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OCHEM 1 > OCHEM 1 importants > Flashcards

OCHEM 1 importants Flashcards

1
Q

An atom with a _______, _______, _______ charge that is “one away” from a _______ or _______ can be involved in resonance

A

lone pair, positive, negative
double or triple bond

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2
Q

What is the one exception to the resonance rule?

A

Lone pair one away form positive charge

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3
Q

The MAJOR resonance contributor is determined by what three rules?

A

1) Octet satisfied
2) minimized amount of charges
3) negative charge on most EN atom

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4
Q

When resonance is possible, the _______ hybridization option will be the truth

A

lower

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5
Q

what 3 physical properties are affected by intermolecular forces?

A

1) boiling point
2) melting point
3) solubility

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6
Q

What are the 3 intermolecular forces from strongest to weakest?

A

1) hydrogen bonding
2) dipole dipole
3) London dispersion (van der Waals)

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7
Q

Boiling point is affected by dispersion forces through _______

A

surface area
- larger surface area = higher boiling point

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8
Q

What is the rule for solubility?

A

like dissolves like

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9
Q

The higher the pKa the _____ the acid

A

weaker

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10
Q

1) Ka»>1 = _______
2) Ka«<1 = _______

A

1) strong acid
2) weak acid

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11
Q

When determining the direction of the equilibrium reaction arrow, the ______ reacts first

A

STRONG REAGENT
- lower pKa (look at acid and conjugate acid)

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12
Q

The stability of the _______ is a good guide to acidity

A

conjugate base

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13
Q

What are the 4 steps to determining acidity?

A

1) Atom EN
2) resonance (quality over quantity)
- while looking at CB
3) Inductivity (EDG or EWG)
4) hybridization

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14
Q

explain the inductive effect on acidity

2-10

A

it decreases the farther the partial positive is from the full negative

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15
Q

How do you differentiate EDGs and EWGs

A

EDG will have lone pairs and or negatives directly connected to main chain
EWG will have partial positive or positive directly connected to main chain
- Halogens are EWGs

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16
Q

explain the effects of hybridization on acidity

A

sp3 < sp2 &laquo_space;sp

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17
Q

What is the only time where size determines acidity and how?

A

hydrogen halides (HF<HCl<HBr<HI)
Oxygen vs sulfur (SH>OH)

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18
Q

nucleophiles are electron _______

A

donors

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19
Q

electrophiles are electron _______

A

acceptors

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20
Q

sigma bonds are allowed to rotate leading to conformations of energy differences, what are the newman conformations of a butane?

think mercedes benz

A

1) totally eclipsed
2) gauche
3) eclipsed
4) anti

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21
Q

What are the two types of strain possible for linear alkanes? Which is preferred?

A

1) steric
2) torsional
- steric is preferred over torsional

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22
Q

What are the two types of strain that make up ring strain?

A

1) angle strain
2) torsional strain

23
Q

What are the 3 types of cyclohexane conformations?

A

1) chair (lowest E)
2) boat (highest E)
3) twist-boat (mid E)

24
Q

substituents in cyclohexane chair conformation can be oriented _______ or _______

A

1) axial
2) equatorial

25
Q

What are the 3 steps to radical mechansims?

A

1) initiation
2) propogation 1 and 2
3) termination

26
Q

Keq > 1 = _______ reaction favored
Keq < 1 = _______ reaction favored

A

1) forward
2) reverse

27
Q

K > 1 is associated with _______ ΔG
K < 1 is associated with _______ ΔG

A

1) Negative
2) Positive

28
Q

What is the formula for bond disassociation energy?

A

the sum of BDE broken - the sum of BDE formed

29
Q

The rate limiting step or RDS is determined by _______

A

highest Ea

30
Q

Hammonds postulate: the structure of the transition state resembles the structure of the closest stable structure in _______

A

energy

31
Q

Cahn-Ingold-Prelog priority is determined by _______

A

atomic number

32
Q

What are two exceptions to chiral compounds without asymmetric atoms?

A

1) biphenyls (Ph-Ph)
- only if sterically crowded
2) Allenes (C=C=C)
- end carbons must have different groups

33
Q

What is the formula to find out how many the max amount of possible stereoisomers in a compound?

A

(2^n) - lines of symmetry

34
Q

What is the key to drawing Fischer projections?

A

1) Draw skeletal with stereochemistry
2) newman projections with longest carbon chain at tops (totally eclipsed)
3) fischer projections

35
Q

Describe geminal and vicinal dihalides

A

geminal are on the same carbon while vicinal are on neighboring carbons

36
Q

What is the only situation where alkyl halides are less dense than water?

A

only alkyl fluorides and chlorides

37
Q

SN2 reactions are _____-step reaction, while SN1 reactions are _____-step reactions

A

one (concerted)
multiple (C+ intermediate)

38
Q

SN2 reactions have ____ molecule(s) in r.d.s

A

2

39
Q

What are the 3 characteristics of a good leaving group?

A

1) electron-withdrawing
2) stable once they have left
3) polarizable to maintain partial bonding in TS

40
Q

Good leaving groups should be _______ bases; therefor, they are the conjugate bases of _______ acids

A

weak
strong

41
Q

What determines the rate of SN2 reactions?

A

1) steric hindrance (slows)
2) resonance (speeds)

42
Q

SN1 reactions have ____ molecule(s) in r.d.s

A

1 (electrophile)

43
Q

Only _______ reactions have the [Nuc] component in the rate-determining step; therefore nucleophile strength is important for _______ reactions

A

SN2

44
Q

nucleophile trends:
1) charged vs neutral
2) from left to right in the periodic table
3) from top to bottom on the periodic table
4) bulky groups vs nonbulky groups

A

1) charged is stronger
2) Nucs get weaker
3) Nucs get stronger
4) nonbulky is stronger

45
Q

What are the differences between polar protic solvents and polar aprotic solvents

A

polar protic solvents have H-bonding, while polar aprotic solvents don’t

46
Q

What are the 2 rearrangements possible in SN1 reactions?

A

1) hydride shift
2) methyl shift

47
Q

_______: both nucleophile and electrophile within the same molecule, results in cyclizations/ring

A

intramolecular

48
Q

When is the only time where the E1 product is not ignored?

A

dehydration of alcohols with no nucleophile available (H2SO4 and heat)

49
Q

most E2 reactions follow _______: the more highly substituted alkene is the major product. The only 2 exceptions are:

A

zietsevs rule:
1) hofmanns rule
2) conjugation

50
Q

E2 reactions take the H that is _______ when in linear or _______ when a cyclohexane

A

anti-coplanar
trans-diaxial

51
Q

What is markovnikovs rule?

A

when adding H-X to C=C the H will add to the C with more H

52
Q

Explain the order of acidity of alkanes, alkenes, alkynes, alcohols, and amines (deprotonation)

A

alkane > alkene > amine > alkyne > alcohol

53
Q

explain why addition of water to alkynes usually involves keto-enol tautomerization

A

doesnt form enol intermediate (C=C-OH) cuz C=O stronger than C=C. So it forms keto (C-C=O)

OCHEM 1 (13 decks)

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