Question

Which of the following statements about the stereochemistry of electrophilic addition of HX to alkenes is true? Group of answer choices Hydrohalogenation occurs with anti stereochemistry only. Hydrohalogenation occurs with syn stereochemistry only. Achiral starting materials yield an unequal mixture of two enantiomers. Hydrohalogenation occurs with syn and anti addition of HX.

Answer 1

Answer:

d) Hydrohalogenation occurs with syn and anti addition of HX

Explanation:

We have to start with the possible options:

a) Hydrohalogenation occurs with anti stereochemistry only.

b) Hydrohalogenation occurs with syn stereochemistry only.

c) Achiral starting materials yield an unequal mixture of two enantiomers.

d) Hydrohalogenation occurs with syn and anti addition of HX.

To answer this question we have to check the mechanism of the addition. The first step of this mechanism is the addition of the hydrogen to the double bond to produce a carbocation and the nucleophile (the halogen "$X^-$"). The second step is the attack of the nucleophile to the carbocation, this attack can be made from the top or bottom (lets remember that the carbocation has a plane structure). Therefore we can have the Syn or the Anti product. See figure 1

I hope it helps!