CH. 8

Question 1

in the final step of the anti dihydroxylation Once again, notice that water is shown as the base (rather than hydroxide) in order to stay consistent with the conditions.
why?

Answer 1

In acidic conditions, hydroxide ions are not present in sufficient quantity to participate in the reaction, and therefore, they cannot be involved when drawing the mechanism.

Question 2

what are the qualities of Qxymercuration? ( list the reagents)

Answer 2

1. Hg(OAc)2, H20
2. NaBH4

• gives the more substituted side the OH - no rearrangement
  markovnikov product

Step one: Hg(OAc)2 and water(or an alcohol)
Step two: NaBH4

Question 3

what are the qualities of hydroboration- oxidation ? ( list the reagents)

Answer 3

1. BH3
2. H2O2, NaOH
   - gives the least substituted side the OH
   (Favors anti-markovnikov (gives OH to least substituted side))
   Will not rearrange, is a concerted
   4-member transition
   Stereochemistry: H and OH are on the same side

Question 4

what are the qualities of Acid-Catalyzed Hydration

Answer 4

Reagents: H+, H20
H3O+
H2SO4, H20
dilute H2S04 ( sulferic acid)
Occurs through proton transfer and then nucleophilic attack by the lone pair on oxygen
Carbocation rearrangements can still occur
Favors markovnikov product (giving the OH to the most substituted side)
know the mech

Question 5

What are the steps of Anti Dihydroxylation

Answer 5

During the formation of an epoxide, the peroxy acid reacts with the alkene, creating the epoxide and expelling a carboxylic acid. In the acid catalyzing step, both proton transfers and nucleophilic attacks occur to the epoxide to form the final trans diol. A rearrangement does not occur in this reaction.

Question 6

Which functional group(s) would be added to 1-methylcyclohexene using the reagents below:
H3O+

Answer 6

When an alkene is reacted with H3O+ an acid-catalyzed hydration occurs and a hydrogen and a hydroxyl group are added. The H3O+ represents the presence of the both water and an acid source.

Question 7

????

Answer 7

Acid-catalyzed ring opening of an epoxide proceeds with anti-selectivity, causing only the R, R and S, S stereoisomers to form in this reaction.

Question 8

catalytic hydrogenation reaction

Answer 8

the C=C double bond is reduced by addition of H2 across the alkene. Only the two hydrogens are added, nothing else.

Question 9

Hydroboration-Oxidation

Answer 9

The reagents of the reaction indicate a hydroboration oxidation reaction. This involves adding an H and OH to opposing sides of an alkene, as shown below.

Question 10

Dilute, aqueous sulfuric acid is generally used to promote acid catalyzed hydration because:

Answer 10

In an acid catalyzed hydration, the reactant is water. A dilute acid will have more water than a concentrated acid, causing the equilibrium to shift which will drive the reaction towards products.

Question 11

Are Syn products cis or trans

Answer 11

Cis ( both wedge or both dash)

Question 12

Regio-selective

Answer 12

?

Question 13

sterioselective

Answer 13

?

Question 14

Acid-catalized ring opening of an epoxide proceeds with anti-selectivity which is why

Answer 14

only the R,R and S,S formations will result from this molecule.

Question 15

Osmium tetroxide promotes syn-dihydroxylation for forming the osmate ester intermediate,

Answer 15

forming both the S,R and R,S stereoisomers.

Question 16

a catalytic hydrogenation reaction, in which the C=C double bond is reduced by addition of H2 across the alkene.
if there is one chiral center is formed what type of product will be formed?

Answer 16

The product has 1 chiral center so two stereoisomers are produced that are enantiomers of one another.

Question 17

Describe Hydrohalogenation reactions

Answer 17

the treatment of alkenes with HX ( X= Cl, Br, or I)
markovnikov
X on more subsitituted side

if ROOR is added then anti-mark addition occurs

Question 18

Describe Hydrohalogenation reaction mechanism

Answer 18

1. Proton transfer
2. Nucleophilic attack

the alkene is protonated, forming a carbocation intermediate and a bromide ion
the bromide ion functions as a nucleophile and attacks the carbocation intermediate