Question

How would you expect phosphorus pentachloride to react with ethanol? How does this reaction resemble the reaction of phosphorus pentachloride with ethanoic acid?

Answer 1

With alcohol:
`PCl_5+ROH rarr O=PCl_3 + RCl + HCl`

Explanation:

With acid:

`PCl_5+RC(=O)OH rarr O=PCl_3 + RC(=O)Cl + HCl`

`"Phosphorus pentachloride"` is a halogenating agent. It is rarely used these days, as you have to remove the `"pockle3"` after the reaction. `PCl_5` is very water sensitive, and a bit hard to handle. A better alternative might be `"thionyl chloride"`, which you can pour out of a bottle and distill off:

`RCO_2H + SOCl_2 + Delta rarr RC(=O)Cl + SO_2uarr + HCluarr`