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Synthesis of cyclohexane -1,2 diol f...

Synthesis of cyclohexane -1,2 diol from cyclohexene may be accomplished in two ways :
I . `MnO_(4)` dilute `OH, O^(@)C` dihydroxylation
II . Peracid epoxidation followed by NaOH opening of the epoxide ring .
Which of the following statement about the products from these reactions is correct ?

A

Methods I and II give same product

B

Method I gives resolvable racemic mixture while method II will give non- resolvable achiral product

C

Method I gives resolvable optically inactive compound while method II gives resolvable racemic mixture

D

Products obtained through method I and II will have diasteriomeric relationship

Text Solution

AI Generated Solution

The correct Answer is:
To synthesize cyclohexane-1,2-diol from cyclohexene, we can use two different methods. Let's analyze each method step by step. ### Method I: Dihydroxylation using MnO4 in dilute OH 1. **Reagent and Conditions**: We use dilute potassium permanganate (KMnO4) in the presence of hydroxide ions (OH-) at 0 degrees Celsius. 2. **Mechanism**: This reaction involves syn-dihydroxylation, where both hydroxyl (OH) groups add to the same side of the double bond in cyclohexene. 3. **Product Formation**: The product formed is cyclohexane-1,2-diol, where both OH groups are on the same side (cis configuration). ### Method II: Epoxidation followed by Ring Opening 1. **Reagent and Conditions**: We use a peracid (like m-chloroperbenzoic acid) to epoxidize cyclohexene, forming an epoxide. 2. **Mechanism**: The epoxide ring is then opened using sodium hydroxide (NaOH), which leads to anti-dihydroxylation. This means that the two hydroxyl groups will add to opposite sides of the double bond. 3. **Product Formation**: The product formed is also cyclohexane-1,2-diol, but in this case, the OH groups are on opposite sides (trans configuration). ### Comparison of Products - **Method I** results in a **cis-1,2-diol** (syn addition). - **Method II** results in a **trans-1,2-diol** (anti addition). ### Conclusion Now, let's evaluate the statements regarding the products from these reactions: 1. **Statement 1**: Method 1 and Method 2 give the same product. **(Incorrect)** 2. **Statement 2**: Method 1 gives a resolvable racemic mixture while Method 2 gives a non-resolvable chiral product. **(Incorrect)** 3. **Statement 3**: Method 1 gives a resolvable optically inactive compound while Method 2 gives a resolvable compound. **(Correct)** Thus, the correct answer is **Option 3**.

To synthesize cyclohexane-1,2-diol from cyclohexene, we can use two different methods. Let's analyze each method step by step. ### Method I: Dihydroxylation using MnO4 in dilute OH 1. **Reagent and Conditions**: We use dilute potassium permanganate (KMnO4) in the presence of hydroxide ions (OH-) at 0 degrees Celsius. 2. **Mechanism**: This reaction involves syn-dihydroxylation, where both hydroxyl (OH) groups add to the same side of the double bond in cyclohexene. 3. **Product Formation**: The product formed is cyclohexane-1,2-diol, where both OH groups are on the same side (cis configuration). ### Method II: Epoxidation followed by Ring Opening ...
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