In which case the product is neither a cyclic ether nor open chain symmetrical ether-

Options

A. `CH_3-CH=CH-CH_3 overset(C_6H_5CO_3H) to`
B. `CH_3CH_2ONa+C_2H_5Br to`
C. `KCN+(CH_3)_3CBr to`
D. `C_2H_5OH("Excess") +H_2SO_4 overset(140^@)to`

Answer

To determine which case results in a product that is neither a cyclic ether nor an open-chain symmetrical ether, we can analyze each option step by step.

### Step-by-Step Solution:

1. **Understand the Types of Ethers**:
- **Cyclic Ethers**: These are compounds where the ether oxygen is part of a ring structure.
- **Open-chain Symmetrical Ethers**: These are ethers where the two alkyl groups attached to the oxygen are identical (e.g., R-O-R where R is the same).

2. **Analyze Each Option**:
- **Option 1**:
- The structure involves a double bond and a peracid (C6H5CO3H).
- The reaction leads to the formation of an epoxide (cyclic ether), which is a three-membered ring.
- **Conclusion**: This is a cyclic ether.

- **Option 2**:
- The reaction involves CH3-CH2-O and CH3-CH2-Br.
- The nucleophile attacks, leading to the formation of CH3-CH2-O-CH2-CH3.
- Both alkyl groups (CH2-CH3) are the same.
- **Conclusion**: This is an open-chain symmetrical ether.

- **Option 3**:
- The reaction involves KCN with a compound having three carbons and a bromine (Br) substituent.
- The nucleophile attacks, and the product does not form an ether.
- The structure remains as CH3-CH3-CH3 (with no ether formation).
- **Conclusion**: This product is neither a cyclic ether nor an open-chain symmetrical ether.

- **Option 4**:
- The reaction involves C2H5OH and leads to the formation of an ether.
- The product formed is CH3-CH2-O-CH2-CH3, which is symmetrical.
- **Conclusion**: This is an open-chain symmetrical ether.

3. **Final Answer**:
- The product that is neither a cyclic ether nor an open-chain symmetrical ether is found in **Option 3**.