Diethyl ether is prepared by passing vapours of ethyl alcohol over a heated catalyst under high temperature and pressure. The catalyst is: (a) \(\mathrm{CuO}\) (b) \(\mathrm{Al}_{2} \mathrm{O}_{3}\) (c) \(\mathrm{SiO}_{2}\) (d) \(\mathrm{Ag}_{2} \mathrm{O}\)

Diethyl ether, also known as 'ether', is an organic compound used as a solvent and a starting material for the synthesis of other compounds. The traditional method for preparing diethyl ether involves the dehydration of ethanol, which is also known as ethyl alcohol. This process requires the presence of a catalyst that can facilitate the reaction.

The preparation typically occurs by passing ethanol vapors over a heated catalyst under high temperatures and pressure, which promotes the elimination of water molecules from ethanol, resulting in the formation of diethyl ether. This transformation is an example of an elimination reaction, where two molecules of ethanol lose water to form one molecule of diethyl ether and one molecule of water.

Conditions such as the catalyst's surface area, temperature, and pressure are crucial in ensuring a successful and efficient conversion. This preparation has historical significance, as diethyl ether was one of the first anesthetics to be used in medicine, although its use has declined due to the development of more advanced and less flammable options.

A catalyst is a substance that accelerates a chemical reaction without being consumed in the process. In the acid-catalyzed dehydration of ethanol to produce diethyl ether, the catalyst's role is pivotal. It lowers the activation energy required for the reaction, allowing it to proceed at a faster rate or a lower temperature than would be possible otherwise.

Catalysts work by providing an alternative pathway for the reaction with a lower activation energy. They are not one-size-fits-all; for each specific reaction, a particular catalyst that is well-suited for the task is used. An efficient catalyst increases the rate of reaction while ensuring selectivity, meaning it helps produce the desired product with fewer byproducts.

For example, in the dehydration of ethanol, a catalyst that can donate hydrogen ions (H+) to facilitate the removal of a water molecule is preferable. These hydrogen ions temporarily bind with reactants, destabilizing certain bonds which makes it easier for the molecules to undergo the necessary rearrangements to form the product, in this case, diethyl ether.

Ethanol dehydration is a chemical reaction that removes a water molecule from ethanol molecules to create alkenes or ethers, depending on the reaction conditions. When two ethanol molecules lose a water molecule, diethyl ether is formed. For this type of reaction, acid catalysis is often employed because it helps stabilize the transition state and facilitate the release of the water molecule.

In the presence of a suitable acid catalyst like aluminum oxide (Al2O3), ethanol vapors undergo a series of steps leading to the formation of diethyl ether. Initially, the ethanol molecules are protonated by the acid catalyst, increasing the likelihood of bond cleavage that releases water. Subsequently, the protonated intermediates combine to form diethyl ether and a water molecule as a byproduct.

Importance of Catalyst Selection

The choice of aluminum oxide as a catalyst is significant as it exhibits acidic properties necessary for this reaction. Other potential catalysts, such as Copper Oxide (CuO), Silicon Dioxide (SiO2), or Silver Oxide (Ag2O), may not provide the correct acidic environment needed for the dehydration of ethanol, either not facilitating the reaction efficiently or leading to different products.