Ethylene oxide when treated with Grignard reagent yields

Options

A. Primary alcohol
B. Secondary alcohol
C. Tertiary alcohol
D. Cyclopropyl alcohol

Answer

To solve the question of what ethylene oxide yields when treated with a Grignard reagent, we can follow these steps:

### Step 1: Understand the Structure of Ethylene Oxide
Ethylene oxide is a cyclic ether with the formula C2H4O. Its structure can be represented as:
```
O
/ \
CH2 CH2
```
This shows that it has a three-membered ring consisting of two carbon atoms and one oxygen atom.

**Hint:** Remember that ethylene oxide is a three-membered cyclic ether, which makes it reactive.

### Step 2: Recognize the Grignard Reagent
A Grignard reagent is typically represented as R-MgX, where R is an alkyl or aryl group, and X is a halogen (like Cl, Br, or I). The carbon in the Grignard reagent (R) is nucleophilic due to the partial negative charge on it.

**Hint:** Grignard reagents are strong nucleophiles that can attack electrophilic centers.

### Step 3: Reaction Mechanism
When ethylene oxide reacts with the Grignard reagent, the nucleophilic carbon (R-) attacks one of the carbon atoms in the ethylene oxide ring. Since the ring is symmetrical, the nucleophile can attack either carbon.

- If R- attacks one of the carbon atoms, the bond between that carbon and the oxygen will break, leading to the opening of the ring.

**Hint:** The attack of R- on ethylene oxide opens the three-membered ring, leading to the formation of a new carbon-oxygen bond.

### Step 4: Formation of the Intermediate
After the attack, we form an alkoxide intermediate:
```
CH2
|
CH2-R
|
O^-
```
The oxygen now carries a negative charge and is bonded to magnesium from the Grignard reagent (MgX).

**Hint:** The alkoxide intermediate is formed after the nucleophilic attack and ring opening.

### Step 5: Hydrolysis of the Alkoxide
The next step involves hydrolysis, where the alkoxide is treated with water (or an acid). This step converts the alkoxide into an alcohol:
```
CH2
|
CH2-R
|
OH
```
This product is a primary alcohol because the carbon bearing the hydroxyl group (OH) is attached to only one other carbon atom.

**Hint:** Hydrolysis converts the alkoxide into an alcohol, and the structure of the product will determine whether it is primary, secondary, or tertiary.

### Step 6: Conclusion
The final product of the reaction between ethylene oxide and a Grignard reagent is a primary alcohol. Therefore, the correct answer to the question is:

**Answer:** A) Primary alcohol