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CHEM 140 > Final Exam > Flashcards

Final Exam Flashcards

1
Q

Tosylate

A
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2
Q
A
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3
Q

Constitutional Isomers

A

two structures with same molecular formula but **different connectivity **

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4
Q

Electronegativity Trend on Periodic Table

A

increases from:

borrom to top of group

right → left of period

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5
Q

Induction

A

withdrawal of electrons toward more EN atom

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6
Q

Steric #

A

total number of s bonds

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7
Q

Steric number indicates?

A

of e pairs that are repelling each other

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8
Q

Steric number of 4

of lone pairs:

0

1

2

A

sp3

tetrahedral

trigonal planar

bent

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9
Q

Steric number of 3

of lone pairs:

1

0

A

sp2

trigonal planar

bent

trigonal planar

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10
Q

Steric number of 2

A

sp

linear

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11
Q

dipole moment is an indicator of?

A

polarity

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12
Q

Bronsted-Lowry Acid/Base

A

proton donor/acceptor

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13
Q

NH3, C=C, C≡C

strongest acids?

A

C=C < NH3 < C≡C

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14
Q

(4) facors affect stability of a negative charge

A

1) Type of atom that carries charge
2) Resonance
3) Induction
4) Type of orbital where charge resides

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15
Q

2 atoms: dominant effect when:

1) Same row
2) Same group

A

1) EN
- the more EN, the better it can stabilize (-) charge
2) Size
- larger atoms can spread charge over larger space which stabilizes (-) charge

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16
Q

How does the type of orbital affect stability of the negative charge?

A

electrons in sp orbital held closer to nucleus than electrons of sp2 and sp3

electrons are stabilized by being close to nucleus

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17
Q

How do resonance effects make a conjugate base (or compound with negative charge) more stable?

A

charge is delocalized, therefore it is more stable

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18
Q

How do inducive effects stablize a negative charge?

A

by withdrawing electron density away from negatively charged region, thereby stabilizing the negative charge

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19
Q

equilibrium always favours formation of…

A

the more stable (weaker) base

(the more stabilzed negative charge)

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20
Q

Lewis Acid/Base

A

electron pair acceptor/donor

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21
Q

torsional strain

A

difference in energy between staggered and eclipsed conformation

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22
Q

gauche interaction

A

steric interaction when two groups are seperated by 60˚

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23
Q

Anti conformation

A

two groups are seperated by dihedral angle of 180˚

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24
Q

Angle Strain

A

increase in energy associated with bond angle deviated from preferred angle of 109.5˚

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25
Q

Most stable conformation of a cyclohexane ring

A

chair conformation

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26
Q

In the chair conformation….

A

All the H’s are staggered

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27
Q

Axial position

Equatorial position

A

parallel to vertical axis passing through center of ring

positioned at angles parallel to sets of parallel lines making up chair

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28
Q

Ring Flip

A

conformational change in which one chair conformation is converted into the other

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29
Q

Which position is lower in energy (more stable)?

Axial or Equatorial

A

equatorial

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30
Q

1.3-diaxial interactions

A

the steric interactions between a substituent in axial position and other axial H’s on same side of ring

31
Q

1.3-diaxial interactions are equivalent to?

A

gauche interactions

32
Q

Stereoisomers

A

compounds with same molecular formula and sequence of bonded atoms (constitution) but differ in the 3D arrangement of atoms

33
Q

Isomers

A

nonidentical molecules with same formula

34
Q

Constitutional Isomers

A

differ in connectivity of atoms

35
Q

Enantiomer

A

stereoisomers that are nonsuperimposable mirror images of each other

(chiral object)

36
Q

Chiral compounds always only have…

A

ONE enantiomer

37
Q

R and S configurations

A

right (R) and left (S)

38
Q

To redraw molecule in appropriate perspective to find if its R or S…

A

Switch group in 4th position with group on dash, and then switch the other two groups

39
Q

Kinetics refer to?

A

rate of reaction

40
Q

Thermodynamics refers to?

A

equilibrium concentrations of reactants and products

41
Q

electrophile

A

capable of accepting a pair of electons

42
Q

nucleophile

A

capable of donating a pair of electrons

43
Q

strength of a nucleophile is affect by many factors, including?

A

polarizability

44
Q

Polarizability

A

ability of an atom or molecule to distribute its electron density unevenly in response to external influence

45
Q

Polarizability is directly related to?

A

the size of the atom

46
Q

Carbocation arrangements dont usually occur when carbocation is already tertiary (3˚) unless?

A

a rearrangement will produce a resonance-stabilized carbocation

47
Q

allylic carbocation

A

positive charge is located at allylic position

48
Q

Allylic position

A

position next to double bond (alkene)

49
Q

Substitution Reaction

A

reaction in which one group is replaced by another group

50
Q

Good Leaving Groups

A

Halogens

Conjugate bases or strong acids (weak bases)

51
Q

What determines reactivity for:

SN1

SN2

A

carbocation stability

steric hindrance

52
Q

SN2 and SN1 are not observed at?

A

sp2 centers

backside attack - steric hindrance

loss of LG produces unstable carbocation

53
Q

4 factors determing whether SN1 or SN2

A

1) substrate (1˚, 2˚, 3˚)
2) Nu
3) LG
4) Solvent

54
Q

Solvent: what solvents favor:

a) SN1
b) SN2

A

a) polar protic - no H’s connected to EN atom
b) polar aprotic - H’s connected to EN atom

55
Q

polar protic favours SN1 because?

A

it stabilizes polar intermediates and transition state

56
Q

polar aprotic stabilizes SN2 by?

A

raising energy of Nu giving a smaller Ea

57
Q

Elimination Reactions

A

type of organic reaction in which two substituents are removed from a molecule

(H+ from ß position is removed with LG forming double bond) - 1,2 Elimination or ß Elimination

58
Q

LG in:

a) Dehydrohalogenation

b) Dehydration

A

a) Halide
b) Water

59
Q

E and Z configuration

A

E - opposite side of double bond

Z - same side of double bond

60
Q

Alkenes are more stable when they are?

A

Highly substituted

  • electron effect (delocalization)
61
Q

Elimination Reactions always have which (2) steps?

A

loss of LG and H+ transfer

62
Q

Zaitsev vs Hoffman product

A

Zaitsev - more substitued

Hofmann - less substituted

63
Q

Regiochemistry of E2 process can be controlled by?

A

choice of base

64
Q

Nucleophiles (only)

A

Halides (Cl, Br, I)

Sulfur Nu’s

(HS-, RS-, H2S, RSH)

65
Q

Base (only)

A

Hydride (H-of NaH)

66
Q

Strong Nu/Strong Base

A
67
Q

Dehydration Reaction

A

elimination of water to form an alkene

68
Q

2 extra steps in E1

A
69
Q

tert-Butoxide favours?

A

E2 over SN2 when substrate is 1˚

70
Q

2˚ alcohol undergo E1 when?

A

H2SO4 + heat

71
Q

Addition Reaction

A

reverse of Elimination

72
Q

Addition or Elimination dependant on?

A

Temperature

High - elimination

Low - addition

73
Q

What bases will deprotonate a terminal alkyne?

A

alkane (with negative charge)

H2N-

H-

Alkynide anion

74
Q
A

CHEM 140 (3 decks)

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