In the distillation of petroleum spirit, what property is exploited to separate the different components of the spirit?

1 Answer
Mar 22, 2017

Answer:

#"The differential volatility of its components............?"#

Explanation:

Typically crude oil is distilled on a fractionating tower, and the volatile components are separated by boiling point; and the boiling points often corresponds (roughly) to chain length.

When we use petroleum ether in the laboratory, typically, we use #40# #""^@C-60# #""^@C# boiling point pet ether, #60# #""^@C-80# #""^@C# boiling point pet ether, #100# #""^@C-120# #""^@C# boiling point pet ether. The lower boiling pet ethers are the isomeric #C4-C5# alkanes and olefins, #60# #""^@C-80# #""^@C# boiling point pet ethers are the isomeric #C6-C7# alkanes and olefins.

An inorganic chemist will often take petroleum ethers from a supplier, and treat this with acidified, aqueous #KMnO_4# over an extended period (so as to oxidize any olefinic component). After 24-48 hours, the pet ether would be separated, carefully washed with fresh water, and then VERY carefully dried. The petroleum ether would then be used as #"olefin-free petroleum ether"# for the synthesis of certain metal complexes.