Question bank: Organic Functions: Cyclic Hydrocarbons

Cyclic hydrocarbons are organic compounds composed only of carbon and hydrogen atoms, where the carbon atoms are arranged in a ring. A common example of this type of compound is cyclopentane. Considering your knowledge of cyclic hydrocarbons and their possible impacts on the environment and human health, which of the following statements is true regarding these substances?

Cyclic hydrocarbons are organic compounds found in common products such as plastic, as well as in pollutants like polycyclic aromatic hydrocarbons (PAHs) found in vehicle emissions and industrial processes. (a) Explain what cyclic hydrocarbons are and their characteristics. (b) Evaluate the possible health and environmental risks caused by exposure to PAHs, considering their toxicity and reactivity. (c) Propose individual and/or collective measures to minimize these risks and promote the responsible use and disposal of materials containing cyclic hydrocarbons.

Cyclic hydrocarbons are organic compounds that have one or more closed chains of carbon atoms, and depending on the number of carbons in this closed chain, they can exhibit distinct characteristics and properties. For example, cycles of 3 and 4 carbons, known as cyclopropane and cyclobutane, respectively, are notorious for their high reactivity due to the angular strain that these structures impose on their atoms. This strain results from the angle between the carbon-carbon bonds, which in cyclopropane is approximately 60°, and in cyclobutane is around 90°, deviating from the ideal angles of 109.5° of the tetrahedral arrangement of carbon. Considering the molecular structure and the described properties, which of the following cyclic hydrocarbon compounds has the lowest angular strain and therefore the highest relative stability due to a conformation that approaches more the ideal tetrahedral angles without disregarding possible steric effects?

Consider cyclopropane, a cyclic hydrocarbon with only three carbon atoms. This compound is known for its high reactivity due to the bond angle between the carbon atoms, which is approximately 60 degrees. Based on this information and your knowledge of Organic Chemistry, describe the relationship between the structure of cyclopropane and its reactivity, explaining how the bond angle influences the chemical behavior of this hydrocarbon. Then, identify a practical example where this reactivity of cyclopropane could be exploited in an industrial or technological application. Justify your choice based on the specific properties of cyclopropane.

When studying cyclic hydrocarbons, it is important to understand that closed chains introduce specific properties, such as the formation of three- or four-carbon rings, which are highly reactive due to bond angle and angular strain. Consider cyclopropane, a cyclic hydrocarbon with three carbon atoms. Its molecular formula is C3H6 and the Lewis structure shows that each carbon atom forms three sigma bonds and one pi bond. The angular strain in cyclopropane is significant, making it a highly reactive compound. To identify one of its properties, describe how the angular strain in cyclopropane affects its reactivity compared to a more stable cyclic hydrocarbon, such as cyclohexane. Additionally, propose a justification for the expected difference in chemical behavior between these two compounds, considering their structures and principles of organic reactivity.