Exam 2

Question 1

Angle strain

Answer 1

increase in energy associated w/ bond angle other than 109.5

Question 2

torsional strain

Answer 2

difference in energy between staggered and eclipsed conformation

Question 3

Cyclobutane

Answer 3

Angle strain bond angles of 88 degrees.

Slight torsional strain: Puckered conformation

Question 4

Cyclopentane

Answer 4

Very little angle strain.

Slight torsional strain: Forms envelope conformation

Question 5

ring flip

Answer 5

the conversion of one chair conformation into the other

Question 6

1,3-diaxial interactions

Answer 6

steric ineractions between axial substituents in chair conformation

Question 7

flagpole interactions

Answer 7

steric interactions between flagpole atoms in boat conformation

Question 8

cis

Answer 8

same side of ring

Question 9

trans

Answer 9

opposite side of ring

Question 10

constitutional isomer

Answer 10

same formula but different connectivity of atoms

Question 11

stereoisomesrs

Answer 11

same connectivity of atoms, different spatial arrangement

Question 12

chiral

Answer 12

objects that are nonsuperimposable on their mirror images

Question 13

chrial center

Answer 13

a carbon atom bearing four different groups

Question 14

enantiomer

Answer 14

stereoisomers that are mirror images

Question 15

diastereomer

Answer 15

stereoisomers that are not mirror images

Question 16

R

Answer 16

clockwise

Question 17

S

Answer 17

counterclockwise

Question 18

polarimeter

Answer 18

device used to measure the ability of chiral organic compounds to rotate plane-polarized light

Question 19

polarization

Answer 19

orientation of an electric field

Question 20

plane-polarized light

Answer 20

light for which all photons have same polarization

Question 21

optically active

Answer 21

• compound that rotates plane-polarized light
• chiral

Question 22

optically inactive

Answer 22

• compound that does not rotate plane-polarized light
• achiral

Question 23

observed rotation

Answer 23

• extent to which plane-polarized light is rotated by a solution of chiral compound
• depends on
  
  • # of molecules light encounters
  • path length

Question 24

enantiomers rotate plane of light to _________ but ________

Answer 24

equal degrees, opposite directions

Question 25

specific rotation

Answer 25

for chiral compound subjected to plane-polarized light, observed rotation whem std concentration (1g/mL) and path length of 1dm used

Question 26

Specific rotation equation

Answer 26

Question 27

specific rotation is a \_\_\_\_\_\_\_\_\_\_

Answer 27

physical constant

Question 28

dextrorotatory

Answer 28

compounds exhibiting positive (+) rotation

Question 29

levorotatory

Answer 29

compounds exhibiting a negative (-) rotation

Question 30

optically pure

Answer 30

solution containing a single enantiomer

Question 31

racemic mixture

Answer 31

solution containing equal amounts of both enantiomers

Question 32

max # of stereoisomers

Answer 32

2ⁿ n=# of chiral centers

Question 33

compound that contains a plane of symmetry is \_\_\_\_\_\_\_

Answer 33

achiral

Question 34

compound that lacks a plane of symmetry is \_\_\_\_\_\_\_\_\_

Answer 34

chiral

Question 35

meso compound

Answer 35

contains multiple chiralitt centers but is achiral

Question 36

Fischer projections

Answer 36

horizontal----wedges vertical----dashes

Question 37

enthalpy

Question 38

bond dissociation energy

Answer 38

amonut of energy required to accomplish homolytic bond cleavage, producing radicals

Question 39

exothermic

Answer 39

reactions involcing transfer of energy from system to surroundings

Question 40

endothermic

Answer 40

reactinos involving transfer of enerfy from the surroundings to the system

Question 41

entropy

Answer 41

disorder of a system, ultimate criterion for spontaniety

Question 42

to be spontaneous

Answer 42

delta s must be positive

Question 43

GIBBS FREE ENERGY

Answer 43

in order for a process to be spontaneous, delta G must be negative

Question 44

gibbs free energy equation

Answer 44

Question 45

exergonic

Answer 45

process with negative delta G

Question 46

endergonic

Answer 46

process with positive delta G

Question 47

if delta G is negative

Answer 47

Keq is greater than 1 and products are favored

Question 48

thermodynamics

Answer 48

study of relative energy levels (delta G) and equilibrium concentrations (Keq)

Question 49

kinetics

Answer 49

study of reaction rates

Question 50

rate equation

Answer 50

relationship between rate of rxn and [reactants]

Question 51

catalysts

Answer 51

speed up rate by lowering Ea

Question 52

transition state

Answer 52

* peaks on an energy diagram * bond being broken/formed simultaneously, happens momentarily

Question 53

intermediate

Answer 53

valleys on an energy diagram

Question 54

hammond postulate

Answer 54

transition state will resemble reactions for exergonic process, but products for endergonic process

Question 55

ionic reactions

Answer 55

involce participation as reactions, intermediates, or products, usually intermediates

Question 56

nucleophile

Answer 56

electron rich atom

Question 57

electrophile

Answer 57

electron-deficient atom

Question 58

polarizability

Answer 58

ability of an atom to distribute its e- density unevenly as a result of external influences

Question 59

4 arrow-pushing patterns

Answer 59

1. nucleophilic attack 2. loss of a leaving group 3. proton transfer 4. rearrangement

Question 60

carbocation rearrangement

Answer 60

* hydride or methyl shift * makes most stable

Question 61

irreversible reactions:

Answer 61

1. nucleophilic attack involving strong nucleophile 2. proton transfer with a vast difference in pKa on each side 3. carbocation rearrangement

Question 62

allylic carbocation

Answer 62

carbocation in which positive charge is adjacent to a c-c double bond