror image is what?

A

Chiral

60
Q

What is the name given to compounds which rotate light to the right?

A

dextrorotatory (+)

61
Q

What is the name given to compounds which rotate light to the left?

A

levorotatory (-)

62
Q

How do you calculate the maximum number of stereoisomers?

A

2^n, where n equals the number of stereocenters (includes both chiral centers and cis/trans stereocenters)

HOWEVER, if you have a MESO compound you won’t reach the maximum

63
Q

Any molecule that has a mirror plane of symmetry is what?

A

Achiral

64
Q

For a molecule to be a Meso compound what is required?

A

1-Must be achiral

2-Must have chiral centers

65
Q

Does a lone pair count as a group for a chiral center?

A

Yes, but with one exception

–Amines with a lone pair are achiral. This is called Amine Inversion

66
Q

The repulsion between the electrons in bonds is called what?

A

Torsional Strain

67
Q

What does Sn2 stand for?

A

Substitution, nucleophilic, bimolecular (two molecules are involved in the slow step)

68
Q

What is the order for decreasing reactivity for SN2 reactions?

A

Me > 1* > 2*

Remember that tertiary electrophiles do not react via SN2

69
Q

What does protic mean in relation to solvents?

A

A solvent capable of hydrogen bonding

70
Q

What happens if you use a protic solvent in an SN2 reaction?

A

It usually slows down the reaction, unless the nucleophile is quite large

71
Q

Can SN1 reactions proceed in an aprotic solvent?

A

NO, it has to have a PROTIC solvent

If you see an aprotic solvent, you know you can’t do SN1

72
Q

What are the classic aprotic solvents?

A
Acetone ( it's aprotic, but still polar so it will react some with nucleophiles)
DMSO
DMF
acetonitrile 
ether
73
Q

What does Zaitsev’s rule predict?

A

Form the most stable pi bond by taking a hydrogen from the carbon with the least number of hydrogens

74
Q

What does anti-peri planar mean for an E2 reaction?

A

The leaving group and the hydrogen being removed have to be oriented 180 deg from each other

75
Q

How do you know if a molecule is capable of cis/trans isomerism?

A

Look at each side of the double bond, if there are two identical structures on one side then it is not capable of cis/trans

76
Q

What are three exceptions to Zaitsev’s rule?

A

1-If you can form a pi bond that is connected to a benzene ring by just one bond allows it to be conjugated (benzylic and resonance stabilized)
2-If you have a bulky base you will form the least substituted pi bond (anti-Zaitsev’s rule)
3-Make sure you have a anti-peri planar hydrogen in a ring (it can’t rotate).This trumps having a more substituted pi bone in the product (E2 doesn’t work otherwise)

77
Q

Cn sp2 halides react via Sn1, Sn2, E1, and E2?

A

NO

78
Q

Why are benzylic and allylic alkyl halides so reactive?

A

Because they are resonance stabilized

79
Q

What are some typical strong Nu but weak bases?

A
CN-
N3-
NR3
PR3
Cl-
Br-
I-
-SH
-SR
80
Q

What is the classic strong base but weak Nu?

A

t-butoxide

Favors E2 b/c it can’t backside attack

81
Q

What are some strong Nu and strong bases?

A

-OH
-OCH3
-OEt
-OR
Just look at the substitution of the halide to determine what mechanism (Sn2 or E2)

82
Q

Does the type of solvent affect the ability of a leaving group to leave?

A

NO

Leaving group ability increases down a column regardless of solvent

83
Q

What is Markovnikovs rule?

A

The Nucleophile adds to the more substituted carbon, and the Electrophiles adds to the less substituted carbon

84
Q

How can you tell if two Fischer projections represent identical molecules, enantiomers, or diastereomers?

A
  • -Look at the number of changes at each chiral center
  • –Even number of changes at each center (0 or 2) = same molecule
  • –Odd number of changes at each center = enantiomer
  • –Odd number of changes at one or more, but not all centers = diastereomer
85
Q

What does ortho- (o), meta-(m), and para-(p) mean and when are they used?

A

Substituted benzene ring substituents are name with these prefixes:
ortho- is used for groups that are one carbon away
meta- is used for groups that are two carbons away
para- is used for groups that are three carbons away

86
Q

What does oxidation with cold KMnO4 of an alkene do?

A

It adds OH groups to either side of the double bond

Remember cleavage comes first, then oxidation

87
Q

What does oxidation with hot KMnO4 in basic solvent, the acidification (add H+ ) of a nonterminal alkene do?

A

Forms to equivalents of Carboxylic acid

Remember cleavage comes first, then oxidation

88
Q

What does oxidation with hot KMnO4 in basic solvent, the acidification (add H+ ) of a terminal alkene do?

A

Forms a ketone and CO2

Remember cleavage comes first, then oxidation

89
Q

What does ozonolysis do to an alkene?

A

It cleaves it at the double bond and create two equivalents of aldehyde

90
Q

What does Lindlars catalyst and quinoline do to an alkyne?

A

It adds hydrogen, but then it is poisoned and can’t continue adding hydrogens past the conversion to a cis-alkene

91
Q

What does Na, and liquid NH3 do to an alkyne?

A

Hydrogens are added to make a trans-alkene

92
Q

What do peroxyacids do to alkenes?

What is an example of a classic peroxyacid?

A

Creates an epoxide

—MCPBA

93
Q

What does ozonolysis do under oxidizing conditions?

A

Turns the newly formed aldehyde into a Carboxylic acid

Remember O3 by itself just breaks a ring at a double bond and adds oxygen double bonds to either side of the original double bond.

94
Q

What does ozonolysis do under reducing (Zn or (CH3)2S ) conditions?

A

The terminal aldehyde stays a terminal aldehyde

95
Q

How do you know if a lone pair of electrons participates in the pi-system of a ring or not?

A

If the atom with the lone pair does not have a double bond, then the lone pair electrons will participate in the pi-system (but only one set of lone pair electrons will participate, even if the are two sets). If the atom does have a pi bond, it’s lone pair electrons will not participate in the pi system

96
Q

What is a quick way to tell if a ring has the correct number of pi electrons to be considered aromatic?

A

If it has an odd number of pi bonds it is aromatic. If it has an even number of pi bonds it is likely anti-aromatic, but check the state of the lone pair electrons if there are any

97
Q

What are the four criteria that must be met in order to determine if something is aromatic, non-aromatic, or anti-aromatic?

A

1-molecule must be cyclic and conjugated
2-must not have any sp3 electrons
3-must be planar (rings with 7 or less atoms can be planar, but if there are more than seven atoms it may or may not be planar)
4-must have (4n + 2) pi electrons

If any of the first three conditions are not met the structure is non-aromatic

If the first three conditions are met, but the the molecule has 4n pi electrons it is anti-aromatic

98
Q

What is a solvolysis reaction?

A

An SN1 reaction in which the solvent serves as the nucleophile

99
Q

How can you predict which molecule has the greatest heat of hydrogenation?

A

Pick the molecule that is the most unstable, and it will release the most energy upon hydrogenation