Question

in 1) this reaction,

H OH H H Cl2 NaOH NaCl H20 H2о H20 H H H CI Cyclohexene trans-2-Chloro- 1,2-Epoxycyclohexane (73%) cyclohexanol 02016 Cengage Learning

professor explain that Cl ion can react if there is little water.

So .....

Why does 'Cl react or water react' differ depending on the amount?

Could you explain it in detail and clearly please?

+plus question

2) why epoxide ring can be opened by nucleophile?

3) why electrons which exist other phase cannot react?

Answer 1

Question 1.

If there is only a little water, then the concentration of Cl^-, i.e. [Cl^-] is high, so Cl^- ion opens the halonium intermediate and forms the Cl₂-addition product where both the Cl's added in anti-manner (trans-1,2-dichlorocyclohexane).

If there is more water, then the [Cl^-] is low, then H₂O opens the halonium intermediate and forms the product, where both Cl and OH added in anti-manner (trans-2-chlorocyclohexanol).

Question 2.

Epoxide ring is considered as an electrophilic, three-membered strained ring, hence it is opened readily by nucleophiles.

Question 3.

The electrons which exist other phases can not react because they are in the opposite plane, but for the reactivity, the electrons should be in the same plane as the incoming electrophile or nucleophile.