Alkynes

Question 1

Hydrohalogenation

Answer 1

1. Addition of HX (X=CL, Br, or I)

2. Markovnikov’s rule is followed. H bonds to the less substituted C in order to form the more stable carbocation

Question 2

Halogenation

Answer 2

1. Addition of X2 (X=Cl or Br)
2. Bridged Halonium ions are formed as intermediates
3. Anti addition of X2 occurs

Question 3

Hydration

Answer 3

1. Markovnikov’s rule is followed. H bonds to the less substituted C in order to form the more stable carbocation
2. The unstable enol that is first formed rearranges to a carbonyl group (ketone).

Question 4

Hydro-boration-oxidation

Answer 4

1. Addition of H2O

2. The unstable enol, first formed after oxidation, rearranges to a carbonyl group (ketone)