Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

MCAT-OCHEM > Structure and Stability > Flashcards

Structure and Stability Flashcards

You may prefer our related Brainscape-certified flashcards:
MCAT flashcards
1
Q

saturated

A

if a compound contains no pi bonds and no rings, will have 2n+2 hydrogen atoms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

unsaturated

A

a compounds has at least one pi bond or a ring, will have fewer than 2n+2 hydrogen atoms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

degree of unsaturation (d)

A

(2n+2-x)/2 (x is the number of hydrogens and any monovalent atoms, oxygen has no effect, replace each N with 1 C and 1 H)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

inductive effects

A

the stabilization of reaction intermediates by sharing of electrons through sigma bonds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

electron-withdrawing groups

A

pull electrons toward themselves through sigma bonds, can stabilize e- rich regions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

electron-donating groups

A

push electron density away from themselves through sigma bonds, can stabilize e- deficient regions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

resonance effects

A

stabilize charge by delocalization through pi bonds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

conjugated system

A

contains three or more atoms that each bear a p orbital and are aligned parallel to one another, creating the possibility of delocalized electrons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

localized

A

electrons that are confined to one orbital; either a bonding orbital between atoms or a lone pair orbital

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

delocalized

A

electrons that can interact with orbitals on adjacent atoms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

resonance hybrid

A

the average of all resonance contributors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

strength of an acid refers to:

A

the degree to which it dissociates (or donates its proton) in solution

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

the strength of the acid is determined by:

A

the extent to which the negative charge on the conjugate base is stabilized

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

nucleophiles

A

species that have unshared pairs of electrons or pi bonds and, frequently, a negative charge. “nucleus-loving”

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

nucleophiles are also known as:

A

Lewis bases (electron-pair donators)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

nucleophilicity

A

a measure of how strong a nucleophile is, or how easily it can donate an e- pair

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what are some trends in nucleophilicity?

A

CARIO

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

polarizability

A

how easy it is for the electrons surrounding an atom to be distorted, larger atoms are generally more polarizable and thus more nucleophilic. generally apply down columns in the periodic table.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

electrophile

A

electron-deficient species that often have a positive charge and an incomplete octet. “electron-loving”

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

electrophilicity

A

a measure of how strong an electrophile is, or how well it can accept an electron pair

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

electrophiles are also known as:

A

Lewis acids (electron-pair acceptors)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what determines a good leaving group?

A

they are more likely to dissociate from their substrate because they are more stable in solution. Ex. weak bases, large atoms, less charged/uncharged

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

ring strain

A

arises when bond angles between ring atoms deviate from the ideal angle predicted by the hybridization of the atoms. the strain weakens carbon-carbon bonds and increases reactivity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

what are conditions required for hydrogenation reactions?

A

heat (120 degrees Celsius), H2, Ni, a ring structure with ring strain (ex. cyclopropane, cyclobutane)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

constitutional isomers

A

compounds that have the same molecular formula but different connectivity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

conformational isomers

A

compounds that have the same molecular formula and connectivity, but differ from on another by rotation about a sigma bond (ex. staggered vs. eclipsed)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

which conformation (staggered, eclipsed) is more stable and why?

A

staggered is more stable because it has less electronic repulsion and less steric hindrance

28
Q

what conformation has the absolute maximum potential energy?

A

syn conformation

29
Q

what conformation has the absolute minimum potential energy?

A

anti conformation

30
Q

in the chair conformation, why do larger groups prefer to be in the equatorial axis?

A

to reduce 1,3-diaxial interactions

31
Q

stereoisomers

A

molecules that have the same molecular formula and connectivity but differ in the spatial arrangement of the atoms (cannot be interconverted by rotation about sigma bonds)

32
Q

chiral

A

any molecule that cannot be superimposed on its mirror image

33
Q

achiral

A

a molecule that can be superimposed on its mirror image, has a plane of symmetry

34
Q

stereocenter/stereogenic centre/asymmetric centre

A

a carbon atom that is a chiral centre and attached to four different groups

35
Q

absolute configuration

A

R/S configuration assigned to chiral centres

36
Q

absolute configuration R

A

clockwise

37
Q

absolute configuration S

A

counter-clockwise

38
Q

enantiomers

A

non-superimposable mirror images, can occur when chiral centres are present

39
Q

what are some properties of enantiomers?

A

will always have opposite absolute configurations, will have many identical physical properties, opposite rotation of plane-polarized light (optical activity)

40
Q

what is an important property that differs between enantiomers?

A

the manner in which they interact with plane-polarized light

41
Q

optically active

A

a compounds that rotates the plane of polarized light

42
Q

dextrorotatory (d), (+)

A

a compound that rotates plane-polarized light clockwise

43
Q

levorotatory (l), (-)

A

a compound that rotates plane-polarized light counterclockwise

44
Q

specific rotation

A

the magnitude of rotation of plane-polarized light for any compound

45
Q

what does specific rotation depend on?

A

the structure of the molecule, the concentration of the sample, the path length through which the light must travel

46
Q

a pair of enantiomers will rotate plane-polarized light with:

A

equal magnitude but opposite directions

47
Q

racemic mixture

A

a 50/50 mixture

48
Q

racemate

A

a racemic mixture of enantiomers

49
Q

what is a property of a racemate/racemic mixture of enantiomers?

A

it is not optically active

50
Q

is there a relationship between configuration (R/S, alpha/beta) and optical activity (+)/(-)?

A

NO

51
Q

if n is the number of chiral centres, how do you determine the number of possible stereoisomers?

A

2^n

52
Q

diastereomer

A

stereoisomers that are non-superimposable, non-mirror images

53
Q

what are some of the properties between diastereomers?

A

different physical and chemical properties, no predictable relationship between the specific rotations of diastereomers

54
Q

how do you separate enantiomers (lab process)?

A

RESOLUTION (use an enantiomerically pure chiral probe that associates with the components of the mixture through either covalent bonds or intermolecular forces to create diastereomers with different physical properties, allows for separation by filtration, work-up step generates the isolated enantiomerically pure product)

55
Q

epimers

A

a sub-class of diastereomers that differ in their absolute configuration at a single chiral centre

56
Q

anomer

A

epimers that form as a result of ring closure

57
Q

anomeric centre/anomeric carbon

A

the carbon/chiral centre that distinguishes the two anomers

58
Q

alpha configuration

A

hydroxyl group is down

59
Q

beta configuration

A

hydroxyl group is up

60
Q

meso compound

A

have chiral centres but are not optically active (achiral) because there is an internal plane of symmetry

61
Q

geometric isomers

A

diastereomers that differ in orientation of substituents around a ring or a double bond (constrained by geometry and cannot rotate freely, fixed configuration)

62
Q

cis configuration

A

two longer alkyl chains are on the same side of the molecule

63
Q

trans configuration

A

two longer alkyl chains are on opposite sides of the molecule

64
Q

(Z) configuration

A

higher priority groups are on the same side of the double bond

65
Q

(E) configuration

A

higher priority groups are on opposite sides of the double bond

MCAT-OCHEM (2 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions