The heat of hydrogenation of 1-hexene is 126kj/mol. When a second double bond is introduced in the molecule, the heat of hydrogenation of the resulting compound is 230kj/mol. What is the resulting diene compound.

To determine the resulting diene compound from the heat of hydrogenation data provided, we first need to understand what hydrogenation is and how it relates to the structure of alkenes and dienes. Hydrogenation is the process of adding hydrogen (H2) across double bonds in unsaturated hydrocarbons, which converts alkenes into alkanes. The heat of hydrogenation gives us insight into the stability of the compounds involved.

Analyzing the Heat of Hydrogenation

The heat of hydrogenation indicates how much energy is released when hydrogen is added to a compound. In your case, the heat of hydrogenation for 1-hexene is 126 kJ/mol. This value reflects the energy associated with breaking the double bond in 1-hexene to form hexane, a saturated compound.

When a second double bond is introduced, the heat of hydrogenation increases to 230 kJ/mol. This increase suggests that the resulting compound is less stable than 1-hexene, which is typical for compounds with multiple double bonds.

Identifying the Diene Structure

1-hexene has the following structure:

• CH2=CH-CH2-CH2-CH2-CH3

When we introduce a second double bond, we can form a diene. The two most common types of dienes are conjugated and non-conjugated. However, given the increase in heat of hydrogenation, we can infer that the diene is likely non-conjugated, as conjugated systems tend to be more stable and would have a lower heat of hydrogenation.

One possible structure for the diene could be 1,4-hexadiene, which has the following structure:

• CH2=CH-CH2-CH=CH-CH3

This diene has two double bonds located at the first and fourth carbon atoms. The heat of hydrogenation for 1,4-hexadiene would indeed be higher than that of 1-hexene due to the presence of the additional double bond, which is less stable than a single double bond.

Conclusion on the Resulting Diene

Based on the heat of hydrogenation values provided, the resulting diene compound is likely 1,4-hexadiene. This compound has two double bonds, and the increase in heat of hydrogenation reflects the additional energy required to break these bonds compared to 1-hexene. Understanding these concepts helps us appreciate the relationship between molecular structure and stability in organic compounds.