Identifying Preferred Reactivity in Organic Compounds

[scott_for_the_game]

In organic if you have more than one functional group.. how do you know which will react in preference?

In the attachment I've got an organic compound which has an ether and alcohol.

In terms of naming the alcohol gets preference.

It reacts with excess HI and the alcohol apparently doesn't react.. chemical changes occur with the ether..

 

[tandoorichicken]

my first reaction was that it should react with the alcohol... but if your text or teacher says it doesn't then...

my guess is that instead of looking at "functional groups" per se, try to understand the structure of the molecule. Both oxygens have free electrons but the ether O is farther out from the phenyl ring = less sterically hindered. So then the acid would protonate the ether O instead of the alcohol O. Then again, I could be completely wrong, but that's what makes sense.

 

[tandoorichicken]

Oh yeah, it won't react with the alcohol because if you protonate the alcohol O, you lose aromaticity in resonance. Since aromaticity is a strong driving force, the reaction with the alcohol O is not favored. Does that make sense?