The following alkenes can be prepared by dehydration of an appropriate alcohol. Show the structure of the alcohol in each case that would provide the alkene shown as the major product.
e. 1,4-Pentadiene

Verified step by step guidance

1. Identify the alkene structure: 1,4-Pentadiene is a diene with double bonds between carbons 1 and 2, and between carbons 4 and 5.
2. Determine the corresponding alcohol: For each double bond in the alkene, consider the addition of an -OH group to one of the carbons involved in the double bond.
3. Consider the dehydration reaction: Dehydration of alcohols typically involves the removal of a water molecule (H2O), which means removing an -OH group and a hydrogen atom from adjacent carbon atoms to form a double bond.
4. Propose the alcohol structure: For 1,4-Pentadiene, propose an alcohol structure where the -OH groups are positioned such that their removal would result in the formation of the double bonds at the 1,2 and 4,5 positions.
5. Verify the major product: Ensure that the proposed alcohol, when dehydrated, would primarily yield 1,4-Pentadiene as the major product, considering factors like the stability of the resulting alkene.

Key Concepts

Dehydration Reaction

A dehydration reaction involves the removal of a water molecule from an alcohol, resulting in the formation of an alkene. This process typically requires an acid catalyst and can lead to the formation of multiple products, but the major product is determined by the stability of the resulting alkene, often following Zaitsev's rule.

Zaitsev's Rule

Zaitsev's rule states that in elimination reactions, the more substituted alkene is usually the major product. This principle helps predict the outcome of dehydration reactions, as more stable alkenes (those with greater substitution) are favored due to lower energy and increased stability.

Structure of Alkenes

Alkenes are hydrocarbons that contain at least one carbon-carbon double bond. The structure of an alkene, such as 1,4-pentadiene, is crucial for understanding its formation from alcohols. The positioning of the double bonds and the overall carbon skeleton influence the reactivity and properties of the alkene.