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Chemistry Homework Help => Organic Chemistry => Topic started by: Vinay on May 27, 2010, 09:53:36 AM

Title: Relative acidity of the most acidic hydrogen
Post by: Vinay on May 27, 2010, 09:53:36 AM
One more question for you please
What is the relative acidity of the most acidic hydrogen in each of the following:

Title: Re: Relative acidity of the most acidic hydrogen
Post by: uma on May 27, 2010, 10:04:54 AM
Acidity means looking at the stability of the conjugate bases, but first we should identify which atom is going to become negative by locating the most acidic H in each case. In i we have an alcohol OH, ii is also an alcohol, but with electronegative F atoms present and iii is an amine NH. So the negative charge will be on these heteroatoms. O is more electronegative than N meaning the O will stablise the anion more, so the alkoxide (from ROH) is more stable than the amide ion (from RNH2).   The F atoms in ii will stabilise the conjugate base due to the electron withdrawing nature of the electronegative F atoms.  So for the acidity,  ii > i > iii