Polar protic vs Polar aprotic solvent?

[vDDmaniaC]

Hi,
I just want to ask how are these two solvent play a role in the reaction. Polar protic is favored in SN1; aprotic in SN2. But what if in elimination reaction? As far as I am concerned protic solvent are something like alcohol OH: but why do we put the polar in front of these term?
Could you guys clarify about the protic and aprotic solvents for me?

Thanks!

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[Mrbubbles]

Hi,
I just want to ask how are these two solvent play a role in the reaction. Polar protic is favored in SN1; aprotic in SN2. But what if in elimination reaction? As far as I am concerned protic solvent are something like alcohol OH: but why do we put the polar in front of these term?
Could you guys clarify about the protic and aprotic solvents for me?

Thanks!

Protic solvents are those capable of donating H's, therefore are favorable in SN1 and E1 rxns because these rxns rate determing step is the formation of the carbocation. protic solvents will stabilize the carbocation state...
Aprotic solvents are those not capable of donating H's (acetone, DMSO)
therefore, it's favorable in SN2 and E2 because it's a 1step rxn...it doesn't want to form or have H's stabilize the Carbocation step...


now..when ti comes to chooseing SN1 vs. E1..that's a whole different story..Kaplan does a great job explaining when one is better than the other...