SME
Organic Chemistry I · Problem type
SN2 rate: fastest to slowest
Use this for “Rank 2-bromopropane, bromomethane and bromoethane by how fast each reacts with iodide in acetone.”
Put in order
Order by SN2 rate with I⁻ in acetone, fastest first.
1
?
2
?
3
?
4
?
Assumptions
•
In SN2 the nucleophile reaches the carbon from the side opposite the leaving group, so groups on that carbon get in its way.
•
Each carbon group in place of an H on that carbon slows the attack many times over; a tertiary carbon is too crowded for SN2.
•
The leaving group (Br), the nucleophile (I⁻) and the solvent (acetone) are the same for all four, so only the crowding changes.
Topic check
See what you know: 5 questions on this topic
New questions each time. Pass to mark it complete.
Related lessons
Substitution and elimination
Main lesson
How the rate changes with [RX] and [Nu]
Use this for “In an SN2 reaction [RX] is halved and [Nu] is made 4 times larger. How does the rate change?”
Reading a two-step energy diagram
Use this for “Step 1 climbs 85 kJ/mol to a cation at 50 kJ/mol; step 2 climbs 15 more and ends at −30. Which step is slow, and what is ΔH?”