Question

Both methane and ethane can be prepared in one step by the reaction of: (a) \(\mathrm{C}_{2} \mathrm{H}_{4}\) (b) \(\mathrm{CH}_{3} \mathrm{Br}\) (c) \(\mathrm{CH}_{3} \mathrm{OH}\) (d) \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OH}\)

Short answer

Option (d)  ext{CH}_3 ext{CH}_2 ext{OH} can produce both methane and ethane in one step.

Step-by-step solution

Understanding the Reaction

To prepare both methane ( ext{CH}_4) and ethane ( ext{C}_2 ext{H}_6) in one step, the starting compound must contain both carbon and hydrogen atoms and be reactive enough to form these simple hydrocarbons.

Analyzing Option (a)  ext{C}_{2} ext{H}_{4}

Ethylene ( ext{C}_2 ext{H}_4) is an alkene and would require hydrogenation to form ethane, but it does not react in one step to produce methane as well.

Analyzing Option (b)  ext{CH}_{3} ext{Br}

Methyl bromide ( ext{CH}_3 ext{Br}) contains a single carbon and does not have an additional carbon source to form ethane. Also, converting it into methane would require a specific reaction not likely to produce both hydrocarbons in one step.

Analyzing Option (c)  ext{CH}_{3} ext{OH}

Methanol ( ext{CH}_3 ext{OH}) has one carbon atom, similar to methyl bromide. Without an additional carbon source, it cannot form ethane while also producing methane in one step.

Analyzing Option (d)  ext{CH}_{3} ext{CH}_{2} ext{OH}

Ethanol ( ext{CH}_3 ext{CH}_2 ext{OH}) has both the necessary carbon atoms and is reactive under reductive conditions to form both methane and ethane. Ethanol can undergo catalytic hydrogenation or reduction to produce both hydrocarbons in one step.

Conclusion: Identifying the Correct Option

After analyzing each option,  ext{CH}_3 ext{CH}_2 ext{OH} can convert directly due to having sufficient carbon and hydrogen atoms, and being reactive under conditions suitable for forming both methane and ethane. Thus, option (d) is the correct answer.

Key concepts

Hydrocarbon Synthesis

Hydrocarbon synthesis is a fascinating branch of organic chemistry that focuses on creating various hydrocarbons from different starting materials. In simple terms, hydrocarbons are organic compounds solely composed of carbon and hydrogen atoms. They serve as a primary foundation for countless organic compounds, including fuels and plastics. The process of hydrocarbon synthesis often involves:

• Combining carbon atoms in different configurations.
• Adding hydrogen atoms through chemical reactions.
• Utilizing catalysts to enhance the reaction rate and selectivity.

Hydrocarbons can be classified as alkanes, alkenes, or alkynes based on the type of carbon-carbon bonds they contain. Alkanes have single bonds, alkenes have double bonds, and alkynes have triple bonds. In the problem we're discussing, the goal is to synthesize methane (\(\text{CH}_4\)) and ethane (\(\text{C}_2\text{H}_6\)) directly from ethanol, a reaction indicative of how reductive processes can be used in hydrocarbon synthesis.

Reaction Mechanisms

Understanding reaction mechanisms is crucial for chemists when predicting the outcome of chemical reactions. A reaction mechanism provides a detailed step-by-step description of how reactants transform into products at the molecular level.

In organic chemistry, these mechanisms can range from straightforward processes like simple addition reactions, to complex multi-step transformations involving intermediates and transition states. For instance, in the context of converting ethanol to methane and ethane, the reaction involves hydrogenation or reduction, where:

• Carbon-carbon bonds are maintained or modified.
• Oxygen or other heteroatoms are removed to form simpler hydrocarbons.
• Transition metals or other catalysts facilitate these transformations by making the intermediate species more reactive.

Recognizing the general mechanism involved can help us understand not only how one set of reactants might yield certain products but also how conditions can be adjusted to optimize yield and selectivity.

Preparation of Alkanes

The preparation of alkanes is a fundamental topic in organic synthesis, given their importance in fuels and industrial chemical processes. Alkanes are characterized by their single carbon-carbon and carbon-hydrogen bonds, providing stability and reactivity under specific conditions.

To prepare alkanes like methane and ethane from ethanol, specific reactions are often employed:

• Catalytic hydrogenation, where hydrogen is directly added to carbon atoms under the influence of a catalyst to saturate alkenes or other unsaturated compounds.
• Reduction reactions, where functional groups like alcohols are reduced to form alkanes, often using metal catalysts to assist in breaking specific bonds.

This particular exercise highlights such reductive conditions applied to ethanol, leveraging its two carbon atoms to directly synthesize methane and ethane. Understanding these preparation methods not only aids in academic exercises but also anchors practical applications in the chemical industry.