To determine the correct IUPAC name for the compound in question, we need to analyze the structure of the compound based on the options provided. Let's break down the naming conventions and the reasoning behind the correct answer. ### Step-by-Step Explanation 1. **Understanding IUPAC Naming Conventions**: - The IUPAC (International Union of Pure and Applied Chemistry) naming system provides a standardized way to name chemical compounds. - The name typically includes the longest carbon chain (the parent chain), the position of any double or triple bonds, and the names of any substituents (branches) along the chain. 2. **Identifying the Longest Carbon Chain**: - The first step in naming a compound is to identify the longest continuous chain of carbon atoms. This chain determines the base name of the compound (e.g., "pent" for five carbons). - In this case, we are looking for a pentene, which indicates a five-carbon chain with at least one double bond. 3. **Locating the Double Bond**: - The position of the double bond is indicated by a number in the name. The numbering starts from the end of the chain closest to the double bond. - For example, in "pent-2-ene," the double bond starts at the second carbon. 4. **Identifying Substituents**: - Substituents are groups attached to the main carbon chain. In this case, we have methyl groups (–CH₃) as substituents. - The position of each substituent is indicated by a number corresponding to the carbon atom to which it is attached. 5. **Analyzing Each Option**: - **Option A: 2,3-dimethylpent-2,3-ene** - This suggests two double bonds (one at C2 and one at C3), which is incorrect for a pentene. Therefore, this option is invalid. - **Option B: 2,3-dimethylpent-2-ene** - This indicates a five-carbon chain (pent) with a double bond starting at C2 and two methyl groups at C2 and C3. This is a valid structure. - **Option C: 3,4-dimethylpent-3-ene** - This suggests a double bond at C3, which would mean that the longest chain is not correctly identified since it would not be the lowest number for the double bond. This option is weaker. - **Option D: 3,4-dimethylpentene** - This option does not specify the position of the double bond, making it ambiguous. It is incomplete and therefore not a valid IUPAC name. ### Conclusion The correct answer is **B: 2,3-dimethylpent-2-ene**. This name accurately describes a five-carbon chain with a double bond starting at the second carbon and two methyl groups on the second and third carbons. ### Revision Summary - The IUPAC naming system requires identifying the longest carbon chain and the position of double bonds. - Substituents must be named with their positions on the main chain. - The correct option must provide a clear and unambiguous description of the compound. - Always ensure that the numbering of the chain gives the lowest possible numbers for double bonds and substituents.