Difference Between SN1 Reactions and SN2 Reactions

Main Difference

Organic chemistry is the compact field, full of simple to complex reactions which forms different organic compounds. On the basis of nucleophilic substitution reactions, SN1 and SN2 are two different types of reactions in the field of organic chemistry. SN1 represents the unimolecular reactions, it is also known as the first order reaction, where the reaction rate can be expressed as K [R-LG], on the other hand, SN2 represents the bimolecular reactions, where the reaction rate can be expressed as K’ [R-LG] [Nu]. The other difference between both these types of nucleophilic substitution reactions is that SN1 is a complex reaction as it is a multi-step process, whereas SN2 is a simple reaction as it is a single-step process. In SN1 reaction, substrate affects the reaction rate, whereas in SN2 reaction, both substrate and nucleophile affects the reaction rate.

Comparison Chart

SN1 ReactionSN2 Reaction
TypeSN1 represents the unimolecular reaction.SN2 represents the bimolecular reactions.
StepsSN1 is a complex reaction as it is a multi-step process.SN2 is a simple reaction as it is a single-step process.
FactorsIn SN1 reaction, substrate affects the reaction rate.In SN2 reaction, both substrate and nucleophile affects the reaction rate.
Reaction Rate expressionIn SN1 reaction rate can be expressed as K [R-LG].SN2 reaction rate can be expressed as K’ [R-LG] [Nu].

What is SN1 Reaction?

It is the type of nucleophilic substitution reaction that is a complex reaction process as it is a multi-step process. This type of reaction can be expressed as K [R-LG], means substrate directly affects the efficiency of this type of reaction. SN1 represents the unimolecular reactions, and with this two-step process a carbocation is initially being formed. It should be kept mentioned that in SN1 Reaction; carbocation stability is the key factor. As mentioned above SN1 is the two-step process that forms intermediate and several transition states as the reaction further proceeds. The intermediate state is more stable than the other transition stages as the stable carbocation is initially being formed in it. The SN1 reaction product can led to formation of racemic mixture.

What is SN2 Reaction?

It is the type of nucleophilic substitution reaction that is a single reaction as it is a single-step process. This type of reaction rate can be expressed as K’ [R-LG] [Nu]. In SN2 reaction, both substrate and nucleophile affects the reaction rate. SN2 represents bimolecular reaction, and it is a single step process. As SN1 reaction is the first order reaction, SN2 reaction is called the second order reaction. Other than SN2 and second order reaction, this type of reaction is also called “associative substitution” or “interchange mechanism.” in the field of organic chemistry. Two molecular species are involved with the rate determining step, which results to the happening of bimolecular nucleophilic substitution reaction or SN2. In SN2 type of reaction, two molecules are involved in the transition state.

SN1 vs. SN2 Reactions

  • SN1 represents the unimolecular reactions, whereas SN2 represents the bimolecular reactions.
  • SN1 is a complex reaction as it is a multi-step process, whereas SN2 is a simple reaction as it is a single-step process.
  • In SN1 reaction, substrate affects the reaction rate, whereas in SN2 reaction, both substrate and nucleophile affects the reaction rate.
  • In SN1 reaction rate can be expressed as K [R-LG], on the other hand, SN2 reaction rate can be expressed as K’ [R-LG] [Nu].

Comparison Video

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Harlon Moss

Harlon currently works as a quality moderator and content writer for Difference Wiki. He graduated from the University of California in 2010 with a degree in Computer Science. Follow him on Twitter @HarlonMoss

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