Which of the following compounds does not have an ester linkage ?

Options

A. Ethyl acid sulphate
B. Diethyl hydrogen phosphate
C. Ethyl acetate
D. `CH_(3) CO-O-CO-CH_(3)`

Answer

To determine which of the given compounds does not have an ester linkage, we need to understand what an ester linkage is. An ester linkage is formed when a carbon atom is doubly bonded to an oxygen atom (carbonyl group) and also bonded to another oxygen atom that is part of an alkyl or aryl group.

Let's analyze the compounds one by one:

1. **Ethyl Acid Sulfate**: The structure can be represented as CH3CH2OSO2OH. In this compound, we can identify the ester linkage between the sulfur atom (which is bonded to two oxygen atoms) and the ethyl group (C2H5). Therefore, this compound does have an ester linkage.

2. **Diethyl Hydrogen Phosphate**: The structure is represented as (C2H5O)2PO(OH). Here, the phosphate group has an oxygen atom bonded to two ethyl groups and one hydroxyl group. The bond between the oxygen and the ethyl group indicates an ester linkage. Thus, this compound also has an ester linkage.

3. **Ethyl Acetate**: The structure is CH3COOCH2CH3. In this case, we have a carbonyl group (C=O) bonded to an oxygen atom that is also bonded to an ethyl group. This clearly shows an ester linkage. Hence, ethyl acetate does have an ester linkage.

4. **Acetic Anhydride**: The structure is represented as (CH3CO)2O. In this compound, we have two carbonyl groups (C=O) connected by an oxygen atom, but there is no alkyl or aryl group connected to an oxygen atom in the way that defines an ester linkage. Therefore, acetic anhydride does not have an ester linkage.

From the analysis above, we conclude that the compound that does not have an ester linkage is **Acetic Anhydride**.

### Summary:
The compound that does not have an ester linkage is **Acetic Anhydride**.