[dorratz]

Hey

I got a question about the picture here:


Why does the OH group doesn't go another protonation and leaving of a water molecule in the end, just like it can be happen during E1 reactin after protonation.

Thanks
Dor

[AWK]

_{Why does the OH group doesn't go another protonation and leaving of a water molecule}
it does, but elimination of water is easy only from tertiary alcohols (draw mechanism for 2,2,5,5-tetramethyltetrahydrofuran)

[dorratz]

I got you.

Thanks a lot!

[Vidya]

Why does the OH group doesn't go another protonation and leaving of a water molecule in the end, just like it can be happen during E1 reactin after protonation.

Thanks
Dor

You already has one positive charge on the chain after first protonation ..do you think molecule is ready to undergo for one more positive charge which is very unstable primary carbocation.

[orgopete]

For a student, that is a good question as it you may find the same conditions listed for the dehydration of 1-butanol, a common student lab experiment. Furthermore, the reaction conditions are also a key predicting the product. I'm guessing heating will result in elimination and low temperature will favor re-cyclization to the starting material. A factor favoring elimination of the alcohol would include the amount of sulfuric acid. Conc sulfuric acid is a good dehydrating agent. Loss of water will dilute the sulfuric acid, hence higher concentration will increase elimination. This would be difficult to know simply from a listing of the reagent.