A chemist requires some 3-hexanone for a reaction, but only has some 3-hexene available. Explain using chemical reactions, how the 3-hexene could be converted to 3-hexanone. Include the conditions needed for each step. (You will need two steps).
3-hexene is
CH3CH2CH=CHCH2CH3
which is nice and symmetrical. Thus if we do an addition across the double bond we are not concerned about Markovnikov's rule ((Broken Link Removed)
Similarly as the final product is a ketone any possible chiral centre(s)generated are destroyed, so the chirality of any intermediates is not n issue.
It is thus a matter of choosing reagents and conditions
CH3CH2CH=CHCH2CH3
i) Hg(OAc)2 + Ether + water
ii) NaBH4 + ether + water + NaOH
CH3CH2CH(OH)-CH2CH2CH3
i) Jones reagent
CH3CH2CO-CH2CH2CH3
On a large scale the first step can he done with concentrated sulfuric acid, but the yield is better on a small scale with the mercury reagent.
There are a number of reagents suitable for the oxidation step. Jones reagent is the most suitable. PCC is also a possibility and easy enough to remove the pyridine during the workup of the reaction.
To convert 3-hexene to 3-hexanone, two steps are required. The first step involves oxidation, and the second step involves a reaction with a ketone. Here's how it can be done:
Step 1: Oxidation of 3-hexene to 3-hexanal
Oxidation of an alkene can be achieved by using a strong oxidizing agent, such as potassium permanganate (KMnO₄) or chromic acid (H₂CrO₄). Let's use KMnO₄ as the oxidizing agent.
Reaction:
3-hexene + KMnO₄ + H₂O → 3-hexanal + MnO₂ + KOH
Conditions:
Temperature: Room temperature or slightly above (20-30°C)
Solvent: Water or a suitable organic solvent (e.g., acetone)
Acidic conditions: The reaction is typically carried out in acidic conditions to provide the necessary proton for the oxidation.
Step 2: Reduction of 3-hexanal to 3-hexanone
The next step involves converting 3-hexanal to 3-hexanone. This can be achieved through a reduction reaction using a reducing agent, such as sodium borohydride (NaBH₄). The reduction converts the aldehyde functional group (-CHO) to a ketone functional group (-C=O).
Reaction:
3-hexanal + NaBH₄ → 3-hexanone + NaBH₃OH
Conditions:
Temperature: Room temperature or slightly above (20-30°C)
Solvent: A suitable organic solvent, such as ethanol or methanol
Basic conditions: The reaction is typically carried out in basic conditions to provide the necessary hydroxide ions for the reduction.
It is important to note that these reactions need to be carried out using appropriate safety precautions in a controlled laboratory setting. Additionally, the yields and reaction conditions may vary, so it is important to consult literature or a qualified chemist for specific details and optimizations.
To convert 3-hexene to 3-hexanone, you can follow these two steps:
Step 1: Oxidation of 3-Hexene to 3-Hexanol
Conditions: Use an oxidizing agent, such as alkaline potassium permanganate (KMnO4) or acidic potassium dichromate (K2Cr2O7), and heat under reflux.
1. Start by adding the 3-hexene to a reaction flask.
2. Next, add the oxidizing agent, either KMnO4 or K2Cr2O7, to the flask.
3. Heat the mixture under reflux, which means the reaction is heated and the vapors are condensed and returned back to the reaction flask.
4. Allow the reaction to proceed for a specific amount of time, typically around 3-4 hours.
5. During the reaction, the double bond in 3-hexene will be oxidized to form a vicinal diol (1,2-diol). In this case, the double bond will be converted to a hydroxyl group (-OH), resulting in the formation of 3-hexanol.
Step 2: Oxidation of 3-Hexanol to 3-Hexanone
Conditions: Use an oxidizing agent, such as Jones reagent (CrO3/H2SO4) or sodium hypochlorite (NaOCl), and perform the reaction under acidic conditions.
1. Start by adding the 3-hexanol, obtained from the previous step, to a reaction flask.
2. Add the oxidizing agent, either Jones reagent or sodium hypochlorite, to the flask.
3. Adjust the pH of the reaction mixture to acidic conditions by adding a suitable acid, such as sulfuric acid (H2SO4).
4. Stir the mixture vigorously or heat it gently, depending on the oxidizing agent being used.
5. Allow the reaction to proceed for a specific amount of time, usually around 1-2 hours.
6. During the reaction, the alcohol group (-OH) in 3-hexanol will be oxidized to form a carbonyl group (C=O), resulting in the formation of 3-hexanone.
After completing these two steps, you will have successfully converted 3-hexene to 3-hexanone.