The following three slides leads students to realize that free rotation around C=C bonds does not occur at room temperature. Characteristics of s and p Bonds. s bonds p bonds s bonds formed from end to end p bonds formed from side interaction to side interaction
The following three slides leads students to realize that free rotation around C=C bonds does not occur at room temperature.
s bonds p bonds
s bonds formed from end to end p bonds formed from side interaction to side interaction
______ orbital overlap ______ orbital overlap
______ bond ______ bond
______ reactive ______ reactive
cylindrically symmetrical not cylindrically symmetrical
~ > 3-5 kcal/mole p orbitals must be in same required for rotation plane for bond. What happens to the bond if the orbitals don't overlap?
a. Nothing b. bond becomes stronger c. bond breaks
“Free" rotation How much energy is required
occurs at room temp. for rotation?
Will free rotation occur at room temperature?
a. no b. yes c. can’t predict
a. C-C bond of ethane b. C=C of ethylene
c. CC of acetylene d. no difference
When an alkene reacts wit H-X, this is also a Lewis Acid-Base reaction.
Which is the Lewis acid and which is the Lewis base?
The next two slides explains the exothermicity of additions across p bonds.
What would you expect to be stronger 1 s bond and 1 p bond or 2 s bonds? Would you expect the reaction to be favorable or unfavorable then?
a. SN2 reaction
b. SN1 reaction
c. E1 reaction
d. E2 reaction
e. Addition reaction
a. p bond weaker than s bond
b. p electrons more accessible
c. Both a and b
d. Electrons on atom with high electronegativity
The next 3 slides compares the mechanism in a biological hydration to the recently covered acid catalyzed hydration.
Is this the same mechanism as that shown for the addition of water to 2-methypropene using sulfuric acid as a catalyst?
a. Yes b. No c. Can’t be distinguished
The next 5 slides asks students to explain experimental results after they have already learned something about electrophilic addition.
a. C-H s bond b. C-C s bond c. p bond
a. cyclic halide ion
b. cyclic halidium ion
c. cyclic carbocation
d. cyclic halonium ion
e. cyclic halocarbocation
b. Addition of HX
(reaction of bromide anion with cyclic halonium ion)
a. The reactive intermediate is resonance stabilized.
b. The reactive intermediate is stabilized by the alkyl groups.
c. SN2 reactions require backside displacement.
d. The trans product is more stable.
e. The bromide ion is too unreactive.
Does this appear to be a syn or anti addition?
a. syn b. anti c. neither
a. nucleophile b. electrophile c. neither d. both
In the biosynthesis of fatty acids, the crotonyl ACP is converted to butyryl ACP. What type of reaction does it formally appear to be?
a. dehydration b. hydration
c. alkyl shift d. hydrogenation
e. hydride shift