Ochem Exam 2 Flashcards
(36 cards)
A molecule with 0 chiral centers is…
A molecule with 1 chiral center is…
0 - achiral
1 - chiral
If a molecule’s chiral centers are all the same configuration, then it is a…
identical molecule
Can a molecule with 1 chiral center have a diastereomer? Why or why not?
No, because if the R/S stays the same it is identical, but if the single R/S changes it is is an enantiomer because “all” the R/S changed.
If a molecule has multiple chiral centers but is overall symmetric, it is a…
meso compound
In a molecule with multiple chiral centers, when all the R/S stay the same then the molecules are…
identical
In a molecule with multiple chiral centers, when all the R/S change then the molecules are…
enantiomers
In a molecule with multiple chiral centers, when only some of the R/S change then the molecules are…
diastereomers
Achiral molecules have a —— mirror image.
superimposable
Chiral molecules have a ——- mirror image.
non superimposable
What is a chiral center?
a carbon with 4 different groups
What are the differences in properties between enantiomers and diastereomers?
enantiomers: some properties except how they interact with chiral things
diastereomers: different properties
What is a racemic mixture?
50/50 mix of enantiomers
When the 4th group is in the back, what direction are the R and S configurations?
clockwise - R
counterclockwise - S
When the 4th group is in the front, what direction are the R and S configurations?
clockwise - S
counterclockwise - R
When you prioritize groups for chiral center configurations, how do you name them?
highest atomic number gets highest priority
if the atom is the same, move out to the first point of difference
What bonds are formed and broken in each of the types of reactions?
substitution - break sigma and form sigma
elimination - break 2 sigma and form a pi
addition - break a pi bond and form 2 sigma
What do the thermodynamics and kinetics tell you about a reacation?
thermodynamics - equilibria/extent/stability
kinetics - rate/speef
What does the Keq tell you about a reaction?
> 1 product favored (exo)
<1 reactant favored (endo)
What does the dH or dG tell you about a reaction?
- product favored (exo)
+ reactant favored (endo)
How do you write the rate equation for a reaction?
SN1 and SN2 specifically
rate=k[reactants of the rate determining step]
SN1 - rate=k[substrate]
SN2 - rate=k[substrate][nucleophile]
The rate determining step is the step with the…
highest transition state
How does activation energy affect the rate of a reaction? How is activation energy affected by catalyst and temperature?
higher Ea = slower
lower Ea = faster
higher temp lowers Ea and increases rate
lower temp increases Ea and slows the rate
SN1 has (1/2) step(s) and (does/does not) have an intermediate
2 step, does have an intermediate
SN2 has (1/2) step(s) and (does/does not) have an intermediate
1 step, does not have an intermediate
