[wings]

i really want to know ..

1 ) HSO3- is a nucleophile and halogeno compound is doing nucleophilic
     substitudion , can they react together ?? why ??

2 ) why ester can't hv reaction with any nucleophiles even it has C=OO ??

3 ) is iodoform test used to test the compound which functional group is near
     methyl group ?? if yes , why CH3COO- can't be tested ??

4) my teacher said aldehyde and ketone can't form hydrogen bond(H-B) in itself
   molecules, but it can form H-B in water.
   Why it can't form H-B even it has O and H inside it molecule ?

i really hope those qestioned can be solved ...
thanks everyone  :]

[azmanam]

Why it can't form H-B even it has O and H inside it molecule ?

you need a hydrogen bond donor and a hydrogen bond acceptor to have hydrogen bonding between two molecules.  Given two molecules of the same aldehyde, which part do you think would act as the hydrogen bond donor?  which part do you think would act as the hydrogen bond acceptor?

[macman104]

2)  Esters can definitely react with nucleophiles.  If your teacher told you this, they're either wrong or there's something else to their explanation that you didn't mention.

3)  Iodoform is used to test for methyl groups that are attached to a ketone or aldehyde functional group.  Read this here for the discussion about the scope of the iodoform test.

I don't understand your first question though.