Context

Theoretical Introduction

Aromatic compounds are a special class of chemical compounds that have a ring of carbon atoms with alternating double and single bonds that form a system of delocalized pi electrons. This delocalization of pi electrons provides certain unique properties to aromatic compounds, such as their stability and resonance. The simplest and most well-known molecule of an aromatic compound is benzene.

Hückel's Rule is an empirical rule that helps determine whether a compound is aromatic, antiaromatic, or non-aromatic. According to the rule, a compound is considered aromatic if it has 4n+2 pi electrons, where n is an integer (including zero).

The properties of aromatic compounds can be very different from those of aliphatic compounds. They have an unusual stability, a direct consequence of their ring structure. Additionally, they have a characteristic reactivity due to the presence of the delocalized pi electron set.

Context

Aromatic compounds are of great importance to a variety of industries, including the petrochemical, pharmaceutical, paint, plastic industries, among others. They are used as raw materials for a myriad of products, from medicines to plastics and dyes.

However, despite their usefulness, aromatic compounds also have a dark side. Some can be toxic, carcinogenic, or harmful to the environment. For example, many persistent pollutants, such as PCBs, are chlorinated aromatic compounds.

Practical Activity

Activity Title: Aromatics Around Us - Analysis, Understanding, and Presentation of Aromatic Compounds in Everyday Products

Project Objective

The objective of this project is to allow students to learn and understand aromatic compounds through a practical and contextualized approach. They will identify, analyze, and present an aromatic compound present in a daily use product, from the perspective of Organic Chemistry.

Detailed Project Description

Groups will choose a daily use product that contains aromatic compounds in its composition. The product can be of any nature - food, cosmetic, pharmaceutical, cleaning material, etc.

After choosing the product, the groups should:

1. Identify at least one aromatic compound present in the product's composition and draw its structure, using Lewis formula and Kekulé representation.

2. Explain why the compound is considered aromatic (using Hückel's Rule, for example).

3. Describe the function of the aromatic compound within the product. For example, the compound may provide a scent to the product, or it may have a bactericidal function, or it may be a preservative, etc.

4. Research and discuss possible impacts of the compound on human health and/or the environment.

5. Create a presentation, oral or in the form of a poster, to share their findings with the class.

Required Materials

• Product containing aromatic compounds in the composition
• Internet access for research
• Material for making the poster (if choosing this presentation format)

Step by Step

1. With the group formed, choose a product that contains aromatic compounds in its composition.

2. Identify at least one aromatic compound present in the product's composition and represent its structure.

3. Conduct research on the compound: what is its function in the product, what are its possible impacts on health and the environment.

4. Prepare a presentation to share your findings with the class.

Project Deliverables

Students must submit a written report regarding the analyzed compound, containing:

• Introduction: where they should contextualize the theme, explaining what aromatic compounds are, Hückel's Rule, the presence of these compounds in everyday products, and the product chosen by the group.

• Development: where they should explain the structure of the analyzed compound, why it is considered aromatic, and the function of the compound in the chosen product. Here they should also present and discuss the possible impacts of this compound on human health and the environment.

• Conclusions: where they should summarize the main points of the work, discussing the learnings obtained from the project, the conclusions the students reached regarding the use of aromatic compounds in everyday products, and the function of the compound they chose to analyze.

• Bibliography: where they should list all research sources used for the work.

Remember that the report should be written by all group members, highlighting the collaboration and participation of all.

A mockup of the presentation/poster should be submitted along with the report.