Propose a mechanism for each reaction, showing explicitly how the observed mixtures of products are formed.
(e) 3-chlorobut-1-ene + AgNO₃, H₂O → but-2-en-1-ol + but-3-en-2-ol

Verified step by step guidance

1. Step 1: Recognize the reaction type. This is a nucleophilic substitution reaction where the AgNO3 in aqueous solution facilitates the removal of the chloride ion (Cl⁻) from 3-chlorobut-1-ene, forming a carbocation intermediate.
2. Step 2: Identify the carbocation intermediate. When the chloride ion leaves, a primary carbocation is initially formed at the 3rd carbon. However, due to carbocation rearrangement, a more stable secondary carbocation is formed at the 2nd carbon via a hydride shift.
3. Step 3: Consider the nucleophile. Water (H₂O) acts as the nucleophile in this reaction, attacking the carbocation to form an alcohol. The attack can occur at either the 2nd carbon or the 3rd carbon, leading to the formation of two different alcohol products.
4. Step 4: Analyze the stereochemistry and regioselectivity. The attack of water on the carbocation can lead to the formation of but-2-en-1-ol (if water attacks the 2nd carbon) or but-3-en-2-ol (if water attacks the 3rd carbon). Both products are formed due to the possibility of attack at different positions.
5. Step 5: Summarize the mechanism. The reaction proceeds via the formation of a carbocation intermediate, followed by nucleophilic attack by water, resulting in a mixture of alcohol products: but-2-en-1-ol and but-3-en-2-ol.

Key Concepts

Electrophilic Addition Reactions

Electrophilic addition reactions involve the addition of an electrophile to a nucleophile, typically occurring in alkenes. In this case, 3-chlorobut-1-ene acts as the nucleophile, while AgNO3 provides the electrophilic silver ion. Understanding this mechanism is crucial for predicting how the double bond in the alkene will react with the electrophile, leading to the formation of various products.

Regioselectivity

Regioselectivity refers to the preference of a chemical reaction to yield one structural isomer over others when multiple products are possible. In the reaction of 3-chlorobut-1-ene with AgNO3, the formation of but-2-en-1-ol and but-3-en-2-ol illustrates regioselectivity, as the addition of the nucleophile can occur at different positions, leading to distinct products based on the stability of the resulting carbocations.

Carbocation Stability

Carbocation stability is a key factor in determining the outcome of reactions involving alkenes. More stable carbocations, such as tertiary or secondary, are favored during the reaction process. In this case, the formation of but-2-en-1-ol and but-3-en-2-ol can be explained by the stability of the intermediate carbocations formed during the electrophilic addition, influencing the final product distribution.