Question

   1. Show all the products obtained from the ozonolysis of the following alkenes.

a.     1-hexene

b.         2-methyl-2-pentene

c.         cis-3-methyl-3-hexene

d.         2,3-dimethylbut-2-ene

e.        2,3-dimethylpent-2-ene

2. Stating whether the reaction between (+)-3-iodo-3-methylheptane and sodium ethoxide would follow S_N1 or S_N2 substitution mechanism, show the complete mechanism of the reaction emphasizing stereochemical changes observed, if any.

3. Showing the detailed stereochemistry, give the mechanism and products of epoxidation (with m-CPBA) and borane (with BH₃-THF) addition reactions on cis- and trans-3-methylhex-3-ene.

Answer 1

Solution :-

Q1 - In the ozonolysis reaction the double bond of alkene is cleaved by the ozone which result into the formation of the two carbonyl products.

followins picture shows the products for the all the reaction of the given alkenes.

Q2 (+)-3-iodo-3-methylheptane is the tertiary halide so it will undergo the SN1 reaction because ut is tertiary halide and also it has iodine which is good leaving group

so when the iodine leave the molecule it will form stable tertiary carbocation which then reacts with the ethoxide ion.

Following picture shows the reaction and its mechanism .

Q3 The mechanism and stereochemistry for the epoxidation using the m-CPBA and borane additions on cis and trans-3-methylhex-3-ene reaction are shown below

epoxidation reaction with cis -3-methylhex-3-ene is shown below

Epoxidation of the trans-3-methylhex-3-ene is as follows.

in the trans substrate the alkyl groups remains the trans.

Additions reaction of the Borane to the cis and trans-3-methylhex-3-ene are as follows.