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Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: saint_john on September 24, 2010, 01:01:37 AM

Title: What makes a ketone more acidic than an alkane??
Post by: saint_john on September 24, 2010, 01:01:37 AM

in terms of pKa, the ketone has a much smaller pKa than a regular alkane.

Can someone please explain the difference in the acidities of a ketone and an alkane !
 
Thanks !

Title: Re: What makes a ketone more acidic than an alkane??
Post by: Dan on September 24, 2010, 03:49:28 AM

http://en.wikipedia.org/wiki/Ketone#Acidity_of_ketones

Title: Re: What makes a ketone more acidic than an alkane??
Post by: rohit on October 02, 2010, 01:09:53 AM

the ketone contains c=o bond where c+ and 0- partial charge is there and the bond is essentially a 1 and a half bond in resonance and hence the hydrogen is loosely attached as the c adjacent to c=o is -ve  and hence removing h as h+ is easy whereas alkanes are nonpolar and no such way of removing h.thus ketones are more acidic.remember  ease of removing h as h+ is condition for acidity.

Title: Re: What makes a ketone more acidic than an alkane??
Post by: james_a on October 02, 2010, 03:44:06 AM

Quote from: saint_john on September 24, 2010, 01:01:37 AM

in terms of pKa, the ketone has a much smaller pKa than a regular alkane.

Can someone please explain the difference in the acidities of a ketone and an alkane !
 
Thanks !

2 important factors - #1 - electron-withdrawing effect of ketone. #2 - stabilization of conjugate base by resonance.

http://masterorganicchemistry.wordpress.com/2010/09/22/five-key-factors-that-influence-acidity/