Cyclopropane is an interesting hydrocarbon. Instead of having three carbons in a row, the three carbons form a ring, as shown in this perspective drawing (see Figure 2.18 for a prior example of this kind of drawing):

Cyclopropane was at one time used as an anesthetic, but its use was discontinued, in part because it is highly flammable. (a) How does it differ from that of propane?

Verified step by step guidance

1. Step 1: Identify the structure of cyclopropane. Cyclopropane is a three-carbon ring structure, where each carbon is bonded to two other carbons and two hydrogen atoms.
2. Step 2: Compare the structure of cyclopropane to propane. Propane is a linear hydrocarbon with three carbon atoms in a row, each bonded to hydrogen atoms to satisfy the valence of carbon.
3. Step 3: Note the differences in bonding and geometry. Cyclopropane has a ring structure, which introduces angle strain due to the 60-degree bond angles, whereas propane has a tetrahedral geometry with bond angles of approximately 109.5 degrees.
4. Step 4: Consider the implications of the ring structure. The ring structure of cyclopropane makes it more reactive and less stable compared to the linear structure of propane.
5. Step 5: Summarize the key differences. Cyclopropane differs from propane in its ring structure, bond angles, and stability, which contribute to its higher reactivity and flammability.

Key Concepts

Cycloalkanes

Cycloalkanes are hydrocarbons that contain carbon atoms arranged in a ring structure. Unlike linear alkanes, such as propane, which have a straight-chain configuration, cycloalkanes exhibit unique properties due to their cyclic nature. This ring formation can lead to increased strain and reactivity, influencing their chemical behavior and stability.

Flammability

Flammability refers to the ability of a substance to ignite and burn in the presence of an ignition source. Cyclopropane is highly flammable due to its low flash point and the presence of C-H bonds that readily react with oxygen. Understanding flammability is crucial for assessing the safety and handling of hydrocarbons, especially in medical or industrial applications.

Structural Isomers

Structural isomers are compounds that have the same molecular formula but differ in the arrangement of atoms. For example, propane (C3H8) is a straight-chain alkane, while cyclopropane (C3H6) is a cyclic structure. This difference in structure can lead to variations in physical and chemical properties, such as boiling points and reactivity, which are important for understanding their uses and behaviors.