question in ochem - solvents

[batista_123]

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hey guys
which one is the better solvent to use for the addition of HCl to 3-hexene?
water
3-hexene

??

i think water, because it is polar, it will stabilize the carbocation. the solutions says water is bad, because it will compete as a nucleophile.
i am just confused because in every mcat prep book i have read, they always say the carbocation being stabilized by the solvent determines which solvent you choose, and they never said it might compete with the nucleophile, but on the other hand, i can understand how you dont want water to compete...so the question is how do you determine for SN2, SN1, E2, and E1, what is a good solvent?

 

[loveoforganic]

You'd just want to use a polar aprotic solvent, e.g. DMSO, DMF, HMPA, etc.

 

[vickpick]

polar aprotic is fine, though there is no need of a solvent, since HCL doesn't occur in liquid form unless aqueous...

 

[Bernoull]

You'd just want to use a polar aprotic solvent, e.g. DMSO, DMF, HMPA, etc.

I agree that a polar solvent stabilizes the reaction intermediate (carbocation) thus favoring the forward reaction, however water will hydrogen-bond to HCl stabilizing a reactant thus disfavoring the forward reaction therefore polar aprotic is better. MY CONFUSION is this, the question gave you two choices, water and 3-hexene and the latter is definitely nonpolar so to directly answer this question, between the two won't water be the lesser of two evils?

 

[vickpick]

this question is still buggin me.. r u sure, those were the only 2 options... lol.. i just made a hundred on my organic final (class average 54)... yet, here I sit confused at the what the answer choices could be..lol

 

[batista_123]

this question is still buggin me.. r u sure, those were the only 2 options... lol.. i just made a hundred on my organic final (class average 54)... yet, here I sit confused at the what the answer choices could be..lol

one was methanol, the other one i cant remember
but their answer, which is supposedly right, is hexene

 

[batista_123]

I agree that a polar solvent stabilizes the reaction intermediate (carbocation) thus favoring the forward reaction, however water will hydrogen-bond to HCl stabilizing a reactant thus disfavoring the forward reaction therefore polar aprotic is better. MY CONFUSION is this, the question gave you two choices, water and 3-hexene and the latter is definitely nonpolar so to directly answer this question, between the two won't water be the lesser of two evils?

maybe the book is wrong, i dont know