Brainscape's Knowledge GenomeTM

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


See full index

Organic Chemistry > Isomers > Flashcards

Isomers Flashcards

You may prefer our related Brainscape-certified flashcards:
Chemistry 101 flashcards AP® Chemistry flashcards Periodic Table flashcards Organic Chemistry 101 flashcards
1
Q

Isomer Definition

A

compound of same molecular formula, but different molecular structures

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

Structural/Constitutional Isomers

A

only thing they share is molecular formula/weights

least similar of all isomers as they have different chemical and physical properties

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

Same Connectivity? Yes/No

A

Yes -> Stereoisomer

No -> Structural Isomer

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

Require Bond Breaking to interconvert? Yes/No

A

Yes: Configurational
No: Conformational

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

Nonsuperimpossible mirror images? Yes/No

A

Yes: Enantiomer
No: Diasteriomer

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

Physical Properties

A

characteristics that don’t change composition of matter

melting, boiling points, solubility, odor, color, density

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

Chemical Properties

A

reactivity of molecule with other molecules resulting in changes in chemical composition

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

Stereoisomers

A

share same molecular formula/weights, but also share same connectivity/molecular backbone

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

Conformational Isomer vs Configurational Isomer

A

ConFOR: differ in roation around single sigma bonds

ConFI: can be interconverted only by breaking bonds

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

Of all isomers ___ are the most similar

A

Conformational Isomers

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

Conformational Isomer

A

they are same molecule but different points in their natural rotation around a single bond

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

Staggered Conformation

A

lowest energy state, no steric repulsion

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

Anti Conformation

A

for staggered where two largest groups are antiperiplanar (same plane, opposite sides)

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

Gauche Conformation

A

staggered conformation where the two largest groups are 60 degrees apart

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

Eclipsed Conformation

A

staggered with 120 degrees

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

Totally Eclipsed Conformation

A

staggered with 0 degrees, highest energy form, least favorable as largest groups are synperiplanar (next to each other on same plane)

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

The higher the energy of the conformation the…

A

less time it will stay int he conformation

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

Conformational transitions at Room/Low Temp

A

Room: easily overturned
Low: interconversion occurs slowly due to lack of energy

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

Ring Strain

A

Cycloalkanes due to 3 reasons:

angle strain, torsional strain and steric strain

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

Angle Strain

A

bond angles deviate from what they should be

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

Torsional Strain

A

cyclic molecules take gauche or eclipsed interactions

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

Steric/van Der Waals Strain/Repulsion

A

nonadjacent atoms/groups compete for space

common in flagpole interactions for steric strain

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

Cyclohexane Conformations

A

Boat, twist and chair

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

Chair Conformation

A

most stable, lowers all 3 strains for cyclohexane

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

Axial

A

atoms/hydrogens standing perpendicular to plane of ring (up and down)

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

Equatorial

A

atoms/hydrogens sticking out parrallel (outwards) from thr ring

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

Chair Flip bonds…

A

equatorial and axial flip but wedges stay wedges and dashes stay dashes

28
Q

Interconversions can be slowed by…

A

Bulky groups!!

29
Q

Bulky Groups in Cyclohexanes

A

tert-butyls for example

favor equatorial to reduce nonbonded strain

30
Q

Cis

A

bulky groups are on same side of ring

31
Q

Trans

A

bulky groups on opposite sides of rings

32
Q

Configurational Isomer

A

only change form by breaking and reforming covalent bonds

33
Q

Optical isomers

A

enantiomers and diasteriomers

affect rotation of plane-polarized light

34
Q

Chiral

A

if its mirror image cannot be superimposed on the original object; lacks internal plane of symmetry

35
Q

Achiral

A

mirror image can be superimposed

36
Q

Chiral center

A

4 different substituents on a carbon atom

37
Q

Enantiomers

A

two molecules that are nonsumerimposible mirror images of one another

same connectivity but opposite configurations at every chiral center

HAVE SAME PHYSICAL AND CHEMICAL PROPERTIES

only difference: optical activity and reactions in chiral enviornments

38
Q

Diasteriomer

A

share same connectivity and molecules are chiral but not mirror images

DIFFERENT PHYSICAL AND CHEMICAL PROPERTIES

often because they differ at some of their chiral centers

39
Q

Optically Active Compound

A

if it can rotate plane-polarized light

40
Q

Ordinary light is__

A

unpolarized

41
Q

At the molecular level, one enantiomer will rotate plane-polarized light to the same magnitude but ___ direction of its mirror image

A

opposite

42
Q

Dextrorotary (+)

A

compound that rotates polarized light to the right

43
Q

Levorotatory (-)

A

compound that rotates polarized light to the left

44
Q

Amount of light rotation depends on…and depends on…

A

number of molecules a light wave encounters

concentration of compound and length of tube which light passes

45
Q

Standard Conditions For Optical Measurement

A

1dm (10 cm) and 1 g/ml concentration

46
Q

Specific Rotation Equation

A

[alpha] = [alphaobs]/(c*l)

alphaobs is rotation observed , c is concentration, l is 1 dm

47
Q

Racemic Mixture

A

Both + and - held in equal concentrations ro make no optical activity observed

48
Q

Separating Enantiomers

A

react with a single enantiomer to produce 2 diasteriomers which are physically different by nature and use lab techniques such as crystallization, filteration, etc. to seperate the diasteriomers and bring back original enantiomers

49
Q

For any molecule with n number chiral centers…

A

there are 2^n possible steroisomers

50
Q

Diasteriomers can rotate plane-polarized light but can’t tell…

A

the rotations of the other diasteriomer

51
Q

Cis-Trans Isomer

A

type of diasteriomer

substituents differ in position around an immovable bond (double/cyclic)

52
Q

Meso Compound

A

contains plan of symetry causing it to lose optical properties even if it contains chiral centers

equivalent of meso compounds

53
Q

Relative/Absolute Configuration

A

R: configuration of one chiral molecule in relation to another

A: exact spatial orientation of atoms and groups independent of other molecules

54
Q

Cahn-Ingold-Prelog Priority Rules

A

priority of E/Z is assigned based on the atom bonded to the double bonded carbons: the higher the atomic number, the higher the priority

**if atomic numbers are similar, compare the next atom

55
Q

E vs Z

A

E: when highest priority substituent to double bond on each side faces different direction

z: when highest priority substituent to double bond on each side faces the same direction

56
Q

R and S Form Procedure

A

1) Assign Priority
2) Invert The Stereochemistry
3) Draw a circle
4) Write the name

57
Q

RS Assigning Priority

A

highest atomic number gets priority over the lowest one

58
Q

RS: Invert the Stereochemistry

A

if lowest priority substituent isn’t in the back, switch it to the back with the other substituent and remember to switch RS for our final answer

59
Q

RS: Draw a Circle

A

Draw a circle going from 1->2->3

if CLOCKWISE it is R (r is right!)

if COUNTERCLOCKWISE it is S

60
Q

RS: Write the name

A

place R or S in parenthesis and then a hypen to the name

ex: (R)-

if multiple chiral centers, remove the hyphen and location number is within parenthesis before the R/S

ex: (3R) ….

61
Q

Fisher Projection: Horizontal Lines

A

wedges, project OUT of plane

62
Q

Fisher Projection: Vertical Lines

A

dashes, project INTO the plane

63
Q

Assigning Priority to Fisher projection

A

same rules as with RS before, just note rotating 90 degrees leads to changing of R/S

**note by rotating two pairs 90 degrees to let lowest go into the plane, you don’t have to change R/S, original stereochemistry is kept!

64
Q

Assigning Priority to Fisher Projection: 0 Switches

A

ignore lowest priority, give numbers, make circle, write the opposite configuration

65
Q

Assigning Priority to Fisher Projection: 1 Switches

A

swap lowest priority group with vertical group, make circle, write the opposite configuration

66
Q

Assigning Priority to Fisher Projection: 2 Swtiches

A

swap lowest priority group to vertical, swap the remaining two, make circle, take the configuration found

Organic Chemistry (11 decks)

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