Addition Reactions of Alkenes

Question 1

What are the reagents of Markovnikov hydrohalogenation reactions?

Answer 1

HX

Question 2

What are the reagents of Anti-Markovnikov hydrohalogenation reactions?

Answer 2

ROOR (alkyl peroxides)

Question 3

What does a hydrohalogenation reaction add?

Answer 3

Adds a halogen across a pi bond

Question 4

Describe the mechanism of a hydrohalogenation reaction.

Answer 4

First, there’a a proton transfer. H ends up on the less substituted side, forming a carbocation intermediate and an ion.
Then, the ion functions as a nucleophile and attacks the carbocation intermediate.

Question 5

What is the intermediate of a hydrohalogenation reaction?

Answer 5

a carbocation`

Question 6

During hydrohalogenation reactions, chiral centers often form. When that happens, what kinds of enantiomers are made?

Answer 6

a racemic mixture - equal amounts of both

Question 7

What is hydration?

Answer 7

the process of adding water (H and OH) across a pi bond

Question 8

What is the reaction mechanism for acid-catalyzed hydration?

Answer 8

Markovnikov addition.

Start with a proton transfer onto the alkene, forming a carbocation intermediate.

Next, water functions as a nucleophile and attacks the carbocation, forming an oxonium ion.

Finally, water functions as a base and deprotonates the oxonium ion.

Question 9

What is the reagent for an acid-catalyzed hydration reaction?

Answer 9

H3O+

Could also be written as H2O and an acid with brackets around, indicating it’s a catalyst.