[thenuttyprofessor]

if i'm arranging in the order of increasing acidity:

       a                   b                   c

                                                        +
CH3-O-CH3,    CH3-NH-CH3,   CH3-O-CH3   (plus charge on oxygen)
                                                 l
                                                H

the book has in order of c,b,a.  but i thought acidity increased from left to right so i had them in the reverse order.  does answer c having a positive charge change the order of acidity???  also isn't o more acidic than n.  i don't understand.

[beheada]

if i'm arranging in the order of increasing acidity:

       a                   b                   c

                                                        +
CH3-O-CH3,    CH3-NH-CH3,   CH3-O-CH3   (plus charge on oxygen)
                                                 l
                                                H

the book has in order of c,b,a.  but i thought acidity increased from left to right so i had them in the reverse order.  does answer c having a positive charge change the order of acidity???  also isn't o more acidic than n.  i don't understand.

Well, oxygen is definitely more electronegative than nitrogen, but acidity is due to specific factors. If we think of the defition of a good acid as being a compound which easily donates a proton, which of these compounds do you think would have the easiest time losing a proton? Think about what the compound will look like and it's relative stability after it has been deprotonated.

Hope that helps.
.rayfe

[lemonoman]

You highlighted the word increasing ... so my guess is that really, you're just asking if it's right or not.

Long story short, if the book asked you for increasing acidity, and said the answer was c,b,a ... it's wrong.

Beheada's logic is right, and are the steps to follow if you are indeed having trouble.

[thenuttyprofessor]

ok thanks beaheado and lemonoman!!!   

[english]

I disagree.  The protonated oxygen should be more acidic than the amine.

(The hydrogen is under the oxygen, it just screwed up)