2-Ethyl-2-oxazoline oxazolines towards ring-opening by chloride ions during protonation of the imine nitrogen. The direct reaction of propanoyl chloride with 2-chloroethylamine hydrochloride in the presence of triethylamine avoids the formation of water. Propanal reacts with 2-aminoethanol in "t"-butanol to 2-ethyl-2-oxazoline in the presence of the iodinating reagent 1,3-diiodo-5,5-dimethylhydantoin (DIH) and potassium carbonate. 2-Ethyl-2-oxazoline is a readily water-soluble, colorless liquid which is also soluble in a variety of organic solvents and possesses an amine-like smell. Aqueous solutions react alkaline. The compound is stable in alkaline but hydrolyses under acid action. In anhydrous form, 2-ethyl-2-oxazoline is mostly used as a monomer. The cationic
2-Ethyl-2-oxazoline one-pot reaction propionic acid is converted first with 2-aminoethanol to 2-hydroxyethylamide, than reacted with boric acid at 130 °C yielding a boric acid ester which is finally thermolyzed at 280 °C in 92% yield to 2-ethyl-2-oxazoline. From propionic acid and thionyl chloride can be obtained propanoyl chloride, which reacts with ethanolamine in the presence of an acid scavenger (for example pyridine) to N-propionyl-2-aminoethanol. With further thionyl chloride this reacts further to 2-chloroethylamide. With the chloride ion as a better leaving group, this intermediate is cyclized by simple heating to the oxazoline. Water must be excluded du to the tendency of