How Can You Determine If an Alkyloxonium Ion Will Lose Water Readily?

[chantella28]

I'm working on a number of problems that tells me to write the structure of the alkyloxonium ion produced after an alcohol is protonated by a strong acid

it says that if the alkyloxonium ion is capable of losing water readily, write the structure of the resulting carbocation and if the carbocation obtained is likely to undergo rearrangment write the structures of all new carbocations that could form

i don't have a problem with the protonation of the alcohols, or the rearrangments of a carbocation (it will rearrange to form increasingly stable compounds) but i don't know how to tell when an alkyloxonium ion is cabable of losing water readily... I'm thinking it might have something to do with the position of the water (1°, 2°, 3° carbon) and waters ability as a leaving group, but I'm not sure.

if somebody could give me some pointers on how to tell when it will rearrange, that would be great

 

[GCT]

yes, it has to do with the position of the water, that is the stability of the resulting carbocation as well as the transition state of the compound. If you have a particular case which you wish to work out, than feel free to post the problem.