Question

Write structural formulas for the major organic product(s) formed by reaction of 1 -methylcyclohexene with each oxidizing agent. (a) \(\mathrm{OsO}_{4} / \mathrm{H}_{2} \mathrm{O}_{2}\) (b) \(\mathrm{O}_{3}\) followed by \(\left(\mathrm{CH}_{3}\right)_{2} \mathrm{~S}\)

Short answer

Answer: (a) 1,2-dihydroxy-1-methylcyclohexane, (b) 2-cyclohexenone and acetaldehyde.

Step-by-step solution

Analyze the structure of 1-methylcyclohexene and oxidizing agents

First, we need to understand the structure of the given alkene, 1-methylcyclohexene. It contains a double bond and a methyl group attached to a six-membered cyclohexene ring. For each part (a) and (b), we will then analyze the properties and reactivities of the respective oxidizing agents.

Determine the major organic product for OsO\(_4\) / H\(_2\)O\(_2\)

In part (a), we are given that the reaction involves osmium tetroxide (OsO\(_4\)) followed by hydrogen peroxide (H\(_2\)O\(_2\)) as the oxidizing agents. This reaction is known as the dihydroxylation reaction, which means it will add two hydroxyl (OH) groups to the two carbon atoms bonded by the double bond, forming a syn-diol (both OH groups are on the same side of the molecule). Since 1-methylcyclohexene is symmetric, there is no issue of stereoselectivity or regioselectivity in this reaction. Thus, the major organic product in this reaction will be a syn-diol where both hydroxyl groups are added to the same face of the cyclohexene ring.

Determine the major organic product for O\(_3\) followed by (CH\(_3\))\(_2\)S

In part (b), we are given that the reaction involves ozone (O\(_3\)) followed by dimethyl sulfide (CH\(_3\))\(_2\)S as the oxidizing agent. This reaction is known as the ozonolysis reaction, which cleaves the double bond in the alkene and forms two new carbonyl compounds. In the first step of this reaction, ozone reacts with the alkene to form an ozonide intermediate. In the second step, this intermediate reacts with dimethyl sulfide, which acts as a reducing agent to break the ozonide into two separate carbonyl compounds: a ketone and an aldehyde. Since 1-methylcyclohexene is symmetric, there is no issue of regioselectivity in this reaction. Thus, the major organic product in this reaction will be a ketone (2-cyclohexenone) and an aldehyde (acetaldehyde). In conclusion, the major organic products for the two reactions are: (a) 1,2-dihydroxy-1-methylcyclohexane (b) 2-cyclohexenone and acetaldehyde