Is an intramolecular hydrogen bond possible in such compounds?
What are the requisites to have intramolecular hydrogen bonding?
Is this possible?
Probably not possible. An elementary explanation would be "too much ring strain."
I'm a bit confused: What are the requisites to occur a intramolecular hydrogen bonding?
5 and 6-membered rings are more favorable. As a matter of fact, beta-ketoacids, when warmed, readily decarboxylate. Why? The intermediate to decarboxylation is stabilized through hydrogen bonding.
Note the 6-membered ring in the picture below.
As the intramolecular H-bonding is absent in both cases.
In aqueous solution of carbonic acid is a weak acid. It dissociates into its constituent ions as carbonate ions and hydrogen ions. Now, the CO3-2 ion, is stabilized by resonance and produce three equivalent resonating structures.
This makes carbonate ion more stable rather than through intra molecular H-bonding. Now, I already said that carbonic acid is weak acid means all the molecules of carbonic acid are not dissociated. The molecules of carbonic acid which remain undissociated form inter-molecualr H-bonding with each other.
One thing that carbonic acid does not exist via intra-molecular H-bonding because, there is too much ring strain.
In gem-diols there are two -OH groups present on a single carbon. You can get detail reason that why intra-molecular H-bonding is absent in gem-diols.
There is a common example of gem-diol where intra molecular H-bonding is present is chloral hydrate.