Ethyl sulfate process in which ethylene is reacted with sulfuric acid to produce ethyl sulfate followed by hydrolysis, but this method has been mostly replaced by direct hydration of ethylene. Ethyl sulfate can be produced in a laboratory setting by reacting ethanol with sulfuric acid under a gentle boil, while keeping the reaction below 140 °C. The sulfuric acid must be added dropwise or the reaction must be actively cooled because the reaction itself is highly exothermic. If the temperature exceeds 140 °C, the ethyl sulfate product tends to react with residual ethanol starting material, producing diethyl ether. If the temperature exceeds
2-Ethyl-2-oxazoline ring-opening polymerization of 2-ethyl-2-oxazoline can be initiated by alkylation with e.g. methyl tosylate or triflates (in particular methyl triflate) and leads to the water-soluble poly(2-ethyl-2-oxazoline) which is a propionyl-substituted linear polyethylenimine and can also be seen as a pseudo-polypeptide. The polymerization of 2-ethyl-2-oxazoline can also be carried out as living cationic polymerization. Copolymers with other 2-alkyl-2-oxazolines and other monomers allow the preparation of random copolymers and block copolymers. The copolymers obtained can be used as biocompatible drug carriers, in coatings and adhesives, and in many other applications. The elimination of the propionyl group from poly (2-ethyl-2-oxazoline) yields linear polyethyleneimine. 2-Ethyl-2-oxazoline