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

We know that the solid phosphorus chloride and the phosphorus pentachloride react with each other violently with a group of alcohol at room temperature meanwhile producing a n number of clouds of hydrogen chloride gaseous. This is not the right process of producing chloroalkanes even though it's used for the test of $-OH$ group in all over organic chemistry.
Also to show that substance is an alcohol we must first need to eliminate all other thing which are also reacting with phosphorus chloride like, carboxylic acids which contains $-COOH$ group and reacts with is all because of $-OH$ in a $-COOH$ and so does this with water $H-OH$
Alcohols react with a liquid phosphorus of level III chloride and also called phosphorus trichloride in order to make chloroalkanes.

Complete answer:
The reaction with alcohol is given by:
$PC{{l}_{5}}\text{ }+\text{ }ROH\text{ }\to \text{ }O=PC{{l}_{3}}\text{ }+\text{ }RCl\text{ }+\text{ }HCl$
Similarly the reaction with acid is carried by:
$PC{{l}_{5}}\text{ }+\text{ }RC\left( =O \right)OH\text{ }\to \text{ }O=PC{{l}_{3}}\text{ }+\text{ }RC\left( =O \right)Cl\text{ }+\text{ }HCl$
Here phosphorus pentachloride is the only halogenating agent which is kind of rarely used around these days. Since there is another process required for the removal of pockle3 after the reaction tales place. $PC{{l}_{5}}$ is water sensitive which we all know but a little bit hard in handling. For better alternative of $PC{{l}_{5}}$ is thionyl chloride which we can pour in and out through a bottle and still can be distilled off and the reaction is given by:
$RC{{O}_{2}}H\text{ }+\text{ }SOC{{l}_{2}}\text{ }\xrightarrow{\Delta }\text{ }RC\left( =O \right)Cl\text{ }+\text{ }S{{O}_{2}}\uparrow \text{ }+\text{ }HCl\uparrow$

Note: Note that the phosphorus trichloride appears as colorless as well as a slightly yellow fuming liquid with a pungent and irritating odor resembling hydrochloric acid. Also this causes some severe burn to skin, eyes and other mucous membranes. Thus its a toxic by inhalation and by skin absorption. Also it reacts with water to evolve itself into hydrochloric acid an irritating and which in turn leads to corrosive gas apparent with burning white fumes and used for process during electrodeposition of metal on rubber.