Which substrate undergoes E1 reaction the slowest?

• A.
• B.
• C.
• D.

Answer: (D)

Verified step by step guidance

1. Step 1: Understand the E1 reaction mechanism. E1 reactions are unimolecular elimination reactions where the rate-determining step involves the formation of a carbocation intermediate.
2. Step 2: Identify the substrate structure. The substrate's ability to form a stable carbocation is crucial for the E1 reaction rate. Tertiary carbocations are more stable than secondary, which are more stable than primary.
3. Step 3: Analyze the provided structures. Look at the position of the bromine atom and the type of carbon it is attached to (primary, secondary, or tertiary).
4. Step 4: Consider the stability of the carbocation formed after the bromine leaves. The more substituted the carbon, the more stable the carbocation.
5. Step 5: Determine which substrate forms the least stable carbocation. The substrate that forms the least stable carbocation will undergo the E1 reaction the slowest.