Question

Acetylene and HCHO react in the presence of copper acetylide catalyst to form: (a) 2 -butyne- 1,4 -diol (b) but-2-yne-1, 2-diol (c) but-1-yne-1, 4-diol (d) None of these

Short answer

(a) 2-butyne-1,4-diol

Step-by-step solution

Identify the Reactants

The reactants in the question are Acetylene, which is acetylene refers to the compound with the formula \(C_2H_2\), and HCHO, which is formaldehyde.

Recognize the Catalyst Role

Copper acetylide is often used as a catalyst for reactions involving acetylenes. In this context, it facilitates the addition of formaldehyde to acetylene.

Understand the Reaction Mechanism

The reaction mechanism typically involves two molecules of formaldehyde reacting with one molecule of acetylene to form the final product. The copper acetylide facilitates the triple bond in acetylene to open up and react with formaldehyde.

Determine the Potential Product

When acetylenes react with aldehydes like HCHO under catalytic conditions, a common product involves the formation of diols. Specifically, two formaldehyde molecules can add to the ends of an opened acetylene triple bond.

Match with Given Options

Given the reaction specifics, the expected product is a diol with hydroxyl groups on the first and fourth carbon, creating 2-butyne-1,4-diol. This matches option (a).

Key concepts

Copper Acetylide Catalyst

In the realm of organic chemistry, catalysts play a pivotal role in facilitating reactions that might otherwise be sluggish or impractical under normal conditions. Copper acetylide is a fascinating catalyst, especially when it comes to reactions involving acetylenes.

Here's why copper acetylide is so special:

• **Efficiency in Reactions**: Copper acetylide possesses the ability to effectively facilitate the addition of other molecules to acetylenes by activating the triple bond. This ability stems from its unique properties and interaction with acetylene molecules.
• **Selective Activation**: The catalyst targets only specific areas in the reacting molecules, ensuring that only certain bonds are broken while others remain intact. By doing so, reactions become selective, leading to high yields of the desired product.
• **Application**: Copper acetylide is widely used in the chemical industry for its ability to initiate reactions that result in valuable compounds. This includes adding various functional groups like hydroxyl groups, as seen in diol formations.

Understanding the role of copper acetylide allows chemists to predict and control reactions, paving the way for synthesizing complex organic molecules efficiently.

Acetylene Reactions

Acetylene, a simple molecule with the formula \(C_2H_2\), is more than just a building block in organic synthesis. It's renowned for its reactive nature due to a triple bond between its two carbon atoms.

Let's delve into some key characteristics of acetylene reactions:

• **Triple Bond Activation**: The triple bond in acetylene is strained and holds a substantial amount of energy, making it highly reactive. When the right catalyst, like copper acetylide, is present, it can open up, allowing additional molecules to attach, as happens with formaldehyde in the formation of diols.
• **Versatile Reactant**: Acetylene is called versatile because it can undergo various reactions with different types of compounds, leading to a broad range of products, from simple additions to complex polymerizations.
• **Industrial Importance**: In industrial chemistry, acetylene serves as a precursor to many useful compounds and materials, like synthetic rubber and certain polymers, thanks to its reactivity.

By mastering acetylene chemistry, chemists can exploit its reactive triple bond to create a wide array of products, including important intermediates and end-products in organic synthesis.

Diol Formation

Diols, also known as glycols, are compounds containing two hydroxyl groups (-OH) attached to separate carbon atoms. The formation of diols from acetylenes, with the aid of catalysts, is an intriguing aspect of organic reactions.

Consider these points on diol formation:

• **Reaction Mechanism**: Typically, in diol formation involving acetylene, catalysts facilitate the simultaneous addition of molecules like formaldehyde at both ends of the acetylenic triple bond, forming compounds like 2-butyne-1,4-diol.
• **Structural Diversity**: The position of the hydroxyl groups can vastly change a diol's properties, leading to a diverse array of compounds with varying applications.
• **Applications of Diols**: Diols are pivotal in synthesizing polymers, pharmaceuticals, and as solvents. Their ability to form strong hydrogen bonds makes them especially useful in various chemical industries.

Understanding how diols form and their subsequent applications can be pivotal in manufacturing synthetic materials and fine chemicals essential to modern industry.