Why??

the process of conversion of carbonyl form into enol form is called wnoliation. and the ease of conversion of carbonyl into enol is called enolisability.

is it always the case in general??

i think it depends ...

pls correct me if i am wrong...

as the acidic nature of α- hydrogen increases enolisability increases.

and in many aldehydes the enolisability is very less. this is because in most of the cases to the α- hydrogen an alkyl group is attached which is an electyron withdrawing group.

hence it decreases the acidity of the α-hydrogen thereby decreasing the enolisability.

therefore stability of enol form is veryy less.

Sorry .....I cant understand .......[2]

Can u explain in simpler words first rather than conventional scientific language....plzzzz[2]

i am sorry dude, thats the best way i could have explained.

so in chem everything wanna attain more stability ..since C=O is more stable than C=C in general cases..so keto form is more stable than enol...
Now this becomes a question for others why C=O is more stable than C=C ??

@govind, something to do with orbital delocalisation and MO theory?

@Pritish
Plz explain abt that orbital delocalistion.....
but the reason i know abt this phenomenon is somewhat different..

For all those ppl who wanna the answer of the abv question can see the thread started by subhomoy..
http://www.targetiit.com/iit-jee-forum/posts/old-thread-was-unsolved-14822.html