Problem 6 - A Complete Resource Book in Chemistry for JEE Main

Question

Acetylene reacts with acetic acid in presence of \(\mathrm{Hg}\) ions at room temperature to give (a) ethyl acetate (b) acetaldehyde (c) vinyl acetate (d) methyl acetate

Step-by-Step Solution

Answer

The product of the reaction is vinyl acetate (c).

Step 1: Identify the Reactants and Reaction Conditions

The reactants given are acetylene (\(C_2H_2\) and acetic acid (\(CH_3COOH\) in the presence of mercury ions (\(\mathrm{Hg}^{2+}\)). This implies a catalytic process, as mercury commonly acts as a catalyst in reactions involving alkynes.

Step 2: Determine the Likely Product

In this reaction setup, acetylene reacts with acetic acid. The presence of mercury ions as a catalyst suggests a specific reaction pathway known by industrial chemists to yield vinyl acetate (\((CH_2=CHOOCCH_3)\). Vinyl acetate is a common product of this reaction.

Step 3: Recognize the Reaction Mechanism

The mechanism involves the formation of an enol intermediate which rearranges to form vinyl acetate. The mercury ions help facilitate the formation of an acetate group bonded to one of the carbons in the acetylene molecule, forming vinyl acetate.

Key Concepts

Acetylene Reactions

Acetylene, also known by its chemical formula \(C_2H_2\), is a hydrocarbon that forms the basis of many chemical reactions in both laboratory and industrial settings. It's an alkyne, meaning it features a carbon-carbon triple bond, which is highly reactive due to the strain in its electronic structure. This reactivity is harnessed in numerous chemical processes, including its interaction with acetic acid.When acetylene is mixed with acetic acid \((CH_3COOH)\), under specific conditions such as the presence of a catalyst, a series of reactions can occur. The triple bond in acetylene provides multiple sites for potential reactions, making it particularly versatile. In the case of this exercise, we see acetylene reacting with acetic acid to eventually form a type of ester known as vinyl acetate.The way acetylene interacts with other chemicals is foundational to many synthetic routes in organic chemistry. Often, professionals in industrial chemistry use it as a starting point for synthesizing more complex compounds. This makes understanding acetylene reactions both practically useful and theoretically interesting for budding chemists.

Catalysis with Mercury Ions

Catalysis is a process where the rate of a chemical reaction is increased by a substance called a catalyst. Catalysts are not consumed within the reaction itself and can be used repeatedly. In the reaction between acetylene and acetic acid, mercury ions \(\left(\text{Hg}^{2+}\right)\) serve as the catalyst. The use of mercury in this context is quite strategic given its ability to facilitate reactions involving alkynes like acetylene.Mercury ions help increase the reaction speed by stabilizing reaction intermediates. They can form transient complexes with reaction intermediates, often leading to the stabilization of otherwise unstable reaction pathways. Even though mercury ions are effective in catalyzing these reactions, their use is often limited due to the toxicity associated with mercury. Understanding the importance and function of catalysis, and specifically the role of mercury in these reactions, is crucial for comprehending how chemical transformations can be efficiently managed and controlled in both laboratory and industrial processes.

Industrial Organic Reactions

Industrial organic reactions are a cornerstone of chemical manufacturing processes. They rely heavily on the principles of organic chemistry to convert raw materials into more complex and valuable products. The synthesis of vinyl acetate from acetylene and acetic acid is an example of such a reaction, which is frequently used in industrial contexts. These reactions typically require precise conditions, including specific temperatures, pressures, and the presence of suitable catalysts to achieve high yields. In the case of acetylene reacting with acetic acid, such reactions are conducted at controlled temperatures with the presence of mercury ions to act as a catalyst. Beyond generating compounds like vinyl acetate, these processes are vital in producing countless other key materials. Products like plastics, pharmaceuticals, and various chemicals are manufactured in similar synthetic pathways, making a robust understanding of industrial organic reactions indispensable in the field of applied chemistry. For anyone looking to explore a career in industrial chemistry, gaining insights into these processes is essential.