SN1 Reaction vs. SN2 Reaction- 11 Key Differences

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SN1 reaction of a two-step reaction mechanism. In which the formation of carbocation takes place before the nucleophile approaches the substrate. Generally, secondary and tertiary haloalkanes show SN1 reactions.

The SN2 reaction is a concerted reaction in which the attack of a nucleophile on the substrate and the departure of the leaving group occur simultaneously. Primary haloalkanes usually display such reactions.

SN1 Reaction vs. SN2 Reaction
SN1 Reaction vs. SN2 Reaction

SN1 and SN2 reactions have different reaction mechanisms. They go through the cation formation step or transition state to produce a product with a different configuration. The key differences between SN1 and SN2 reactions are as follow:

S.N.SN1 ReactionSN2 Reaction
1.It follows first-order kinetics.It follows second-order kinetics.
2. It is a two-step reaction process.It is a one-step reaction process.
3.The rate of reaction depends on the concentration of substrate only.The rate of reaction depends on the concentration of both substrate and nucleophile.
4.The nucleophile can attack from either side, but the product from the backside attack predominates.The nucleophile attacks from the back exclusively.
5.The rearrangement of carbocation occurs.Rearrangement products are not possible.
6.The reactivity order of alkylhalides is CH3X < 10 < 20 < 30 .The reactivity order of alkylhalides is CH3X > 10 > 20 > 30 .
7.An elimination product is formed due to a side reaction.No side reaction occurs.
8. Mainly electronic factors influence the rate of reaction.Steric factors influence the rate of reaction.
9.Partial racemized product is formed.Complete stereochemical inversion takes place.
10.Mild nucleophiles ( e.g., alcohol, water) generally favor SN1 reaction.Strong nucleophiles ( e.g., alkoxide) generally favor SN2 reactions.
11.Solvents of high polarity favor the SN1 reaction.Solvents of low polarity favor SN2 reaction.

References

  1. March, J. (1992). Advanced organic chemistry: Reactions, mechanisms, and structure. New York: John Wiley & Sons.
  2. Peter sykes, A Guide Book to Mechanisms in organic chemistry, (6th edition) Pearson.
  3. https://chemicalnote.com/sn1-and-sn2-reaction-kinetics-mechanism-stereochemistry-and-reactivity/
  4. https://www.vedantu.com/chemistry/difference-between-sn1-and-sn2
  5. https://byjus.com/chemistry/difference-between-sn1-and-sn2/
  6. https://unacademy.com/content/jee/difference-between/sn1-and-sn2/

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Kabita Sharma

Kabita Sharma is a Ph.D. student in the Department of Chemistry at the University of North Texas, USA. Her research focuses on understanding protein degradation mediated by PROTAC (Proteolysis-Targeting Chimera) molecules and on exploring their potential for targeted protein degradation to treat diseases such as cancer. Through this work, she aims to advance drug discovery by targeting previously inaccessible or undruggable sites where PROTAC molecules can operate effectively. Additionally, she is analyzing how the buried surface area of proteins affects their binding and unbinding affinities. Using computational tools, she explores the challenges of removing one infected protein from another during treatment. Driven by a passion for solving complex scientific challenges, Kabita uses her knowledge in chemistry, chemical biology, and computational tools to advance her research. Beyond her academic pursuits, she aspires to inspire others toward science and its wonders through writing and sharing her knowledge.

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