Oxazolines are five-membered heterocyclic compounds with one double bond. The double bond may be in one of three positions, so there may be three different oxazoline rings. The 2-oxazoline structure is the most common, and 3-oxazoline and 4-oxazoline exist mainly as laboratory research compounds. Oxazolines exist between oxazole and oxazolidine in terms of saturation.
Tetrahydrofuran is a heterocyclic organic compound with the molecular formula C4H8O. Tetrahydrofuran belongs to ethers and is the complete hydrogenation product of furan. It is a colorless, water-miscible organic liquid with small viscosity at normal temperature and pressure. Because of its long liquid range, it is a commonly used medium polar aprotic solvent. Its main use is as a precursor of high molecular polymers.