Sn1

[crazyasian]

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So i'm working on a TPHR problem and it says the best solvent for the addition of HCl to 3-hexene is 3-hexene (over H2O, CH3OH, CH3CO2H) because it is not nucleophilic. My question is whether or not I treat a H-X addition like a SN1. If I treat it as an SN1 isn't the best solvent a protic solvent that will stabilize the carbocation intermediate by forming H bonds?

 

[PiBond]

this is different from an Sn1 reaction. In Sn1 we have a leaving group that peaces out first while in this situation we have a pi-bond acting as a nucleophile and taking the hydrogen from HCl. both are forming a carbocation intermediate but the mechanism and scenario are different.

i'm assuming we're trying to make an alkyl halide so we want to limit the potential of side reactions. we're going to want to pick a solvent that facilitates this by having no nucleophilic properties. H20 can act as a nucleophile (as we see in a halohydrin formation) as can methanol. the pi bond would potentially take off the hydrogen in the acetic acid and thus turn in into a nucleophile as well. thus we're left with 3-hexene

 

[crazyasian]

Wow I can't believe I just focused on the carbocation intermediate. Now that i'm thinking about the mechanism I'm realizing how simple it is. Thanks for pointing that out.

 

[Hemichordate]

Just curious, but what are some common solvents for SN1 and SN2 reactions?

 

[PiBond]

Just curious, but what are some common solvents for SN1 and SN2 reactions?

Sn2 is favored with polar aprotic solvents like acetone or DMF

Sn1 is favored with polar protic solvents like water

 

[Hemichordate]

Sn2 is favored with polar aprotic solvents like acetone or DMF

Sn1 is favored with polar protic solvents like water

Thanks👍