Tetrahydrofuran(THF) is a colorless, volatile, flammable, pleasant-smelling liquid with low viscosity and a bp of 64°C. It is one of  the most polar cyclic ethers. THF should not be distilled to dryness because it leaves a residue of high explosive  peroxides. The 1 H NMR spectrum in CCl4  showed two peaks at δ 3.61 ppm for C2 –H and C5 –H, while a peak at δ 1.79 ppm is  designated for C3 –H and C4 –H protons. The 13C NMR showed two peaks at δ 68.60 ppm for C2  and C5 , while a peak at δ 26.20 ppm was assigned for C3 and C4.

Chemical Reactivity 

OXIDATION 

Tetrahydrofuran reacts readily with oxygen to form hydroperoxide and thereafter is transformed to peroxides. The formation of  peroxide can be inhibited by addition of certain stabilizers such as 3,5-di-tert-butyl-4-hydroxytoluene.

METALATION 

Like furan, THF is also lithiated with n-butyllithium to give 2-lithiotetrahydrofuran, 

which finally undergoes cycloreversion generating ethylene and acetaldehyde lithium enolate. 

Ring-Opening 

Reaction Ring opening of THF by magnesium bromide and acetic anhydride in acetonitrile has been reported285 to yield  methyl 5-bromopentanoate.