[dsk123]

when cyclohexanol bonds does a substitution reaction with PBr3, why does a Br atom remove from the chain? Doesn't phosphorus make 5 bonds in total?

Another question is how does the detachment of the H atom gets the oxygen to become neutral charge? Lastly, how does Nitrogen from the pyridine take the H atom if Nitrogen is already bonded to 3 pairs in the pyridine?

Thank you for answering.

[Babcock_Hall]

It is a forum rule that you must provide your attempt to answer before we can help you.  I will try to get you started, however.  It is important to distinguish between a hydrogen atom and a proton.  The rules that you learned about formal charges on atoms are valuable in deciding which atoms have positive charges, which have negative charges, and which are neutral.