secondary alcohol substrates

[bluekade5050]

Just recently took a quiz and one of the problems that got to me was this

The following are involved in reactions that produce halides from secondary alcohol substrates , EXCEPT:

		pyridine
		PBr3
		SOCl2
		HBr   I got the problem wrong but was wondering what is the true answer.......

[hypervalent_iodine]

Have you considered the structures of all of the options? You’ll notice that one of them is missing a crucial aspect that the others all have if you do this.

[BabcockHall]

I might be tempted to quibble a bit with the answer, because even the one substance that is clearly unlike the others is sometimes used as a solvent in one reaction.