In each pair, which would you expect to have the higher melting point?
(a)

Verified step by step guidance

1. Step 1: Analyze the molecular structures of the two compounds. The first compound has a bulky tert-butyl group attached to a cyclohexane ring, while the second compound has a linear alkyl chain attached to a cyclohexane ring.
2. Step 2: Consider the impact of molecular symmetry and packing efficiency on melting point. Molecules with higher symmetry and better packing tend to have higher melting points.
3. Step 3: Evaluate the steric hindrance caused by the bulky tert-butyl group in the first compound. This group disrupts the packing efficiency, making it harder for the molecules to form a solid lattice.
4. Step 4: Compare the linear alkyl chain in the second compound. Linear chains generally allow for better packing in the solid state, leading to a higher melting point.
5. Step 5: Conclude that the second compound, with the linear alkyl chain, is expected to have a higher melting point due to its better packing efficiency compared to the first compound with the bulky tert-butyl group.

Key Concepts

Melting Point

The melting point of a substance is the temperature at which it transitions from a solid to a liquid. It is influenced by the strength of intermolecular forces present in the substance. Generally, compounds with stronger intermolecular forces, such as hydrogen bonds or ionic interactions, exhibit higher melting points compared to those with weaker forces like van der Waals interactions.

Structural Isomerism

Structural isomerism occurs when compounds have the same molecular formula but different structural arrangements of atoms. This can lead to variations in physical properties, including melting points. In the given question, the two compounds are structural isomers, and their differing structures can significantly affect their melting points due to variations in packing efficiency and intermolecular interactions.

Steric Hindrance

Steric hindrance refers to the repulsion between atoms that occurs when they are brought close together, often due to the size of the groups attached to them. In organic compounds, increased steric hindrance can lead to less efficient packing in the solid state, which typically results in lower melting points. Understanding the steric effects in the given compounds is crucial for predicting their melting point behavior.