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Alkylhalides: Substitution reactions 5 (Sn1)


Alkylhalides: Substitution

Nucleophile substitution reaction (Sn1 reaction)

Solvent effects
To start off, have a look on the rate determing step of the Sn1 reaction, what happens with the compound becoming split into 2 ions:



The dielectric constant is a measure on how the solvent insulates the opposite charges from eachother. F.e. water will either contain the positive charged ion by using its partial negative oxygen, and it will contain the negative charged ion by using its partial positive hydrogen, thus separating both ions from eachother. A visual picture below from the Organic Chemistry book from Bruice found below to clear this up, on the left side the negative ion gets contained, on the right side the positive ion. 



Relative rates of water and ethanol solvents are the following:

100% water    1200

80% water / 20% ethanol   400
50% water / 50% water   60
100% ethanol   10


In the next blog post it will be the last one of the chapter of Substitution reactions, finally! 

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