Naphthalene

Definition

Naphthalene is a polycyclic aromatic hydrocarbon composed of two fused benzene rings, resulting in a molecular formula of C$_{10}$H$_8$. This compound is a key example of polycyclic aromatic hydrocarbons due to its stability and characteristic properties, such as its ability to undergo electrophilic substitution reactions. Naphthalene's aromatic nature also connects it to Hückel's rule, which dictates the stability of cyclic compounds with a certain number of pi electrons.

5 Must Know Facts For Your Next Test

1. Naphthalene is often found in mothballs and serves as a precursor for the synthesis of various chemicals, including dyes and plastics.
2. The compound is solid at room temperature but sublimates easily, which means it can transition directly from solid to gas without becoming liquid.
3. Naphthalene follows Hückel's rule with 10 pi electrons (as it has four double bonds), satisfying the requirement of 4n + 2 for aromatic stability.
4. Due to its strong odor and volatility, naphthalene has been linked to respiratory issues when inhaled in high concentrations.
5. Naphthalene can undergo both electrophilic aromatic substitution and reduction reactions, making it versatile in organic synthesis.

Review Questions

• How does naphthalene illustrate the principles of aromaticity and Hückel's rule?
  • Naphthalene exemplifies aromaticity because it consists of two fused benzene rings that create a continuous cycle of pi electrons. It contains 10 pi electrons, fitting Hückel's rule of 4n + 2 (where n=2), which confirms its stability as an aromatic compound. This structure allows naphthalene to participate in various reactions typical for aromatic compounds, showcasing the significance of these principles in its chemistry.
• Discuss the implications of naphthalene's physical properties for its use in consumer products like mothballs.
  • Naphthalene's ability to sublimate at room temperature makes it ideal for use in mothballs, as it can effectively repel moths without leaving a liquid residue. Its strong odor acts as a deterrent, while the solid form allows for easy packaging and use. However, these same properties raise health concerns about inhalation and environmental impact, emphasizing the need for careful handling and regulation in consumer products.
• Evaluate the environmental and health concerns associated with naphthalene and suggest safer alternatives for its common applications.
  • Naphthalene poses several environmental and health risks due to its volatility and potential to cause respiratory issues upon inhalation. Its presence in air pollution and water contamination can have harmful effects on wildlife and ecosystems. To mitigate these risks, alternatives such as cedar wood chips or natural essential oils can be used as insect repellents. These substitutes offer effective protection against pests while minimizing harmful exposure and environmental impact.

Related terms

Polycyclic Aromatic Hydrocarbons: A class of organic compounds that contain multiple fused aromatic rings, known for their chemical stability and potential health risks.

Aromaticity:

A property of cyclic compounds that possess resonance stabilization due to a delocalized pi electron cloud, making them more stable than non-aromatic counterparts.

Electrophilic Substitution:

A chemical reaction in which an electrophile replaces a hydrogen atom in an aromatic compound, often used to modify aromatic systems like naphthalene.