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Organic Chemistry > Exam 2 > Flashcards

Exam 2 Flashcards

1
Q

What is a constitutional isomer?

A

different molecule, same molecular formula

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2
Q

What is a conformational isomer?

A

different 3-D shape of the same molecule

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3
Q

What is a staggered conformation?

A

The back atoms are evenly spaced from the front atoms

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4
Q

What is eclipsed conformation?

A

the back atoms are directly behind the front atoms

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5
Q

Is staggered or eclipsed conformation favored and why?

A

stagger… lower energy conformation

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6
Q

What is a dihedral angle?

A

angle in Newman projection between two bonds, one to the front atom and one to the back atom

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7
Q

What is torsional strain?

A

repulsion between bonds when eclipsed

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8
Q

What is steric strain?

A

When non-bonded atoms are too close, causes higher energy (depends on size… amount of strain can vary)

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9
Q

What is gauche?

A

adjacent, large molecules in a staggered conformation

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10
Q

What is anti?

A

large molecules are opposite each other in staggered conformation

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11
Q

What is syn?

A

large groups are eclipsed with each other

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12
Q

Where should the largest groups be in order for the molecule to be in its lowest energy conformation?

A

anti

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13
Q

Where should the largest groups be in order for the molecule to be in its highest energy conformation?

A

syn

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14
Q

Can cyclic molecules rotate bonds?

A

no, they would break

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15
Q

What is angle strain?

A

strain caused by bonds angles being significantly different than what they ideally should be

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16
Q

Which molecule has the butterfly conformation?

A

cyclobutane

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17
Q

Which cyclic molecule has no angle strain?

A

cyclopentane

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18
Q

Which cyclic molecule has the envelop conformation?

A

cyclopentane

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19
Q

What type of strain is present on the envelop conformation?

A

minimal amount of torsional

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20
Q

What is the conformation of cyclohexane?

A

chair conformation

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21
Q

What are the two group types present on a chair conformation?

A

axial and equatorial

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22
Q

What direction does an axial group point?

A

the direction of the bond its coming from

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23
Q

What direction does an equatorial bond point?

A

parallel to the C-C bond in front of or behind it

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24
Q

Why is a boat conformation not as favored as the chair conformation?

A

causes two groups to eclipse so its higher in energy

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25
Q

What does cis mean?

A

both substituents are on the same side of the plane

26
Q

What does trans mean?

A

substituents are on opposite sides of the plane

27
Q

What is a stereoisomer?

A

molecules that have the same molecular formula and atom connectivity but differ in the 3-D arrangement of atoms in space

28
Q

What is a chiral center?

A

SP3 atom with four DIFFERENT groups attached to it

29
Q

How do you assign priorities to chirality centers?

A

highest atomic number goes first, make sure number four group is point back

30
Q

Which direction is the R configuration?

A

clockwise

31
Q

Which direction is the S configuration?

A

counterclockwise

32
Q

How do you determine the amount of stereoisomers for a molecule with more than one chiral center?

A

2^n
n=chiral centers

33
Q

what is an enantiomer?

A

Stereoisomers mirror image.. different configuration at all centers

34
Q

What is a diastereomer?

A

Stereoisomer that is not a mirror image, not all centers change configurations

35
Q

What is a meso compound?

A

molecules that posses chiral centers but are optically inactive due to plane of symmetry

36
Q

Which way are ‘forward’ groups’ represented on Fischer projections?

A

to the left

37
Q

Which way are ‘backward’ groups represented on Fischer projections?

A

to the right

38
Q

What is a D- designation?

A

high priority on the right

39
Q

What is a L- designation in a fischer projection?

A

high priority on the left

40
Q

What is the E- designation?

A

two top priorities are on opposite sides of double bond

41
Q

What is a Z- designation?

A

two top priorities are on the same side of the double bond

42
Q

What is true of the physical properties of an R-,R- or S-,S- molecule?

A

they are all the same except they have opposite sign for rotation of light

43
Q

What is the optical rotation of an chiral molecule?

A

0

44
Q

What is meant by dextrorotary?

A

clockwise rotation of light, alpha > 0, + or d

45
Q

What is meant by levorotary?

A

counterclockwise rotation of light, alpha < 0, - or l

46
Q

What is true of physical properties of diastereomers?

A

not mirror images so all properties are different

47
Q

What are optical isomers?

A

stereoisomers that are optically active

48
Q

What is optically active?

A

rotate plane polarized light

49
Q

What is a terminal functional group?

A

can only be found at the end of the chain or the outside of a ring

50
Q

What FG is oxo- used for?

A

aldehyde

51
Q

What is the prefix for nitriles when there is a higher priority group present in the molecule?

A

cyano-

52
Q

What is the prefix for an aldehyde at the end of a chain?

A

-oxo

53
Q

What is the prefix for an aldehyde branching off a chain or ring?

A

formyl-

54
Q

What is the suffix for an acid chlorine?

A

-oyl chloride

55
Q

What is the suffix for an ester FG in a chain?

A

-oate

56
Q

What is the suffix for an ester FG branching off a ring?

A

-carboxylate

57
Q

What is the suffix for NO2?

A

nitro

58
Q

What is the suffix for OCH3?

A

methoxy

59
Q

What is the suffix for OCH2CH3?

A

ethoxy

60
Q

What is the suffix for SCH3?

A

methylthio

61
Q
A

Organic Chemistry (3 decks)

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